Field observations of time-place behaviour in scavenging birds.

Encoding the spatial location and the time at which significant biological events occur is thought to be a fundamental way in which one form of memory is organized in animals (Gallistel, 1990, The Organization of Learning. MIT Press, Cambridge, MA). If this is true, one would expect to find evidence of this process in a wide variety of animals and in a wide number of situations. We report field observations of scavenging birds at two outdoor locations at which people tend to congregate and eat food, primarily around midday. Scavenging birds appeared to anticipate this peak in food availability and arrived at these locations before the number of people was at a maximum; time of day, not the absolute number of people, was the best predictor of the number of birds at both sites. At a third location where food is not consumed this relationship was not observed. Taken together these observations support the notion that animals represent the spatial and temporal characteristics of biologically important events and use this knowledge to forage efficiently.