THE BRITISH TAWNY OWL. 93 



before wing- and tail-feathers are fully grown but often not com- 

 plete until Oct. or even Nov. and occasionally Dec. Primaries, 

 secondaries, primary -coverts and tail-feathers are not moulted. 



Measurements and structure.— <$ wing 245-265 mm. (one 270), 

 tail 145-165, tarsus 35-45, bill from base of feathers 27-29 (22 

 British measured). $ wing 255-275 (17 British measured). 

 Primaries : 4th and 5th longest, 3rd 8-12 mm. shorter, 2nd 25-35 

 mm. shorter, 1st 65-80 mm. shorter, 6th 12-15 mm. shorter ; 

 2nd to 5th emarginated on outer webs ; outer feather of bastard - 

 wing and outer web of 1st primary with long serrations, of 

 emarginated portions of 2nd and 3rd with short serrations which 

 are less distinct on emarginated portions of 4th and 5th. Outer 

 secondaries shorter than 10th primary, rest becoming longer and 

 inner ones equalling about 8th primary, tips rounded. Tail rounded, 

 12 feathers, tips rounded. Toes and tarsus covered with feathers, 

 1st toe short and capable of lateral motion, 4th toe not much 

 longer and reversible, claws long, curved, compressed, tapering 

 and very sharp. Bill strong, much compressed and upper mandible 

 strongly curved and projecting at tip, which is sharply pointed, 

 lower mandible shorter with rounded tip. Nostrils covered by 

 bristle-like feathers of disk. 



Soft parts. — Bill pale greenish -yellow, claws dirty white at 

 base, blackish at tip ; iris bluish-black. 



Characters and allied forms. — S. a. aluco (Europe) is like 

 S. a. sylvatica but larger (wing (J 265-290 mm. $ 270-305) and grey 

 or grey -brown examples are more frequent than tawny ones ; 

 S. a. mauritanica (north-west Africa) has darker upper -parts and 

 conspicuously marked under -parts, but is close to S. a. aluco ; 

 S. a. sancti-nicolai (south-west Persia) has pale upper -parts with 

 fine brown markings and fine dark markings on white under -parts ; 

 S. a. biddulphi (north-west India) is larger, grey upper -parts with 

 prominent blackish and rounded white markings on crown and 

 mantle and broad, widely spaced dark bars on white under -parts ; 

 S. a. nivicola (eastern Himalayas) is similar but darker and not so 

 large ; S. a. harmsi (west Turkestan) has also been separated. 

 Tawny or brown upper -parts, large rounded head and wing -formula 

 distinguish Tawny Owl. 



Field -characters. — Essentially nocturnal. If forcibly ejected 

 from its diurnal retreat among dense branches, in a hollow tree 

 or ivy-covered crags, only visible as it seeks to regain cover. It 

 then appears as a large brown -grey bird with rounded wings, 

 disproportionately large head, and slow, noiseless flight. If detected 

 at rest drawn up against a tree-trunk, black eyes and absence of 

 ear-tufts distinguish it from smaller Long-eared Owl. Call-note, a 

 clicking " ke-wick, ke-wack " heard oftenest in early summer after 

 young have left nest, but best known call is melodious hoot, a long- 

 drawn quavering " hoo-hoo-hoo-hoo." Bold in defence of nest : 



