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 filo plumes (w r hich 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 5th 

 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 



