A. Status of the Spectacled Eider - U.S. Fish and Wildlife Service

Hens may move the brood up to 14 km from the nest site by the time young fledge (J.B.
Grand, pers. comm.). However, most broods are raised within 5 km of where they were
hatched (Dau 1974; Harwood and Moran 1993; Moran and Harwood 1994; TERA 1995; J.B.
Grand, pers. comm.). Studies tracking hens with broods on a regular basis through the broodrearing
period on the YKD (J.B. Grand, pers. comm.) and on the North Slope (TERA 1995)
suggest that broods rarely move more than 1.5 km during any 24 hour period. Initial
movements away from the nesting areas may be a response to potential duckling predation
(TERA 1995) or movements toward better brood rearing habitat.
The only quantitative measure of adult female and duckling survival is from a study at Hock
Slough on the YKD; over the first 30 days of the brood rearing period in 1993-1995, adult
female survival averaged 93%, and duckling survival averaged 34% (Flint and Grand in
press).
Fledging occurs approximately 50 days post-hatching, after which females and their broods
move directly from freshwater to marine habitats (Dau 1974; Kistchinski and Flint 1974).
Dau (1974) believed that physiological stresses occurring partially as a result of this abrupt
shift from freshwater to marine habitats may cause significantjuvenile mortality.
On their nesting grounds, Spectacled Eiders feed primarily by dabbling in shallow fresh or
brackish ponds, or on flooded tundra (Dau 1974; Kistchinski and Flint 1974). Cottam (1939)
analyzed 16 adults collected in May-July (possibly including migrant birds) and found that
animal foods, primarily molluscs, comprised 75% of stomach contents. Cranefly larvae
(Tipulidae, Prionocera spp.) dominated in pre-break-up (YKD) (Dau 1974) and June (AR)
(Kistchinski and Flint 1974) adult diets, and insects in general dominated all age-class diets
after break-up (Dau 1974; Kistchinski and Flint 1974). Kondratev and Zadorina (1992) found
that trichopterans and chironimid larvae dominated the diet of adult hens on the Chaun River
Delta, especially in spring, followed by crustaceans later in the season. Chicks feed
predominantly on small, freshwater crustaceans (ibid). Plants were taken by all age classes,
particularly Potamogeton seeds (Dau 1974) and Ranunculus seeds (Kistchinski and Flint 1974),
which may act as stomach gastrolites in the absence of available gravel (ibid). Upland feeding
on Empetrum nigrum (crowberry) also has been recorded (Cottam 1939; Dau 1974).
Few data are available on the diets of Spectacled Eiders at sea. Cottam (1939) found primarily
amphipods, as well as molluscs, in 2 birds collected at St. Lawrence Island in January. The
most common foods taken by Spectacled Eiders shot by subsistence hunters in May and June
near St. Lawrence Island were molluscs and crabs (M. R. Petersen, pers. comm.).
The little information available on diseases in Spectacled Eiders comes from birds in captivity:
captive eiders are known to be susceptible to aspergiliosis (Hillgarth and Kear 1979; Allen and
Allen undated). More research has been conducted on parasites of Spectacled Eiders than on
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