18 A PRACTICAL HANDBOOK OF BRITISH BIRDS. 



year ; lined grasses, moss, roots, straw, hair, wool, etc. Eggs. — 

 Usually 3-5, sometimes 6, rarely 7 ; vary much as Crow's : ground- 

 colour from light bluish-green to green and greyish-green but 

 never so blue, and rarely show much of ground-colour, being more 

 uniformly marked with shades of ashy-grey and brown. Erytliristic 

 varieties have occurred abroad, but not in British Isles. Average 

 size of 100 eggs, 40.7 X 27 mm. ; smaller than Crow's. Breeding- 

 season. — Begins latter half of March and early April. Incubation. — 

 Lasts 17-18 days ; both sexes said to incubate, but generally male 

 is seen to feed female on nest. Eggs incubated as laid. One 

 brood. Fledging-period. — 29-30 days (S.E. Brock). 



Food. — In agricultural districts mainly corn ; Collinge estimates 

 vegetable matter at 71 % and Gilmour says 58 % is corn and 

 husk ; earthworms, insects, millipedes also regularly taken, and 

 at times various fruits, acorns, walnuts, potatoes, fish, eggs of 

 many birds, small birds, small mammals, and carrion. Proportion 

 of animal-matter is highest in summer and lowest in \\inter. 



Distribution. — British Isles. — Resident. Generally distributed. 

 Increasing and spreading north in Scotland, and now breeds 

 Caithness, Sutherland, Ross, and Cromarty, 0. Hebrides and 

 Orkneys, but only visitor Shetlands. Now breeds western isles 

 of Ireland. 



Migrations. — British Isles. — ^After nesting our residents are 

 subject to partial and irregular movements — some probably 

 emigrating to Continent. Great numbers arrive east coast Great 

 Britain from central Europe and Scandinavia, end Sept. to third 

 week Nov., extremes Sept. 1 to end Nov., and depart mid-Feb. 

 to third week April. Occasional records of emigration from 

 south coast in late autumn and immigration in mid-March. 

 Winter-movements also noted in Hebrides ; in Ireland apparently 

 a cross-channel movement autumn and spring. 



Distribution. — Abroad. — Europe generally from north Russia, 

 Finland, and 60^ north in Sweden, but rare or absent in south 

 Europe. Casual Madeira, north Africa, Greenland, and Iceland. 

 Represented by allied forms in parts of west and east Asia. 



Genus COLCEUS Kaup. 



CoLCEUS Kaup, Skizz. Entw.-Gesch. und Natiirl. System, p. 114 (1829 — 

 Type C. monedida, because German name of genus " Dolile "= Jackdaw. 

 C. monedida first-named species, and accepted as type by Sharpe, 1874, 

 and others).* 



* In the same year, 1829, the name Lycos was given to the Jackdaws 

 by Boie, but the name Colceus is preferable, because in 1787 the name Lycum 

 had already been established for another genus. 



