Mortality of Eggs and Young Cramp et al. (1977) reported that egg preda- 

 tion by Hooded Crows (Corvus corone ) and Magpies ( Pica pica ) was the main cause 

 of egg loss for Black Scoters nesting in Ireland. In 109 nests at Lake Myvatn, 

 Iceland, in which at least one egg hatched, 86% of the remaining eggs were in- 

 fertile and 3% contained dead embryos (Bengtson 1972). Bengtson ascribed egg 

 loss in 19 nests that failed to hatch eggs to predation (58%), desertion (32%), 

 and flooding (11%). He believed that Raven ( Corvus corax ) predation was the 

 most important cause of nest failure at Lake Myvatn. We found no observations 

 of actual death of young. 



Renesting Bengtson (1972) estimated that 31% of 45 females examined in 

 Iceland renested. 



Maximum Natural Longevity An adult banded in the Old World was recovered 

 15 years, 11 months, and 9 days after it was banded (Rydzewski 1978). 



Weight The average weight of 8 males was 2.4 lb (1,089 g); 4 females av- 

 eraged 1.8 lb (816 g)(Nelson and Martin 1953). 



SUSCEPTIBILITY TO OIL POLLUTION 



The Black Scoter is especially vulnerable to nearshore and offshore oiling 

 throughout its range (Greenwood 1970, Hope-Jones 1971, Table 8). As a diving 

 duck that forms large rafts in the open ocean where it both feeds and rests, 

 this sea-duck seems particularly vulnerable to oiling. 



Black Scoters were one of the most common oil-related casualities along 

 both the Dutch and Belgian coasts , according to several separate beached bird 

 surveys conducted from 1948 to 1962 (Hautekiet 1955, Morzer Bruijns 1959, de 

 Ridder 1961, Tanis and Morzer Bruijns 1962, Kuyken and Zegers 1968, all In Ver- 

 meer and Vermeer 1974). Goethe (1961 _in Vermeer and Vermeer 1974) reported 

 that Black Scoters were the species most frequently found dead as the result 

 of oiling on German coasts from 1953 to 1961. 



Tanis and Morzer Bruijns (1968) considered the Black Scoter the species 

 most affected by oil in the eastern North Sea, and Bourne and Devlin (1969) re- 

 garded it as the waterfowl species most vulnerable to oil in areas offshore 

 Britain. Perry et al. (1979) estimated that 335 Black Scoters died following 

 two spills in the Chesapeake Bay. 



We have little knowledge of the size of Black Scoter populations wintering 

 in the southeastern United States. Some evidence suggests that substantial num- 

 bers may occur in waters off South Carolina and Georgia. Fair numbers winter 

 in North Carolina, but few are found off Florida or in the Gulf of Mexico. We 

 also know that this is a species subject to considerable damage from oiling and 

 one whose populations elsewhere have been affected by oil pollution. We do not 

 have an adequate idea of the world population or of that nesting in North Amer- 

 ica. Neither do we know much of migratory pathways used by the species. Con- 

 sequently, we cannot be certain of the effect of oil pollution along the Atlan- 

 tic coast. If large numbers (i.e., tens of thousands) winter there regularly, 

 oil pollution potentially could severely reduce North American populations. If 



360 



