80 BIRDS' NESTS 



argentatus) not unfrequently builds a more substantial 

 nest than usual, made of stalks and twigs, turf, and 

 masses of seaweed, lined with grass and wool, and 

 perhaps a few feathers, but it is made in a slovenly 

 fashion. This bird has also been known to make a 

 large nest on a tree, a change of habit by the way 

 that has taken place within the memory of man. 

 The Kittiwake (Rissa tridadylus) is one of the most 

 elaborate architects in the order, and its nest may 

 fairly be included in the following chapter dealing 

 with open nests. Some of the Black-headed Gulls 

 make much more substantial nests, yet these may 

 with propriety be included under the present heading. 

 Bonaparte's Gull (Larus Philadelphia), however, must 

 certainly be classed with the kittiwake as a fairly 

 able architect. The Black-headed Gull (L. ridihindus) 

 shows a remarkable variety in the structure of its 

 nest, doubtless according to special circ imstances. 

 Some of these nests are little more than hollows in 

 the spongy ground, whilst in other instances the eggs 

 can scarcely be said to rest in a nest at all. Others, 

 especially such as are built in shallow w^ater, are 

 large floating structures composed of reeds, flags, and 

 other aquatic vegetation lined with grass and other 

 fine materials ; whilst even more interesting still, 

 nests are occasionally made in trees or on the roof 

 of some building, such as a boathouse. We thus 

 have another most remarkable instance of the 

 adaptability displayed by birds in the matter of 



