291 THE NESTS AND EGGS OF 



and froPxi fifteen to twenty feet from the ground, and 

 when in a bush is seldom less than four feet from the 

 ground. Several nests are frequently made in the same 

 tree. The nest is made of sticks and twigs, and lined 

 with dry grass, moss, or bits of dry reed. MacFarlane 

 describes one of the nests (out of thirty-seven taken) as 

 " composed of down and velvety leaves, held together 

 by some stringy turf." When disturbed at their nests, 

 the birds rise and fly to and fro in alarm, uttering 

 anxious cries. 



Range of egg colouration and measurement : 

 The eggs of Bonaparte's Gull are two or three in number. 

 They vary considerably in ground colour, from rich- 

 brown through every shade to yellowish-buff on the one 

 hand, and to olive-brown and olive-green on the other, 

 spotted with dark brown, and with underlying markings 

 of pale brown and brownish-gray. The spots are seldom 

 large, and pretty evenly distributed over the entire 

 surface of the Ggg, but as a rule the larger ones are on 

 the major half, where also the markings generally are 

 most numerous, and sometimes form an irregular zone. 

 Average measurement, 2'0 inches in length, by 1*4 inch 

 in breadth. Incubation is performed by both sexes, and 

 lasts from twenty-one to twenty-four days. 



Diagnostic characters : The eggs of Bonaparte's 

 Gull closely resemble those of the Black-headed Gull, 

 but are smaller. The locality of course will distinguish 

 them in doubtful cases. They also resemble those of 

 Franklin's Gull, but are smaller. 



