550 BRITISH BIRDS. 



are greatly increased by migrants in the winter. It is an occasional 

 autumn visitor to the Burmudas. 



It is probable that the Teal was a circumpolar species during the last 

 interglacial period, and that the Nearctic and Palsearctic Teals have become 

 differentiated at a comparatively recent period, since the Arctic ice-fields 

 have driven them far enough south to make the areas of their distribution 

 discontinuous. So long as they all bred near the Arctic Ocean and on 

 the islands within it, constant interbreeding would cause any change to be 

 universal; but as soon as the Nearctic Teals became isolated from the 

 Palaearctic Teals, and each colony could only interbreed within itself, the 

 changes would be sure to follow different lines, and soon result in the 

 separation of the Teals into two closely allied species. 



The habits of the American Teal are described as precisely the same as 

 those of our bird. It chooses the same localities, both in its winter- 

 quarters and at its breeding-grounds. It is not known that the nest or 

 eggs differ in any way. The latter are creamy white in colour, and vary 

 in size from T85 by 1*35 inch to T75 by 1-3 inch. 



The American Teal closely resembles its Euro-Asian ally, but the white 

 line which encircles the green patch on the side of the head, and passes 

 down to the base of the bill, is almost obsolete ; the scapulars are uniform 

 pale slate-grey, and there is a broad white crescent on each side of the 

 breast in front of the shoulder. 



The variations attributable to age and season are said to be very similar 

 in both species, and Baird, Brewer, and Ridgway state that the female of 

 the European Teal is not distinguishable with certainty from that of the 

 American Teal. Young in first plumage of the two species are also indis- 

 tinguishable. Males of the year may be distinguished by the white 

 crescent on each side of the lower breast. Young in down are described 

 by Baird, Brewer, and Ridgway as resembling those of the Mallard in 

 having the dark spot on the ear-coverts disconnected from the loral 

 streak. 



