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 



' 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. 



^ Citdlus; see E. A. Mearns, Bull. U.S.Nat. Mus., 1907, No. 56, 317. 



' W. R. Rickmers, Geographical Journal, 1899, 604-605. 



* J. A. Willmore, Zoologist, 1885, 304. For a good account of a captive dormouse 

 by Hadfield, sttjourn. cit., 1862, 8025 ; 1863, 8481. 



* Lataste, op. 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, Nature Notes, 1899, 75. 



' An observation which, as he points out, applies generally to small vertebrates, 

 as bats, reptiles, and, even more so, to batrachians. 



