Grizzly bears in captivity will engage in contrafreeloading- which is where an animal works to obtain a reward that they already have freely available to them. While there are many theories regarding why animals engage in this behavior, it is agreed that zoos should explore contrafreeloading as a foraging enrichment strategy. 

[Photo and caption by Isabelle McDonald-Gilmartin]

Reference: McGowan, R. T. S., Robbins, C. T., Alldredge, J., & Newberry, R. C. (2009). Contrafreeloading in grizzly bears: implications for captive foraging enrichment. Zoo Biology, n/a. https://doi.org/10.1002/zoo.20282

[Edited by Ian Ramshorn Haliburton]