ROOK. 9 



often be remarked, many nests are much smaller than 

 others, these being the produce of young and newly- 

 mated birds. Very often an odd nest or so is occasion- 

 ally seen in trees at some distance from the colony, but 

 these are rarely occupied many seasons in succession ; 

 although I have in several instances known them to 

 form the nucleus of a thriving colony. In one case a 

 new rookery was thus formed after a tree had been 

 felled in the main colony. Rooks, however, are most 

 gregarious birds, very conservative, and cling to their 

 favourite breeding-places time out of mind. 



Range OF egg colouration and measurement: 

 The eggs of the Rook vary from three to five in number, 

 and should any of the first eggs be taken only the usual 

 clutch seems to be completed, the birds sometimes being 

 content to sit on a single q^^. They range from pale 

 blue, nearly white, through various shades of green in 

 ground colour, blotched, spotted, and clouded with 

 olive-brown of varying degrees of intensity and under- 

 lying markings of paler brown and gray. Usually the 

 larger end of the shell is most heavily marked. Some 

 specimens are spotted minutely with very dark brown, 

 nearly black ; others are streaked with faint olive-green ; 

 whilst others, yet again, are almost entirely devoid of 

 colouring matter. They also vary considerably in size 

 and shape, some being very rotund, others elongated. 

 Average measurement, 17 inch in length, by V2 inch in 

 breadth. Incubation lasts from seventeen to eighteen 

 days, and is performed by both sexes, the female taking 

 the largest share of the task. The eggs are sometimes 

 sat upon as soon as laid. 



Diagnostic characters : It is impossible to give 

 any reliable character by which the eggs of the Roo''J 

 may be distinguished from those of the Carrion an'^ 

 Hooded Crows. The best means of identification is at 



