STATIONARY SPECIES 151 



and roosting all winter in their chosen pines. Yet there is distinct 

 evidence of an over-sea movement — not heavy certainly, but 

 systematic. 

 (18) Mallard (Anas boscas). 



The local race which breeds on the moors, or wherever an acre 

 or two of marsh-land is suffered to survive, can be distinguished at 

 a glance from the immigrant foreigners by their extra bulk. For 

 while the two races are of exactly the same expanse of wing, the 

 native drake weighs from 3 to 34 lbs., the foreigner barely 2^ lbs. 



The latter, moreover, while here, confine themselves exclusively 

 to the salt water, or its immediate neighbourhood : while the home- 

 bred ducks hold to their native loughs, and never leave these till 

 driven out by ice to the tide. 



[Note that, as regards validity of species, subspecies, or climatic varia- 

 tions, I express no personal opinion. Such points are purely for systema- 

 tists, who (having large series from distant localities for comparison) have 

 differentiated as above.] 



