Unraveling the behavioral mechanisms behind contrafreeloading

Ragen Marie Trudelle-Schwarz McGowan

doi:10.7273/000005784

Contrafreeloading occurs when animals choose resources that require effort to exploit when identical resources are freely available. Though contrafreeloading is well documented across species, little is known about the mechanisms behind the development of this behavior. This dissertation encompasses three projects which provide new insights into contrafreeloading in three species: grizzly bears, chickens, and mice. Two experiments were conducted with captive grizzly bears to assess information primacy as a theoretical foundation for foraging enrichment. Contrafreeloading was examined in response to concealed food. Bears spent more time manipulating devices that contained concealed food than devices without food, showing that they were motivated to explore concealed resources. Bears did not always consume extracted food suggesting that consumption is not an exclusive motivating factor of foraging behavior. Three experiments were conducted examining food choice in domestic fowl. To better understand apparent sex differences in foraging tactics in this species, two experiments were conducted in which sex hormones were manipulated. Contrafreeloading behavior, based on level of preference for foraging on small food particles in the presence of larger particles, was compared between treatments. In a third experiment, sex differences were investigated directly, comparing contrafreeloading among hens and roosters. Contrary to prediction, there was no effect of steroid treatment on contrafreeloading behavior. The behavior of roosters was consistent with predictions for energy maximization and hens showed variability in contrafreeloading tendencies. Little is known about motivation in relation to contrafreeloading. A consumer demand approach was utilized, requiring mice to pay a ‘cost’ to gain access to foraging resources to assess the strength of motivation of mice to contrafreeload. Despite increasing costs, motivation remained high for accessing all resources provided. Mice were most strongly motivated to access a contrafreeloading opportunity and non-nutritious food items, suggesting that mice may actively seek opportunities to engage in behavior that allows for information gain in relation to unconventional resources. These studies of contrafreeloading behavior demonstrate that, when housed in captivity with access to reliable, easily exploited food sources, animals may retain a seeking motivation that is adaptive under natural conditions, where survival is dependent upon finding food in an unpredictable environment.

Unraveling the behavioral mechanisms behind contrafreeloading

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