62 THE CROW FAMILY 



to make its home apart One tame pair has been known to drive 

 another away from the tower in which it had built, though all four 

 birds had roosted there in amity together during the winter. Nests 

 found by Mr. Ussher and Mr. Warren in Ireland were observed to 

 " occur on an average a mile apart." One pair in one place is said 

 also to be the rule in Switzerland. This habit may account for the 

 comparative rarity of the species, as compared with the Alpine 

 chough and the jackdaw, both of which nest in communities. 1 



When the young are fledged they remain with their parents for 

 several weeks, returning to the nest to roost. Where the species is 

 numerous the families gradually unite to form flocks ; where scarce, 

 they are seen either in families, in pairs or singly, according to 

 circumstances. In Switzerland the birds flock to make local migra- 

 tions. And in the mountain regions of Abyssinia, where choughs 

 are plentiful, they have been observed to quit the common roost early 

 in the morning and spread thence to feed in detachments over the 

 neighbouring country, much like starlings or rooks. They do not 

 appear to mix readily with other species, but have been seen with 

 rooks and daws, and sometimes in Switzerland with the Alpine 

 chough. An interesting fact noted by Mr. P. G. Ralfe in the Isle of 

 Man is that individuals of the species are to be seen in flocks in the 

 breeding season. He holds the view that these are birds which have 

 not been able to find nesting sites. If we assume that the young 

 birds of the previous year are mature by the spring, and would not, 

 therefore, be flocking umnated, the explanation has much in its 

 favour, and it finds support in the habit, already noted, that the birds 

 have of breeding apart, and of resenting intrusion into their nesting 

 area by other pairs. 2 



1 B. J. Ussher and R. Warren, op. cit. ; P. G. Ralfe, Birds of the Isle of Man, 1906 ; Gadeau 

 de Kerville, Faune de la Normandie, 1890 ; Field, 1882, Ix. 441 ; Naumann, Vogel Mitteleuropas, 

 1897-1905, iv. 52 (quoting Schinz for Switzerland). It quotes (p. 45) the same authority for the 

 gregarious breeding of the Alpine chough: " Sie nisten haufig in Gesellschaften in geringer 

 entfernung von einander wie die Dohlen." 



2 P. G. Ralfe, op. tit. ; Zoologisches Garten, 1877, pp. 146-164 (A. Girtanner) ; R. J. Ussher and 

 R. Warren, op. cit. ; V. Fatio, Faune de la Suisse, ii. ; Naumann, 033. cit. (for quotations from 

 Schinz, Konig, Heuglin) ; J. B. Bailly, Ornithologie de la Savoie, 1853, ii. 143. 



