Seminar: Hidden on a midden

Hoarding provides animals access to resources during periods of scarcity. Studies on mammalian hoarding indicate effects of morphology and ecology but are biased to a subset of rodents. Whether the behavior is generalizable at other taxonomic scales and/or is influenced by other ecological factors is less understood. Population density may influence hoarding due to food competition, but this remains untested. Additionally, hoarding may leave animals vulnerable to predation as they bury or exhume food from caches because they are less vigilant. Predation may therefore select pelages that match the substrate color of cache locations, via background matching crypsis. Using phylogenetic analyses, we assessed the role of ecology on hoarding evolution at multiple taxonomic scales. We also used a long-term dataset on caching behavior of southwestern red squirrels to test key ecological factors on hoarding intensity. Wheras population density was strongly related to hoarding evolution at all taxonomic scales, climate influenced hoarding to a lesser extent. Finally, we tested whether hoarding behavior in squirrels was related to pelage color via background matching using spectrophotometry and visual discrimination models. We found support for the background matching hypothesis at cache locations, suggesting predation during food hoarding can drive interspecific phenotypic variation based on crypsis. I will discuss our findings in relation to the mangement and conservation of Mt. Graham red squirrels.

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