568 * REPORT OF STATE GEOLOGIST. 



etc., tipped with buff, the rump and upper tail-coverts spotted with 

 same. Adult, Dark Phase. Entirely dark, sooty slate, with a plumbe- 

 ous cast in certain lights. Young. Entirely sooty slate, the lower 

 parts more or less barred with buff." (Eidgw.) The descriptions are 

 of extreme examples of coloration. Specimens are found showing 

 every possible intermediate condition of plumage. 



Length, 20.00-23.00; wing, 13.50-14.00; tail, 8.00-9.00; bill, 1.45- 

 1.75; tarsus, 2.00-2.10. 



RANGE. Northern portion of Northern Hemisphere, principally on 

 the seas, but also visiting the larger inland waters. In America, south 

 to Nebraska, Great Lakes and New Jersey. Breeds far northward. 



Nest, of moss and grass on the ground. Eggs, 2 to 3, grayish-olive, 

 spotted with brown. 



The only record I know of its occurrence is that given by Dr. A. W. 

 Brayton (Trans. Ind. Hort. Soc., 1879, p. 150): "A rare winter vis- 

 itant to Lake Michigan. October 9, 1876, in company with my friend, 

 Mr. E. W. Nelson, * * * we saw a fine specimen of this bird 

 flying along the lake shore near the State line." Mr. E. W. Nelson 

 notes a record under the same date which is possibly the same. Birds 

 of Northeastern Illinois, p. 145.) Prof. E.L.Moseley reports a specimen 

 shot at Sandusky, Ohio, October, 1889, and the late W. H. Collins 

 reported one specimen taken on the Detroit River, and now in the 

 collection of the Museum of Comparative Zoology, Cambridge, Massa- 

 chusetts. (Cook. Birds of Michigan ,p. 31.) From these notes it 

 would appear that the bird is of occasional occurrence on the Great 

 Lakes in fall, and doubtless in winter and spring. They spend the 

 warmer parts of the year far to the northward, much of the time fre- 

 quenting places where other water fowl, particularly Terns, congre- 

 gate. They prey upon Gulls and Terns. By reason of their powerful 

 wings they overtake their victim and compel it to drop or disgorge its 

 food. They are called "Pirates/' "Gullchasers," "Sea Hawks" and 

 "Jaegers" (hunters), each of which terms represent some one's 

 attempt to fit the birds with a name that will express their notable 

 habits. Mr. Basil Hicks Dutcher has given a good account of the 

 habits of birds of this .genus on the Long Island coast in The Auk, 

 April 1889, pp. 125-126. 



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