THE SWALLOW. 505 



tion of moulting birds proves. This plumage is acquired by a 

 gradual complete moult as in adult but of those examined earliest 

 moulting wings and tail (in Africa) were in October. 



Measurements and structure. — cowing 120-129 mm., tail: central 

 pair 34-46, outermost pair 93-122, tarsus 10-13, bill from skull 10-12 

 (26 measured). $ wing 116-128, tail : central pair 40-48, outermost 

 pair 76-107 usually broader than in male but sometimes as narrow 

 (18 measured). Juvenile (^ wing 117-126, tail : central pair 40-47, 

 outermost pair 60-70 always broader than in adults, $ wing 113-117, 

 tail : outermost pair 60-64. Primaries : 1st minute about half 

 primary-coverts, 2nd longest, 3rd occasionally equal but usually 2-4 

 mm. shorter, 4th 10-13 shorter, oth 18-22 shorter, 6th 25-31 shorter ; 

 primaries narrow, outer webs not emarginated. Secondaries very 

 short, shorter than 10th primary, tips rather deeply notched, except 

 innermost Avhich are slightly longer with rounded tips. Tail deeply 

 forked, 12 feathers, tips sharply sloped off on inner webs and outer- 

 most pair greatly elongated beyond the sloping off. Bill broad 

 and flat almost an equilateral triangle in shape, tip slightly curved. 

 Gape wide. Nostrils jDartially covered by membrane. Some fine 

 rictal and nasal bristles. Tarsi and feet very short, not feathered. 



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

 of bill in juvenile pale yellow. 



Characters and allied forms. — H. r. savignii (Egypt, Nubia) 

 has chestnut breast and belly and white portions of tail-feathers 

 tinged chestnut ; H. r. transitiva (Palestine) is paler on under- 

 parts than last ; H. r. gutturalis (Baikal, north China, Japan) is 

 smaller, has white belly and chestnut of chin extends through centre 

 of blue throat -band ; H. r. tytleri (Kamtschatka, north-east Siberia) 

 is like last but has rufous bell}^ ; H. r. erythrogastra (N. America) 

 has paler rufous belly. 



Field -characters. — In form and behaviour Swallows and Martins 

 are unlike any other British birds, except perhaps Swifts (which 

 see). Slender build, long wings f nd forked tails no less than their 

 great powers of flight and habit of hawking for their insect prey, 

 either over Water or at varying heights in the open, are very 

 characteristic. Swallow differs from Martins in its uniform blue- 

 black ujiper-parts, elongated outer tail-feathers, and chestnut-red 

 throat and fore-head. Flight rapid with many twists and turns. 

 Less gregarious than Martins at nesting-time, but in late summer 

 congregates in large flocks prei)aratory to roosting in reed- or osier- 

 beds. Song, a musical twittering. Call -note, "clitt." Alarm-notes, 

 " clittit " and a sharj), clear " feet-a-feet." 



Breeding-habits. — Widely distributed but generally nests inside 

 sheds and outbuildings, though in some districts many pairs breed 

 inside chimney stacks. Exceptionally also breeds in roofs of 

 caves and rarely on branches of trees. Nest. — Built of mud, but 



