HABITAT 



Nesting North American Red-breasted Mergansers breed both inland on lakes, 

 rivers and ponds and along the coasts on shores and on marine islets (Palmer 

 1976b). Palmer (1976b) described ideal breeding habitat as small islets with 

 low, prostrate vegetation or other natural features to cover the nest, and with 

 open strand, gravel bars, or rocks to provide roosting and preening areas for 

 drakes and young. Johnsgard (1975) noted that Red-breasted Mergansers breeding 

 in northern Europe nest mainly on lakes and rivers that have barren shores and 

 clear water. Cramp et al. (1977) pointed out that the species is largely boreal 

 in its breeding distribution, but also nests to some extent in tundra and tem- 

 perate forest. 



Nest sites of Red-breasted Mergansers are highly varied. They nest in 

 marshes, rocky islets, on vegetated islands in large lakes, on river banks and 

 lake shores, in cavities in banks and under rocks, and beneath piles of drift- 

 wood, fallen logs, or conifer boughs (Bellrose 1976, Palmer 1976b). These ducks 

 also have used nest-boxes in Finland (Palmer 1976b). Palmer (1976b) pointed out 

 that overhead cover may be a requirement for nesting and that these ducks prefer 

 to nest on small islands within about 10 m (33 ft) of the edge of the water. A 

 half dozen or more nests may be found near one another; this reflects habitat 

 preference rather than social nesting (Palmer 1976b). 



Feeding Johnsgard (1978) reported that wintering Red-breasted Mergansers 

 preferred to forage in clear and shallow waters not affected by heavy waves. 

 Non-breeding Red-breasted Mergansers are often found on less sheltered waters 

 than their congener, the Common Merganser, and are more marine in distribution 

 than that species (Palmer 1976b). 



Winter and Offshore Wintering Red-breasted Mergansers are found on both 

 inland fresh waters and coastal marine waters but are found in the largest con- 

 centrations along the coasts where they are most common inshore and in tide- 

 water areas (Palmer 1976b). They are found more frequently in open ocean and 

 on salt and brackish bays than on fresh or slightly brackish waters (Johnsgard 

 1978). 



FOOD AND FEEDING BEHAVIOR 



Red- breasted Mergansers usually dive for food (Bellrose 1976) but they 

 also pursue prey along the surface with only their heads submerged (Munro and 

 Clemens 1939). The feet provide most of the propulsion but the wings are oc- 

 casionally used (Palmer 1976b). Most food Is brought to the surface to be swal- 

 lowed, but smaller items are eaten underwater (Cramp et al. 1977). Most feeding 

 dives last for about 10 to 30 sec, with only short pauses between dives (Palmer 

 1976b). Authors cited in Cramp et al. (1977) and Bellrose (1976) provided a 

 range of submergence times from 15 to 48 sec. 



Red-breasted Mergansers feed most actively in the early morning and evening 

 (Cramp et al. 1977) and they often cooperate to drive fish into shallower water 

 where they may be more easily captured (authors cited Jji Cramp et al. 1977). 

 They feed in pairs and in small and large flocks. Rolls and Rolls (1974) des- 



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