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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I50 



also in being highly aggressive, so that, except during migration, 

 only pairs or small family groups are found in company. 



In the nesting season the male has a loud call, cow cow cow cow 

 cow repeated rather slowly, that carries for some distance. It is often 

 given from cover. Males fight savagely and also attack other 

 aquatic birds that may approach their nesting territory. The nests 

 are rounded masses of wet vegetation, pulled together in raftlike 

 form to project a few centimeters above the surface, located amid 

 open stands of water plants. 



In Panama I have noted mated pairs from January to March and 



Fig. 5. — Head of pied-billed grebe, buzo, Podilymbus podiceps, with large, banded 



bill. 



have seen fully grown immature birds at the same season, indicating 

 a prolonged nesting period. The following notes are from eggs 

 collected in the United States and Mexico. The usual set numbers 

 5 to 7, but occasionally 10 are found. The pointed oval eggs are 

 faintly bluish white in color, thick-shelled, smooth, or occasionally 

 with small excrescences, and measure 39.0 to 47 mm. long by 28 to 32 

 mm. wide. Their color is darkened irregularly by stain from wet nest 

 material during incubation. 



The species ranges locally from Canada south through Central 

 America and the West Indies, and throughout South America to 

 Chubut in south central Patagonia. Two of the 3 geographic races 

 reach Panama. The third, Podilymbus podiceps antillarum Bangs, 

 of the Greater and Lesser Antilles, differs from the other two mainly 

 in shorter wing {(^, 122-126; $, 112.8-114.2 mm.). 



