As human populations rapidly expand, forests have become increasingly fragmented. Forest fragmentation creates a pronounced change in habitat types by diminishing interior forest habitat while increasing brushy edge habitats. Birds are good indictors of habitat changes because of they are plentiful and easy to observe. The purpose of our research was to characterize how forest fragments varying in size and connectivity support differentially breeding bird communities in terms of diversity, species composition, and breeding productivity. We studied bird communities in two forest fragments in the Hudson Valley, NY: one small fragment adjacent to the SUNY New Paltz campus (87 acres) that is surrounded by the campus, suburban housing and agriculture, and another forest fragment at the edge of the Mohonk Preserve (8,000 acres), which is adjacent to other preserved parcels, but is also bordered by agricultural lands. We used the Monitoring Avian Productivity and Survivorship (MAPS) bird banding protocol established by the Institute for Bird Populations. The MAPS protocol relies on the simultaneous use of ten mist nets scattered over a 50 acre area within each site. We banded birds captured in all nets for six hours starting at dawn on 6-7 days from May through August of 2016.
We expected a greater diversity of birds at the Mohonk site because of its large size and connection to the nearby larger preserved forest lands, while we expected lower diversity at the Campus site, because of its small size, suburban surroundings, and lack of connectivity. Surprisingly, we found that the Campus site had a higher species richness (Campus had 26 species, while Mohonk had 22). In addition, the Campus had 8 unique species while Mohonk had only 5. However, species composition plays arguably a more important role than richness. The Mohonk site had a higher number of neotropical migrant species not found at the Campus site, including the eastern pewee, indigo bunting, and red-eyed vireo. Species found only at the Campus site included the American robin, American goldfinch, and European starling. These species are all residents and they all are human-associated species, while the European starling is invasive. These results indicate that while forest fragment size and connectivity may not affect overall species richness of bird communities, they do affect bird community composition, and that smaller, unconnected forest fragments may favor invasive and human-commensal species over vulnerable neotropical migrants.