Foraging strategies of sympatric lagomorphs: implications for differential success in fragmented landscapes

In recent decades, the distribution of New England cottontails (Sylvilagus transitionalis) has declined substantially in response to forest maturation and fragmentation. Populations of eastern cottontails (Sylvilagus floridanus) have expanded into the range of S. transitionalis, since they are apparently less affected by the consequences of habitat modifications. We suspected that S. floridanus was able to exploit small patches of habitat where S. transitionalis was vulnerable to intense predation and we evaluated this explanation using large enclosures within which we manipulated the quality and distribution of food in relation to escape cover. In trials with low-quality food in cover and high-quality food in open areas, S. transitionalis sacrificed food quality for safety by remaining in close proximity to cover. Sylvilagus floridanus avoided low-quality food in cover and foraged at sites containing high-quality food away from cover. When food was removed from cover, S. transitionalis was reluctant to forage in the open and lost a greater proportion of body mass and succumbed to higher rates of predation than did S. floridanus. We applied these results to patterns of foraging by free-ranging rabbits in a fragmented landscape and estimated that S. transitionalis could successfully exploit only 32% of the available habitat without experiencing elevated rates of predation, whereas S. floridanus could exploit 99% of the habitat. Thus, the consequences of habitat fragmentation (especially higher predation risk) may not be as detrimental to S. floridanus, and this species will likely persist, whereas populations of S. transitionalis will continue to decline.