EGGS OF NOBTH AMERICAN BIRDS. 67 



northward. Nests placed in trees, often in the deserted 

 nests of other large birds, or in natural cavities of stubs. 



375a. Western Horned Owl, Bubo oirginkanis siiharcti- 

 cus. Eggs, indistinguishable from those of No. 375. Breeds 

 in Western United States, from the Great Plains, westward ; 

 southward to the Mexican table-lands. 



3755. Arctic Horned Owl, Bubo vir(/i?nanus arcticus. 

 Eggs, indistinguishable from those of No. 375. Breeds in the 

 interior of Arctic America. 



o75c. Dusky Horned Owl, Bubo virginianHs saturatiis. 

 Eggs, indistinguishable from those of No. 375. Breeds in tlie 

 northwest coast region, from Columbia River northward ; 

 also in Labrador. 



376. Snowy Owl, Nyctea nyctea. Eggs, 4 to f^, oblong 

 oval ; 1.85 -|- 2.50 to 1.88 -\- 2.55. Breeds in the northern 

 portions of the Northern HemisiDhere, in North America, usu- 

 ally north of the United States, in May and June. Nests 

 placed on the ground or on rocks. 



377. Ha-wk Owl, Svrnia uhda. Eggs, 4 to 7, oblong oval ; 

 1.20 -{- 1.50 to 1.30 -f- 1.(32. Breeds in the arctic portions of 

 the Old World, and is thus extralimital ; bird casual in Alaska. 



377a. American Hawk Owl, Surnia uhda caparoch. Eggs, 

 4 to 7, similar in form and size to those of No. 377. Breeds in 

 Arctic America, in April and May. Nests placed in liigii 

 trees. 



378. Burrowing Owl, Speotyto ciinicularia hypogcea. 

 Eggs, 5 to 10, rounded oval ; 1.05 + 1.30 to 1.13 + 1.35. 

 Breeds in the United States, from the Pacific coast to the 

 Great Plains, south to Central America, in April. Nests 

 placed in the burrows dug by the prairie dog. 



378a. Florida Burrowing Owl, Speotyo cunicularla fiori- 

 dana. Eggs, indistinguishable from those of No. 378. Breeds 

 in Florida, in March and April, probably in the holes dug by 

 the Gopher turtle. 



