272 Wild Birds and their Haunts 



bird moistens the clay with saliva, for the presence of 

 large salivary glands have been shown upon dissection. 



This bird is a great promoter of vegetation, which 

 would proceed but lamely without it, by boring, perforat- 

 ing, and loosening the soil, and rendering it pervious to 

 rains and the fibres of plants, by drawing straws and stalks 

 of leaves and twigs into it ; and, most of all; by throwing 

 up such infinite numbers of lumps of earth called earth- 

 casts, which, being their excrement, is a fine manure for 

 grain and grass. Earth worms make their casts most in 

 mild weather, about March and April. 



The fact is the casts are not their excrements, but a 

 sort of masonry, somewhat rude, indeed, but not the 

 less efficient in protecting their burrows, both from too 

 much rain, which would destroy them, and from the in- 

 trusion of enemies. 



The swallow is a great favourite. He comes to us 

 when nature is putting on her most smiling aspect, and he 

 stays with us through the months of sunshine and glad- 

 ness. " The swallow," says S. W. H. Davy, " is one 

 of my favourite birds, and a rival of the nightingale; for 

 he glads my sense of seeing, as much as the other does 

 my sense of hearing. He is the joyous prophet of the 

 year, the harbinger of the best season ; he lives a life of 

 enjoyment amongst the loveliest forms of nature ; 

 winter is unknown to him, and he leaves the green 

 meadows of England in autumn, for the myrtle and 

 orange groves of Italy, and for the plains of Africa. 



' ' Gentle bird ! we find thee here 

 When nature wears her summer vest ; 

 Thou com'st to weave thy simple nest ; 

 And when the chilling winter lowers, 

 Again thou seek'st the gentle bowers 

 Of Memphes, or the shores of Nile, 

 Where sunny hours of verdure smile." 



