parasitism by this or other species (Low 194 1 ) and some are flooded (Siegfried 

 1976a). Bellrose (1976) suggested that desertion was the major cause of nesting 

 losses in this species, and that flooding was next in importance; he also re- 

 corded some loss to predation by crows ( Corvus brachyrhynchos ) and magpies ( Pica 

 pica ) . 



Renesting Siegfried (1976a) and Bellrose (1976) believed that renesting 

 occurs infrequently; however, replacement of lost clutches has been known to 

 occur occasionally (Hays ^n Bellrose 1976). 



Maximum Natural Longevity A Ruddy Duck banded in British Columbia was 

 found in Oregon at a minimum age of 13 years, 7 months (Clapp et al. in press). 



Weight Nelson and Martin (1953) gave the average weight of 12 males as 

 1.3 lb (590 g), and of 17 females as 1.1 lb (499 g) . 



SUSCEPTIBILITY TO OIL POLLUTION 



Ruddy Ducks are frequent victims of oil pollution, often severely so (Table 

 15). Johnsgard (1978) attributed their decline in numbers in recent years to 

 loss of breeding habitat and to the "periodic losses of large numbers of birds 

 on wintering areas as a result of oil-spill disasters." King and Sanger (1979) 

 felt that although oil spills in the Pacific Northwest would not be catastrophic 

 to the Ruddy Duck population, the species' status should be monitored during 

 the course of programs developing petroleum resources. Because this species 

 prefers fresh or brackish waters, it would probably not be in much danger from 

 oil spills in the marine waters of the southeastern United States; on the other 

 hand, spills into riverine and estuarine situations from holding tanks onshore 

 could cause losses severe enough to significantly threaten the species' North 

 American population. Moderate to major kills of Ruddy Ducks from oil pollution 

 have occurred recently in the Delaware River and Chesapeake Bay, north of the 

 study area. Consequently, we feel that oil pollution within the northernmost 

 part of the study area in North Carolina, particularly Pamlico Sound, could 

 cause severe damage to this species. The effects of oil on Ruddy Ducks winter- 

 ing in the sheltered waters of the Laguna Atascosa, in Texas, might also be 

 harmful; as many as 45,000 birds winter there (Webster 1971). 



BIBLIOGRAPHY 



1980 



Shackford, J. S. 1980. Breeding of the Ruddy Duck in Oklahoma. Bull. Okla. 

 Ornithol. Soc . 13: 9-11. 



1979 



Perry, M. C. and J. W. Artmann. 1979. Incidence of embedded and ingested shot 

 in oiled Ruddy Ducks. J. Wildl. Manage. 43: 266-269. 



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