Do bird habitat preferences limit the spread of exotic fig trees in South Florida?

The spread of invasive plants with animal-dispersed seeds may be constrained or facilitated by animal seed dispersal. We hypothesized that the distribution of exotic fig trees in Florida is limited by lack of dispersal to undisturbed habitats. We quantified the abundance of native and exotic figs in sites on the Atlantic and Gulf Coasts of South Florida. Sites were classified into four types: undisturbed forest, forest fragments within an urban environment, parkland within an intact forest, and urban parkland. In this context, parkland refers to an anthropogenic habitat with a mown understory of turf grass and sparse trees, including cabbage palms, the main host for strangler figs. Exotic figs were found almost exclusively within urban parkland, while native figs occurred in all habitats surveyed. The sharp division between the distribution of native and exotic fig trees is paralleled by the distribution of birds in Florida habitats; certain bird species are found almost entirely in open, anthropogenic environments. We evaluate the role of birds in limiting the spread of exotic figs by comparing assemblages of fruit-eating birds found visiting exotic and native fig trees. Our results have implications for the role of plant/animal mutualisms in determining the dynamics of invasions.