Nests play a crucial role in the life history of tree squirrels, and can be a critical component of their biology that enables them to be a successful invasive species. Red-bellied squirrels (Sciurus aureogaster) were introduced to Elliott Key, Florida, in the late 1930s, and spread to nearby islands. Red-bellied squirrels were believed extirpated by Hurricane Andrew in 1992, but were rediscovered on Elliott Key in 2005. In 2006 and 2007, we surveyed for squirrel nests and measured vegetation to evaluate forest characteristics associated with nest-site selection by squirrels, and compared these data to measurements collected at random locations. Squirrels placed nests in large trees with more canopy linkages in mixed-hardwood forest, and the nest trees were in areas with large trees, high tree density and canopy cover, and lower recent hurricane damage. Red-bellied squirrels selected characteristics of nest trees and forest structure in similar ways to individuals in their native range, and to other species of tree squirrels in general. Results from our research allowed land managers to assess possible management actions and provided important information for them to develop an effective management strategy. Park officials are currently working toward complete eradication of the introduced population of red-bellied squirrels from the Florida Keys. We suggest that behaviors of individuals in native ranges may elucidate patterns for individuals introduced to novel environments; however, we also caution that care must be taken in further extrapolation. Our findings emphasize the importance of understanding ecology of introduced species for effective management.