First North American Nesting and Occurrence of Haliaeetus albicilla on Attu Island, Alaska

Abstract

The nearctic range of White-tailed Eagles (Haliaeetus albicilla) is listed as casual in the Aleutian Islands, Alaska (Attu, where probably breeds, Unalaska), in eastern Greenland and off Massachusetts, near Nantucket Lightship (AOU 1983). The species breeds only in western Greenland in the nearctic; a breeding report from Baffin Island has not been confirmed (AOU 1983). Reference in the AOU Check-list to H. albicilla breeding at Attu is based on data presented herein. We discovered an active aerie of this species on Attu Island (52049'N, 173010'E) in 1982. We have numerous observations of four individual H. albicilla there in May to September, 1977 to 1986 (summary follows). These observations and the nest site are all from the river valleys and coastline at the east end of Attu Island. We located the active nest in Temnac Valley on 25 May 1982 after watching both adult eagles take turns sitting in a rocky depression on a cliff ledge. On subsequent trips to this site in 1982 (31 May, 4 June) both adults were seen attending to a single downy chick. Photographs of the nest site are on file at the University of Alaska Museum (UAM). The same nest was active in 1983 with a single chick present. This chick was fledged and feeding on pink salmon (Oncorhynchus gorbuscha) with the adults along the Temnac River in September 1983. This nest has not been active since 1983; only one adult eagle has been recorded at Attu since 1983. The nest site was located on the north side of Temnac Valley, 2.7 km from the Temnac River mouth (and salt water) at approximately 80 m above sea level. The nest cup sat on a fractured rock ledge 20 m up the southeast face of a rock pinnacle. This pinnacle stood immediately in front of a south-facing 40-m high cliff face. A heavily vegetated 350 talus slope stretched from the pinnacle base to a point close to the river, roughly 30 m away. With a rim about 10 to 15 cm high on the outside, the nest was approximately 1 m in diameter. The wellpacked cup consisted of kelp (probably Laminaria), fronds and rachis of Athyriumfilix-femina, and Elymus arenarius. Stalks and a few umbel heads of Heracleum lanatum were included in the rim. This is a similar to contents from Aleutian nests of Bald Eagle H. leucocephalus (Murie 1959).