Ted,
You offer (what amounts to) instinctual pattern recognition as an explanation of the success of the nutcrackers in finding a stash. If your hypothesis is true, then birds will just store and look where they always store and look. There will be a certain inflexibility in how they look for their stored seeds.
However, here's evidence (abstract from the 5 Jul 2009 issue of Animal Cognition) that memory, rather than instinctual pattern recognition, explains the success of nutcrackers in finding thousands of stashes of pine seeds -- up to 9 months after burying them:
************************
Landmark use by Clark's nutcrackers (Nucifraga columbiana): influence of disorientation and cue rotation on distance and direction estimates.Department of Psychology, University of Saskatchewan, 9 Campus Drive, Saskatoon, SK, S7N 5A5, Canada, debbie.kelly@usask.ca.
Many species have been shown to encode multiple sources of information to orient. To examine what kinds of information animals use to locate a goal we manipulated cue rotation, cue availability, and inertial orientation when the food-storing Clark's nutcracker (Nucifraga columbiana) was searching for a hidden goal in a circular arena. Three groups of birds were used, each with a different goal-landmark distance.
As the distance between the goal and the landmark increased, nutcrackers were less accurate in finding the correct direction to the goal than they were at estimating the distance (Experiment 1). To further examine what cues the birds were using to calculate direction, the featural cues within the environment were rotated by 90 degrees and the birds were either oriented when searching (Experiments 2 and 3) or disoriented (Experiment 3). In Experiment 4, all distinctive visual cues were removed (both internal and external to the environment), a novel point of entry was used and the birds were either oriented or disoriented.
We found that disorienting the nutcrackers so that they could not use inertial cues did not influence the birds' total search error. The birds relied heavily but not completely on cues within the environment, as rotating available cues caused them to systematically shift their search behavior. In addition, the birds also relied to some extent on Earth-based cues. These results show the flexible nature of cue use by the Clark's nutcracker. Our study shows how multiple sources of spatial information may be important for extracting multiple bearings for navigation.
PMID: 19579038 [PubMed - as supplied by publisher]
************************
Recap:
If instinctual pattern recognition explained the success of the nutcracker in finding things, then "memory" would be inflexible (the birds would look where nature has "trained" them to look, and not elsewhere). However, this study shows that the birds' use of cues is flexible and non-absolute.
Ed
(Edited by Ed Thompson on 10/15, 6:32am)
|
