CorresjJondence.



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You say “Surely changes in colouration in summer and winter are greatly

due to outward surroundings, for causes of concealment.” Are not “ outward

surroundings ” cases of environment? and as to the “concealment” idea, I am

not in favour of holding too much to such a theory. You proceed to quote

examples in the bird world to substantiate your idea of winter colouration from

a “ concealment ” point of view and you unluckily choose two very poor examples

to illustrate your point, namely the Snowy owl and the Iceland falcon, and you

compare them to the raven. Of course the Snowy owl and the Iceland falcon

possess quite as much “ Vigour” as the raven, perhaps a stronger vigour even ;

but your remarks would lead the general reader to suppose that the owl and

falcon named by you ‘ 1 assume white feathers in winter to conceal themselves

from their prey.” * In other words that these two species of birds possess a dark

plumage in summer and a white plumage in winter. To put the matter quite

briefly, I may as well say at once that the Snowy owl is a white ” bird all the

year round, and that the males are “ whiter” than the females, and that the

degree of “whiteness” is assumed with age, because young birds of both sexes

are heavily ticked with black during their first winter, and as they grow older the

black marks gradually become less at each succeeding moult.


As regards the Iceland falcon, I am afraid you have mistaken the Iceland

for the Greenland ! The Iceland falcon (Falco islandus) is always a brown bird

all the year through, f The Northern falcons have been one of my pet subjects

for some time, and I consider them all to belong to one species and divided up

into racial forms according to their environment, and thus you get the very

darkest form of all (Falco labradorus) from Labrador and Hudson’s Bay, grading

into the slightly lighter form from Iceland (Falco islandus) to the still lighter

form from South Greenland (Falco holboelli) to the whitest form of all from

North Greenland (Falco candicans). For confirmation of the above theory see

Dr. Hartert in Novitates Zoologies, pp. 167-185, June 30th, 1915, Tring Museum.


From this you will see that when you choose the Snowy owl and Iceland

falcon as cases to prove your theory of “concealment and colouration,” you

choose two examples which cannot assist your argument. Again, I have very

grave doubts of the correctness of your theory that gorgeous coloured males of

certain species, e.g. the males in the duck and pheasant families, have any effect

on the females in selection of their mates ; and to substantiate my point, I

would refer you to the ruffs (Machetes pugnax ) ; here we have a species of bird

in which the males are very conspicuously coloured and vary greatly in degree of

colouration, all the males “ show ” before the females, yet it has been proved

conclusively by Mr. Edmund Selous that the females often “ pair ” with one of

the most sober-coloured males, quite ignoring the brightest and most strikingly-

coloured cocks ; and on the “Vigour ” theory these hens in choosing those most



* We are sorry that this was expressed in a manner which would lead to a

misinterpretation of facts. ED.

t A lapsris calami — ‘ Greenland ’ was the bird referred to. -ED.



