SWALLOWS. 533 



the Martin perceives the winged fly passing through the air at the 

 distance of more than a hundred and twenty yards. 



Swallows are celebrated for their migratorjr journeys. In the 

 early days of spring they reach Europe, not in flocks, but as iso- 

 lated individuals or in pairs. They occupy themselves almost 

 immediately either in repairing their last year's nests, or, if these 

 have been destroyed, in constructing new ones. Among the arrivals 

 are many young birds of the previous year which have not had 

 nests, and yet it is not a little extraordinary that these, after six 

 months' absence, return with unerring certainty to the old dwelling 

 where hatched. This fact has been too often recorded to admit of 

 any doubt on the subject. 



The form, structure, and locality of the Swallow's nest vary 

 with the species. The Common Swallows {H. rustica), Fig. 240, 

 build theirs in the upper angles of the window of some country 

 house, under the eaves of a roof, or on the interior wall of a 

 chimney. A chimney seems an odd place to select for such a 

 purpose ; and White of Selborne relates, not without some expres- 

 sions of wonder at such a choice, that near the middle of May 

 one of these little birds began to form her nest about five or six 

 feet down a chimney adjoining the kitchen fire. Their nests con- 

 sist of a crust or shell of m.ud mixed with straw, and lined with 

 fine grass and feathers. Other species, sometimes in vast numbers, 

 establish themselves in the clefts of dead trees. Audubon esti- 

 mated at the incredible number of eleven thousand the quantity of 

 Swallows which had taken up their dwelling in a sycamore tree 

 (familiarly known there as a button wood) near Louisville, Ken- 

 tucky, United States. Some Swallows prefer rocks or caverns, 

 and hollow out in steep escarpments a gallery from two to three 

 feet in depth, at the extremity of which they place their nest. 

 Sometimes the nest is formed of twigs torn by the bird from the 

 dead branches of trees, and bound together hj a viscous liquid 

 which flows from the bird's mouth. 



When, after a month's labour, the Swallows have finished their 

 dwellings, the female deposits from four to six eggs. Incubation 

 commences, and continues from twelve to fifteen days, during 

 which the male bird exhibits inten.se interest in the proceedings, 

 carrying food continuaUj^ to his mate,, and passing the night in 



