290 THE BIOLOGY OF THE SEA-SHORE 



to the surface with their feet ; but this may be an exaggera- 

 tion. Cockle-gatherers riddle out their catch, taking the 

 large shells and leaving the smaller on the surface " practi- 

 cally presented to the gulls " (see Fig. 19). 



The heron frequently fishes in tidal waters, and Dr. 

 F. Ward (1912) estimates that i| lbs. of fish are consumed 

 per day for each young heron, while the adults take 3 lbs. 

 A heronry of 50 nests would thus require 500 lbs. of fish 



Fig. 19. — Food of black-headed gull (adapted from CoUinge). 



daily. Two broods may be raised and the heronry occupied 

 from April to August, giving a consumption of 45 tons of 

 fish per nesting season. On muddy flats, eels are the chief 

 food, but where trout and salmon-parr are accessible, these 

 are used. 



Kellogg (19 10) states that many New England farmers 

 living near the shore made it a practice to fatten their hogs 

 on clams, up to a quarter of a century ago. According to 

 this writer, " there are many places on the New England 

 coast where the low tide exposes hundreds of acres of 



