Double-Crested Cormorants in New England: Population and Management Histories

Abstract

-The Double-crested Cormorant (Phalacrocorax auritus) was extirpated from New England after settlement by Europeans, reportedly becoming re-established as a nesting species in Maine about 1925. Breeding cormorants increased rapidly in Maine between 1925 and 1945 and again between the 1970s and the mid 1980s. Currently, cormorants nesting in coastal Maine may be approaching carryin capacity as the rate of population growth has declined and birds have begun nesting inland. Breeding cormorants apparently became established in Massachusetts in the late 1930s and, during the last twenty years, have increased rapidly in coastal New Hampshire, Massachusetts, Rhode Island, and Connecticut (i.e., southern New England). Between 1977 and the early 1990s, the rate of increase of cormorants nesting in southern New England increased more than five times faster than in Maine. Southern New England may have more limited suitable nesting habitat than does northern New England, and as cormorants are better protected today than earlier, the time required to reach carrying capacity for breeders in southern New England should be less than in Maine. Concurrent with the increase in numbers of breeding cormorants in coastal Maine, there have been repeated reports of conflicts between these birds and fishing interests. Concerns from the 1930s to 1950s focused on marine fisheries. In response, almost 188,000 cormorant eggs were sprayed with oil between 1944 and 1953. Spraying failed to reduce the breeding population and the practice was discontinued. In the 1960s, state and Federal agencies began an intensified program to restore the Atlantic salmon (Salmo salar) to New England. Cormorants were documented eating substantial numbers of hatchery-reared smolts in the mid-1960s in eastern Maine and in the mid 1980s in central Maine. These findings prompted the shooting of hundreds of birds annually. Since 1972, when cormorants came under Federal protection, the U.S. Fish and Wildlife Service has annually issued a master permit to the State of Maine, which in turn has issued subpermits to wardens and the public to collect cormorants along salmon rivers. Currently, Federal and State management authorities are cooperating on a study of cormorant ecology in the Penobscot River-upper Penobscot Bay ecosystem. In southern New England, conflicts between cormorants and fisheries are also being reported, with at least one state contemplating a food-habits study. The effectiveness of past cormorant management in Maine and the information needed to improve management are discussed.