202 ANIMAL LIFE IN THE YOSEMITE 



The conduct of the California Gray Squirrel in cutting down the green 

 cones of the two important lumber trees, yellow and sugar pine, has been 

 commented upon adversely by foresters. The claim is made that the 

 squirrels consume so much of the seed that not enough is left for natural 

 reforestation. This point, so far as we know, has not been thoroughly 

 tested by experimentation ; the issue now stands between the judgment 

 of the forester on one hand, and that of the naturalist on the other. We 

 do know that many other factors, such as parasitism of the growing trees 

 by mistletoe or fungus, destruction by fire started by lightning or by 

 human agency, and killing of young growth by grazing, operate to limit 

 the numbers of the trees. And of the seeds which remain in cones on 

 the tree, a very considerable percentage is attacked by certain insects whose 

 young subsist on the embryo plant. The squirrels thus comprise but one 

 factor out of many ; attention is likely to be focused upon their work 

 because of its conspicuousness ; it is carried on in the open. Other agencies 

 fully as significant operate in an unobtrusive manner, and their importance 

 is thus likely to be underestimated. 



It is our opinion that in most places where natural conditions still 

 obtain, the necessary reseeding progresses as fast as is possible anyway, 

 and that the activities of the squirrels do not retard the regeneration of 

 the forest. Where man has interfered by logging off much of the timber 

 or by close grazing, the case may be different. 



One resident at Snyder Gulch stated to us that he believed that Gray 

 Squirrels indirectly do damage to sugar pines by leaving heaps of cone 

 scales at the bases of trees when shucking out seeds. When a forest fire 

 sweeps over the country these piles take fire easily and start 'burns' at the 

 bases of the trees. As bearing on this contention we noted many sugar 

 pine trees with kitchen middens at their bases, and many trees showed 

 basal burns which may have been made in the manner indicated. At Hazel 

 Green there were heaps of scales about several oak trees, and at one par- 

 ticular tree there was a kitchen midden fully 18 inches high within the 

 hollowed base of the tree. 



The California Gray Squirrel, so far as known, rears but one brood 

 of young each year, and this is brought off during the early summer 

 months. None of the female squirrels which we obtained contained 

 embryos; but litters elsewhere are known to range from 2 to 4. By mid- 

 summer the young animals are beginning to appear abroad, being then, 

 on the average, about half the size of adults. 



The Gray Squirrel population is affected by a number of factors. Birds 

 of prey capture a certain percentage of the animals ; some young are killed 

 by falling out of the nest; other young animals are caught by dogs, and 

 in wild country probably also by native carnivores ; disease greatly reduces 



