New England and eastern cottontail data for Maxent and niche overlap modeling

When introduced species invade new environments, they often overlap with
native species currently occupying those spaces, either spatially through
suitable habitat or environmentally through their realized niches. The
goal of this research is to determine the overlap between native New
England cottontail (Sylvilagus transitionalis) and introduced eastern
cottontail (Sylvilagus floridanus) to identify potential areas of invasion
by the eastern cottontail and potential areas of refuge for the New
England cottontail from the eastern cottontail (Connecticut, USA). Using
presence data from a regional, standardized monitoring protocol, we
developed habitat suitability models using Maxent and conducted niche
overlap analyses using environmental principal component analysis. We used
several covariates that reflected proximity to habitat characteristics,
such as young forest, shrubland, and understory, as well as proximity to
threats, such as development. We also included topographic and climatic
covariates. We used the Guidos software to categorize the spatial
arrangement of young forest, shrubland, and understory vegetation. We
found that the overlap in both niches and suitable habitat was high for
two species. Only areas of low precipitation and high elevation shifted
niches in favor of the New England cottontail. We also found that habitat
suitability for the New England cottontail was higher when patches of
mature forest without understory were within complexes of young forest,
shrubland, and mature forest with understory. Increasing habitat
heterogeneity could improve the habitat suitability of existing patches or
create new patches for New England cottontail. However, habitat management
alone is likely not enough to discourage eastern cottontail; thus, direct
species management, such as removal of eastern cottontail and augmentation
of New England cottontail populations, should be explored.