SPECIAL PRECAUTIONARY HABITS 321 



Even the Fruit- Bats (Pteropus) partly affect an animal diet, 

 devouring various small vertebrates, from fishes to mammals. 

 The large majority of the Insectivora are night-feeders, pro- 

 bably because their prey is more easily secured at that time 

 than for the sake of protection. 



So powerful a creature as the Elephant seems at first sight 

 to require no special means of protection, and its nocturnal 

 habits are no doubt largely due to its dislike of heat and desire 

 to avoid the unpleasant attention of flies. No animal, however, 

 is more persecuted by the arch-enemy man, who is more par- 

 ticularly given to hunting during the day, so that nocturnal forms 

 have the best chance of avoiding him. 



Many of the Ungulates feed at night, partly, it would seem, 

 for the sake of thereby lessening the chance of attack, but also 

 in order to avoid heat and flies. The habit is particularly well 

 developed in the case of certain forms which affect damp surround- 

 ings and wooded country, of which good examples are afforded 

 by Hippopotami, Tapirs, Swine, some kinds of Deer, and Cape 

 Buffaloes. Regarding the Hippopotamus, Vogt (in The Natural 

 History of Animals) says: "The hippopotamus is on the whole 

 a nocturnal animal, and where it has made acquaintance with 

 firearms leaves the water only by night, or if by day, only to 

 bask in the sun on sand-banks and islands out of the range 

 of bullets ". Regarding the Cape Buffalo the same writer re- 

 marks : " It is fond of plains and marshy forests, and delights 

 to remain the whole day buried in mud up to the shoulders in 

 order to protect itself against insects by which it is infested, and 

 from which it is partly delivered by birds that settle on its back ". 



The Gnawers or Rodents constitute a very large and widely- 

 distributed order of Mammals, living mainly on vegetable food, 

 mostly of small size and ill-provided with the means of defence, 

 on which account they are particularly liable to the attacks of 

 predaceous forms. Taking all these facts into consideration, we 

 shall probably not be far wrong in attributing a protective func- 

 tion to the nocturnal habits by which most of them are charac- 

 terized. Rats and Mice may be regarded as a case in point, and 

 the ordinary House-mouse (Mus musculus) in particular would 

 have but a poor chance of existence if all its depredations were 

 carried on during the day. Another feature of interest in this case 

 is that it presents a pretty clear case of a protective habit which 



VOL. II. 53 



