Assessment of contrafreeloading preferences in giraffe (Giraffa camelopardalis).

Contrafreeloading is an intriguing phenomenon in which animals will work to obtain resources, such as food, when the same resource is simultaneously freely available. Multiple hypotheses exist for why animals might choose to contrafreeload. In this study, we assessed preferences for contrafreeloading in giraffe at the Bronx Zoo to determine whether they actually preferred to contrafreeload or were simply demonstrating a willingness to contrafreeload. Food was presented in a range of distributions between an easily accessed feeding device and a more challenging one and the giraffes' feeding behavior at these two types of feeding devices was recorded. As the experiments progressed, more giraffe used these more challenging feeders. There was significant individual variation in the expression of preference for contrafreeloading and willingness to contrafreeload. Individual, phase of the experiment, and an interaction between these factors were significant predictors of challenge feeder use. Three foraging strategies emerged among the giraffe that we termed "freeloaders," "contrafreeloaders," and "opportunists." The results of this study demonstrate that multiple indices of preference are necessary when assessing contrafreeloading behavior, and that giraffe are affected to different degrees by the factors that stimulate contrafreeloading. These results may shed light on why different individuals use complex feeding enrichment devices to varying extents.