Observations of a Nesting Colony of American Brant

Abstract

THE AMERICAN BRANT (Branta bernicla hrota), an important game species on the Eastern Seaboard, suffered great declines in the 1930's. For some time, the brant population has been known to fluctuate considerably from year to year. Presumably arctic storms on the nesting grounds cause declines in some years. Its numbers also have been reduced by encroachment of civilization, increased commercial navigation, oil pollution, over-shooting, and especially by the disappearance of eelgrass (Zostera marina), the bird's staple winter food. Cottam, Lynch, and Nelson (1944) reported that the American Brant population dropped in 1933-1934 to 10 percent of the 19301931 figure as a result of eelgrass destruction. In the Boas River area of Southampton Island, NWT, in the summer of 1953, there existed approximately 700 nesting pairs of brant and 400 yearlings. This indicates a tremendous increase in the last two decades. Manning (1942) reported only two nests in 1934, and Bray (1943) saw eleven in 1936. This increase may have taken place at the expense of another colony, but perhaps comparative studies of other brant colonies in the Eastern Arctic will show a widespread increase in numbers. I was able to study the 1953 brant colony on Southampton Island while accompanying F. Graham Cooch of Cornell University (now of Canadian Wildlife Service), who was studying Blue and Lesser Snow geese (Anser caerulescens). I wish to acknowledge the kindness of the Air Transport Service, RCAF, and the Department of Transport, Canada, for making the air trip possible. The western coast of Southampton Island, facing on the Bay of God's Mercy, is a low, level tidal-plain tundra. The brant colony was centered in the mass of islands in the two-mile-wide delta of the Boas River and thinned out to the east and west for four and one-half miles. This brant concentration was entirely separate from the Blue and Snow geese which nested at least one-fourth mile inland from the high tide line. The area corresponded almost exactly to the brant nesting area described by Bray (1943). The islands, averaging about one foot above high tide, were as small as six feet across and as large as two acres. They were covered with very short thick grass, sphagnum, or limestone gravel. Some were strewn with kelp washed in by fall storms. Weather here was marked by strong and unrelenting winds and