476 * A PRACTICAL HANDBOOK OF BRITISH BIRDS. 



varying in ground from olive-brown or greenish -olive to umber, 

 generally but not always spotted or blotched sparsely with blackish. 

 Average of 100 eggs, 74x45.8. Max. : 81.3x47.9 and 72x48.8. 

 Min. : 66x45.1 and 68x41 mm. Breeding -season. — Latter half 

 May and early June in Scotland. Incubation. — Shared by sexes, 

 but probably chiefly by female. Period 24-28 days (Faber). 

 Single-brooded. 



Food. — Mainly fish, especially herring, but also flounder, coal-fish, 

 sprat, sand-eel, trout, dace, gudgeon and northern char. Also 

 mollusca (Mytilus, etc.) and occasionally larger water -insects, and 

 Crustacea. Vegetable remains occasional. 



Distribution. — British Isles. — Resident and winter -visitor. Breeds 

 from south Inverness northwards, in Orkneys, Shetlands and O. 

 Hebrides, and in co. Donegal. Otherwise common winter -visitor 

 (mid-Sept, to March) to all coasts, and often ascends rivers and 

 visits inland waters. 



Distribution. — Abroad. — Greenland, Iceland, Faeroes, Spitsbergen, 

 Kolguevand Novaya Zemlia, Finland, Scandinavia and north Russia, 

 east through Siberia to Kamtschatka and Commander Is., perhaps 

 also Sachalin ; Aleutian Is. and N. America from Alaska to New- 

 foundland and Labrador. On passage and in winter from Iceland to 

 Mediterranean, Baltic Sea to Black and Caspian Seas, China, 

 Formosa, Japan ; in America to California, Florida and Maine. 



Order COLUMBUS. 



Contains the Pigeons and Doves. A well circumscribed group. 

 Skull schizognathous and holorhinal ; basi -pterygoid processes 

 present, except in Dodo and ally, which differ in many ways. Oil- 

 gland bare or absent. Basal part of bill not horny but covered with 

 more or less soft and swollen skin, which envelops the usually slit- 

 like nostrils as with a cap. Tarsus differently covered, generally 

 with feathers on uppermost part. Feathers soft and plentiful, as 

 with a " bloom," loose in skin, skin soft ; aftershaft rudimentary 

 or absent. Primaries 11, wing usually aquintocubital, sometimes 

 quintocubital. Rec trices 12-20. Hallux connected with flexor 

 longus hallucis, not with flexor perforans digitorum. Crop strongly 

 developed, as in Gamebirds. Young born blind, nidicolous. Real 

 down absent. Nests in caves or holes of trees, very light open 

 structures on trees or on ground. Eggs white (only in few tropical 

 forms yellow), nearly always 2, but sometimes 1, very seldom more 

 than 2. Nearly 500 forms in nearly all parts of globe except arctic 

 and subarctic. Division in families not satisfactory at present, 

 but Dodos (Raphus, Didus auct.) and Treronidad (tropical, mostly 

 green, some white, or other bright colours) apparently deserve 

 family rank, some Australian forms require study. 



In British Isles only one family admitted. 



