Adapted from Volume Four of The Natural History of Animals: The Animal Life of the World in Its Various
Aspects and Relations by James Richard Ainsworth Davis (1903)
The examples of protective resemblance so far quoted are mostly permanent adaptations to one particular sort
of surrounding. There are, however, numerous animals which possess the power of adjusting their color more
or less rapidly so as to harmonize with a changing environment.
Some of the best known of these cases are found among those mammals and birds that inhabit countries more
or less covered with snow during a part of the year. A good instance is afforded by the Irish or variable hare,
which is chiefly found in Ireland and Scotland. In summer, this looks very much like an ordinary hare, though
rather grayer in tint and smaller in size, but in winter it becomes white with the exception of the black tips to the
ears. Investigations that have been made on the closely allied American hare seem to show that the
phenomenon is due to the growth of new hairs of white hue.
The common stoat is subject to similar color change in the northern parts of its range. In summer it is of a
bright reddish brown color with the exception of the under parts, which are yellowish white, and the end of the
tail, which is black. But in winter, the entire coat, save only the tip of the tail, becomes white, and in that
conditions the animal is known as an ermine. A similar example is afforded by the weasel. The seasonal
change in the vegetarian Irish hare is purely of protective character, but in such an actively carnivorous creature
as a stoat or weasel, it is aggressive as well, rendering the animal inconspicuous to its prey.
Why is the American hare mentioned in the passage?
