Ground-nesting waterbirds and mammalian carnivores in the Virginia barrierisland region: Running out of options

We examined changing patterns of distribution of two large mammalian predat ors, the raccoon (Procyon lotor) and red fox (Vulpes vulpes), and beach-nes ting terns and Black Skimmers (Rynchops niger) along ca. 80 Irm of the Virg inia barrier island landscape between the periods 1975-1977 and 1998. Based on evidence from trapping, scent stations, den observations and sightings of the two predators, there has been a marked increase in their island rang es. In 1975-77, only 6 of the 11 surveyed barrier islands definitely harbor ed at least one of the two mammals, but by 1998, 11 of 14 islands showed ev idence of one or both during the spring and summer. Concurrently, annual be ach-nesting bird surveys have been conducted since the mid 1970s during Jun e. From 1977 to 1998, the number of colonies of terns [Common (Sterna hirun do), Gull-billed (S. nilotica), Least (S. antillaram), Royal (S, maxima), a nd Sandwich (S. sanduicensis)] and Black Skimmers declined from 23 colonies on 11 barrier islands to 13 colonies on 10 islands. In addition, the popul ations decreased dramatically for all species except the marginal Sandwich Tern and Least Tern. This pattern suggests that mammalian predation may be a major factor in colony site selection or success, although we have no dat a on success at most locations. The only consistently large colony over the years has been the Royal Tern colony on Fisherman Island, one of the few w ith no resident large mammals. Because these declining waterbirds appear to be running out of options for safe colony sites in coastal Virginia, we di scuss the prospects of conducting Limited predator removals on certain isla nds. In addition, considerations of strict management and enforcement of pr otection at critical manmade colony sites that now attract large numbers of certain species, are timely. Lastly, where dredged material disposal proje cts are planned, providing nesting sites for these colonial species and roo sting sites for migrant birds may be appropriate.