760 Life-histories of Northern Animals 



As a general argument, mating customs are so deeply 

 rooted as to be very uniform in a given family; thus all the 

 true pigeons pair, all the true Deer are polygamous; and every 

 evidence, direct or collateral, I can find on any of the true Dogs, 

 except the case of the Alaskan team dogs (in domestication), 

 points to perfect and permanent monogamy as the rule. 



The nursery den is either a natural cave, a hollow log or 

 stump, or a hole in the ground, dug out by the parents them- 

 selves. Sometimes they enlarge a Badger hole, and in any 

 case the bed is not far from the entrance. 



The Gray-wolf apparently does not line its nest. Roland 

 D. Carson, of the Philadelphia Zoo, writes me concerning those 

 that bred in the gardens: 



"The females dug a hole in the earth but made no attempt 

 at lining the nests, and when hay and other materials were put 

 in it to form a bed they were promptly thrown out." 



As the lining habit is instinctive in the kinds that practice 

 it, we note with interest that many animals are tormented with 

 parasites which harbour and breed among the nest material, 

 so that lining is a dangerous comfort. 



GESTA- According to all observers the period of gestation is 63 



days in the Gray-wolf, as in most, if not all, of the true Dogs. 



The young number 3 to 13, but are usually 6 or 7. When 

 born they are blind and almost naked, and, like young dogs, 

 their eyes are not opened until the ninth day. Carson says that 

 the only litter of the Wolf pups that he was able to watch closely 

 "did not get their eyes opened till the thirteenth day." Pos- 

 sibly these were prematurely born. 



W. H. Blackburn reports that he has watched several litters 

 in the National Zoo at Washington and found their eyes opened 

 a little on the seventh day and fully opened on the ninth. Lit- 

 ters have been born there on March 23, 27, 29, and April 4. 



Those in the London Zoo (parents from Texas) were 

 born March 28; all the four litters bred in the Philadelphia 



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