Barrow's Goldeneye - Bucephala islandica
Male Barrow's Goldeneye, On Lake - Bucephala islandica
Global Rank:
G5
State Rank:
S5B
Agency Status
USFWS:
none
USFS:
none
BLM:
none
CFWCS Tier:
3
PIF:
2
General Description
Medium-sized diving duck. Total length, early-spring mass: male 48.4 cm, 1,278 g; female 43.2 cm, 818 g. Compact, chunky appearance with short neck and round body, with relatively large rounded head and short gray-black bill. Adult sexes are strongly dimorphic in size and plumage most of the year. Breeding male has striking pattern of iridescent, purplish-black head with bright, white crescent-patch between bill and eye; brilliant white sides, breast, belly and secondaries contrasted against black back, wings, and tail. Female has dark chocolate-brown head; slate-gray back, wings, and tail; and white flanks, belly, and breast. Both sexes have bright amber irides (hence the name "goldeneye"). Wing-beat is rapid with relatively deep arc; produces a distinctive "whistle." (Eadie, J. M., Savard, J.-P. L. and Mallory, M., The Birds of North America, No. 548, 2000).
Diagnostic Characteristics
See Tobish (1987) for details on identification of Barrow's and Common Goldeneyes in all plumages.
Distribution
Montana Range
Migration
Migration periods are centered around the first week in April in western Montana, and November 20 in the Bozeman area (Bergeron 1992).
Habitat
Chiefly a bird of the western montane region of North America. This species is generally restricted to areas west of the Continental Divide. Prefers alkaline to freshwater lakes in parkland areas; to lesser extent, subalpine and alpine lakes, beaver ponds, and small sloughs (Eadie, Savard and Mallory 2000).
Food Habits
Aquatic invertebrates (insects, mollusks, crustaceans) and fish eggs. Seeds and tubers provide a small fraction of the diet (Eadie, Savard, and Mallory 2000).
Reproductive Characteristics
Cavity nester; live or dead trees, but will infrequently nest in other sites, such as rock crevices or under tree stumps. Females with breeding experience exhibit high fidelity to previous nest sites. Eggs are elliptical to oval in shape. Bluish green to olive green in color. Smooth texture, slightly glossy. Clutch size ranges from 6 to 12 eggs (Eadie, Savard, and Mallory 2000). Chicks less than one week old in the Fortine area were seen from May 29 to July 15. Brood size averaged 8.