ECOLOGY OF ISLE ROY ALE. 411 



by the variety of trees and shrubs whose bark and twigs had been eaten. 

 All such injury seen was attributed to hares, as it occurred close to the 

 ground in places frequented by them. The most extensive injuries to 

 vegetation were on the jack pine ridge (I, 5) where the smaller lower 

 branches of the Jack Pines had been eaten off up to about three feet 

 above the ground. The cut ends clearly showed that the branches had 

 been bitten off. The young Wild Eed Cherry {Prunws pennsylvanica) 

 growing in the crevices of the lava were often cut back, the bark re- 

 moved and stems killed by the injury; Amelanchier showed similar in- 

 jury. Along the trail to McOai'goe Cove (II) Rock Maple, aspens and 

 alders were seen with the bark injured. Max M. Peet observed the 

 bark eaten from birches and Ground Hemlock at Washington Harbor, 

 and from apples at Siskowit Bay (near VIII, '04). 



At dusk the Hares came out to feed in the clearing about our camp 

 at Siskowit Bay (Y, 3), and were quite tame, coming close up to the 

 camp. On a small island in Siskowit Bay, about 1/2 mile west of camp 

 they Avere exceedingly abundant at dusk in a small clearing at a fish- 

 ing camp. They were also abundant at Washington Harbor, along the 

 road from the Club House to the old mining camp — Wendigo — and in 

 the clearings at Neutson's Resort (IV, 5). 



A very young specimen was taken (IV, '04) Aug. 22, 1905. whose 

 total length was 190 mm. This shows that young are born in August, 

 and it perhaps represents the last brood of the season. The size of 

 other young specimens (215 and 310 mm.) suggest that at least one 

 brood has preceded the one just mentioned, although it is probable 

 that the broods are not sharply defined. 



A very interesting periodic variation in the fertility of the Varying 

 Hare {L. americanus niacfarlani Merr.) has been pointed out by Mac- 

 Farlane ('05, p. 740) who says "A litter usually consists of three or 

 four; but when on the 'periodic' increase, females are known to have 

 as many as six, eight and even ten at a time, and then gradually re- 

 turn to three or four." This periodicity- he also shows (1, c, pp. 691, 

 692, 710) is of fundamental ecological importance in the nature his- 

 tory of the fur bearing carnivores of the far north. The staple food of 

 the Lynx is Hare, so that when the latter decline in fertility and abun- 

 dance, the Lynxes, not only also become reduced in number but are 

 even known to starve. The Marten and to a much less degree the Mink 

 also seem to be influenced in a similar manner. 



Dr. Merriam ('86, p. 306) thinks that in the Adirondack Mountains 

 there may be two litters in a season, of from four to six, the former 

 being the usual number. The first litter is born late in May. 



Upon Isle Royale in addition to those mentioned, other possible 

 enemies of hares, at least for the young, may be the weasels, and the 

 hawks, owls and the Bald Eagle. 



There is an interesting seasonal variation of habitat (Merriam, '86, 

 p. 305), in the Adirondack Mountains of New York; during the sum- 

 mer they tend to frequent the coniferous forests, and in winter the 

 swamps, alder and spruce thickets bordering lakes and beaver mea- 

 dows. 



Notes on Color Yariation. — A series of 27 specimens was secured dur- 

 ing July and August, the examination of which shows that there is a 



