Use of open, edge and forest areas by pumas Puma concolor in winter: are pumas foraging optimally?

Optimal foraging theory predicts that an animal should optimize its time spent in food patches based on resource levels and, if preyed on by another species, predation risk. In large mammal predator‐prey systems, previous studies have suggested that prey do consider predation risk when foraging and tend to avoid high‐risk areas. In contrast, if large mammalian predators are trying to optimize their foraging, we predict that they should select these high‐risk areas because such areas represent higher predation success. For pumas Puma concolor in southeastern Idaho, previous work showed that edges of forests were the most successful hunting areas for mule deer Odocoileus hemionus compared to open and forest areas. We tested the prediction that pumas should optimize their foraging strategies by selecting edge areas during periods of movement. We followed puma tracks in the snow and recorded for every 20 m whether the pumas had been in an edge, open or forest area. We used a resource selection function and composition analysis to test if pumas were preferentially selecting edge areas over open or forested areas. Based on the resource selection function, pumas were four times more likely to use edge than open areas, but used edge and forest areas equally. Results of the composition analysis indicated that pumas also used edge areas significantly more than open but similar to forest areas. As pumas were selecting edge areas and avoiding open areas to forage, these results indicated that pumas may be foraging optimally. However, the equal use of edge and forest areas did not support our predictions, and we discuss possible explanations of these results.