bagvette

Bugnyar T, Heinrich B.

Department of Biology, University of Vermont, Burlington, VT 05405,
USA. thomas.bugnyar@univie.ac.at

Human social behaviour is influenced by attributing mental states to others.
It is debated whether and to what extent such skills might occur
in non-human animals. We here test for the possibility of ravens
attributing knowledge about the location of food to potential competitors.
In our experiments, we capitalize on the mutually antagonistic interactions
that occur in these birds between those individuals that store food
versus those that try to pilfer these caches. Since ravens' pilfer
success depends on memory of observed caches, we manipulated the view of birds
at caching, thereby designing competitors who were either knowledgeable or ignorant
of cache location and then tested the responses of both storers
and pilferers to those competitors at recovery. We show that ravens modify
their cache protection and pilfer tactics not simply in response to
the immediate behaviour of competitors, but also in relation to
whether or not they previously had the opportunity of observing caching.
Our results suggest that the birds not only recall whom they had seen
during caching, but also know that obstacles can obstruct
the view of others and that this affects pilfering.

PMID: 16087417 [PubMed - indexed for MEDLINE]