Food caching in city birds: urbanization and exploration do not predict spatial memory in scatter hoarders.

Abstract

Urbanization has been shown to affect the physiological, morphological, and behavioral traits of animals, but it is less clear how cognitive traits are affected. Urban habitats contain artificial food sources, such as bird feeders that are known to impact foraging behaviors. As of yet, however, it is not well known whether urbanization and the abundance of supplemental food during the winter affect caching behaviors and spatial memory in scatter hoarders. We aim to compare caching intensity and spatial memory performance along an urban gradient to determine (i) whether individuals from more urbanized sites cache less frequently and perform less accurately on a spatial memory task, and (ii) for the first time in individual scatter hoarders, whether slower explorers perform more accurately than faster explorers on a spatial memory task. We assessed food caching, exploration of a novel environment, and spatial memory performance of wild-caught black-capped chickadees (Poecile atricapillus; N = 95) from 14 sites along an urban gradient. Although the individuals that cached most in captivity were all from less urbanized sites, we found no clear evidence that caching intensity and spatial memory accuracy differed along an urban gradient. At the individual level, we found no significant relationship between spatial memory performance and exploration score. However, individuals that performed more accurately on the spatial task also tended to cache more, pointing to a specialization of spatial memory in scatter hoarders that could occur at the level of the individual, in addition to the previously documented specialization at the population and species levels.