260 
ANATIDiT:. 
unusual to hear the remark : — “ Ah, the fine weather is come 
again ; hark how the Calloos are singing !” It is difficult to 
determine whether the cry is one of alarm or of pleasure. It 
may he heard as weU when they fly off after a shot has been 
fired as when they are peaceably enjoying themselves, un- 
conscious of the near vicinity of a listener; it is also constantly 
uttered by the male at pairing time, as he swims bowing round 
liis mate. One calm day in December the chorus of many 
voices was perfectly bewildering, as, rowing sharply round the 
point, I came unexpectedly upon a flock numbering upwards 
of a hundred, more than half of them males, as is nearly always 
the case with this species, whether the flocks be large or 
small. 
In Shetland I have never observed the Long-tailed Ducks on 
land, nor have I ever heard of their diving for food upon a sandy 
or muddy bottom, or in very deep water. The most attractive 
spots of all are low ledges or groups of rocks, lying but a few 
feet beneath the surface at low water, and swarming with the 
minute periwinkles on which they seem to entirely subsist. It 
is singular that I have never yet found any other kind of food 
in the stomach, although I have examined some scores ; and 
yet our very best authorities state that this bird feeds largely 
upon bivalves. The latter, of numerous species, are abundant 
in many parts of Shetland, but the Calloos perhaps consider 
them less worth the trouble of procuring than the univalves 
wliich so immeasurably exceed them in quantity. 
The scarcity of these Ducks in certain winters used to puzzle 
me greatly, until the fishermen explained the reason, which 
I afterwards proved to be correct. It appears that, with a very 
proper feeling, readily to be understood by those who know the 
two birds, the Ducks never like to associate with the Shag or 
Green Cormorant, and, indeed, entertain a strong antipathy to it ; 
so that when sillacks,the young of the coalfish {Merlangus carhon- 
arius) chance to be unusually abundant in the voes, the Shags, 
assembling in great numbers, completely scare away the Ducks. 
I.ong-tailed Ducks are often procured by lying in wait among 
