1 700 THE PERCHING BIRDS 



lished in. For example, in Norway, Mr. Chapman found house martins breeding 

 in the crags of the river banks, and we have seen them nesting in precipitous cliffs, 

 as they do generally in some parts of Europe. The house martin builds its nest 

 generally during the month of May, but frequently finds its labors frustrated by the 

 intrusion of a pair of sparrows which proceed to oust the rightful owners from their 

 domicile. The nest is lined with feathers, and the eggs are pure white. It should 

 be understood that the British Isles lie directly in the line of many birds when 

 migrating from their breeding grounds in Northern Europe to their usual winter 

 quarters in Africa, the birds that breed in the north of Europe naturally nesting 

 later than those which breed further south. Consequently, these northerners, or at 

 least a proportion of their number, chiefly young birds, make their appearance in 

 the British Isles in the month of November almost as a matter of course, and it is 

 therefore only natural to expect that a few young house martins tarry in England 

 until the commencement of winter. Like the swallow, the house martin is subject 

 to some variation of plumage, although albinos are much rarer than amongst swal- 

 lows. This species is the most gregarious of all the European swallows, and may 

 often be seen clustering in hundreds upon the roofs of houses. The adult male has 

 the crown and sides of the head, back, and wing coverts rich bluish black; the rump 

 and central upper tail coverts are pure white; the wings and tail dull black; and the 

 chin and all the lower parts dull white. The sexes are identical in color, but the 

 adults very unlike their sooty-brown young. 



The slender, plain-colored martins of this group ( Cotile) possess a 



small depressed bill, broadest at the base; the wings are long in 

 Martins 



proportion to the tail, which is slightly forked; and the feet are small 



and slender. The metatarsus is bare, save for a tuft of feathers at its base. The 

 sand martins are pre-eminently gregarious in the nesting season; the best-known 

 and most widely distributed member of the genus being the European species ( C. 

 riparia), which extends its range to Northern Asia and North America. The In- 

 dian species (C. sinensis} is resident throughout the northern portions of the Indian 

 Empire, while Cowans' sand martin is peculiar to the island of Madagascar, several 

 species also inhabiting Africa. The common sand martin (C. riparia] arrives in 

 the northern parts of its breeding range a week or two in advance of the larger 

 swallows, and may generally be seen in sheltered situations during the last days of 

 March, frequently hawking flies under the crags that overhang salmon rivers. It 

 soon proceeds to the nesting grounds, and commences to tunnel the chamber in- 

 tended to contain its eggs in some sandy bank, gravel pit, or railway cutting, 

 although sometimes it digs a hole in the bank of a small stream, or even burrows 

 in a heap of sawdust. The male sand martin is a somewhat jealous bird, and often 

 indulges in a struggle with some rival. The eggs, which are pure white, without 

 spots of any kind, are laid in a hole lined with stems of grass and feathers. When 

 the young are able to fly, they join, the company of other swallows and martins, 

 and are constantly to be found by the riverside. The sand martin leaves its sum- 

 mer quarters earlier than its congeners, and its movements are less extended. On 

 one occasion we fell in with thousands of these martins steadily migrating along the 

 east coast of England, the air being literally full of birds for half an hour, flock 



