1912] Ditmars: Feeding Habits oj Serpents 237 



Feeding Traits of Serpents 



Various curious feeding traits exist among serpents, which may- 

 be characteristic of individual species or of all the members of a 

 genus. The reluctance of some species to feed at all as captives has 

 already been described. This particularly relates to species of the 

 Viperidae. Exceptions to this habit are found among the species 

 of Ancistrodon which readily feed, even under adverse conditions. A 

 general habit among all serpents is the abrupt and entire cessation of 

 feeding with the female as pregnancy develops. This relates to both 

 • oviparous and viviparous species. With the former, there is a shorter 

 period of fasting, this lasting about four weeks. With the viviparous 

 species there is a period of positive fasting, varying among serpents of 

 different groups from six to eight weeks. Theoretically it would 

 appear that excess nourishment would be needed during the period of 

 the development of the young, but exceptions to this rule, which 

 feed occasionally up to the deposit of eggs or birth of the litter, are 

 rare. The period of gestation among the viviparous Colubridae is 

 about eighteen weeks; among the Viperidae it appears to be about 

 twenty weeks. With the Boidae, gestation seems to require a longer 

 period. The writer has usually noted the viviparous members of 

 the Boidae to commence their fast three months before the appearance 

 of the young. Oviparous species that have been received while con- 

 taining eggs, never fed until the eggs were deposited. 



In the assimilation of its food, the snake, if in healthy condition, 

 wholly dissolves the bones, and usually the teeth. Strangely enough, 

 the claws of a mammal do not appear to be generally attacked by the 

 reptile's gastric juices. The pelage of a mammal is little affected by 

 these juices, and masses of it when dried and separated from the 

 excreta so retain the color and lustre as to render identification pos- 

 sible. 



During the action of digestion on the great mass of unlacerated 

 prey, decomposition with its attendant gases, is rapid, and the stom- 

 ach of the reptile becomes greatly distended until the gastric juices 

 break through the body walls of the engulfed animal. Poisonous 

 snakes appear to more quickly assimilate prey dying from their ven- 

 oms than if it be killed in other ways. 



A great number of serpents can be induced to take freshly killed 

 animals. With most specimens of this type it is necessary to move 

 dead animals in order to attract the snake's attention. The 



