Falkner Island is one of the ‘crown jewels’ of Connecticut bird habitats. Since the 1960’s, Falkner Island has been the site of the largest Common and Roseate Tern breeding population in the state. It currently supports over 95% of the nesting Common Terns in Connecticut. It is the site of one of the ten largest Roseate Tern (~45 pairs) breeding populations in Northeastern North America and is the only regular nesting location for this federally endangered species in the state.

In addition to the island’s importance to these two species in Connecticut, it is important to several other groups of birds. Several pairs of American Black Ducks nest on the island along with as many as two pairs of American Oystercatchers.

Falkner Island is a crescent-shaped island approximately 3 miles south of Guilford. It is the only vegetated 'marine' island in Connecticut. It has been a part of the Stewart B. McKinney NWR since 1985; prior to that, it was owned by the U.S. Coast Guard. The island consists of a rocky shoreline surrounding an eroding sand/gravel upland. The upland habitats include mowed paths, poison ivy, other low brushy vegetation, and a small sumac stand.