2IO THE BIRDS OF THE BRITISH ISLES. 



from those of the Lesser Black-backed Gull, though as they 

 grow the paler mantle serves to distinguish them. Although 

 the Herring-Gull is certainly resident, it is also a partial 

 migrant ; there is a marked northward movement at the end 

 of April and in early May, though the diurnal movements 

 to and from feeding and roosting grounds are easily confused 

 with migration. In autumn British-marked birds have been 

 recovered in Germany, but the species is decidedly kss 

 migratory than the Lesser Black-back. 



The flight of the Herring-Gull is typical of all the larger 

 _gulls, and can be studied when clouds of these birds follow in 

 a steamer's wake. It drifts or sails, without noticeable wing 

 action, even in the teeth of the wind, automatically adjusting 

 its pose so as to benefit from every change of air current ; thus 

 it will poise above the stern, travelling exactly at the rate of the 

 ship, and glancing with yellow eye to right or left, ready to 

 swoop to pick up from the waves any morsel thrown over or 

 churned to the surface by the screw. After it has settled and 

 been left far behind it rises, and in a few strong but never 

 hurried wing-beats recovers its position and again sails. I 

 have frequently seen birds drop one foot as if to adjust 

 the balance whilst they scratched the beak with the other, 

 and neither lose altitude nor speed. Indeed, all its graceful 

 aerial actions are perfectly controlled. Often a number will 

 rise for high flights, wheeling, mere specks in the sky. With 

 the Black-head it comes to harbours and coastal towns, 

 wrangling amongst the fishing boats for the garbage and offal, 

 a useful scavenger. In the Mersey it floats with the tide past 

 the anchored liners, flying back again and again to keep a 

 watch for the appearance of cook or steward disposing of scraps. 

 In rows it lines the dock sheds, or perches on the chimneys 

 and pinnacles of high buildings. On its native cliffs it will 

 stand, looking seaward, and at Tenby and other towns where 

 the houses crest the cliffs it is just as ready to use the roof 



