84 



YOSEMITE NATURE NOTES 



Photo by Algerian 

 The bear trap. 



naturalists have indicated that, at this 

 latitude, bears sleep rather lightly during 

 hibernation. * 



It has been generally supposed that hi- 

 bernation was to enable the bears to 

 escape the cold weather of the winter 

 months. Observations in Yosemite indi- 

 cate, however, that the availability of 

 food during this period is the chief con- 

 trolling factor. 



It is believed that late June is the 

 time when most Yosemite bears mate. 

 Cubs are, for the most part, born around 

 the latter part of January, or early Feb- 

 ruary, while the mother is in hiberna- 

 tion. Cubs are generally born in pairs, 

 although triplets or even solitary cubs 

 .ire not uncommon. Rarely there are 

 quadruplets. 



At birth, they are extremely tiny, 

 weighing less than a pound. Their growth 

 and development are at first very slow. 

 In one case, it was 3 1 > days before the 

 cub opened its eyes. The nursing period 

 lasts tor about six months, but the cubs 

 will be with the mother their first year, 

 usually hibernating in the same den with 

 her, or in a den nearby. 



In Yosemite, new-born cubs seldom 

 emerge with their mothers until late 



*The term "hibernation" is used loosely here. The 

 temperature remains normal and rate of breathing 



April, and are rarely observed on the 

 Valley floor before May or June. They 

 are then about 14 inches long, a foot 

 high, and weigh 10 or 12 pounds. They 

 soon supplement their milk diet with 

 other food and put on weight rapidlv. 



The mother bear is usually quite so- 

 licitous of her cubs, fondling and plav- 

 ing with them, and protecting them 

 when in danger. They soon learn to 

 scramble up a tree at the first warning 

 sound from the mother. A mother has 

 been observed cuffing her cubs because 

 they did not go up a tree quickly enough 

 after she had given them a warning of 

 danger. 



Despite maternal care, however, as the 

 cubs grow in size, they usually dwindle 

 in number. Sickness and accidents take 

 their toll. The male bear may try to 

 kill or injure any cub that might come 

 within his reach, including his own off- 

 spring. 



The adult, female normally produces 

 young every other year. Cubs hibernating 

 with the mother the winter after their 

 birth will generally be put "on their 

 own" during the second summer when 

 the mother again prepares to mate. 



January 28, 1950, a small cub was 

 discovered by the rangers in the area be- 

 hind Park Headquarters in Yosemite 

 Valley. About 17 inches in length and 

 1 1 inches high at the shoulder, weighing 

 between 8 and 10 pounds, it could not 

 possibly have been born in the current 

 winter. Yet the presence of small, sharp 

 "milk teeth" characteristic of an animal 

 less than a year old, precludes the idea 

 that it was born in January 1949, the 

 time of the previous cub crop. The logi- 

 cal conclusion based on these facts is 

 that it was born not earlier than August 

 1949, though the writer (H. C. P.) is 

 unable to find any records of late births 

 for the species in the literature. 



Although classed as carnivores (flesh- 

 black bear is not a true hibernator since the body 

 slows but little, among other factors. 



