Saturday, May 22, 2010

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

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?

Saturday, May 1, 2010

Walkabouts, local ecology, and the importance of novelty

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?