Spatial Memory in Hoarding and Nonhoarding Tits (Paridae)
Sara J. Shettleworth University of Toronto
Some birds and mammals store food in scattered locations and find it again days, weeks, or even months later using memory ( Sherry, 1985). The analysis of their memory incorporates the methods and insights of natural history, behavioral ecology, animal cognition, comparative psychology, and neuroscience. I begin this chapter by briefly reviewing what we know about memory in food-storing birds, particularly the chickadees and titmice (Paridae). The importance of good spatial memory for a food-storing way of life raises the question whether memory for stored food is in some sense an adaptive specialization ( Rozin & Kalat, 1971). The main part of the chapter describes some results from a program of research that has tackled this question by comparing memory for stored and encountered food in storing species and by comparing memory of storing and nonstoring species in a variety of tasks.
The study of memory in food-storing birds is one of the best examples of how a naturally occurring memory phenomenon can be analyzed with all the tools behavioral biology has at its disposal in what Kamil ( 1987) has termed the synthetic approach to animal intelligence. To begin with, formal modeling has been used to argue that food storing will only evolve if individuals have either highly specific site preferences or memory for the locations of their own hoards ( Andersson & Krebs, 1978). Otherwise, "cheaters" who pilfer others' stores without investing any effort in storing themselves will have an evolutionary