IUCN / SSC Cat Specialist Group - Digital Cat Library |
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| Baker, L.A.; Warren, R.J.; Diefenbach, D.R.; James, W.E.; Conroy, M.J. | |
| Prey selection by reintroduced bobcats (_Lynx rufus_) on Cumberland Island, Georgia | |
| 2001 American Midland Naturalist (145): 80-93 | |
We released bobcats (_Lynx rufus_) on Cumberland Island, Georgia, during 1988 and 1989 as part of a cooperative effort to restore an extirpated predator to the island. We collected data on prey use and prey abundance three times a year during 2 y following the initial bobcat releases. We tested four hypotheses concerning bobcat prey selection: (1) use of a prey species was closely associated with its abundance (functional relationships), (2) the number of prey species included in bobcat diets increased as the abundance of principal prey species decreased (diet optimisation), (3) the number of species included in bobcat diets and diet diversity increased as population density increased (interference) and (4) increases in the proportion of males resulted in increases in the use of large prey and decreases in the use of small prey. Bobcats' use of marsh rabbits (_Sylvilagus palustris_) and cotton rats (_Sigmodon hispidus_) was positively correlated with each species' abundance as predicted by a hypothesis of functional relationships. The number of prey species in bobcat diets and diet diversity was negatively correlated with the abundance of marsh rabbits as predicted by a hypothesis of diet optimization. Changes in diet diversity in different regions of the island between years were not correlated with changes in bobcat density within each region, suggesting interference was not occuring at the bobcat densities observed in our study. Changes in the use of Eastern grey squirrels (_Sciurus carolinensis_) between years were negatively correlated with increases in the proportions of male bobcats in different regions of the island. Our results suggest that diet optimization and functional responses are both useful models for describing bobcat-prey relationship. The diet optimization model had greater power to explain use of prey species that were not used in all seasons. |
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