Air:
Aerial

Burns and clearings:
Herbaceous stage
Shrub stage
Paper birch—aspen stage
Young hardwood forest stage

Artificial conditions:
Overflow swamp
Cultivated-field
Edificarian

This list of habitats is admittedly not complete for the regions visited, but is intended to include those which we studied. We had no opportunity of studying either the shores of a large river or jack pine ridges, both of which situations will undoubtedly have habitats not here recognized.

The habitats studied in Gogebic and Ontonagon counties but every habitat has been listed which seems to form a distinct type of mammal environment. We are firmly convinced that it is better to describe a great number of habitats rather than to lump different kinds of environments together. It is infinitely easier for a later worker to combine several habitats, which have been split too finely, than it is to separate the component habitats which may have been lumped together under one name.

No attempt is made to give complete lists of the plants found in each habitat, but only the more conspicuous plants or those of special importance to the mammals are mentioned. The plant names used are mostly taken from Darlington's list of Gogebic County plants.[1]

Exposed Shores

Open-water habitat: This habitat includes the areas of open water with no rooted vegetation in the deeper parts of the lakes and rivers. On Lake Superior at Little Girl's Point this habitat comes directly to the beach, for the wave action on this exposed point is sufficient to prevent the growth of plants along the shore. In Gogebic Lake and in the smaller lakes of the Cisco Lake Region there are also many parts where there is no rooted vegetation along shore. This habitat, therefore, covers by far the larger part of the aquatic conditions of northwestern Michigan. We secured no records of mammals for this habitat, and, though some aquatic species must occasionally occur in the open water along lake shores, they are rare there, and are practically absent from the areas of open water farther out in the lakes.

Beach habitat: The shore of Lake Superior at Little Girl's Point is subjected to heavy pounding by the lake waves, leading to the formation of a well-developed beach. To the east of the point the beach for some distance is five to ten yards wide, mostly of small gravel, with sand on the upper part; it ends abruptly against a steep dirt bluff. On the beach no vegetation grows and only a few scattered drift logs occur. To the west of Little Girl's Point undetached masses of solid rock are more prominent, though small patches of gravel occur in partially protected places. The beach here in general is narrow and rises steeply, so that the different beach zones, lower, middle, and upper, are not well marked. On the shores of Lake Gogebic are a few small sand beaches; but around this lake, as well as around the smaller lakes of the region, the forest comes, in general, directly to the edge of the water. There was no opportunity to trap for mammals on a beach, and no records for the habitat were obtained.

Dirt-bluff habitat: To the east of Little Girl's Point the beach of Lake Superior runs along the base of a dirt bluff about 35 feet high. The storm waves of winter evidently wash against this bluff, eroding it away and destroying the forest, which is of the hemlock type, growing on the level above. The bluff is quite steep, and along with small exposures of bare clay bears a number of scattered herbs and a few shrubs and small trees, such as alder, willow, arbor-vitae, yellow birch, paper birch, and red maple. No collecting was done in this habitat and no records of mammals were obtained from it.

Forest—shore habitat: Along all the lakes of the region, except Lake Superior, the forests in general come down to the water's edge. The marginal forests are frequently dominated by hemlock, though often a wet hardwood forest occurs along the shores, and in a number of places along Gogebic Lake black ash swamps border the water. Red maple (Acer rubrum) and mountain ash (Sorbus americana) frequently occur along the exposed shores of Gogebic Lake. Frequently young forests of paper birch or quaking aspen have replaced the original forests in the clearings and burned areas along the lake borders. The shore beside a forest commonly rises abruptly a few inches to a foot or more in a firm bank, and in most cases the trees overhang the water to some extent. These shores are the favorite promenade of the porcupine; and the mink, muskrat, and otter are typical of the habitat.

Protected Shores

Water lily habitat: In shallow, protected parts of the lakes and channels of the Cisco Lake chain there are extensive growths of white and yellow water lilies (Castalia tuberosa and Nymphaea advena). Water lilies also occur in many places as a narrow border at the edge of deep water. Muskrats were the only mammals noted in this habitat, but mink and otter probably occur also.

Pondweed habitat: A thick growth of pondweeds (Potamogeton spp.) occurs in protected places along the shores in many parts of the lakes of the Cisco Lake chain. Muskrats were noted in this habitat. In Gogebic Lake the exposure to wave action is in most places too great for a good development of pondweeds, though in the northern end of the lake there are a number of widely scattered plants of this type, but not forming a very well marked habitat.

Rush habitat: On somewhat protected shoals, both in the lakes of the Cisco Lake Region and in Gogebic Lake, there is sometimes a growth of rushes (Juncus sp.). Along the lower course of the Merriweather River, just before it enters Gogebic Lake, rushes thickly cover numerous small areas. The plants in both cases grow partly submerged in the water. No records for mammals were obtained from this type of habitat, though doubtless some of the amphibious forms frequently occur here.

Submerged-sedge habitat: Sedges in general do not occur as a definite belt about the margins of the lakes in the region studied. The only place where any considerable growth of sedges was noted at the edge of the water was along the lower course of Merriweather River, just before it enters Gogebic Lake. Here there are considerable areas of sedges partially submerged by the water. No records of mammals were obtained from this habitat.

Cat-tail habitat: Under native conditions cat-tails (Typha latifolia) apparently do not often form extensive habitats in the region. Along the marshy borders of the lower Merriweather River at Gogebic Lake a few small patches were seen. Small patches were seen in other places along railroad tracks where embankments had produced small areas of marshy ground.

In the Cisco Lake Region a few of the areas of timber killed by the raising of the water-level have grown up to cat-tail swamps. In these swamps there are many standing dead trees and fallen logs as well as some areas of open water. The cat-tails seem to occur mostly in those swamps having only a small connection with the main body of the lake. In these places the cat-tail is dominant, though numerous sedges occur, and there is some sphagnum growing on the fallen logs and along the shore. A few small black spruces are starting. Along the