Behavioral interactions between invading and endemic lagomorphs: Implications for conser ving a declining species Original Research Article

New England cottontails Sylvilagus transitionalis were the only rabbits indigenous to the extreme northeast portion of the United States. However, following massive introductions that began in the 1930s, eastern cottontails S. floridanus expanded their range into this region. Concurrent to the range expansion by eastern cottontails, the abundance and distribution of New England cottontails declined. Because these two species utilize similar habitats, competition has been suggested as an explanation for the decline of S. transitionalis. To test this hypothesis, we examined the dominance relationship between these two rabbits in confined areas, and evaluated interference competition in large enclosures where cover and food were manipulated to create good and poor sites. New England cottontails were dominant in 42% of the behavior dyads where there was a clear winner. No differences were detected in habitat selection trials. These results do not support the hypothesis that interference competition has affected the decline of New England cottontails. However, we suggest that scramble competition for disturbance patches of habitat may be influential in determining the distributions of these rabbits in New England. Populations of S. transitionalis may be sustained by maintaining occupied patches of early-successional habitat (10–25 years post disturbance) rather than attempting to restock habitats occupied by S. floridanus.