THE ROOK. 17 



and wing-feathers as in adult, but underneath more brownish- 

 black ; wing-coverts as in adult but browner and with less gloss. 



First winter. — ^Nasal bristles glossy black ; rest of head (fully 

 feathered) glossed greenish-purple, otherwise like adult, but tail 

 and wing-feathers and greater wing-coverts considerably browner 

 and less glossy. The juvenile body-feathers, lesser and median 

 and two innermost greater wing-coverts are moulted in July and 

 August, but not rest of wings and tail. First summer. — ^Nasal and 

 gape bristles and feathers at base of lower mandible and on 

 lores, chin, and upper- throat are gradually moulted from January 

 to May, commencing with chin, sides of face following, and nasal 

 region being last. Two latter regions become covered with 

 " knobs " (aborted feather-sheaths) as in adult, but on chin and 

 upper-throat some degenerate down-like feathers grow as well as 

 many " knobs." These degenerate feathers, with the plumules 

 and filoplumes (which do not moult), form a slight covering which 

 gradually wears down until skin is bare greyish-white as in adult. 

 Rest of plumage does not moult, but abrasion causes loss of gloss, 

 and wings and tail become very brown and almost without gloss. 



Measurements and structure. — ^ wing 305-330 mm., tail 157-175, 

 tarsus 52-58, bill from nostrils 35-40, depth at angle of lower 

 mandible 15-17 (12 measured), bare skin from nostril to feathers 

 under or just behind eye 29-37, bare skin from angle of 

 lower mandible to feathers of throat 37-66 (22 measured in flesh). 

 $ wing 290-311, bill from nostril 31-38 (10 measured). Primaries : 

 1st usually between 8th and 9th, more rarely between 9th and 

 10th, 2nd between 5th and 6th, 3rd and 4th about equal and 

 longest, 5th 5-10 mm. shorter, 6th 35-45 shorter ; 2nd to 5tli 

 clearly emarginated outer webs. Secondaries about equal 9th 

 primary, tips rounded. Tail rounded. 



Soft parts. — Bill, legs, and feet black ; iris dark brown. 



Characters and allied forms. — C. f. tschusii (north Persia, 

 Turkestan, south-west Siberia) is slightly smaller, and C. f. pasti- 

 nator (China, Japan, east Siberia) is smaller, and adult has 

 feathered chin but bare fore-head. For differences from Carrion- 

 Crow, see that species. 



Field-characters. — Bare, greyish-white face of adult noticeable 

 whether bird is at rest or in flight. Young, until face becomes 

 bare, resembles Carrion-Crow, but bill always more slender and 

 culmen less curved. At all ages baggy appearance of Rook's 

 thighs — due to the loose flank-feathers — distinguishes it from 

 Crow on ground. Its " caw " cannot be confused with Crow's 

 hoarse croak. 



Breeding-habits. — Sociable, nesting in colonies in large trees, 

 and quite exceptionally on buildings such as church-spires or 

 chimneys, and in large bushes. Nest. — Similar to Crow's, built 

 of sticks solidified with earth, and often on old nest of previous 



c 



