374 BIRD-LIFE OF THE BORDERS 



a fathom or two, over a shingly bottom, a company of 

 long-tails are nearly always to be found, in company with 

 a few of the somewhat similarly-formed golden-eyes. 



The long-tailed ducks are rather late in arriving — 

 often not till November, and disappear during the early 

 days of April — sometimes simultaneously with the advent 

 of the terns, about April 8th, by which date the adults 

 are already assuming their rich breeding- phi mage ; while 

 even immature drakes, some of which had acquired the 

 long white tertials in October, begin in March to show 

 traces thereon of the warmer colours. 



The long-tail is the only British duck that possesses 

 a distinctive breeding-dress at all ; and this species 

 illustrates one fact, among the many obscure phases of 

 colour-change, which was first pointed out to me by my 

 late friend Charles Murray Adamson, as follows : — That 

 the new feathers, when they have commenced to grow so 

 early in the year that the younger birds had not then 

 acquired their "summer-condition'' of blood, at first 

 come zvhite, as in winter ; but that, as the blood-condition 

 of the bird develops, so the growing feathers change 

 from their white, winter colour to the warmer tone in- 

 dicative of the breeding-time. The colour of growing 

 feathers, in short, changes with the changing seasonal 

 "condition" of the bird' — a rule which obtains generally 

 throughout bird-life, and is not confined to this species, 

 though it appears to apply chiefly to those genera (such as 

 the Limicolce) that in spring assume a bright distinctive 

 breeding-dress. In their build these ducks are heavy 

 and thick-set, like the rest of the diving-ducks ; not long 

 and slim, as most illustrations of them appear to convey. 

 Though the females are always plain and sombrely 

 clad, an old drake, when newly killed, with his chaste 



