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Abstract

Mast seeding by oaks (Quercus) and other seed species has fundamental impacts on the behavior of individual scatter-hoarding animals as well as their population and community dynamics. Scatter-hoarding squirrels are highly sensitive to acorn germination schedule and stop germination by removing the embryo of non-dormant acorns to prevent losses of energy and nutrients by rapid germination. However, we know little about how this behavior is affected by mast seeding. We investigated foraging decisions made by free-ranging Pére David's rock squirrel (Sciurotamias davidianus) with three species that produce non-dormant seeds and two species that produce dormant seeds (Fagaceae) during mast and non-mast years in Central China from 2007–2010. Consistent with the food perishability hypothesis that squirrels make decisions to minimize the perishability of their caches, non-dormant seeds were hoarded at a lower rate, but had a higher probability of embryo removal than dormant seeds. Compared with non-mast years, a lower proportion of seeds were harvested during mast years, but a higher proportion of the harvested seeds were hoarded. In addition, the probability of embryo removal in the hoarded seeds was higher during mast years. Squirrels also dispersed seeds at shorter distances during mast years. Moreover, the interactions between mast seeding and seed germination schedule had significant effects on squirrel foraging decisions, including embryo removal. This study is the first to demonstrate that squirrels show greater sensitivity to seed germination potential when seeds are abundant.