272 



KNOWLEDGE. 



[December, 1902. 



oihiT ill flctiiils of form or structure -iiiul td siidi the 

 iiaino of iliiiioriiliir spccii-s is tochiiit-ally ii|ii)li<'d. Natu- 

 ralists have affroed in ilfsifjiiati' tin! Arctic fox l)y the same 

 title, altliiivij;b. were it not that it luifjht i)e tjikeii to 

 convey an alto^'cthcr ditfcront incanini:^, tlic (crin didiroic 

 woukl he more ap]ir<>j)riato, seeing' that the ditTcrence 

 between the two jdiases is solely one of colour, and has 

 nothinj; to do with shape or structure. Usintf, then, the 

 term diniorj>hism as indicative of the existence in one 

 animal i>f two distinct colour-phases totally unconnected 

 •witli either locality or season, the Arctic fox appears to be 

 the only mammal to which the dcsi^'natiou can be 

 properly applied. 



The reason for this remarkable dimori>hisni iu the Arctic 

 fox is hard indeed to discover, and no satisfactory explana- 

 tion of the puzzle appears hitherto to have been ottered. 

 It is almost unnecessary to say that the reason why 

 Arctic and sub- Arctic animals turu white in winter is that 

 they mav be as inconspicuous as possible in their environ- 

 ment of snow and ice. And if blue foxes were met with 

 only in countries where snow lies but a short time in 

 winter, while white ones occurred solely in more northern 

 lauds, some clue to the puzzle might be forthcoming. But 

 as a matter of fact this is not the case. 



The distribution of the Arctic fox is circumjjolar, ex- 

 tendiny; in the New World about as far south as latitude 

 50°, that is to say, nearly to the southern extremity of 

 Hudson Bay, and in the Old World to latitude 60°, or, 

 approximately, to the latitude of Christiania and the 

 Shetland Isles. Northwards the species extends at least 

 as far as Grinnel-land. 



In Iceland all the Arctic foxes appear to belong to the 

 blue phase, and as that island is far to the south of many 

 portions of the habitat of the species, it might be thought 

 that this is the reason why the white phase is unre- 

 ])reseuted there. But that island is far north of the line 

 where the mountain hare and the stoat begin to assume 

 a white winter livery ; and if it is essential for these species 

 that they should assimilate their colour to that of their 

 surroundings, why is it not equally so in the case of the 

 Arctic fox? 



Again, although, as already mentioned, blue foxes are 

 rare ni Labrador, in Alaska they are comparatively common, 

 and the same is the case in Greenland, whence, according 

 to Mr.W. Poland, the Royal Greenland Company imported 

 1,451 to Copenhagen in 1891. And if it be essential for 

 animals to turu white in winter iu any country in the 

 world, it is surely Alaska. It is difiicult to ascertain the 

 jtroportion of blue to white foxes in either Alaska or the 

 Pribiloff Islands, but it is certain that in both localities the 

 two phases are found together, living apparently under 

 precisely the same physical conditions. 



As regards the islands last named, Mr. Elliot, in his 

 work on the "Seal Islands of Alaska," writes that — "Blue 

 and white foxes are found on the Pribilott' Islands, and find 

 among the countless chinks and crevices in the basaltic 

 formation comfortable holes and caverns for their accommo- 

 dation and retreat, feeding upon sick and pup seals, as well 

 as water-fowl and eggs, during the smnmer and autumn, 

 and living through the winter on dead seals left on the 

 rookeries, and the carcases on the killing-grounds." 



This account, then, fully establishes the fact that blue 

 and white foxes occur iu regions where, according to all 

 accepted rules, there ought to be none but white in- 

 dividuals, during the long and dreary winter. It gives, 

 however, no deiiuite clue to the reason for the strange 

 association. 



There is, however, a descrij)liou of the habits of Arctic 

 foxes in Grinnel-land given by Colonel I'ielden iu his 

 " Voyage to the Polar Sea," which may possibly throw 



some ligiit on the subject, although unfortunately it does 

 not t<'ll us whether blue as well as white foxes are found 

 in that region. After referring to the numbers of lem- 

 mings to l)c seen looking out from the mouths of their 

 holes, or feeding in thi' vicinity, the author i>rocccds as 

 follows : — 



" Wc noticed that numerous dead lemmings were 

 scattered around. In every case they had been killed in 

 the same manner ; the sharp canine teeth of the foxes had 

 ])enetrated their brain. Presently we came ui>on two 



ermines killed iu the same manner Then, to our 



surprise, we discovered numerous deposits of dead lem- 

 mings ; in one hidden nook under a rock we pulled out a 

 heap of over fifty. We disturbed numerous ' caches ' of 

 twenty and thirty, and the earth was honey-combed with 

 holes, each of which contained several bodies of these little 

 animals, a small quantity of earth being placed over them. 

 In one hole we found the greater part of a hare hidden 

 away. The wings of young brent-geese were also lying 

 about; and as these birds were at this time just hatching, 

 it showed that they must be the results of successful forays 

 of prior seasons, and that consequently the foxes occupy 

 the same abodes from year to year. I had long wondered 

 how the Arctic fox exists in winter." 



Now it will be evident that in this instance the foxes 

 killed the prey stored up for winter use while they were 

 in the dark summer coat. And since in winter, when the 

 birds have left and the lemmings have retired t<i the depths 

 of their burrows, they have no game to capture and no 

 enemies to fear save polar bears (which would not be likely 

 to do them much harm), it would appear to be a matter of no 

 consequence whether their coats be dark or light. Conse- 

 quently, it seems a possible explanation of the phenomenon 

 under consideration that the blue phase of the Arctic fox 

 indicates a reversion to the ancestral coloration of the 

 species, due to the fact that no advantage is to be gained 

 by the assumption of a white livery. Such reversion might 

 well take place only in certain individuals of a species, and 

 would probably tend to become more or less completely 

 hereditary. Before such an explanation can, however, be 

 even tentatively accepted, it is necessary to ascertain 

 whether the blue Arctic foxes of Iceland are in the habit of 

 making winter stores of jirovisions. If they are not, but 

 hunt iheir prey in winter, the theory will not hold good. 



As regards animals which hunt their prey in winter, or 

 are themselves hunted, it would seem essential that they 

 should be white even in the highest latitudes, where the 

 long polar night lasts half the year. For in the bright 

 starlight — to say nothing of moonlight — they would, if 

 dark-coloured, be almost as conspicuous on the snow as 

 iu daylight. 



As regards the number of Arctic fox-skins which find 

 their way into the market, Mr. Poland, writing ten years 

 ago, states that from 25,000 to 60,000 of the white phase 

 were then annually imported from Siberia, the greater 

 number coming to Lei]>sic. The fur of these is i_)f a rather 

 coarse quality, quite different to that of the tine-haired 

 Greenland skins. In 1891 about 9000 white skins were 

 imported by the Hudson Bay and Alaska Companies, and 

 nearly lOOO by the Eoyal Greenland Company. Of blue 

 skins about 2000 were annually imported into London by 

 the Alaska Company, and some 500 to Copenhagen by the 

 Greenland Company, although in 1S91 the number of 

 skins sold by the latter body reached 1-151. It is note- 

 worthy that iu the fur-trade Greenland blue fox skins are 

 uoted as being of the same tine-haired quality as the white 

 skins from the same locality, while the Alaskan blue 

 skins are eijually coar^c-hillled, consequently there is 

 presumptive evidence of the existence of a Greenland and 

 an Alaskan local race of the species. 



