4 COWARD, Change in Habits of the Black-headed Gull. 



when the tide is running, but they do not need to be in 

 sight of the water to judge the right moment to leave the 

 roosting for the feeding ground. 



The inland feeding Black-head either knows nothing 

 about tides or ignores their influence ; they have ceased 

 to regulate its feeding times ; it roosts, like any other 

 diurnal bird, when it gets dark. This, at any rate, is the 

 case with the gulls which frequent the country to the 

 south of Manchester, say between the Lancashire border 

 and Knutsford. Every afternoon, a little before dusk, 

 these birds leave their scattered feeding grounds in the 

 fields, the Carrington sewage works, and the various meres 

 and pools, and trail to Rostherne, where in a compact 

 mass or masses they roost on the water. In the Dee and 

 Mersey estuaries the gulls rest during the flow on the 

 mud flats or marshes, sleeping or preening their feathers ; 

 on the coast they congregate on the shore, or in fields, 

 selecting positions from which they can command a wide 

 view to guard against the approach of enemies. The 

 centre of a large water like Rostherne gives them even 

 more security. Foxes, men, or other foes cannot steal 

 upon them. 



In most animals hereditary habits survive long after 

 they have ceased to be of practical use ; one would imagine 

 that the habit of regulating feeding hours according to 

 tides would have persisted amongst these birds, which 

 only a few years ago were maritime feeders. How is it 

 that certain birds of the same species, which feed in con- 

 tiguous areas in the country south and east of the Mersey 

 estuary should have distinct habits ? Some of the birds 

 near Warrington, for instance, must fly in a westerly 

 direction to feed whenever the tide ebbs, and others, but 

 a little further away, travel south at the approach of dusk 

 to roost at a time fixed relatively to sunset. 



