BONAPARTE'S GULL. 309 



either. Another nest was made on the dry branch of a pine tree, about 

 ten feet from the ground. Twenty-three nests described by MacParlane 

 were all in elevated situations, on stumps, bushes, or trees, and were made 

 of sticks, lined with dry grass, and in some cases moss and lichen had 

 been used ; they were generally built on flat, horizontal branches at some 

 distance from the trunk. He found eggs from the 10th of June to the 

 10th of July ; the usual number of eggs was three, in rare instances four. 

 Kennicott found the nests of Bonaparte's Gull near Fort Yukon. One 

 was built on the branch of a green spruce, near a lake, about twenty feet 

 from the ground, and others were in similar positions, but on smaller 

 trees. Richardson found this bird breeding in colonies in similar situations, 

 some trees containing seven or eight nests, which were made of sticks. 

 He states that it frequently perches on posts, and may often be seen 

 standing on the summit of a spruce-fir. The eggs of Bonaparte's 

 Gull vary in ground-colour from pale brown to dark brown and olive- 

 brown, but the range of variation is not very great. The spots are 

 generally evenly distributed over the surface of the egg, but occasionally 

 they form a zone round the larger end ; they vary in size from that of a 

 small pea down to mere specks. The surface-spots are dark brown, and 

 the underlying spots on those eggs where the ground-colour is pale are 

 brownish grey and distinct, but where the ground-colour is darker they 

 are greyish brown and indistinct. The eggs vary in length from 2*05 to 

 1'9 inch, and in breadth from T45 to 1'35 inch. Small eggs of the 

 Black-headed Gull may easily be confused with large eggs of Bonaparte's 

 Gull ; but in a series the difference in size between the eggs of the two 

 species is very conspicuous. 



In winter, Bonaparte's Gull is almost exclusively a coast-bird; it is 

 gregarious as in summer, and appears to be more shy than in the breeding- 

 season. The food of this bird is composed largely of coleopterous insects, 

 crustaceans, larvse, and small fish. It appears to obtain its food at night 

 as well as during the day. 



Bonaparte's Gull is intermediate in size between the Black-headed and 

 Little Gulls, but in the colours of its plumage it more closely resembles 

 the former. It differs in having the hood of the adult in summer plumage 

 greyish black instead of brownish black, in having the primary-coverts 

 white instead of grey, in having white tips to the primaries, and in having 

 a black instead of a red bill. In the changes of its plumage it does not 

 differ from the Black-headed Gull ; but the white tips of the primaries 

 appear at the second autumn moult. Young in down are described as " of 

 a dirty yellowish colour, thickly spotted [presumably on the upper parts] 

 with dark brown/' 



