368 THE THRUSH FAMILY 



season would naturally hasten the process of dissolution among our 

 resident birds, while of course, on the other hand, it would lead to 

 larger aggregations in the case of the migrants. 1 



For purposes of comparison it will be interesting to note here a 

 peculiar habit of the American-robin (T. migratorius). 2 This species 

 begins to form into flocks to roost before the breeding season is 

 over. The early flocks, in June, consist of the fledged young of 

 the first broods, accompanied by the adult males, the latter returning 

 from the roost to their family duties each morning and departing 

 again in the evening. Later the second broods and the hens 

 join the flight to the roost, where they continue to go until October, 

 when they all emigrate to their winter quarters. It is further 

 interesting to note that this species, unlike many others, is described 

 as shooting direct into the roost itself, instead of making a halt in the 

 near vicinity before finally going to their sleeping perches. 3 



The redwing is gregarious in winter and, of course, on migration. 

 The fieldfare, as already noted, has developed the social instinct to a 

 degree unknown to any of its congeners. It is gregarious throughout 

 the year, though the evidence shows that its habit of nesting in 

 colonies is not without exceptions. That this habit is always of 

 advantage to the species is doubtful, except in so far as safety is to 

 be found in numbers against birds of prey. The massing of nests 

 together within a restricted area can serve only to facilitate the 

 work of the spoiler unless, as in the case of rooks, the nests are 

 placed high up enough to make the trouble of reaching them 

 scarcely worth taking. But fieldfares, though they usually build 

 fairly high up, often in slender birches, have not altogether abandoned 

 the Family habit of placing their nests at low levels. While these 



1 Lilford, Birds of Northants, i. ; Macgillivray, History of Birds; Waterton, Essays on 

 Natural History; Gray, Birds of the West of Scotland ; Stevenson, Birds of Norfolk; D'Urbau 

 and Matthew, Birds of Devonshire, 2nd edit. ; Forrest, Fauna of N. Wales ; Ussher and Warren, 

 Birds of Ireland ; Nelson, Birds of Yorkshire ; W. H. Hudson, Nature in Dmvnland ; the 

 Fauna of the Tay Basin, and the other Scottish Faunal works edited by J. A. Harvie-Brown ; 

 G. Sim, Birds of Dee, etc., etc. 2 See p. 348. 



3 Auk, 1890, p. 360 (\V. Brewster). The species may of course vary at times its method of 

 entering the roost. 



