Alaska Sandhill Crane Blog

Best books - Sandhill Cranes in the Great Plains and elsewhere

2011-03-15T17:36:00.793-08:00

BOOK REVIEW:
Sandhill and Whooping Cranes: Ancient Voices over America's Wetlands by Paul A. Johnsgard. Bison Books of the University of Nebraska Press [published 2011] and

On Ancient Wings: the Sandhill Cranes of North America by Michael Forsberg [published 2004]

The spring staging of Sandhill Cranes in the shallows of the Platte River in Nebraska ranks among the great mass migratory events on the globe.

Paul Johnsgard provides an overview of the status for Sandhill and Whooping Cranes that updates his classic Crane Music [1991].
The prose is consistently graceful and the illustrations both meticulously accurate and artistically delightful. The first three chapters of this book are status reports on "Lesser Sandhills", "The Other Sandhills", and "Whooping Cranes". Each blends history and biology, spiced with personal observations. Paul imbues the descriptions with awe and respect for these magnificent birds.

Lesser Sandhill Cranes endured the depredations of 19th century market and sport hunting and now the Platte collects 400,000 to 500,000 birds every March. Nonetheless, these cranes are still under some threat, from hunting pressure during the winter in Texas, from atrophy of the Platte due to agricultural irrigation, and from competition for food from thousands of resident Canada Geese and millions of migratory Snow Geese that arrive in Nebraska a few weeks earlier.

The mid-continent crane populations have a hourglass-shaped migration pattern. In late February and March, they converge on the Platte from wintering sites spread from western New Mexico and northern Mexico to the Gulf Coast of Texas. Once in the spring fueling mode in Nebraska, the cranes spend weeks of day-times converting waste corn from the surrounding fields into fat to store for the second major leg of their migration. Every night, they return to dodge the powerlines and touch down in cacophonous cascades until they can roost, huddled in swirling transient clusters in the shallows of the river.

On a warm March day with rising thermals, groups of birds spiral gently upward and splay out to the north, finally ending their journeys at higher latitudes from Hudson Bay to Siberia. As they near their traditional nesting territories, ponds and marshes are still icy. Within 3-4 months, the crane colts are fledged and as temperatures dip below freezing again and families start a long more leisurely journey south.

The Other Sandhills are a collection of populations or races that are rather like clans of nomadic people. The birds differ somewhat in size (weight, wing-spread, bill-length, etc.) but are mostly distinguished by migration geography. Some (technically Lessers) migrate from nesting grounds in southwest Alaska to California, others (technically Greaters) from Idaho to New Mexico or (the Great Lakes population) from Michigan to Florida. These migratory patterns probably reflect the distinct cultures of each population that are passed year-by-year from experienced birds to younger ones as they travel together.

Some Other Sandhill populations (subspecies?) are non-migratory. The resident cranes in Florida grasslands, suburbs, and shopping centers overlap with migrants from Michigan in winter months. The more remote groups in Mississippi and Cuba remain threatened and isolated. A tiny population of these long-lived birds has persisted for many decades on a National Wildlife Refuge in Mississippi, often with yearly infusions of new colts hatched in captivity.

The stature and majesty of Whooping Cranes and their plumage captivates almost everyone who sees them. During the early years of the 20^th century, pressure from the millinery markets of sophisticates decimated their populations. In 1937, the establishment of the Port Aransas National Wildlife Refuge on the Gulf coast of Texas preserved a dedicated wintering ground, albeit precariously close to heavy commercial barge traffic on an intercoastal waterway. Occasional illegal harvesting persisted, but somehow numbers held steady at a few dozen adults until the remote nesting ground for the Port Aransas flock was discovered in Canada twenty years later. Conservation efforts in Texas and Alberta and appeals to reduce hunting have paid off such that 263 cranes started from Texas on their journey toward Canada in 2010, along the path depicted in Johnsgard's map to the left. Continued vigilance and monitoring of the individual birds each year must remain a high priority.

Many well-publicized efforts have been devoted to establishing other Whooping Crane populations. These include a failed attempt to cross-foster Whoopers with Sandhill parents in Idaho that started well but faltered, and a multi-year struggle, that was ultimately abandoned, to create a resident population in Florida. As of 2009, the 22 surviving Whooping Cranes from this flock are being protected and monitored.

Still ongoing is Operation Migration, an entrancing project of a non-profit corporation working with the International Crane Foundation and the USGS in Patuxent (MD). Operation Migration nurtures hatchlings chicks at the ICF in Wisconsin and then teaches the young colts to migrate in the fall by following an ultralight airplane to Florida and returning in the spring, led by the ultralight back to Wisconsin. This flashy project seems to be working as some of the the returning Whooping Cranes are making nests in Wisconsin. The next critical landmarks are sustained nesting in the wild, fledging of significant numbers of colts, and independent migration (without an ultralight leader) to Florida.

Very recently, there is a new attempt to establish another resident population, this time in Louisiana. It will be many decades before we will know if any of these investments yield self-sustaining populations.

Like Sandhills, Texas Whooping Cranes migrate through Kansas, Nebraska, and the Dakotas, but they travel in small groups in the late spring. Cranes are particularly vulnerable during these long migrations. The impacts of changing fashions in agricultural economics, pressure for increased biofuel production, and drought cycles which may be exacerbated by global climate change, are some of the factors that menace crane stopover sites, of which the most important is the Platte River valley.

The Appendix of Johnsgard's s slim, information-packed volume tells the reader exactly when and where to find cranes in 34 states and provinces of the US and Canada. It is very helpful to have one list of these unheralded habitats where cranes can be observed by carefully scheduling a visit.

Mike Forsberg may be best-known for his stunning images of fauna, flora, and scenery of the Great Plains. He is a keen observer and careful student of natural history, an avid conservationist, and a lucid writer. On Ancient Wings grew from several years of watching and photographing different populations of cranes.

On Ancient Wings is a series of vignettes of cranes in the wild, as Mike traveled from Alaska to Mexico, across to Florida and down to Cuba.

The informative text is enhanced by Mike's striking photographs of the cranes, their behavior, the neighboring animals and plants, and the landscapes. The images almost overpower the narrative that likewise deserves very careful study. Mike introduces the reader to the local culture and the people who study and protect the cranes. Each crane population is unique and Mike's journal entries provide great local flavor.

Although Mike Forsberg started as a still photographer, more recently he has become skilled with video as well. His talent was showcased a few years ago in a NET (Nebraska Educational Television) video production for On Ancient Wings.

For a lyrical introduction to Mike's skills, view the recent Flash video promoting his upcoming NET production on the Great Plains - America's lingering wild or visit his exhibition in April 2011 at the National Museum of Wildlife Art in Great Falls, Montana.

Great Plains promo - NET Nebraska and Michael Forsberg from Michael FORSBERG on Vimeo.

Johnsgard's Sandhill and Whooping Cranes and Forsberg's On Ancient Wings very nicely complement one another. Both have a mix of the big picture and specificity, and each offers an informed original perspective on cranes and their biologies. Royalties from these books go to the Rowe Audubon Sanctuary, a craniac's mecca a few miles east of Kearney, Nebraska.

Cranes may sniff aphrodiasiacs

2010-10-09T18:15:00.240-08:00

Do cranes emit and perceive sex pheromones?

Personal perspective

In 1958, one of the Blogauthors (George) chose Cornell University for graduate study in bird behavior and animal communication. I was intrigued by three kinds of signals:

Sounds - Birds and insects have rich repertoires of chirps, songs, and buzzes.
Visual displays - Birds present feathery dynamic postures and insects flash markings on their wings.
Scents - In 1958, clever chemists used new technologies like gas chromatography to isolate pheromones¹ and defensive secretions². Scientists were astonished to discover that a single substance could trigger a whole chain of behaviors in insects.

Chemical signaling was the emerging field, but searching for avian pheromones appeared to hold little promise. Pierre Grassé's Traité de Zoologie³, the zoologist's Bible of that era, stated that most birds are anosmic, without a robust sense of smell.

Thus I opted to do my doctoral thesis on insects when I changed advisers in 1959.

What a difference a half-century makes!

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What data argue that birds use pheromones?

In 1959, we knew:

1. Birds have well-developed exocrine glands, including uropygial glands at the base of the tail, anal glands, salt glands, and ear glands, most of which produce greasy odorous mixtures.

2. Birds spread these secretions upon their feathers when they preen.

In 2010, we also know:

3. Exocrine secretions, especially those from the uropygial glands, vary according to age, species, season of the year, and hormonal state^4-10.

4. Birds are far from anosmic. Bird brains "have the right stuff" to distinguish odors.

Birds have nostrils, olfactory cavities, and olfactory neurons that are anatomically like those of mammals. Olfactory information flows to well-developed brain centers that include the piriform cortex, amygdala, and entorhinal cortex^32,33, parts of the brain that are associated with emotion. As theropod dinosaur descendants gave rise to birds (see How birds think blog, 9-Feb-2011), the olfactory bulb became larger³¹, suggesting increasing importance of the sense of smell to the life styles of birds.
Olfactory receptor (OR) genes encode proteins that are embedded in the surfaces of olfactory neurons and can discriminate among odorous molecules. Silke Steiger in Starnberg Germany^10-12 showed that birds have hundreds of OR genes, comparable in diversity to mammal ORs. The fact that one large gene clade, termed γ-c, is expanded across the class Aves, argues for the importance of olfaction for many birds.
In the last decade, there has been wholesale rethinking about bird brain architecture¹³. The superficial appearance of the brain differs between birds and mammals, but the contrasts are mostly due to topological shuffling of neuron clusters and centers. Birds have sophisticated information processing capacity.

5. Birds use their sense of smell, for example: to find food, to distinguish individuals from one another, to recognize nest sites (petrels), and for many other purposes⁵. Three notable examples involve mating.

Since 1979, Jacques Balthazart and others at the University of Leige in Belgium have been convincingly pleading the case for duck sex pheromones from the uropygial glands, starting with their classic paper demonstrating hormonal control of secretion¹⁴.
Male chickens (roosters) court with a sequence of behaviors: first waltzing, then mounting, and finally copulating. Hirao and colleagues (2009) surgically excised uropygial glands of female chickens and then placed roosters with either intact or "glandectomized" females. Roosters waltzed equally with both groups of hens, but they mounted and copulated significantly more often with intact hens. Surgically anosmic roosters couldn't tell the difference¹⁵.
Tobias Krause and his colleagues at Bielefeld University in Germany recently reported that a songbird can recognize kin by smell. The experimental data clearly demonstrate that zebra finch chicks fostered at 2 days of age into unrelated broods prefer the odor of their hatch-nest over that of the foster-nest³⁴.

6. In 2010, the molecular components of sex-specific odorants were identified in the oils from uropygial glands.

Jerome Mardon and colleagues showed that, during the breeding season, there is a sex-biased chemosignal (more C23-C28 esters) in uropygial secretions of female petrels. It has not yet been possible to demonstrate that the "Sex signal" affected male behavior under field conditions¹⁶.
Jian-Xu Zhang and others from the Chinese Academy of Sciences (Beijing) report that a blend of 18-, 19-, and 20-carbon alcohols, found in uropygial secretions of both male and female budgerigars, are strongly enriched in males. With a classic Y-maze bioassay, they showed that the alkanol blend, reconstituted from pure chemicals, was attractive to female budgerigars¹⁷.

Why haven't more ornithologists seen birds use pheromones?

Birders have logged millions of hours watching birds. How could pheromones escaped their attention for so long?

We think that the answer is threefold:

= First, because birds don't wave mobile pendulous snouts as they walk about.

In a seminal article, Samuel Caro and Jacques Balthazart argue persuasively for the existence of bird pheromones. These authors suggest that birds aren't obvious when they use chemical signals:

"Mammals extend their neck, move their head, sniff, and track the source of the odor.....Birds, in contrast, have developed a wide array of alternative communication signals and do not show behaviors typically associated with olfactory sampling..." ⁵ (italics added).

= Second, because most of the accumulating evidence¹has been published in biochemical publications rather than the birder journals that are read by most ornithologists.

= Third, because it takes a lot of expensive scientific slogging to get from observation and experiment in the field and laboratory, to purification of the molecules, to behavioral assay, and finally to manipulating physiological context, all of which must come together to definitively prove pheromone function.

The roles of pheromones can be obvious or subtle.

Pheromones (including blends of several substances) can be classical releasers that trigger a quick behavioral response or primers that cause a specific but sustained change in physiological state.
Pheromones could mediate general arousal, like a perfume that is "chemical mood music".
A given pheromone signal could be emitted by both sexes and/or could impact both sexes.

Pheromone research starts with observations of behavior. Let me digress by presenting a personal example:

In 1969 after several years of behavioral experiments, George and his students concludedthat mealworm beetles use multiple sex pheromones^{18, 19} (diagram left): A) an attractant produced by male beetles for females; B) a substance from females that excites males; C) an antiaphrodisiac produced by males that inhibits other male competitors, and D) primer pheromones that accelerate oocyte maturation in females.

Next, the behavior needed validation by chemistry. But my laboratory and other colleagues failed in attempts to chemically purify even one of these four putative pheromones. So instead, after 1970, we pursued research themes in cell and developmental biology.

In ensuing last 40 years, our conclusions, based on behavior, have been validated by the work of chemists. In 1986, a Japanese group identified B, the female beetle's attractant²⁰. Recently (2005), an English group isolated A, the male's attractant²¹. Since the existence of antiaphrodisiac C and primer D have not been definitively confirmed by isolation and bioassay of a pure substance, the case for each of these is yet incomplete.

The case for pheromones in Sandhill Cranes

Three lines of evidence strongly suggest that cranes use pheromones:

=First - Cranes have capacious uropygial glands that secrete a melange of oils and waxes. The drawing to the right is the uropygial gland of a Sandhill Crane²². In his classic inventory of uropygial secretions^23,24, Jürgen Jacob found that crane uropygial secretions contain unusually large proportions of sesquiterpenes and diterpenes, substances built up from isoprene building blocks like those used to make steroids. Isoprenoids are auspicious pheromone candidates.

=Second - Every crane repeatedly harvests secretions of its uropygial gland (left, below) and wipes the greasy gue over their wing and body feathers (right, below) as it preens.

=Third - In nature, both crane sexes exhibit a fascinating exploratory behavior (photo to the right) as they pace forward just before copulation. It has been sketched for Eurasian Cranes by Paul Johnsgard²⁵ (who called it 'parade march'). It has been named 'bill-raising' in Red-crowned Cranes by Masatomi and Kitagawa²⁶, and included in most accounts of crane precopulatory rituals^25-28.

In our Crane Display Dictionary²⁹, we suggest that the 'Parade-march' can facilitate olfaction.

We agree with Caro and Balthazart that most species of birds "... do not show behaviors typically associated with olfactory sampling".⁵ However, there are exceptions where sniffing seems evident. We believe that two of the notable exceptions are the Parade-march posture of cranes and the Ruff-Sniff behavior of Crested Auklets (seen to the right in a drawing from Hunter and Jones).³⁰

Given these three lines of evidence, we conclude that it is quite plausible that cranes emit and perceive reproductive pheromones. This idea deserves serious further investigation:

Uropygial glands of captive cranes could be milked and analyzed. Are the secretions sex specific? age specific? seasonally changing? species specific? affected by changes in hormones?
A quantitative bioassay needs to be developed for cranes. With a behavioral or physiological bioassay, one could ask whether responsiveness to crude uropygial secretions, purified components, or defined mixtures varies with sex, season, endocrine background, etc.
Can purified pheromones or mixtures be tools for improved crane husbandry and thus assist in conservation of endangered species of cranes?

References:

1. Karlson P. Lusher M 1959. 'Pheromones': A new class of biologically active substances. Nature 183:55-56.

2. Roth LM, Eisner T 1962. Chemical defenses of arthropods. Ann Rev Ent 7:107-136.

3. Grassé P-P 1950. Traité de Zoologie, Tome XV. Oiseaux.

4. Hagelin JC, Jones IL 2007. Bird odors and other chemical substances: a defense mechanism or overlooked mode of intraspecific communication? Auk 125:741-761.

5. Caro SP, Balthazart J 2010. Pheromones in birds: myth or reality? J Comp Physiol A 196:751-66.

6. Kolattukudy PE, Rogers L 1987. Biosynthesis of 3-hydroxy fatty acids, the pheromone component of female mallard ducts, by cell-free preparations from the uropygial gland. Archiv Biochem Biophys 252:121-129.

7. Bhatttacharyya SP, Chowdhury M 1987. The effect of androgen on the composition of lipid material of the preen gland of pigeons. Folia Biologica 26: 15-32.

8. Bohnet SI, Rogers G, Sasaki G, Kolattukudy PE, 1991. Estradiol induces proliferation of peroxisome-like microbodies and the production of 3-hydroxy fatty acid diesters, the female pheromones, in the urogygial glands of male and female mallards. J Biol Chem 266:9795-9804.

9. Bhatttacharyya SP, Chowdhury M 1995. Seasonal variation in the secretory lipids of the uropygial gland of a subtropical wild passerine bird, Pycnonotus cafer, in relation to the testicular cycle. Biol Rhythm Res 26:79-87.

10. Steiger SS, Fidler AE, Valcu M, Kempenaers B 2008. Avian olfactory receptor gene repertoires: evidence for a well-developed sense of smell in birds? Proc Roy Soc B 275:2309-2317.

11. Steiger SS, Kuryshev VY, Stensmyr MC, Kempenaers B, Mueller JC 2009. A comparison of reptilian and avain olfactory gene repertoires: Species-specific expansion of group γ genes in birds. BMC Genomics 10:446-456.

12 Steiger SS, Fidler AE, Mueller JC, Kempenaers B 2010. Evidence for adaptive radiation of olfactory receptor genes in 9 bird species. J Heredity 101:325-333.

13. Jarvis ED, Gunturkun O (25 colleagues), Reiner A, Butler AB, 2005. Avian brains and a new understanding of vertebrate brain evolution. Nature Reviews Neuroscience 6:151-159.

14. Balthazart, J, Schoffeniels E 1979. Pheromones are involved in the control of sexual behaviour in birds. Naturwiss 66:55-56.

15. Hirao A, Aoyama M, Sugita S 2009. The role of uropygial gland on sexual behavior in domestic chicken Gallus gallus domesticus. Behav Process 80:115-120.
16. Mardon J, Saunders SM, Anderson SM, Chouchoux C, Bonadonna F 2010. Species, gender, and identity: Cracking the petrel's sociochemical code. Chem Senses 35:309-321.
17. Zhang J-X, Wei W, Zhang J-H, Yang, W-H. 2010. Uropygial gland-secreted alcohols contribute to olfactory sex signals in budgerigars. Chem Senses 35:375-382.
18. Happ GM 1969. Multiple sex pheromones of the mealworm beetle, Tenebrio molitor L. Nature 222:180-181.

19. Happ GM, Schroeder ME, Wang JCH 1970. Effects of male and female scent on reproductive maturation in young female Tenebrio molitor. J. Insect Physiol 16: 1543-1548.

20. Tanaka Y, Osawa K, Honda H, Yamamoro I 1986. A sex attractant of the yellow mealworm beetle, Tenebrio molitor, and its role in mating behaviour. J Pest. Sci 11:49-55.

21. Bryning GP, Chambers J, Wakefield ME 2005. Identification of a sex attractant from male yellow mealworm beetles, Tenebrio molitor. J Chem Ecol. 31: 2721-2730.

22. Johnston DW 1988. A morphological atlas of the uropygial gland. Bulletin of the British Museum (Natural History). Zoology series. 54(55):199-258.
23. Jacob J, Plawer J, Rosenfeldt P 1979. Gefiederwachskompositionen von Kranichen und Rallen. Beitrag zur Systematik der Gruiformes. J Ornithol 120:54-63.

24. Jacob, J. 1982. Uropygial gland secretions and feather waxes. Avian Biology, Vol VI, edited by Farner DS, King JR, Parkes KC , Academic Press, New York, pp199-324.

25.Johnsgard P 1983. Cranes of the World. 2. Individualistic and social behavior. Papers in Biological Sciences, University of Nebraska, Lincoln, pp. 11-24.

26. Masatomi H, Kitagawa T 1975. Bionomics and sociology of the Japanese Crane, Grus japoniensis, II. Ethogram. Jour. Fac. Sci. Hokkaido Univ. Ser. VI, Zool. 19:834-878.
27. Ellis DH, Swengel SR, Archibald GE, Kepler CB 1998. A sociogram for cranes of the world. Behav Process 43:125-151.

28. Masatomi H 1983. Some observations on mating behaviour of several cranes in captivity. J. Ethol. 1:62-69.
29. Happ, CY, Happ GM 2011. Sandhill Crane Display Dictionary. What cranes say with their body language. Waterford Press.
30. Hunter FM. Jones IL 1999. The frequency and function of aquatic courtship and copulation in least, crested, whiskered, and parakeet auklets. The Condor 101:518-528.
31. Zelenitsky DK, Therrien F, Ridgley RC, McGee AR, Witmer LM. 2011. Evolution of olfaction in non-avian theropod dinosaurs and birds. Proc Roy Soc B doi:10.1098/rspb.2011.0238.
32. Reiner A, karten HJ 1985. Comparison of olfactory bulb projections in pigeons and turtkes. Brain Behav Evol 27:11-27.
33. Abellan A, Legaz I, Vernier B, Retaux S, Medina L 2009. Olfactory and amygdalar structures of the chicken ventral pallium based on the combinational expression patterns of LIM and other developmental regulatory genes. J Comp Neurol 516:166-186.
34. Krause ET, Kruger O, Kohlmeir P, Caspers BA, 2012. Olfactory kin recognition in a songbird. Biology Letters, published online doi:10:198/rsbl.2011.1093.

Updated: April 17, 2011 & January 5, 2012

Twin colts hatched in 2010

2010-06-20T16:30:00.013-08:00

Roy and Millie returned to their Goldstream Valley cranberry bog and its snow-covered frozen pond on April 22 -- Earth Day. The pair soon began exploratory nest building (left) and then started serious incubation as the snow fell lightly on May 4 (photo right).

We have seen cranes on this pond for 15 years. 2010 is the 10^thyear that we know a pair of cranes has nested here. Photographs confirm that Roy and Millie have been the individuals nesting here since 2004. We suspect they have been summer residents here since the late 1990's.

The first crane colt (Lucky) hatched on June 4, 2010 and a second (Chance) on the next day. They spent the first two days near the nest, being fed insects by their parents and otherwise sheltering under Millie's wings.

By day 3, the colts were trailing after their parents, peeping loudly as the family of four foraged all around the pond (map in a previous blog).

Better quality images covering the first two weeks of Lucky and Chance can be found at Christy Yuncker Photo Journal.

It is a formidable task to raise two colts to the point of migrating south in September. The full history over the past 15 years is summarized on our web page. Hyperlinks to photo galleries showing some of these colts are included below.

2002 & 2003 - Colts hatched but did not survive.
2004 - Two colts hatched but only Peter Pan-04 left on migration.
2005 - The nest was flooded and no colts hatched.
2006 - Two colts hatched but one died after two weeks. Barbaro-06 lived to learn to dance (often with a parent), to fledge and to migrate southward.
2007 - The nest was flooded.
2008 - Oblio-08 hatched, developed well in June. The colt was somehow injured and could not run well in midsummer. The parents delayed their migration until Oblio was able to fly in mid-September.
2009 - Jacques-09 and Phyl-09 hatched but Phyl died overnight at three weeks. The parents exhibited a crane version of grieving on the day after Phyl's death. [see also our Blogpost of June 11, 2009). At the end of the summer, Jacques migrated south with his parents.
2010 - Lucky-10 and Chance-10 hatched on June 4 & 5. They gamboled and foraged around the pond for two weeks. In week 2, they were absent from the pond for most of the day on two occasions; we assume this was a neighborhood walkabout. Chance did not appear on the morning of June 19. We do not know the cause of his death.

Crane brains and behavior 3 - Mental maps of local ecology in a Parahippocampal Place Area (PPA)?

2010-05-22T20:40:00.021-08:00

For the past 18 days, our Sandhill Crane pair, Millie and Roy, have been trading incubation duties every 6-8 hours. The off-duty crane feeds, loafs, calls, and inspects the neighborhood, including the nest-site pond and bogs across Goldstream Valley.

We believe that inspection allows cranes to monitor their environments. Inspection provides frequent updates to the mental map of the crane's world and also detects novelty (which might signal danger). In our previous Blogpost, we introduced the idea of such a map and drew parallels with spatial information that some bird species use to find food items that they have hidden previously.

Within the brain of a crane, where is the map of the neighborhood? How is the information stored?

We can't readily investigate memory mechanisms by implanting electrodes into the brains of free-flying wild birds. But we can indirectly address questions about the mental capacities of wild birds by invoking laboratory research on people and other animal species.

For birds as for mammals, spatial data is stored in the hippocampus and associated parahippocampus, indicated by red arrows in the diagram of the bird brain¹. In humans, the parahippocampal regions of the neocortex are implicated in spatial memory and navigation. The hippocampus is important for homing in pigeons² and caching of food items in many avian species^2,3. It is likely that the similarity in localized function reflects similarity by descent from their ancestral stem amniotes. Fish also store spatial information (including perhaps a cognitive map⁴) within their lateral pallium⁵, a brain region homologous to the hippocampus.

When Crows, Rooks, Jays, or Chickadees hide food tidbits for later retrieval, information about each item and its location is stored in the hippocampus. The storage capacity is prodigious; tens of thousands of cached items are held in memory for later retrieval. Items with limited "shelf life" (dead juicy caterpillars) are distinguished from durable items (acorns or peanuts)⁶.

Meticulous neuroanatomical research has shown that this region of a bird brain has an unusually regular architecture. The nerve cells are not randomly scattered but instead are clustered in patches or stripes that are reminiscent of the mammalian visual cortex⁷.

How is the data organized in the bird hippocampus?

At present, there are no data to directly answer this question in birds. For the present purposes, we'll look at on two of the many alternatives.

Flat file - The mental map could be an analogue of a "flat file database" -- simply a list with environmental items in one field linked to responses in another field. This memory mechanism is analogous to the operant conditioning of experimental psychologists. Pigeons in a Skinner box can distinguish among hundreds of geometric shapes and link each shape to a correct response.

In the local ecology, a crane might compare each item in the environment with a previous environmental inventory. Every object and its coordinates would be compared with memories to arrive at a response based in previous experience. An example of such a Flat File (like an Excel Spreadsheet) is shown in Footnote #8 below.

The Flat File might recommend itself as a bird memory mechanism because it is scientifically reductionist. It is built from individually learned stimulus-response pairings - the classical learning paradigm that has been validated by many thousand pigeon pecks on keys in Skinner boxes. It assumes no high-level cognition by the bird. This pairing of item and response must somehow be coupled with a mental mapping coordinate system that seems hard to build from the Skinner-box assumptions.

We suspect that from the perspective of a computer programmer, the flat file would be viewed as a robust and adequate memory mechanism. But it is a very clunky solution.

The second alternative could stem from the architecture of the brain.

Special Cognitive Center - Parahippocampal Place Area (PPA). The crane's mental map could be homologous to a human mental map or "cortical representation of the local visual environment", to use the terminology of Nancy Kanwisher of the McGovern Institute for Brain Research at MIT⁹.

In humans, Kanwisher's functional MRI (Magnetic Resonance Imaging) reveals the existence of the PPA and other localized specialized cortical centers for high-level cognitive functions (for example recognizing faces, places, or body parts)¹⁰.

fMRI is a very powerful tool for mapping and imaging brain activity. If a group of nerve cells in an intact brain are working hard (firing often), they use lots of glucose and incur oxygen debt, just like your leg muscles when you run a 220-yard dash. The "wisdom of the body" dictates an increase in blood flow to bring more oxygen-rich hemoglobin to those oxygen-starved patches of cells. The ratio of fully loaded hemoglobin (rich in oxygen) to emptied hemoglobin (stripped of oxygen) can be precisely localized on the fMRI imaging screen. When very tiny areas of the brain "light up", neuroscientists can link brain regions with cognitive tasks.

In humans, Kanwisher and her colleagues have shown that the human PPA (anatomically the "collateral sulcus adjacent to the parahippocampal cortex") lights up with fMRI in response to visual scenes. It is particularly significant that for both people and rats, the PPA responds to the layout of the space, not simply to objects or landmarks. The objects must be mapped into a mental reference space, and recent work demonstrates that another class of nerve cells, called "grid cells", appear soon after birth in young rat pups^10,11. These grid cells can provide a coordinate system for locating each object specified by the place cells.

As we discussed in a previous Blogpost, recent research has established the common origin (homology) of the hippocampal complex in birds with that of mammals, and numerous experiments have linked spatial memories with the bird hippocampus^3,4,6, apparently reflecting functional parallels with the mammalian hippocampus.

Therefore we think it is reasonable to use the evolutionary, developmental, and functional identities between bird brains and mammal brains to propose that the bird hippocampus, like that of a mammal, may contain a PPA and grid cells.

If cranes have a PPA that is homologous to mammals, then we suggest that the crane's PPA, a localized special cognitive center to recognize objects, could work in concert with grid cells to be the situs of environmental reference information.

We propose that maps in the crane PPA could accrue through experience and would be subject to updates and remodeling as the environment changes. Furthermore, they would provide a stable context to asses objects as they enter the visual field. Crane PPA mental maps could function at several scales, from the global scale as guides for seasonal migration to the local scale as a reference to register novelty. For Millie and Roy, that mental map might provide a reference picture which reveals novelty that augers threats.

As we enter the 21st new century, scientists are beginning to understand brain mechanisms that are linked to our human minds. Ignorance of the bird mind is even more profound.

Insightful research on human brains, like that from the Kanwisher laboratory¹², offers striking perspectives on brain function. There are intriguing parallels for the neuroscience underlying bird behavior.
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1. Figure modified from Jarvis ED, Gunturkun O (25 colleagues), Reiner A, Butler AB, 2005. Avian brains and a new understanding of vertebrate brain evolution. Nature Reviews Neuroscience 6:151-159.
2. Kahn MC, Bingman VP, 2009. Avian hippocampal role in space and content memory. European J Neuroscience 30:1900-1908.
3. Clayton NS, 1998. Memory and the hippocampus in food-storing birds: a comparative approach. Neuropharmacol 37:441-452.
4. Jacobs LF. 2003. The evolution of the cognitive map. Brain Behav Evol 62:128-139.
5. Rodriguez F, Lopez JC, Vargas JP, Brogolio C, Gomez Y, Salas C, 2002. Spatial memory and hippocampal pallium through vertebrate evolution: Insight from reptiles and teleost fish. Brain Res Bull 57:499-503.
6. Emery NJ, Clayton NS, 2009. Comparative social cognition. Annu Rev Psychology 60:87-113.
7. Kovjanic D, Redies C, 2003. Small-scale pattern formation in a cortical area of the embryonic chicken telecephalon. J Compar. Neurology 456:95-104.
8. A crane might compare each item in the environment with a previous environmental inventory.

The mental item-and-response list could have fields, for example Stimulus-Object, Location, Compare-to-memory, Response that function like a name-and-address list. In the Table below, we use arbitrary numbers for Location Coordinates.
1. Stimulus (object seen in crane's vicinity) 2. Location Coordinates 3. Compare to Previously Stored Memory 4. Response
Spruce tree 1234, 4567 Spruce tree Ignore
Poplar tree, leaves 1234, 4588 Poplar tree, no leaves Update memory
Green grass on SE bank of pond

1234, 4592 Brown grass on SE bank of pond Update memory
Red fox on SE bank 1234, 4592 New Item and a known Potential Predator DANGER, attack
Birch tree, no leaves 1234, 4576 Birch tree, no leaves Ignore
etc. etc. etc. etc.
This Flat File database (an Excel Spreadsheet) can be built from a well-accepted learning paradigm in experimental psychology labs. However, the explanatory table glosses over the "Coordinates"; perhaps this memory model also requires a series of fields to specify each location for each object, and therefore a much larger flat file.

9. Epstein R, Kanwisher N, 1998. A cortical representation of the local visual environment Nature 392:598-601.
10. Wills TJ, Cacucci F, Burgess N, O'Keefe J, 2010 Development of the hippocampal cognitive map in preweaning rats. Science 328:1573-1576.
11. Langston RF, Ainge JA, Couey JJ, Canto CB, Bjerknes TL, Witter MP, Moser EI, Moser M-B, 2010 Development of the spatial representation system in the rat. Science 318: 1576-1580
12. Kanwisher N, 2010. Functional specificity in the human brain: A window into the functional architecture of the mind. Proc Nat Acad Sci USA (in press).

Walkabouts, local ecology, and the importance of novelty

2010-05-01T12:09:00.014-08:00

Millie and Roy returned on Earth Day 2010. Within minutes, they erupted into energetic spinning jumps and deep forward bows on Bog Central - a dance that probably reflected emotional release. Then they began to check out the local ecology.

Although they have nested here for many years, these cranes are meticulously cautious when they first arrive in the spring. Apparently the neighborhood needs vetting and re-vetting. Sometimes bad things happen while we are traveling; it pays to inspect the home premises when we return. This appears to be true for cranes as well as people.

These wild Alaska Cranes are ever vigilant. Ongoing quiet reconnaissance seems almost compulsive. They take no notice of the daily barking by neighborhood dogs, yet a novel sound, like a delivery truck on a nearby road, piques their curiosity as they assume a Tall Investigative posture. Intruding ravens release agitation and attack.

The contrast to suburban Florida Sandhill Cranes who tolerate endless human traffic is striking (see footnote¹).

For these wild Alaska Sandhill Cranes, it appears that familiar is benign but any novelty triggers interest (Tall Investigative posture) that can escalate to edginess (Tall-alert posture). In order to detect deviations in their environment, we think that Roy and Millie must hold in memory some representation of their local ecology . How do they create the reference worldview?

Our cranes' neighborhood has three concentric zones:

a core nest territory that is readily visually inspected,
nearby ponds within walking distance, and
the wider surround of Goldstream Valley accessible by short flights.

Reconnaissance allows accumulation of local geodata.

During the first few days after their arrival, Roy and Millie scrutinize their nest pond and the adjacent marsh. Following a bout of feeding or loafing, they pace slowly ahead with necks extended as if they were sniffing. This ritualized posture is often a prelude to copulation but it might also reflect exploration.

In both the photos above, Roy, distinguishable from Millie by his larger white patch, is closest to the camera. This posture is different from the familiar "intention to fly" (see Social Body Language) in that the neck is not arched.

The picture above shows a crane's-eye view of bog central. Daily patrol around the bog allows collection of seeds and insect prey. General surveillance is punctuated with deliberate examination of notable items. For example, the remnants of Phyl's skeleton (Blogpost July 2009) merited 30 seconds of intense staring on Earth Day.
Goal-oriented tasks, like selection of a premium site to build the nest, are another priority. At many spots across the bog, Roy explores local construction possibilities by seizing, waving, and deliberately piling a few fragments of cattail. As the first and second weeks roll on, he focuses upon fewer sites and Millie begins to take some interest as she nears time for egg-laying.

On two occasions during the second week, pacing-gazing was followed by a slow walk to the northwest, toward Upper Pond which is almost a half-mile away. In past years, the Upper Pond has been a nesting site for ducks and grebes. The route to Upper Pond is the same each year; the cranes do not explore in other directions. Generally, Millie and Roy revisit the Upper Pond in July and August when they take the colts for a stroll.

The third level for reconnaissance is Goldstream Valley. On every evening for the first 10 days after their arrival, the cranes fly across southeast to valley to roost for the night in the Cross-Valley Ponds and Bogs. They come back the following afternoon to feed, explore, sleep, mate and dance in Bog Central and to call in unison several times each day. On many occasions, they are answered by other cranes - one pair to the east, one to the south-southwest, and another to the southwest.

During the 30 day incubation period while one crane is incubating the eggs, the other often flies across the valley to the south or to the southeast and then returns in a few hours to assume incubation duties. In past years after the colts are hatched, Roy conversed with other valley cranes on a daily basis and often flew off toward their calls for an hour or two.

We conclude that the crane's "mental representation" of the local ecology of Goldstream Valley is informed by visual information through walkabouts and flyabouts reinforced by the territorial calling through the summer.

What is the the crane's mental map of the local neighborhood?

Some birds have phenomenal capacities for spatial memory. The best studied species are jays and crows that remember the locations of tens of thousands of hidden food tidbits they have hidden.

Do they retrace the exact path that was followed to hide each item?
Do they remember a particular location for each item by relating to an array of specific landmarks ?
Do they hold in their minds a general neighborhood reference map that includes spatial coordinates for each cached item?

Simple cues and even retracing paths for a few items have been validated in laboratory experiments that control all other variables for jays and crows. But in natural environments, the contexts are diverse; there are multiple and variable cues, and the spectrum of responses is large. We suspect that their penchant for exploration could allow cranes and other birds to construct mental maps of their surroundings. In philosophical jargon, these would be termed decoupled representations, "registrations of the environment that are relevant to many possible actions but specific to none" ².

Such cognitive accomplishments would go well beyond lists of specific cues that release fixed responses. Cranes are wary, long-lived birds who remain paired for a decade or more because they are canny. Although creatures of habit, they are not automatons. We suggest that one critical capacity might be a cognitive "novelty detector", like that employed by a policeman who strolls down the street quietly scanning for anything out of normal.

Danger anticipated can be disaster avoided.

=================
1. Cranes in more civilized climes can habituate to human activity. Florida Sandhill Cranes inhabit golf courses and suburban neighborhoods, seem unperturbed by proximity to people, and even become part of the cross-species social scene.

Diana Burton of Indian Harbour Beach Florida emailed as follows:

I am not a biologist, but an ophthalmologist living in Florida. [The cellphone snapshot to the left was taken at the entrance to her clinic.]
I wanted to share an interesting Sandhill Crane behavior and see if you've ever heard of it. One of the technicians in my clinic came in very excited and told this story. A pair of cranes which is often around her house was in the backyard. Her girls wanted to jump on the trampoline. Carleen told them they might scare the cranes away but they went out carefully and the cranes stayed. The girls started jumping on the trampoline and Carleen said the birds looked at the girls, then each other, then started jumping (I guess dancing.) Carleen ran and got her video camera but the battery was dead. One other time, the pair was there and her daughter went and started to jump. That time, one of the cranes started to jump but the other didn't.

Dr. Burton's email describes a crane that exploits the automatic door opener of a hospital emergency room to beg for food.

I take call for an area hospital and went to the emergency room to see a patient. I've seen cranes in the parking lot there on several occasions, but one of them walked up to the sliding door to the emergency room entrance and it opened. He stood there and looked in. A patient came to the door and the crane walked away about 10 feet, but immediately returned after the patient passed. The door opened. He stood looking in. This happened over and over for several minutes, with the sliding door opening and closing because of the crane. Finally, a nurse at the desk said, "OK, Henry." She went over to the popcorn stand and got a bag, and walked out the sliding doors past "Henry." He loped after her and she spread some popcorn on the grass for him (her?). She said, "He does this all the time."

2. Sterelny K, 2003. Thought in a Hostile World. The evolution of human cognition. Blackwell Publishing, page 50.

Crane brains and behavior 2 - The wiring plan

2010-03-10T15:24:00.035-09:00

"To represent the world is to have a special kind of wiring inside your head and special physical connections between that wiring and the world."
Peter Godfrey-Smith¹

Evolution has placed the executive brain (blue in the crane's head to the right) linked by short transmission lines to the forward scanners (eyes, nose, and ears). Within that tiny efficient brain, data inputs are integrated, compared with memories, and matched to coordinated adaptive responses.

In this blogpost, we introduce some recent research about the structural layout within bird brains. From that anatomical context, we can reason upstream, starting with observations of behavior and then making informed guesses as to how the bird brain works.

Within its mind, the crane must have some "representation" of the surrounding world:

That representation could be just a long list of cues (stimuli) that are linked to behaviors (responses) so that each stimulus from the environment automatically triggers a fixed response.
Or that "representation of the world" could much more complicated -- organized in space and time into a coherent worldview with specific historical memories, maps of different environments, and primitive reasoning skills to produce flexible behavioral responses.

In either case, the representation is based in genetics, incessantly informed by data from the surroundings, and adaptively modified during development and through learning.

Even casual observations show us that a bird's brain can discriminate. Roy and Millie, our crane pair, recognize our cars in our driveway and our voices in the house. When strange cars appear or strange people visit, they withdraw deeper into the marsh.

Birds are capable of much more impressive feats:

Birds are wizards at distinguishing shapes. In experimental laboratory situations, pigeons can memorize up to 725 different visual patterns². Pigeons can even learn to distinguish paintings of Monet from those of Picasso³.
Birds find their way while migrating enormous distances. Using radiotelemetry, John Wright tracked a population of Sandhill Cranes migrating from Fairbanks, Alaska to west Texas, over 3000 miles. In the spring, these same individual cranes return to interior Alaska, often homing in to nest on exactly the same pond, year after year.
Three hundred miles south of Fairbanks in Homer Alaska, Ed Bailey and Nina Faust tracked another Sandhill population that nest in south-central Alaska to their wintering grounds in central California⁴.
The capacity to navigate is surely innate - a talent encoded in crane DNA. The broad regional destination for winter feeding or summer nesting may be partly specified by genetics. But the exact targets and precise migration routes for the various populations are not genetically programmed. Apparently they are socially learned and then stored in the memories of experienced cranes for replay year after year.
Birds make and use tools, and teach toolcraft to others. New Caledonian crows make tools from sticks or leaves, use these tools to fish for insect larvae in burrows, select the right tool for individual holes⁵, and pass the knowledge on to other crows via social learning⁶.

Armed with the knowledge that bird behavior is sophisticated, let's ask about the brain wiring. How are the nerve cells clustered together in centers and how are the centers connected in the brain? We don't have detailed brain data for cranes, but we know a lot about other birds and even more about mammals.

So we'll use a comparative approach. Cranes are end-products of lineages; their brains and their behaviors reflect their evolutionary history. If we know which parts of bird and mammal brains are similar by descent, then research on mammal brains might offer insights into crane behavior. And vice versa.

How much do mammal and bird brains resemble each other? They share the same broad architectural plan, but the lineages have been diverging and the brains differ in appearance⁷. In people, the cerebrum with its wrinkled cortex is linked to higher mental functions. The songbird cerebrum is smooth: what does this imply about intelligence? For a time, scientists thought that such differences in structure showed that birds can have only hard-wired instinctive behavior and lack adaptive intelligence. Then behavioral evidence, such as that we cited above, proved that birds are clever. To help us understand bird brains, we need to compare their structure and early development with mammal brains.

The nervous system in fish, birds and mammals arises in the early embryo as a thick-walled tube with the Forebrain, Midbrain and Hindbrain in the head⁸.

The top of the embryonic telencephalon (neuro-anatomists love Greek words) is the Pallium (Greek for "cloak"). The pallium will develop into the executive brain centers for relating input from sense organs, like eyes and ears, to output (muscle contractions). It is also the site for cognition and consciousness. Beneath the pallium are the basal ganglia that are concerned with instinctive behavior, movement, and motor learning.

Since the brain contains a world view, we could ask: Is it is possible to for us to put ourselves at the viewpoint and see a map of the world somewhere in the brain? In the early 20th century, a brilliant Montreal neurosurgeon named Wilder Penfield⁹ was able to find maps on the surface of the human brain - maps that depict sensory input from each patient's world and also direct the motor output to each patient's muscles.

Penfield opened the skulls of anaesthetized but fully conscious patients who suffered from epileptic seizures. . Since our brains have no pain receptors, Penfield could use tiny electrical probes to stimulate various regions of the brain without discomfort to the person. He explored here and there to find the sites in his patients that triggered their epileptic seizures. Then he could try to treat disease by surgically removing the local diseased region of the brain.

In response to Penfield's exploratory probing stimuli, patients reported smells or sounds or flashing lights or even twitched their muscles. From all those results, Penfield and others constructed maps of human cerebral cortex. The figure below shows such a map for touch (left) and motor control (right). Not every part of the body is equally represented. Motor control for the hand occupies a lot of space (on the right) as does sensory input from the face and lips (left).
As embyos develop, the forebrains fold, bulge, and become contorted so that the brains of birds and mammals look quite different on the surfaces. Look again at the songbird brain in the photograph above. At first glance, it is hard to tell exactly how the various parts of smooth-surfaced bird brains correspond to particular regions of the mammal cerebrum. Using the best information available in the early 20th century, brilliant anatomists tried to relate brain structure to the evolutionary histories of birds and mammals. They concluded that the higher centers in the adult bird brain developed from embryonic basal ganglia whereas the mammalian cerebral cortex came from the embryonic pallium. Since bird did not evolve the wrinkled mammalian pallial neocortex, it followed that birds are feeble-minded.

The conclusion was logical but based on incomplete data. Over the last 50 years, results converging from many scientific fields including brain imaging, cell biology, electrophysiology, genetics, molecular biology, ethology, comparative psychology, developmental biology, and even philosophical biology, all led to a single common conclusion - the early 20th century depiction of the bird brain was wrong in many respects.

In 2002, a group of eminent scientists gathered the new data together and produced a coherent modern terminology^6,10. The new nomenclature clarifies evolutionary relationships and identifies the anatomical sites that are probably responsible for higher cognition in birds. We need to understand this model and its implications in order to relate crane behavior to the crane brain.

Look below at cross-sections through the embryonic brain of a quail and of a rat¹¹. The orange pallium overlies purple basal ganglia. Already at this stage, the differences in shape are obvious. The rounded pallium of the bird is divisible into the hippocampus (Hp) and other regions (mesopallium etc.) where higher nerve centers will form. The flattened pallium of the rat is mostly the neocortex which overhangs the the hippocampus.

A cartoon using the modern consensus terminology for bird (left) and mammal (right) brains is shown below⁷. This is a section through the middle of the adult brains. The large pallial components (green in the cartoon) in the bird reflect the maturation of the orange regions in the embryo above. In mammals, the large pallial cerebral cortex overlaps the thalamus and cerebellum (blue) and buries hippocampus (red arrow) which is visible as a small green area just to the left of the blue thalamus in the human brain. The hippocampus is a brain region important for spatial learning.

Crows and jays use their hippocampi (red arrows on the left) to store over 10,000 individual locations where food items have been hidden. The differences in the hippocampi for birds and mammals shows one of many ways in which brain wiring for high mental functions has diverged.

As Penfield showed, the flattened mammalian cortex can be mapped in two dimensions across its surface. But evolution has yielded a different pallial architecture for birds and mapping must be in three dimensions. The higher centers (called nuclei) in the bird pallium are not conveniently arranged across the surface.

Terminology note: In cell biology, the word "nucleus" refers to the cellular organelle that encloses the genetic material. In neuroanatomy, the word "nucleus" refers to a compact cluster of nerve cells.

In birds, brain nuclei are jammed tightly together, piled on top of one another so that many are deep in the pallium. As an example, look at the robust nucleus of a towhee (the darker ovals in the figures below) that lie in the middle of the brain¹². This robust nucleus builds more cells in the spring when the male needs to sing (left) but the cells die off in the fall when the male is silent (right). Speaking personally, I would like to be able to grow new brain cells in order to think faster, but I'm not able to do so. The ability to grow new brain cells is exciting and the nuclei for birdsong have become models for basic biomedical research on multiplying brain cells.

Why are the bird brain nuclei piled up on top of one another? Not just to tease and confound brain cartographers! Probably because space is at such a premium. The expanded surface area and volume of a mammalian cortex may be one convenient design that birds simply cannot afford. Birds need to fly, and a large heavy brain and skull at the leading edge of the airship would be bad aeronautical engineering. Natural selection for a good flying machine favors a small head.

More about brain size and bird intelligence in a future blogpost.

References:

1. Godfrey-Smith P, 2002. On the evolution of representational and interpretative capacities. Monist 85:50-69.
2. von Fersen L, Delius JC, 1989. Long-term retention of many visual patterns by pigeons. Ethology 82:141-155.
3. Watanabe S, Sakamoto J, Wakita, M, 1995. Pigeons' discrimination of paintings by Monet and Picasso. J. Exp. Anal. Behav. 63:165-174.
4. See www.cranewatch.org.
5. Bluff LA, Troscianko J, Weir AA, Kacelnik A, Rutz C, 2010. Tool use by New Caledonian Crows Corvus moneduloides at natural foraging sites. Proc. Roy. Soc. London Biol. Sci. DOI rspb.2009.1953 [pii] 10.1098/rspb.2009.1953.
6. Hunt GR, Gray RD, 2003. Diversification and cumulative evolution in New Caledonian crow tool manufacture. Proc. Roy. Soc. London B 270:867-874.
7. Photo plate and drawing from Jarvis ED, Gunturkun O (25 colleagues), Reiner A, Butler AB, 2005. Avian brains and a new understanding of vertebrate brain evolution. Nature Reviews Neuroscience 6:151-159. This paper provides an overview of the modern nomencalture.
8. The embryonic brain drawing is adapted from Wikipedia.
9. Figure from http://www.pbs.org/wgbh/aso/databank/entries/bhpenf.html
10. For a meticuous exposition on the nuclei of the bird telecephalon, see: Reiner A, (27 colleagues), Jarvis ED, 2004. Revised nomenclature for avian telencephalon and some related brainstem nuclei. J Comp Neurol 473:377-414.
11. Adapted from from Nomura T, Takahashi M, Hara, Y, Osumi N, 2008. Patterns of Neurogenesis and Amplitude of Reelin Expression Are Essential for Making a Mammalian-Type Cortex. PLos ONE 3:e1454. 2009. We have labelled using modern terminology.
12. Figure adapted from Tramontin AD, Benowitz EA, 2000. Seasonal plasticity in the adult brain. TINS 23:251-258.

Crane brains and behaviors 1 - the evolutionary legacy

2010-01-30T16:24:00.076-09:00

Crane brains control crane behavior. To understand the present-day crane brain, we need to appreciate its evolution.

Cranes are members of Gruiformes - an ancient order of birds. One chicken-sized gruiform (fossil to the right) lived 30 million years ago on the grasslands of present-day France¹. The famous ornithologist Alexander Wetmore identified fossil leg bones from the Paleocene prairies of Nebraska and Kansas as those of Sandhill Cranes from 7 million years ago², an argument for cranes as the oldest bird species alive today. There are no fossil skulls found for these Paleocene Sandhills, but their brains, like those of modern birds, must have carried a legacy of adaptations acquired through natural selection over hundreds of millions of years.

Birds and mammals are descended from a four-legged little beast that looked something like a lizard. In Triassic times about 250 million years ago, these lizardy vertebrates (Solenodonsaurus³ to the left) made a major evolutionary breakthrough. They acquired a special sac, called an amnion, that protected embryos and thus allowed eggs to be laid on land.

As the "stem amniotes" invaded terrestrial ecosystems, they split into two lineages: the mammal branch and the reptile-bird branch. Reptilian dinosaurs reigned on the land, in the sea, and even flying through the air. Inconspicuous mammals furtively scuttled around as they dodged voracious reptiles. By 100 million years later, the famous bird-dinosaur Archeopteryx had appeared⁴. But after a gigantic meteor slammed into the Yucatán peninsula 70 million years ago, the earth's climate cooled and the huge reptiles died off.

Of all the major groups of dinosaurs, only the flying feathered lineage survived and prospered to give rise to our present-day birds. Flight enables birds to colonize vertical niches for foraging and safer nesting and, perhaps just as important, to travel great distances in order to exploit seasonal food bonanzas. Today, the migratory lifestyles of billions of birds allow access to lush summer food sources at middle and high latitudes and then escape to warmer climes during winter.

With the passing of generation after generation, birds and mammals independently improved upon the brain of their stem amniote ancestor. The descendant groups retained the basic brain components (cerebrum, cerebellum, and so forth) but each lineage added neuro-architectural enhancements. For example, the profound increases in the numbers of nerve cells of the mammalian cerebral cortex (light blue in the drawing)⁵ caused it to become deeply infolded. Early anatomists linked intelligence to the mammalian brain's 6-layered cortex. Since the bird's cerebral hemispheres weren't so deeply wrinkled, these anatomists concluded that birds lacked higher cognitive functions. Early 20^th century psychologists made a similar presumption, and dismissed birds as mere reflex machines. In some scientific circles, that view still persists. However, an increasing body of data is convincing more and more scientists that birds have been underestimated. In surprising ways, birds are quite bright.

The 21^st century is often called the "Century of the Brain". As discoveries about human brain mechanisms cascade from university laboratories, new lines of evidence help strengthen the case for avian intelligence. Bird scientists now use molecular biology, neuroendocrine physiology, cognitive ethology, imaging technologies, field biology, computer modeling, and other diverse approaches to reveal the secrets of brain function.

Research on bird brains and bird cognition might seem somewhat esoteric at first blush, but it has proved to be important to understanding ourselves. Experimentation with birds has led to better comprehension of the human brain. Birds showcase some widespread aspects of brain function. In subsequent Blogs, we will discuss some of those data and relate them to crane biology.

We welcome your reactions to our blog. If you have comments, interpretations or observations that you are willing to share with others, either click on the word "Comment" at the bottom of this blogpage or email us directly.

References:
1. Mayr G, 2005. A chicken-sized crane precursor from the early Oigocene of France. Naturwissenschaften 92:389-393.
2. Wetmore A, Martin HT, 1930. A fossil crane from the Pliocene of Kansas. Condor 32:62-63.
3. Dimitri Bogdanov's drawing of a stem amniote (Solenodonsaurus) is from Wikipedia Commons.
4. The drawing of Archaeopteryx is from NASA.
5. The brain diagram is from www.crowstarver.com.

Death, visitations, and dance of "solidarity"

2009-07-10T22:39:00.274-08:00

---For July 2 photos on Christy Yuncker Photo Journal , click here.

On July 2, we were aroused at 7 AM by unison calling of Roy and Millie.

Twin colts, Jacques and Phyl, had trailed their parents around our cranberry bog for almost three weeks since hatch on June 10^th and 11^th.

When we glanced at Cattail Point on that morning of July 2, we saw only Jacques running back and forth between his parents, begging for food. The adults flapped their wings twice, peered down at a tawny mass half-hidden in the grass, preened, and shuffled around. After careful examination through a spotting scope, we saw that the object of their gaze was Phyl's motionless body. The photo to the left shows Millie looking down at Phyl.

In the following hour, the three cranes foraged for insects in the grass. Then at 8 AM, the adults exchanged unison calls with a part of cranes across the valley while Jacques watched (below).

At 10 PM on the previous evening, both colts went to sleep as usual, snuggled under Millie's wings at the habitual family roosting site.

Phyl's immobility was not a total surprise to us. The temperature on the first of July was almost 80º F, hot for Interior Alaska. All day Phyl lagged 10-15 meters behind the rest as they foraged and when they paused, she sat down. Jacques followed close upon the heels of his parents and thus garnered most of the insects. Periodically, Millie carried a dragonfly back to Phyl and she ate (pictured below). We don't know whether these tidbits provided sufficient nourishment for her needs, but later Jacques, Phyl and their parents shared a hearty supper of fresh duckling provided by Roy (another duck feast was described in the previous blogpost) before all repaired to Cattail Point. Jacques pecked very gently at Millie's shoulder; she sat down in the tall grass, and both colts slipped under her wings.

Phyl did not arise to forage with Jacques in the morning, and we could not tell whether Phyl was alive or dead.The events of July 2 reminded us of behavior we saw in 2004 on the day before the colt named Woodstock died. At that time in 2004, the twin colts were 2.5 months old. On Woodstock's next-to-last day, he often huddled on the ground with head under wing. At least once, Peter Pan, the stronger colt, went over to Woodstock, settled down next to him, and spent many minutes looking at his twin, as seen in the picture below. We saw no full-blown agonistic displays or serious fighting between healthy and failing colts in 2004 or 2009. [Note added: No antagonism between healthy and dying colt in 2010 either.] After Woodstock's death, our notes show that the parents carefully examined the corpse, but we do not have extended observations like those for Phyl's death in 2009. Phyl's death (or incapacity followed by death) profoundly affected the behavior of Millie and Roy. It evoked memories of the poignant PBS Nature depictions of an obsessive female chimpanzee who carried the corpse of her deceased infant for many days. Unusual behaviors associated with dying or death have been reported for many species, including primates¹ and elephants².

[See also the Comment below from Roger Payne, who describes the behavior of two helper whales when another whale is ill or dying. As to what emotion underlies such behavior, Roger prudently notes: "I think that the only answer is that we still don't know what emotions species experience..."]

We can't put ourselves inside the head of another species, but behavior reflects physiology. The cranes' behavior on July 2^nd indisputably reflected their arousal and is consistent with a distressed emotional state. Repeatedly, Roy and Millie interrupted their foraging to return to the Cattail Point and to linger near Phyl in what we term a "visitation". At the end of the day, all three cranes danced with fierce intensity.

Five minutes after the family had begun their first morning dragonfly safari, Roy returned alone to Cattail Point to stand next to Phyl. Once there, he craned his neck and peered at the fluffy colt for about five minutes. He appeared to offer an insect to the ground; then he rejoined the hunt in the deep grass. Six minutes later, all three cranes stopped harvesting insects and came back to Phyl. Roy and Jacques stayed briefly but Millie spent 28 minutes preening.

Diverse authors have recounted behavioral disruption after the death of a related crane. One of the earliest dates from about 500 BC. The Ramayana, one of the great Sanskrit epic poems of India, describes similar behavior after the death of a Sarus Crane. In this classic, the Hindu sage Valmiki recounts the anguish of a female Sarus who wailed interminably after her mate had been killed by a hunter³. Likewise after the death of his mate a few decades ago, a Red-crowned Crane stood vigil for days over her frozen corpse in the demilitarized zone between North and South Korea (see George Archibald's comment below). Finally, Eugenia Bragina (comment below) reports that Siberian Crane parents were attentive to the corpses of colts at the Oka Crane Breeding Center.

Were these visitations of Roy and Millie in 2009 merely to check Phyl's status? Perhaps she was still alive but incapacitated and they were waiting for Phyl to revive? During their many visits to Phyl's body, there was no hint of scavenging nor any behavior remotely resembling the savage butchering of the duckling on the previous evening.

Roy visited Cattail Point briefly three more times (2, 7, and 15 minutes) in the morning, sometimes uttering low vocalizations that were just audible to us one hundred meters away. Shortly after he rejoined the others in foraging, it became Millie's turn to visit Cattail Point. She preened, walked around Phyl, examined her closely, and bent down so that the underside of her beak was close to the immobile mass of feathers. She made two more visitations (2 and 7 minutes). At noon, the whole family walked over to the roost site. In the picture above, the adults are preening. Phyl is in the grass to Jacques' left.

In the early afternoon, the family hunted. At 3:15 PM, Roy spent 45 minutes in Phyl's vicinity, looking, preening, stepping around her body, and then somewhat curiously, going through ritualized slow head movements: turning left, bending down and picking up something (perhaps a piece of grass, a twig or blade of cattail), and then turning right, bending down, and apparently dropping the object. The motor pattern was indistinguishable from nest-building that we have watched each May. He repeated the sequence as if he was starting to make a pile of grass beside the body. Then Roy shifted slightly to one side and made another "pile" in a new place. In the picture below, Phyl is barely distinguishable in the grass at lower right corner. Roy stands on guard and Millie is bending down in a typical nest building stance as she holds a brownish bit of cattail blade in her beak.
In her Master's thesis written over thirty years ago, Karen Voss described repetitive ritualized placement of twigs and grass when Greater Sandhill Cranes built their nests in Wisconsin. She also observed ritualized nest-building in 6-month-old cranes, even though these young birds had no actual nest site.⁴ But for this July 2 episode, we haven't seen nest building behaviors except in early May.

There were more visitations in late afternoon and early evening. Four more times, Millie or Roy initiated grass-piling bouts. In three cases, the pile, had it been visible, would be located beside Phyl and once on top of her body. Just before roosting time, all three cranes walked to bog central and foraged.

The sun was sinking behind the west ridge, creating long shadows like that produced by Roy's neck (above) and broad bright and dull stripes across the grass (below).

At 9:52 PM, Roy stepped into a stripe of sunlight, jumped, and all three cranes began to dance explosively. They danced and danced and danced on the dramatically side-lit grassy stage. Even Jacques, barely three weeks old, joined in with gusto. Fortuitously, Christy's cameras were focused on bog central when the dance erupted for three minutes and 107 photographs. After the dance coda, Roy walked forward into shadow and stood for a minute or more. Then all three cranes returned to roost at Cattail Point. Roy slept standing on one leg; Millie settled down next to Phyl's body, and Jacques climbed under her wing. For more images go to Christy Yuncker Photo Journal .
The memorable dance was neither frenetic nor flailing. It was extended in duration, intense, and very fast, but the moves were controlled, fluid, graceful, and balanced. Each bird exhibited with high energy, and yet all three were attuned. The photo above shows Roy as he dashed from the right in front of Millie who is at the apex of a spectacular Run-flap-glide with wings held straight out. As she landed, Roy wheeled to face her and bowed in a Wing-spread-forward-tilt display (see Quicktime movie below). Then he spread his wings, jumped, and turned left to engage Jacques in a Wing-spread-hold face-off. The movie below shows a 4 second segment of the overall dance that lasted 160 seconds. See also the link to our Photo Gallery.

The intensity and duration of the dancing after the death of Phyl strongly suggests that dancing provides emotional release for cranes. It is widely recognized that dancing strengthens and reaffirms the pair-bond, and in this instance, dancing probably reinforced family solidarity and and promoted continuity.

All summer from May into August, Roy replaces his flight feathers, one-by-one. During the vigorous dancing, several old feathers fell out and floated to the grass. The photo below was taken just after the finale of the solidarity dance. Roy is walking toward us. A loose whitish primary feather that is dropping from his left wing has been highlighted by the sunlight.
In the days since, Roy and Millie carry on as characteristically attentive crane parents, feeding and guarding Jacques as they guide his progress through core subjects of Foraging and Display/Dance.

When we first posted this blog, it had been a week since Phyl died. We had seen no dancing during that entire week. We monitored the pond all day; Phyl's body was not scavenged nor did the crane family returned to Cattail Point. After July 2, the cranes began to roost 50 meters to the east.

The photo to the right shows Phyl's skeletonized corpse on August 10 - 6 weeks after her death. Insects and bacteria have cleaned away flesh, but the body is still not scavenged.

For us, July 2 is unforgettable - repeated visitations to Phyl's body climaxed by what we call the Dance of Solidarity.

There are so many aspects of such behavior that need further study and explanation. For example, what is the adaptive significance of the ritualized grass-piling behavior?

For re-nesting? The grass-piling could be tentative restarting of nest-building in response to death of an offspring. In this context, "death of a colt" (reproductive failure) leads cranes to initiate another reproductive cycle. When eggs fail to hatch, a second nesting is common at lower latitudes where summer seasons are longer than Alaska.

For concealing the body? The grass-piling might be like a motor behavior module, a sequence of postures and movements driven by neural circuitry (a fixed-action pattern in classical ethology). Such a piling module could be used to build a nest or to hide a corpse that might otherwise atttract predators to the nest territory.

For grieving? Piling could be part of animal version of grieving behavior. Marc Bekoff has reported similar "funeral" incidents, in magpies (standing vigil for several minutes and piling grasses near a dead magpie at the side of a road)⁵ and in a fox (piling dirt on the corpse of a fox killed by a cougar).⁶ Perhaps ritualized piling behavior has deep evolutionary roots and is somehow hard-wired in the nervous systems of birds and mammals?

Merely a general expression of stress? In classical ethological terminology, piling might be displacement behavior, as suggested by the comment below from Eugenia Bragina. George Archibald notes below that cranes dance when they are upset by some event, such as the approach of a predator. Perhaps grass-piling and the intense dance simply reflect emotional stress.

Emotions have physiological bases. In humans, grief behaviors include lethargy, subdued responsiveness, and bouts of wild emotional release. When medical researchers image the brains of people in bereavement, they see localized brain centers light-up in MRI scans and proinflammatory cytokines increase as well.^7,8 Since both birds and mammals descended from primitive reptiles, their brains have similar basic architectures, but the final placements of cognitive brain centers evolved along different trajectories. Facile generalization from human data to bird neuroscience is not legitimate since similarities in detailed function of the higher cognitive centers are unproven. But from a behavioral perspective, the visitation bouts and solidarity dancing in cranes show parallels with human grieving - in some senses, reminiscent of an Irish wake. Putative parallels in physiological correlates, such as inflammation and activation of brain nuclei, are intriguing starting points for further comparative research.
In the words of Peter Marler⁹:

"...emotion-based displays can of course convey a lot of information."

We suspect that both emotional and cognitive factors contributed to the displays and other behaviors we witnessed after the death of Phyl.

We know that Phyl expired sometime on July 2, but we can't determine the exact hour or minute. The parent visitations over the day might have been for monitoring a dying colt (the behavioral expression of crane solicitude) or grieving at her death. The prolonged dance at day's end certainly reflects arousal that stems from heightened intensity in the crane version of emotion. Some may contend that it is presumptuous to apply a term like grieving with its subjective overtones, because we cannot precisely specify the underlying physiological correlates. But passing off these striking behaviors as mere "displacement" flies in the face of the evidence.

We welcome your reactions to our blog. If you have relevant interpretations or observations that you are willing to share with others, either click on the word "Comment" at the bottom of this blog or email us directly. With your permission, we will paste your email as a Comment below.

References cited:
1. Citations in LiveScience column entitled "Grief: the price of love" by Meridith F. Small.
2. Citations on Elephant information website.
3. Hammer N 2009. Why Sarus Cranes epitomize Karunarasa in the Ramayana. Journal of the Royal Asiatic Society, Ser 3 19:187-211. See also Ali S, Ripley SR 1983. Handbook of the Birds of India and Pakistan, Compact Edition, II. Delhi, Oxford University Press.
4. Voss KS 1976. Behavior of the greater sandhill crane. Thesis for Master of Science in Zoology, University of Wisconsin-Madison.
4. Bekoff M. 2007. Are you feeling what I'm feeling? New Scientist. 26 May 2007, p. 44 (Grief).
6. Bekoff M. 2009. A fox, a cougar, and a funeral. Psychology Today blog
7. O'Connor MF, Irwin MR, Wellisch DK 2009. When grief heats up: Pro-inflammatory cytokines predict regional brain activation. Neuroimage May 29 Epub.
8. O'Connor MF, Wellisch DK, Stanton AL, Eisenberger NI, Irwin MR, Lieberman MD, 2008. Craving love? Enduring grief activates brain's reward center. Neuroimage 42:969-72.
9. Marler P 2004. Bird songs: a cornucopia for communication. In Nature's Music: The Science of Bird Song, P. Marler & H Slabbenkoorn (eds.),132-177. Elsevier, Amsterdam, p. 172.

Revised April 16, 2010.

Alaska Crane Kindergarten

2009-06-18T19:45:00.169-08:00

---For photos on the Christy Yuncker Photo Journal webpage, click here.

Sandhill Crane colts are intensively tutored from day 1. For their parents, summer school teaching is a 24/7 job. The three core subjects (crane versions of the three R's) in Colt School are: Foraging, Display/Dance, and Flying, each of which addresses biological imperatives: nourishment, socialization, and migration. We think of the 14 days after hatching to be crane kindergarten, when the curriculum stresses Foraging first and Display/Dance next.
Crane colts run about on the day they hatch; they are physiologically precocial. Body plan, brain anatomy, and motor abilities are genetic, encoded in their DNA just as for every crane generation over 10 million years. Yet colts don't scatter like a brood of leghorn chicks for they are far from self-sufficient.

Young colts require parental protection and instruction for many months; effectively they are behaviorally altricial. For cranes as for people, nature enables and nurture refines. The genetic program provides only a framework that roughly defines capacity and potential. On hatch day in mid-June in Alaska, colt schooling begins to shape and expand the native talents.

Foraging: Life is especially fragile in the first week. As the colts struggle to cope with the sensory storm in the bright new world outside the egg, they learn not only to avoid predators but also to distinguish food from pebbles and sticks. From hatch day forwards, parents devote most of their days to searching for suitable food items and offering them to the hungry colts, as illustrated by 10-day old Phyl accepting food from Millie in the picture below.

Food items may be frightening or the packaging formidable. To the right, Roy has caught a dragonfly that he offered to 3-day old Jacques. The colt looked baffled. Next, Roy dismembered the insect and successively fed the isolated head (a neat package), the thorax and the abdomen. Jacques was more interested in the next dragonfly presented to him. Perhaps the most impressive meal of this season was a dead ducking. This ungainly package of protein frightened even Millie at first. But Roy picked the duckling up by the neck (photo below) and then shook repeatedly until he could extract small bits of flesh that he passed to each colt.
For at least 14 hours each day during the first week after hatch, Roy and Millie scoured the grass for insects. At seven days of age, both colts were thriving. By ten days of age, they were beginning to peck at morsels on the ground, although most of their nourishment came via parent's beak.They had transformed from bumbling stumbling little butterballs to full partnership in the foraging foursome at twelve days of age, as shown at the end of this blogpost.

Displaying/Dancing: Many scholarly publications emphasize the easily-viewed aggressive encounters in mobs of cranes at staging and roosting areas. These flashy in-your-face displays often involve 1-2 year old birds that are probably pre-reproductive. Similar postures are used by older birds to defend nest territory. But agonistic signals are only one chapter in the display/dance lexicon. Amid the the crush of adolescent face-offs on the Platte River shallows during the annual "March Melee," mated pairs of cranes dance in synchrony with one another, like teen-age lovers oblivious of the hubub in the surrounding crowd on New Year's eve in Times Square.

Crane dancing often involves a mated pair, but cranes dance solo as well. Dancing generally reflects a positive emotional state. In the June 11, 2009 blogpost, we described Roy's joyous dance upon return from migration; this was largely a solo performance but also involved Millie as she dashed across the ice. Another example is shown to the right - Roy dancing alone in early evening at the center of the marsh on colt day seven (2009). It was his first dance since hatch days. He jumped and ran while Millie nestled, thirty meters away, with sleeping colts under her wings (see hyperlink for image). It is tempting to think that Roy's dance expressed elation: after an exhausting first week of non-stop parenting, both colts had survived and were healthy. Dancing of a pair promotes reproductive synchrony. The dancing of Roy, Millie, and Jacques after the death of Phyl effectively promoted family solidarity and provided emotional release (blogpost of July 10, 2009)

In some cases, we may not see dancing for weeks. In 2009, Roy did not dance during incubation yet he danced briefly alone (spontaneously) on the evening of June 10, the hatch day of Jacques and again on June 11, the hatch day of Phyl. In 2008, we observed no dancing by Roy in late July or through August, during the 6 weeks while his colt recovered from an injury, but then Roy began to dance again when the colt finally began to fly (see hyperlink and May 20, 2009 blogpost).

Displays and dances are communications. Crane displays involve posture, movement, timing, and context. In order for us to understand fully the displays of cranes, we need to construct a catalog of the complex moves and try to asses their meanings from the worldview of a crane. Body language, loud calling (long distance), and soft purring (short distance) are the channels for the social messaging networks of cranes. Displays can deliver information with a single unambiguous posture (leaning forward as a signal to fly or jumping back when startled), or with sequences linking several dance steps (jumping and turning), or through a series of multi-step sequences flowing together and lasting for seconds or even minutes.

Dancing is a spectacular distinguishing behavior of cranes. As noted by Ellis and his coworkers, the rich repertoire of stereotyped displays and postures puts cranes at one apex of social complexity in the animal world¹.

A display can be a a single statement or a part of a conversation. Dance is not just an announcement of territory or of mood, but also allows two-way information exchange. Just as bird music is divisible into notes, phrases and full songs, so crane dancing is divisible into steps, sequences, and full dances. For a mated pair, dance sequences are complementary and responsive to the partner. Dance is an important cement for crane social structure, and dance proficiency requires years of practice.

There are parallels between dancing and bird song. The full adult song of many passerine birds depends not only upon innate ability but also learning. The "song system" has been extensively studied². The sequence is listening, storage, retrieval, early motor output, and then practicing and practicing until the full adult song crystallizes. Young 3-month-old birds listen to songs of experienced adults and store those memories in a precisely localized brain nucleus. It is only later at 7 months of age, that they begin to sing under the control of another nucleus in their brains. The first attempts are choppy but with time and practice, young birds become good enough to mimic the songs heard 4 months earlier. Thus song output is initiated and refined at one site in the brain that draw upon memories stored in another site.

Cranes are born with the capacity for dance but early attempts are halting. Anatomy and neurocircuitry allow dance postures and movements, but for cranes as for the Bolshoi ballet, repetition helps movements appear to be effortless and the sequencing to become liquid. For a colt, we see a three step lesson-plan for display/dance training: 1) motivation by adult and observation by colt, 2) imitation, and 3) complementary response to adult steps. Display training for crane colts can begin as early as day 4. Just before the photo on the left was taken, Roy and Millie gave little jumps that caused both colts to watch in rapt attention. Then tiny Jacques (colt in the middle right, above) faced off to Roy in a forward display . As Roy stretched out both his wings, Jacques

mimicked his father with his own tiny wing stretch (left image above). The enlargement to the right lets you see the little guy better. During kindergarten, dance training stops at imitation, step 2 of the lesson-plan.

Only this year, we discovered that colts display with one another. The picture to the left shows Roy probing for food while Jacques and Phyl (4 days old) face off to one another. Jacques is jumping in a baby wing stretch directed toward Phyl. It is possible that this baby display is a baby face-off - precursor of the behaviors of teenagers jumping on the shallows of the Platte.

Graduation from kindergarten is marked by efficient family team foraging. The "four gunslingers" in the photograph below are a formidable sweeping machine for harvesting dragonflies. Twelve-day old colts move smoothly as they flap their front appendages (wings) and run between their parents. In the coming weeks, the colt-parent pairs will forage together on the home marsh. In addition, the family will begin exploratory day-trips to adjoining bogs. Except for physical conditioning during foraging and dance training, flight school lies a month ahead.

References cited
1. Ellis DH, Swengel SR, Archibald GW, Kepler Cb 1998. A sociogram for cranes of the world. Behavioral Processes 43:123-151.
2. Marler P 2004, Slabbenkoorn H (eds.)2004. Nature's Music: The Science of Bird Song, Elsevier, Amsterdam.
Revised July 12, 2009

Return to nestsite and hatch of twin colts

2009-06-11T20:46:00.118-08:00

---For photos on the Christy Yuncker Photo Journal webpage, click here.

Our 2009 spring snowfall was heavy; the Fairbanks cross-country ski season lasted into mid-April. Last year's grasses and cranberry bushes are poking above the shrinking snow cover on April 29 as a pair of sandhill cranes drops through the gentle light of early evening onto our Goldstream Valley pond. The signal skin atop their heads is turgid with blood; each bird sports a crimson helmet. They join in unison calls, his pulsating and hers a double note.

Roy dances at 11 PM in the fading light that renders him monochromatic. Dark, severe, silhouetted against the rough gray ice.
He vocalizes as he spins - crouching, turning, wings outstretched, jumping, wings folded tight to his body, like an avian Baryshnikov dervish, whirling on an empty stage. Joy! Rapture! Triumph! Home again! Relief!

We cannot document the neurological mechanisms driving this showy behavior, but we believe that it has physiological and subjective correlates akin to those of emotion. In our view, to dismiss emotion as a contributor and to dogmatically categorize such arousal as mere "displacement" is to ignore objective evidence.

Millie darts past Roy as he dances solo, focused. Two hundred and thirty days and over seven thousand miles since he flew south from this place with Millie and Oblio on a bright September morning in 2008.

One or two primary feathers are missing on Roy's left wing, showing that cranes replace their flight feathers one-by-one, even during a migration. Apparently the demands of nesting and fledging in the short summer season at 65 degrees North allow no flightless "down time" when all feathers could be regrown simultaneously (see Rowher link).

The Quicktime movie below shows some of the steps in Roy's jumping turn, or tour jete. For more of this dance, see Christy Yuncker Photo Journal.

Gulls harassed the crane pair as they settled in. Other crane couples and single intruders threatened the territory but Roy and Millie held firm.

The pair meticulously inspected the bog for a week. Repeatedly, Roy picked up grasses and twigs (below, left) and gently initiated nest building but Millie vacillated. They mated several times.

Then on May 9, though a narrow opening between spruce trees, far across the cranberry bog, we saw Millie sitting in tall grass (above, right). Tedious incubation duties alternated every 3-6 hours for 30 days, with Roy's shifts tending to be longer. He did not dance throughout incubation, but during respites off the nest, he frequently called. When a crane answered from across the valley, Roy flew toward the response and was absent for a few hours.

On at least two occasions a strange crane landed on the bog while Roy was absent. Millie came off the nest, calling as she confronted the new crane. Roy reappeared quickly, flying from across the valley and landing with legs forward in kicking-attack mode directed toward the interloper on the far right in the picture. The intruder flew away immediately and unison calls followed.

Neither crane left the nest vicinity on June 9 or 10. On the evening of the 10th, Roy walked from the nest area to the center of the bog, fed briefly, and broke into by a short energetic dance. He repeated the performance early next morning.

Minutes later, we spied the heads of two minuscule crane colts, barely visible as they stumbled through the sedges and cottongrass, waving their stumpy wings. The family of four now prospects for food among pinkish low-bush cranberry blossoms and white laborador tea. After a sedentary month, the adults have become harvesters, seizing juicy caterpillars and adult dragonflies and even birds (see next post) that can be dismembered and brandished gently to the vocal colts we named Jacques and Phyl.

Crane parents compensate for colt's injury

2009-05-20T15:58:00.034-08:00

---For photos on the Christy Yuncker Photo Journal webpage, click here.

Each colt is an individual. If a colt is injured, adults can compensate and delay their migration - apparently waiting for the colt to become flight-competent. We saw such compensation in 2008.

By 18 days of age, Oblio-08 was running
about waving her tiny wings in tandem with Roy (pictured to the right). But in early July, she began to favor her right leg, suggesting an injury. Although she continued to grow, she was physically hampered. For some weeks Oblio rarely ran and did not dance, jump or bound. Roy and Millie postponed the basics of colt education and physical conditioning an tarried in Alaska to give her a chance to catch up.

Throughout June and July, Millie and Roy (the parents) were attentive, protective and frequently offered food. Yet Oblio seemed solitary, foraging 20-30 meters from her parents. (For photos, see Christy Yuncker Photo Journal) In contrast to other years, Roy and Millie danced little with each other and not at all with Oblio, perhaps reflecting their emotional state?

As the leg slowly healed, Oblio began to run a little and to flap her wings again in mid-August. Roy and Millie ran with her and then gave flight demos around the pond. As shown on Christy Yuncker Photo Journal, Oblio managed to lift off on August 26 at 74 days of age - two weeks late. Over ensuing days, Oblio tried several short flights around the pond. She gained competence and confidence.

On the morning of August 31, Roy and Millie spent hours purring, as if coaxing Oblio to fly. Finally, after several abortive attempts, all three lifted off. Oblio flew with her right leg hanging down, but they cleared the trees and disappeared across the valley. Three hours later, the cranes returned; the rest of the day was spent in preening and feeding.

Dancing became a staple activity of the family. Millie, Roy, and Oblio spent the next ten days feeding (every two hours) and dancing as a group of three - the first dances we had seen for over a month. Several times each day, the family flew off for an hour and then returned. At first, Oblio rested in the grass after these flights. At night, the family roosted across the valley (2-3 km distant).

Early September weather was mild and with each day, Oblio grew stronger. By September 10th, she was able to keep up with her parents (see Christy Yuncker Photo Journal).

On the morning of September 11, bouts of feeding and preening alternated every hour. At 11:05 AM, the three flew off to the south, then turned west down the valley and disappeared, departing (we hope) on their migration south. Departure had been delayed for almost two weeks while Oblio gained strength, yet the timing was auspicious since the first serious frost occurred only four days later.

Yumin Guo has described similar parental solicitude in response to injury of a hooded crane colt.

The origins of the Alaska Sandhill Crane blog

2009-05-19T16:03:00.031-08:00

This blog and the complementary webpage, Christy Yuncker Photo Journal, developed from our fascination with a pair of Sandhill Cranes who return each summer to Alaska. For the past several years, they have nested on a cranberry bog in Goldstream Valley, a few miles north of Fairbanks. Cranes are migratory, coming to Alaska only for the summer months. John Wright, a wildlife biologist for the state of Alaska, has tracked a banded crane from Fairbanks for 3100 miles, to stop-over sites on the Platte River in Nebraska and finally to a wintering site near Snyder, Texas.

We refer to our crane pair as Millie and Roy. Over 14 seasons, we have watched cranes arrive in late April/early May, court one another with calls and dances, mate and nest, feed and educate their colts (young cranes), communicate with neighboring cranes in the valley, and leave in early September for the long southward migration.

The summer season in Interior Alaska is barely long enough for the crane reproductive cycle. When the adults first drop from the sky to the surface of the bog, snow covers the grasses and cattails and the open pond is solid ice. As incubation starts in the second week of May, the ice gradually darkens and then melts during daylight but often reforms when darkness falls. The weeks pass quickly as the adults raise their colt(s) and teach motor and social skills. In most years, young colts first lift off the bog in mid-August and then must practice hard to become airworthy in time for migration at the end of the month.

We learn first-hand from watching, listening, photographing, recording, and then contemplating. When we tinker with Nature, we affect not only other species but also ourselves.

As you read this blog and look at our webpage , we hope that you will share your own observations and offer interpretations for all readers to consider.

Please post your comments directly on this blog, or email them to ghapp@uvm.edu. We are particularly interested in the education of the colts and in the cross-talk among cranes within a neighborhood. Our goal is a better appreciation of the "world view'" from a crane's perspective, with hopes that better cross-species understanding can promote crane welfare.

1. Stimulus (object seen in crane's vicinity)	2. Location Coordinates	3. Compare to Previously Stored Memory	4. Response
Spruce tree	1234, 4567	Spruce tree	Ignore
Poplar tree, leaves	1234, 4588	Poplar tree, no leaves	Update memory
Green grass on SE bank of pond	1234, 4592	Brown grass on SE bank of pond	Update memory
Red fox on SE bank	1234, 4592	New Item and a known Potential Predator	DANGER, attack
Birch tree, no leaves	1234, 4576	Birch tree, no leaves	Ignore
etc.	etc.	etc.	etc.