ECOLOGY OF ISLE ROYALE. 13 



Hymenoptera {Uroceriis) , and their parasites. In addition to such si^e- 

 cies as feed npon Balsam, White Spruce and Paper Birch and their asso- 

 ciated vegetation, there were those animals Avhich are dependent upon 

 the shade, moisture, soil, decaying logs and other features associated 

 with forests. To this class belong certain insects which frequent decay- 

 ing timber or the fungi growing \ipon them, and the earthworms of the 

 soil, the ground beetles or Carabids, and the ground-inhabiting spiders, 

 Lycosids. Some of the birds found were: Chickadee. Red-breasted 

 Nuthatch, Golden-crowned Kinglet, Whitewinged Crossbill and Purple 

 Finch. 



Station I, 4- Tamarack and Arl:)or Yitae or White Spruce Sivanvps. 

 This swamp is located in one of the valleys near the head of Tonkin 

 Bay, and extends back from the bay about one-fourth of a mile. It 

 begins just back of the beach and is bordered by a strip of Alders, 

 Paper Birch, Mountain Ash, young Balsams and White Spi'uces. The 

 rock walls of this valley are about 75 or 100 feet apart and are well 

 shaded and covered by lichens and mosses, the south surface largely by 

 lichens alone. Back of the marginal beach strip above mentioned, comes 

 the dense growth of very large Arbor Vitae trees, intermingled with nu- 

 merous large fallen trunks, partially decayed and covered with a dense 

 growth of mosses. In the dryer places the ground is covered with a 

 dense litter, and a thick damp or wet mass of mosses, but no pools of 

 water. The undergrowth is composed of young Balsams, Birch and 

 Ground Hemlock, Fig. 10. 



Proceeding farther up the valley, the Arbor Vitae is replaced by 

 Balsams and Paper Birch; the forest is more open, and the amount of 

 moss on the ground is greatly reduced, and is replaced by a growth of 

 Large-leaved Aster and large quantities of Ground Hemlock — all of 

 this vegetation being indicative of mesophytic conditions. In this re- 

 gion there are scattered pockets or small pools of water containing 

 dogwoods. Still farther up the valley the Balsams and Arbor Vitae con- 

 tinue and Tamaracks are added, but no standing water was found. The 

 valley turns, and returns to the bay on the north side of the ridge which 

 bounds the Arbor Vitae swamp on the north; the entire basin is thus 

 somewhat horseshoe shaped. The returning sedtion becomes almost pure 

 Tamarack and contains numerous small pools of water. The conspicu- 

 ous feature of this environment is its jungle-like character, the rapid ac- 

 cumulation of litter and humus, and the damp substratum. 



The fauna of such a bog is surprisingly limited in variety and amount. 

 A few shells were found, as Pi/inmidula cronkhcitei anthoni/i and, ii^ 

 the small pools, Pisidium. The large numbers of Mosquitoes and Black 

 Flies made up for all deficiencies, and were almost intolerable. The 

 birds frequenting this forest were the Eed-breasted Nuthatch, Black- 

 throated Green Warbler and Chickadee. 



Station I, 5. The Jack Pine Bidge. This ridge is located near the 

 mouth of Conglomerate Bay, on the north shore. Some general idea 

 of the location is given in IPig. 11, which is a view looking toward the 

 head of Conglomerate Bay. Just back of the beach, on an outcrop of 

 conglomerate, was a small rock clearing, with Cladonki. Juniperus nana, 

 and a wild rose. From here the trail extended through a narrow strip 

 of forest, composed of Balsams, White Spruce and Arbor Vitae, with an 



