276 HIRUNDINID.E. 



frequently the courses of rivers and canals. As the season 

 advances, they spread themselves more generally over the 

 country, still, however, being most numerous in the vicinity 

 of water. In May they build their shallow open nests of 

 mud and straw lined with feathers, a few feet down a 

 chimney, in an outhouse, a bell-tower, the shaft of a de- 

 serted mine, or any other place which is at once dry and 

 dark, rarely in more exposed places. They lay four or five 

 eggs, and rear two or three broods in a season. The young 

 being, from the usual situation of the nest, unable to leave 

 their nursery until they are fully fledged, require to be fed 

 a long time, but they continue to be, partially at least, 

 dependent on the parent birds for many days after they 

 have learnt to hawk for themselves. The process of 

 feeding is carried on while both old and young are on the 

 wing; or the young, perched on the top of a house or the 

 branch of a tree, receive in turn the morsels which their 

 more skilful parents have caught for them. In autumn, 

 many days before migration is actually about to take place, 

 Swallows, old and young, assemble in large flocks, especi- 

 ally towards evening, and roost on trees in the vicinity of 

 water. At this season they seem to be more socially dis- 

 posed, even during the day, than at any other period of 

 their sojourn with us. In October they take their departure 

 collectively, and so strongly is the migratory instinct then 

 in force, that it overcomes parental affection, powerful 

 though this feeling is in the Swallow ; some of the late 

 broods being left behind. 



