Learned Cache Retrieval

Psychologists refer to the time of memory used in learned cache retrieval as "episodic memory". This means that the memory is attached, or associated, with a specific experience in an animal's life. In this model, for the caching animal, each caching event is an episode which is stored in memory. Birds in the families Paridae (chickadees and their relatives) and Corvidae (jays, crows and their relatives) are champions at retrieving cached food from remembered locations.

The easiest experimental approach to determine if learning is involved in cache retrieval is to allow an animal to cache food in a observation area (this could be a natural home range, if the behavior can be seen throughout the area, or an enclosure). The rate of cache recovery is then observed and compared with that of a second animal is then allowed to search the area. Generally both animals are not present at the same time, but the investigator may allow sequential cache-retrieval by the animals to control for the effect of cache depletion on the rate of discovery. In this type of experiment, which has been conducted using both birds and mammals, the caching animal has a significant advantage over the other animal in finding food, and data to this effect are taken as supporting the learned retrieval hypothesis.

Whenever an experiment is done to test the hypothesis of learned cache retrieval, two alternative hypotheses, reforaging and search by rule, must always be considered.

Balda R P, Kamil A C 1992 Long-term spatial memory In Clark’s nutcracker, Nucifraga columbiana. ANIMAL BEHAVIOUR 44 (4): 761-769
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Tomback D F 1980 How nutcrackers find their seed stores. CONDOR. 82 (1): 10-19
Brodin A, Lundborg K 2003 Is hippocampal volume affected by specialization for food hoarding in birds? PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON SERIES B-BIOLOGICAL SCIENCES
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Moller A, Pavlick B, Hile AG, Balda RP 2001 Clark's nutcrackers Nucifraga columbiana remember the size of their cached seeds. ETHOLOGY 107 (5): 451-461
Vander Wall SB 2000 The influence of environmental conditions on cache recovery and cache pilferage by yellow pine chipmunks (Tamias amoenus) and deer mice (Peromyscus maniculatus). BEHAV ECOL 11 (5): 544-549

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