232 A PRACTICAL HANDBOOK OF BRITISH BIRDS. 



Juvenile. Male. — Fore-head yellow ; stripe over eye. white 

 extending backwards in yellow stripe which continues round back 

 of croAvn ; croAvn and hind-neck dull greenish-browii ; nuchal spot 

 pale yellow ; rest of upper-parts including upper tail-coverts dull 

 olive-green ; black line through lores and behind eye as in adult ; 

 short stripe under eye white, but rest of cheeks and ear-coverts 

 yellow ; chin and throat yellow with an ill-defined brownish centre 

 becoming at base of sides of neck well-defined narrow greenish- 

 brown line ; whole of rest of under-parts yellow ; tail as adult, but 

 duller and tinged greenish ; primaries and secondaries browner 

 than in adult and outer webs greenish-blue and of inner secondaries 

 green ; primary-coverts bluish-green ; greater coverts grey-brown 

 with yellowdsh -white tips and narrow blue-green edgings to outer 

 webs ; median and lesser coverts slate-grey. Female. — Like above, 

 but tail duller, outer webs of wing-feathers more greenish and inner- 

 most secondaries, primary-coverts and greater wing-coverts browner. 



First winter and summer. Male and female. — Like adults, but 

 not so bright on crowai and outer webs of wing- and tail-feathers 

 (except those newly moulted) and primar3'-coverts like those of the 

 juvenile. The juvenile bod^^-feathers, greater, median and lesser 

 wing-coverts, two (occasionally three) imiermost secondaries and 

 occasionally central pair of tail-feathers are moulted July-Oct., 

 but not primary-coverts or rest of wing- and tail-feathers. 



Measurements and structure. — ^ wing 60-65 mm., tail 46-52, 

 tarsus 16.5-18.5, bill from skull 8-8.5 (12 measured). $ wing 57-64. 

 Primaries : 1st 6-10 mm. longer than primary-coverts, 2nd between 

 8th and 9th, 4th and 5th longest, 3rd and 6th 1 mm. shorter, 7th 

 2-6 shorter, 3rd to 7th emarginated outer webs. Secondaries 

 about equal 10th primary, tips rounded with somewhat pointed 

 apex. Tail almost square. Bill small but strong. Good many 

 rictal and nasal bristles and short bristle-like feathers covering 

 nostrils. Tarsal joint feathered. 



Sojt parts. — Bill black, tip horn ; legs and feet dark slate-blue ; 

 iris dark brown. 



Characters and allied forms. — For allied forms see p. 230. The 

 blue crown, wings and tail distinguish it from other British Tits. 



Field-characters. — Cobalt-blue crown, blue wings and tail, and 

 black line through eye are diagnostic. A characteristic note, heard 

 from early Januarj^ until summer, is a loud " tsee-tsee-tit -it-it." 



Breeding-habits. — Nests in holes of trees and walls, occasionally 

 inside open nests of other species or in foundations of large nests, 

 and in holes of banks and nest-boxes. Where natural sites fail holes 

 of any kind may be used : in letter-boxes, pumps, old cans, etc., and 

 an open nest is' said to have been built on a bough. Nest. — 

 Foundation built of moss mixed with grass ; lining of hair or wool 

 with feathers ; eggs covered up before incubation by lining. Eggs. 



