300 Field Museum of Natural History — Zoology, Vol. IX. 



small spots or marks of chocolate brown, and measure about 2.75 x 

 1.80 inches. 



" An irregular but not uncommon visitant during the migrations 

 and in winter upon Lake Michigan." (Nelson.) " Not common, 

 except perhaps on northern Lake Michigan and Green Bay. Breeds, 

 or did in 1879-80-81-84 and 1893, on different islands in Green 

 Bay and on the north shore. Frequently found on Lake Michigan in 

 winter." (Kumlien and Hollister, Birds of Wisconsin, 1903, p. 12.) 



Prof. Henry L. Ward found this species breeding in company 

 with Herring Gulls on Gravel Island, Dove County, Michigan, in July, 

 1905. (Bull. Wisconsin Nat. Hist. Soc, Vol. IV, No. 4, 1906, p. 113.) 



24. Sterna maxima Bodd. 

 Royal Tern. 



Distr.: Tropical America and warmer parts of North America, 

 casually as far north as Massachusetts and perhaps the Great Lakes. 



Adult in spring: Entire top of head, black, including but not ex- 

 tending below the eye; the black occipital feathers lengthened like 



Royal Tern. 

 Top of head is at times entirely black. 



a crest; back and wings, pale pearl gray; rest of plumage, white; 

 greater portion of the inner web of the outer primaries, white; bill, 

 orange red; feet, blackish, becoming dull yellow on the soles. 



Adult in winter, and in summer after the breeding season: Similar, 

 but the top of the head streaked with black and white. 



Immature: Head spotted and streaked black and white; the gray 

 upper parts marked with buff, pale brown, and blackish. 



Aside from the difference in size, the white markings on the outer 

 primaries will distinguish this species from the Caspian Tern in any 

 plumage. 



Length, 18 to 20; wing, 13.75 to 15 ; tail, 6 to 8; bill, 2.45 to 2.70; 

 depth of bill at base, about .70; tarsus, 1.30 to r.35. 



