migration appears similar to that of North American birds. 



HABITAT 



Nesting Oldsquaws largely breed on high-Arctic tundra and are often the 

 most abundant nesting ducks there (Cramp et al. 1977). They usually nest on 

 treeless or nearly treeless islands in large lakes or ponds, and on coastal is- 

 lands (Bellrose 1976, Palmer 1976b). Others nest in upland areas near tundra 

 ponds (Bellrose 1976). Cramp et al. (1977) reported similar nesting habitat 

 for Oldsquaws breeding in the western Palearctic. Nest sites are usually near 

 water and are often partially hidden beneath shrubs or among sedges, or in cre- 

 vices between rocks (Palmer 1976b). 



Alison (1975a) did an intensive study of Oldsquaw breeding biology near 

 Churchill, Manitoba. Alison reported that 59% of 95 nests were located in is- 

 lands in freshwater ponds or lakes. Most of the rest of the nests (24.3%) were 

 on mainland ponds; 9.5% were in marshy areas, 4.2% were in scrubland, and 2.1% 

 were in dry upland. Black Spruce ( Picea mariana ) boughs concealed 27.3% of the 

 nests from above; these nests were well concealed from the side by grasses, 

 dwarf willows ( Salix spp.), or dwarf birches ( Betula spp.). Most of the nests 

 (64.1%) were open from above but well-concealed from the side; the rest were 

 partially or poorly concealed. Nests found on the mainland were significantly 

 better concealed than those found on islands. About 65% of all active nests 

 were within 1.4 m (4.6 ft) of open water, and only 10% were further than 14 m 

 (46 ft) from water (Alison 1975a). 



Feeding Oldsquaws apparently prefer to feed in marine waters even during 

 the breeding season. At other times of year they feed in open ocean, deep 

 lakes, salt and brackish bays, and occasionally in freshwater estuaries (Johns- 

 gard 1978). Alison (1972 In Bellrose 1976) reported that Oldsquaws fed in wa- 

 ter 30-50 ft (9-15 m) deep near Toronto; in Lake Ontario, they were seen feed- 

 ing in water 3-32 ft (0.9-9.8 m) deep (Bellrose 1976). Johnsgard (1975) sug- 

 gested that the foraging depth over sub-tidal feeding areas in coastal areas 

 is no more than 25 ft (7.6 m) , and Palmer (1976b) remarked that they probably 

 commonly dive to depths of 10 fathoms (18 m) . Cramp et al. (1977) stated that 

 normal foraging depths are 3-10 m (10-33 ft). 



Winter and Offshore Wintering Oldsquaw are found both on open water in- 

 land and off the coast, but most are found along coasts. They are one of the 

 most pelagic ducks and are often found far from shore. Palmer (1976b) indi- 

 cated that wintering birds seldom or never left the water. Birds wintering on 

 fresh water are generally well out in the open; those wintering on the Great 

 Lakes are usually 7-10 mi (11-16 km) or more from shore (Palmer 1976b). 



FOOD AND FEEDING BEHAVIOR 



Oldsquaws feed by diving, sometimes to great depths. Bellrose (1976) 

 suggested that foraging Oldsquaws dive deeper than any other duck. Alison 

 (1975a) examined Oldsquaws caught in gill nets at a depth of 51 m (167 ft); 

 Palmer (1976b) believed that a dive of 34 fathoms (62 m) was the deepest 



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