A. K. Blumton | USGS Science

USGS1990

Pesticide and PCB residues for loggerhead shrikes in the Shenandoah Valley

The decline in loggerhead shrike ( Lanius ludovicianus ) populations is widespread and coincides with the use of organochlorines that began in the late 1940's and increased until the 1970's (Morrison 1981; Robbins et al. 1986; Tate 1986). An inhabitant of farmland areas, loggerhead shrikes prey on invertebrates and small vertebrates (Bent 1950), and thus risk exposure to pesticides and other agricultural chemicals. The role of contaminants in the decline of loggerhead shrikes has only been partially assessed (Busbee 1977; Anderson and Duzan 1978; Morrison 1979; Rudd et al. 1981). Studies of the nesting and winter ecology of loggerhead shrikes (Luukkonen 1987; Blumton 1989) during 1985-88 in the Shenandoah Valley, Virginia provided the opportunity to collect eggs and carcasses for contaminant residue analysis. In this paper we provide pesticide and polychlorinated biphenyl (PCB) residue data for eggs and carcasses collected.

Shenandoah Valley↗

USGS1988

Habitat Suitability Index Models: American eider (breeding)

INTRODUCTION The common eider (Somateria mollissima) consists of five subspecies; four are found in North America (Palmer 1976). Six management populations of common eiders have recently been defined in eastern Canada and the United States (Reed and Erskine 1986). The American edier (S. mollissima dresseri), of which three populations are recognized (Reed and Erskine 1986), is the southernmost subspecies and the focus of this paper. The common eider is a member of the order Anseriformes, family Anatidae, and the tribe Mergini. A seabird of the northern latitudes of the world, the common eider is the largest duck of North America, ranging in weight from 1.2 to 2.8 kg and having a total length from 53.3 to 68.6 cm (Bellrose 1980). The American subspecies averages 2.0 kg and 61.0 cm for males, and 1.5 kg and 57.0 cm for females (Bellrose 1980). The drake is distinctly patterned,, having a white back and breast and a black belly and sides. The smaller female is brown and heavily barred with dark brown. Both sexes have a leathery extension of the bill which forms a Y-shaped frontal shield that reaches almost to the eyes. Maine, which supports part of the Atlantic population of common eiders (Reed and Erskine 1986), is the only major eider breeding population in the lower 48 States. American eiders are colonial nesters and use a variety of nesting sites, but they prefer relatively small, uninhabited islands (Mendall 1976). The coastal islands of Maine, which are essential to the eider's life cycle, are increasingly subjected to recreation and development, creating potential disturbances to eider breeding colonies. During recent years, aesthetic and sporting interest in eiders has increased. Sea ducks in Maine are experiencing increased hunting pressure. Compared to hunting seasons and bag limits for inland ducks, sea duck seasons and limits are liberal (Maine Department of Inland Fisheries and Wildlife [MDIFW] 1983).

FWS/OBS↗