498 ANNUAL REPORT SMITHSONIAN INSTITUTION, 192 8 



opposite direction. The chestnut grows abundantly on the eastern 

 side of the lake, but is comparatively scarce on the western, and these 

 extensive migrations always take place in years when the yield of 

 chestnuts is large ;" and again, quoting Winslow C. Watson, " The 

 autumn of 1851 afforded one of these periodical invasions of Essex 

 county." 



MATING 



In Ontario red squirrels mate in March and at this time there is 

 more chasing about among the branches than at any other time. 

 Seton (1909) says that in Manitoba they mate late in March or early 

 in April. Nelson (1918) notes that the males fight in the spring and 

 sometimes inflict serious injuries on one another. 



Whether they pair for life or even for a single season is a doubtful 

 point. Seton has seen two adults at work building a nest, and notes 

 that the two albino squirrels mentioned above were seen together all 

 summer and winter. Certainly neither the male which I had under 

 observation for two years, nor the female which I observed for over a 

 year, had a mate associated with it, though the latter brought one 

 young to the tree with her during late June and early July. 



NESTING 



The nests of the red squirrel are of two kinds : nests made in holes 

 in trees or stubs, and the large outside nests made of leaves and other 

 materials. Both kinds serve as winter homes, but the young are 

 usually born in a cavity in a tree, frequently in one excavated by the 

 flicker. 



In the far north where the timber is small the outside nests are used 

 almost exclusively. Osgood (1900) says of the red squirrel of the 

 Yukon, " Its globular nests of grass, moss, bark and refuse are com- 

 mon and are usually found situated near the trunk of some slender 

 t^pruce, 10 or 20 feet from the ground. Sometimes several will be 

 found in the same tree, and half a dozen or more are very often to be 

 seen at the same time." 



Cram (1901) says of these outside nests: 



When convenient, he chooses the nest of some large bird for a foundation, 

 and in this builds a structure of moss, bark, pine-needles, and dead leaves, with 

 walls several inches in thickness, and a soft nest of dry grass and feathers in- 

 side. The bark used is of two sorts, the rough outer bark of different trees, 

 broken into small pieces, and what appears to be the inner bark of the red 

 cedar, torn into narrow strips, or ribbons to bind the whole together. The nar- 

 row opening at one side is provided with a hanging curtain of moss or some 

 similar substance, easily pushed aside by the inmates, but immediately falling 

 back into place and effectually concealing the entrance. If unable to find a 

 bird's nest situated to their taste, the squirrels arrange a loose platform or 

 framework of twigs in a convenient crotch and build their nest on that. 



