CHAEADEIIFORMES. 379 



often, however, several of the Laridm pass inland and live upon 

 various insects, especially such destructive larvae as wireworm, 

 leather -jackets, and cockchafer grubs. They may often be 

 found, preceding and during stormy weather, sixty and seventy 

 miles inland, following the plough as readily as the rook, and 

 devouring with avidity the grubs turned up during its progress 

 across the fields. These birds usually appear inland, as on the 

 coast, in flocks. Most species breed on the coast, but some, such 

 as the Black-headed Gull (Larus ridibundus), breed inland on 

 the banks of lakes and rivers and in marshes. The young are 

 nestlings. The Herring Gull {L. argentatus), as well as the 

 Common Gull {L. canus), must also be included amongst those 

 whose services are beneficial to us. Small mammals, such as 

 mice, voles, and shrews, also form part of their bill of fare when 

 driven by stress of weather inland. 



The Black-headed Gull {L. ridibundus). — This gull is very 

 different in plumage in summer and winter. In summer the 

 head and neck of both male and female are dark-brown ; in 

 winter this coloration has quite gone, those parts being pure 

 white. In spring the brown colour again appears. This change 

 is not due to a fresh moult, but to an actual change of colour in 

 the existing feathers. The legs and bill are bright red. The 

 young birds have quite a different plumage, being much darker, 

 the dark-brown feathers being mottled at their edges with yellow, 

 and the feet yellow, not red. This gull breeds inland on 

 marshes and flats as well as along the coast, and it is especially 

 during the breeding season that they destroy so many noxious 

 insects. The nest is made by trampling down a number of 

 reeds, grass, and sedges ; in this concavity during April and 

 May three dusky-olive eggs spotted with black are laid. 



The Herring-gull {L. argentatus). — This gull is one of our 

 largest species, often reaching two feet in length. The head 

 and neck are white, often in summer with brown streaks ; the 

 wings and the back are pale bluish-grey, the primary feathers 

 being black and grey with black shafts and white tips, and the 



