THE DORMOUSE OR SLEEPER 371 
by a warm nest’ or otherwise protected; it is rather a means 
of slowing the vital processes and utilising over-accumulation 
of fat during the season when food is harder to.obtain. Hence 
it is caused by questions of food-supply rather than of tempera- 
ture, although temperature must not be left out of account. 
The varying behaviour of a species under different condi- 
tions is shown by its habits on mountains, where the altitude 
determines the nature and date of hibernation. A North 
American Rock-Squirrel’ hibernates only at high altitudes, and 
in the Marmots* of the Yakh-su Valley, Bokhara, the annual 
routine varies as follows :—At a height of 6000 feet they do not 
appear at the entrance of their subterranean abodes after the 
middle of August. Two thousand feet higher their feed is 
green much longer, and there they do not retire before the 
beginning of September. At 10,000 feet the cold alone sends 
them to sleep, because the water trickling from the snow keeps 
little kitchen-gardens growing for them. 
Few animals are better suited than the Dormouse for the 
cages of those who love pets. Although it can on occasions 
be frightened into biting, as stated above, it rarely resents 
being handled or loses its temper, and it may become so tame 
as to recognise its owner and respond to a call.* It readily pro- 
duces young in confinement. Like other small rodents, under the 
unnatural conditions of captivity it occasionally gnaws away por- 
tions of its own® or of a comrade’s tail, and may even become 
cannibalistic.” The two last tendencies may indicate the 
absence of something necessary to its comfort, and Monsieur 
Lataste attributes’ the death of captives during hibernation 
to loss of moisture by evaporation in a dry atmosphere. 
Both when wild or in captivity this is a particularly silent 
1 After the severe winter of 1860-61 Laver found many dead in their nests in Essex. 
Yet they survive much severer winters in continental Europe, where they probably 
hibernate earlier or make their winter-nests more carefully. 
* Citellus ; see E, A. Mearns, Bull. U.S. Nat. Mus., 1907, No. 56, 317. 
3 W. R. Rickmers, Geographical Journal, 1899, 604-605. 
4 J. A. Willmore, Zoologist, 1885, 304. For a good account of a captive dormouse 
by Hadfield, see Journ. cit., 1862, 8025 ; 1863, 8481. 
5 Lataste, of. cit., 42-43. 
° For a female killing and eating a portion of a male confined with her in a roomy 
cage, see C. A. A. Dighton, Mature Notes, 1899, 75. 
* An observation which, as he points out, applies generally to small vertebrates, 
as bats, reptiles, and, even more so, to batrachians. 
