52 THE BIRDS OF THE BRITISH ISLES. 



band of slate-blue, much broader in the drake than the duck ; 

 the legs are slate-grey. In the young drake the irides are 

 yellow, but become redder as the bird matures ; in the duck 

 they are brown. Lyddcker states that the iris is reddest when 

 the bird is excited, and Mr. Millais noticed that the pupils were 

 contracted till the eyes "blazed" red when the male was sex- 

 ually excited. In the previous series (page 302) I referred to 

 the effect of excitement upon the iris of the Eagle- Owl. Length, 

 19 ins. Wing, 8'25 ins. Tarsus, 1*5 ins. 



Scaup. Nyroca marila (Linn.). 



Although the Scaup (Plate 23) has, within recent years, been 

 discovered nesting in Scotland and the Outer Hebrides, it is 

 mainly a winter visitor, often abundant, to our coasts. It 

 seldom appears on inland waters, but when it does so consorts 

 with other diving ducks. It breeds in both the Pala^arctic and 

 Nearctic regions, but has been " split " into geographical sub- 

 species by some systematists ; it only breeds in the moie 

 northerly and often Arctic portions of its range. 



The Scaup is as partial to salt water as the Pochard to fresh. 

 Its black head and breast, grey mantle, and white flanks show- 

 up well on quiet water, but when at a distance, tossed on a 

 rough sea, it is not so easy to distinguish from the much larger 

 Scoter or even other marine ducks. It is a typical diving duck, 

 short and squat, and, as in the Pochard, its bill slightly uptilts. 

 From this bird the drake Scaup can be distinguished by its 

 black, green-shot head and the distinct white bar on its wing, 

 very noticeable in flight, and the female by a broad white 

 mask surrounding her lead-blue bill. From the black-backed 

 drake Tufted it can be told by its larger size, grey back, and 

 absence of crest, but with females more care is needed. The 

 immature Tufted Duck, in brown uncharacteristic dress often 

 has a patch of white at the base of the bill. The wing bar is 



