The habitats studied in Gogebic and Ontonagon counties may be listed as
follows:
Exposed shores:
Open-water
Beach
Dirt-bluff
Forest--shore
Protected shores:
Water lily
Pondweed
Rush
Submerged-sedge
Cat-tail
Willow-thicket
Mud-flat
Meadow:
Ditch-border
Tall-sedge
Grassy-meadow
Alder-thicket
Swamps:
Black ash swamp
Arbor-vitae swamp
Bogs:
Leather leaf bog
Sphagnum bog
Black spruce--tamarack bog
Forests:
Hemlock forest
White pine forest
Wet hardwood forest
Dry hardwood forest
Mountains:
Rock-bluff
Mountain-heath
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 edge of such a
swamp a few deer-mice were taken, but these were evidently stragglers
from the adjacent forest.
_Willow-thicket habitat:_ Willows do not occur commonly along the water
margins of the lakes of the region. The only place, except in
clearings, where willows were noted as a definite growth is along the
lower course of the Merriweather River at Gogebic Lake. Along this part
of the river there are extensive growths of shrubby willows, growing
(in early September) in a foot or more of water. The indications were
that earlier in the summer the water about these plants must have been
at least a foot higher. Signs of muskrat were noted at the edge of
these willows.
_Mud-flat habitat:_ Around the margin of a pond formed by an old
deserted beaver dam near Gogebic Lake, two miles southwest of
Merriweather, is a narrow strip of mud, very wet and sparsely covered
with a growth of low rushes. The strip of muddy ground varies from
about 1 to 4 meters in width and extends a short distance up along the
edge of the small ditch draining into the pond. At the upper border of
the strip of muddy shore is a thick growth of sedges, meeting the muddy
shore at a fairly sharp line.
In this habitat meadow mice are common and four jumping mice (_Zapus
hudsonius_) were taken.
_Meadows_
_Ditch-border habitat:_ A number of small ditches run through an old
beaver meadow of considerable size near Gogebic Lake, about two miles
southwest of Merriweather. The borders of the ditches are muddy and the
banks are from 6 to 18 inches high; in places the ditch borders are
closely encroached upon by the tall sedges of the adjacent meadow. A
small amount of water was present (in early September) in most of the
ditches. In mouse traps set at the edges of these ditches, partly in
the water, star-nosed moles and navigator shrews were taken. In a
larger trap a skunk was taken.
_Tall-sedge habitat:_ In the beaver meadow studied near Gogebic Lake,
an area about 200 meters by 100 meters or more is occupied by a heavy
growth of high, coarse sedges, reaching a height of about .75 to 1.00
meter. A few grasses and some low herbs occur sparingly among the
sedges. The habitat had not been burned over and the ground is covered
with a thick mat of the decaying leaves and stems of the sedges and
grasses. In most places the ground is quite wet, sometimes soggy to
walk upon, and in a few places low hummocks are numerous. A similar
habitat was found in rather a narrow strip at the edge of Mud Lake,
one-fourth mile southwest of Thousand Island Lake, Gogebic County. Here
a small area of meadow occurs along the inlet of a tiny stream. This
area apparently had been artificially cleared of its forest, but the
level of the lake had not been raised.
The habitat differs from the submerged-sedge habitat of protected lake
shores in being higher above the water and in not being covered with
water from July to September; probably water does not stand to any
depth on it at any time. The Richardson shrew is apparently a
characteristic mammal of this habitat, though other shrews and mice
were taken here also.
_Grassy-meadow habitat:_ Part of the beaver meadow studied near Gogebic
Lake is covered by a thick growth of grasses and sedges of a number of
species. The ground of the habitat was rather dry and had been burned
over the previous year. Grasses are also dominant over a few small
areas near Mud Lake in Gogebic County. On a small area of the clearing
near this lake a thick stand of bluegrass (Poa) is almost the only
plant present. This occurs on an area of fairly moist mud. On the drier
slope near the forest Poa also is abundant, forming the dominant
species over a strip about 5 to 10 meters wide. Jumping mice are common
in this habitat.
_Alder-thicket habitat:_ On very wet ground just below an old beaver
dam near Gogebic Lake there is a heavy growth of alder (_Alnus incana_)
about 20 feet high. No other shrubs were noted in the thicket. The
ground under the alders is mostly bare, there being only a few ferns,
grasses, and other herbs. On the ground are many dead sticks fallen
from the alders. This situation contained few mammals, only one Blarina
being taken in four days' trapping with 25 traps. At the south end of
the beaver meadow willows and alders are invading the sedges in very
wet ground. No trapping was done in this situation.
_Swamps_
_Black ash swamp habitat:_ A number of black ash swamps occur along the
shores of Gogebic Lake, being apparently partially flooded during
periods of heavy rains and during stages of high water. In a swamp of
this type near the north end of Gogebic Lake on the west side, black
ash (_Fraxinus nigra_) is the dominant tree, the trunks reaching
diameters up to 2 feet. Elms (_Ulmus americana_) sometimes reaching a
trunk diameter of 3 feet are common, and yellow birches and hard maples
are common also. Black maples are rare, and lindens are few. The trees
are high and the forest crown nearly closed. Underbrush is common in
the more open places, this being mostly mountain maple (_Acer
spicatum_) with a few young firs, young arbor-vitae, and Virginia
creepers (_Parthenocissus quinquefolia_). There are numerous ferns, and
herbs are abundant. Under the more closed parts of the forest canopy
the ground is mostly bare, underbrush and herbs being scanty. Smaller
black ash swamps occur in the Cisco Lake Region, and in the vicinity of
Little Girl's Point a number of small black ashes were noted in a swamp
of mixed arbor-vitae and black spruce.
_Arbor-vitae swamp habitat:_ In the Cisco Lake Region arbor-vitae
(_Thuja occidentalis_) occurs commonly near the edges of the lakes and
in the wet depressions in the forest. Near Gogebic Lake also the
arbor-vitae grows commonly near the shores of the lake and in wet
places in the woods, especially at the edges of swamps. But the trees
in both these areas, so far as seen, were small, and the arbor-vitae
did not form a dominant species, but occurred in a small percentage
mixed with the other types of forest. However, in part of the region
near Gogebic Lake extensive arbor-vitae swamps are reported to occur.
In the vicinity of Little Girl's Point arbor-vitae swamps are common,
occupying the wet lower northern slopes of the high ridge.
In a swamp of this type three miles southeast of the point arbor-vitae
is the dominant tree, reaching trunk diameters of two feet and more.
Under the dense shade of the high forest crown there are many young
trees of the same species, and the forest has evidently reached a
temporary climax. Of other trees, a few small yellow birch, a few young
firs and hemlocks, and one fallen white spruce (_Picea canadensis_)
were noted. The ground is very wet and there are numerous tiny
streams, which frequently disappear under the ground. Fallen trees and
decaying logs on the ground make a thick tangle, very difficult to
penetrate. The underbrush is scanty; mountain maple is rather common,
and there are a few young black ashes. Much moss grows on the ground
and on the decaying logs.
In a depression two miles south of Little Girl's Point is a mixed
growth of arbor-vitae, black spruce, with a few black ashes. The trees
are mostly small, none of them exceeding about eight inches in trunk
diameter. In August the ground was very wet, there being standing water
in some places, and the ground was heavily covered with sphagnum. This
situation may be considered transitional between the black spruce bog
and the arbor-vitae swamp. No traps for mammals were set in this
situation.
_Bogs_
_Leather leaf bog habitat:_ In the northwestern corner of Fish-hawk
Lake and at several places along the channel connecting Lindsley and
Cisco lakes a heavy growth of leather leaf (_Chamaedaphne calyculata_)
adjoins and overhangs the water, a considerable portion of the growth
actually floating on the water. With the leather leaf is associated
much sweet gale (_Myrica gale_) and alders, and these plants form
almost the entire mat in some of the wetter areas. At other places
sphagnum becomes abundant and the conditions approach those of a
sphagnum bog. Other plants commonly found in the leather leaf bog in
the Cisco Lake Region are the Labrador tea (_Ledum groenlandicum_),
swamp laurel (_Kalmia potifolia_), wild rosemary (_Andromeda
glaucophylla_), small cranberry (_Oxycoccus oxycoccus_), pitcher-plant
(_Sarracenia purpurea_), and small trees of black spruce and tamarack.
In a typical leather leaf bog on the Ontonagon River near the outlet
from Thousand Island Lake a large beaver house is located.
_Sphagnum bog habitat:_ In a restricted sense the name is here applied
to the part of a bog which is free from trees. It differs from the
leather leaf bog in having a greater amount of sphagnum, for while the
leather leaf bog when first developed over the water has little or no
sphagnum, the sphagnum bog, as here considered, is almost entirely
covered by sphagnum. The shrubs found in the two situations are
apparently identical, except that the leather leaf is less abundant. A
small bog of this type borders the edge of Mud Lake in the Cisco Lake
Region, and small parts of many bogs are free from trees. So far as was
determined, the mammal fauna is the same as that for the black
spruce--tamarack bog, from which the only difference is the absence of
trees.
_Black Spruce--Tamarack Bog habitat:_ The dominant bog tree in this
region is the black spruce (_Picea mariana_), which is usually small
and stunted. With the black spruces are a lesser number of small
tamaracks (_Larix larcina_), which in places may be dominant. The
ground is heavily covered with sphagnum, which is normally soaked with
water. Shrubs are abundant, though usually not forming a closed mat. Of
the shrubs the leather leaf is the most abundant, though Kalmia,
Andromeda, Ledum, and blueberries are common. A few young white pines
and red maples were noted. Sedges occur frequently, and the pitcher
plant is very characteristic.
_Forests_
_Hemlock forest habitat:_ In the Cisco Lake Region groves of hemlock
(_Tsuga canadensis_) frequently occupy the lower parts of steep slopes
adjoining the lakes. One such area studied is made up of practically a
pure stand of hemlocks, the trunks being from about 6 to 18 inches in
diameter. A few very old yellow birches are present, and also a few
young sugar maples and arbor-vitae, the latter chiefly near the
water's edge. Shrubs and herbs are nearly absent, and the forest floor
is covered by a thick carpet of dead needles. There are many decaying
logs, usually covered by a thin coat of moss. In the Little Girl's
Point Region nearly pure stands of large hemlocks cover many of the
lower parts of steep slopes and also occur commonly on well-drained
soil elsewhere. In the vicinity of the north end of Gogebic Lake a few
small groves of hemlocks were noted, but the ground in general is so
low and swampy that the species mostly occurs as a part of the mixed
forest of the region. Animals are rare in the habitat.
_White pine forest habitat:_ White pine (_Pinus strobus_), which
formerly was a common forest tree in northern Michigan, has now been
mostly removed for lumber. Near Little Girl's Point a small natural
grove of this species was studied, occupying a moderate southerly slope
above a black spruce bog. The area is about 50 by 150 meters in size.
White pines are by far the most numerous and dominant tree, the trunks
measuring up to about five feet in diameter. In the grove yellow birch,
some of large size, are common; toward the bottom of the slope hemlocks
are also common; and near the edge of the bog there are a few
arbor-vitae. Shrubs are almost absent, there being merely a few small
seedlings of arbor-vitae, hemlock, and fir, mostly toward the bottom of
the slope. A few scattered clumps of grass appear, but the forest floor
is mostly covered only by a thick carpet of dry pine needles. Numerous
dead limbs and sticks have fallen from the pines.
_Wet hardwood forest habitat:_ The land adjoining much of Gogebic Lake
is low and poorly drained. Here is found a mixed forest dominated by
sugar maple (_Acer saccharum_), black maple, hemlock, yellow birch
(_Betula lutea_), linden, elm (_Ulmus americana_), ash (not black ash),
and ironwood (_Ostrya virginiana_). The hardwoods are decidedly
dominant over the conifers. The forest crown is high and closed, and
the trees are large. The underbrush in general is scanty, though in
some places there is a thick growth of mountain maple (_Acer spicatum_)
and of sugar maple seedlings. Leatherwood (_Dirca palustris_), hazel,
ferns, and a few young firs (_Abies balsamea_) also occur.
Some of the lower forests in the Cisco Lake Region approach the wet
hardwood forest type, though none are extensive in area, and they are
usually surrounded and dominated by the dry forest condition.
_Dry hardwood forest habitat:_ The highest development of the dry
hardwood type of forest was found on the upper parts of the moderately
high ridge near Little Girl's Point. The slopes in general are very
gentle, but well drained. The forest here is dominated by the sugar
maple (_Acer saccharum_), yellow birch (_Betula lutea_), and linden
(_Tilia americana_). Hemlocks are rare, and only one elm was seen. The
trees are large, the trunks frequently reaching diameters of two feet
or more. The forest crown is high and heavy. Underbrush is scanty and
low, being mostly young seedlings of sugar maple, though seedlings of
linden are numerous. Other shrubs and herbs noted were the leatherwood
(_Dirca palustris_), hazel (_Corylus rostrata_), yew (_Taxus
canadensis_), gooseberry, ferns, false Solomon's seal, and grass. On
the ground are many decaying leaves, these usually forming a heavy
carpet; decaying logs and freshly fallen sticks are common.
In the Cisco Lake Region the drainage is not so good as in the vicinity
of Little Girl's Point, and the forests of that district are of a type
somewhat intermediate between the wet hardwood forest and the dry
hardwood forest. In the Cisco Lake Region the topography is much
broken, there being many small hills and ridges, and many small
depressions, often poorly drained. In the damp depressions, if not wet
enough for a bog, arbor-vitae and hemlock are common, while on the
ridges sugar maple and linden are characteristic, though hemlock occurs
here sparingly also. There is accordingly much local variation in tree
forms, but the whole forest is decidedly of a hardwood type.
The dry hardwood forests of the Little Girl's Point Region are
inhabited by many deer-mice, while only a few of this species are found
in the wet hardwood forests near Gogebic Lake, bob-tailed shrews being
there the most abundant mammal and red-backed voles being common, both
of which are rare in the other districts. In the dry hardwood forest
near Little Girl's Point four woodland jumping mice (Napaeozapus) were
taken, while in the Cisco Lake Region only two were taken in a period
twice as long, and at Gogebic Lake none were secured. These
observations indicate that moisture conditions in hardwood forests have
an important influence on the mammal fauna.
_Mountains_
_Rock-bluff habitat:_ Rock exposures are rare in the region studied.
However there are several high hills with steep exposures of rock a
short distance north of Ironwood and Bessemer. These hills could not be
studied in the time available, and the only cliff examined was on a
small range of hills northeast of the station of Lake Gogebic. On one
of these hills is a nearly perpendicular rock cliff about 200 feet high
and facing to the southward. The small talus slope at the bottom is
overgrown with shrubs and trees, and on the small ledges and gullies of
the face of the cliff a few small trees, shrubs, and herbs are also
growing. The most conspicuous plants of the rock habitat are scrub
oaks, aspens, and heaths. No trapping was done in the habitat, and no
notes on mammals were secured. Probably the mammal fauna is not very
large.
_Mountain-heath habitat:_ A narrow, poorly developed belt of heath
fringes the upper edge of the rock cliff examined north of Lake
Gogebic. Characteristic plants are the blueberry and bearberry, mixed
with creeping juniper and a few scattered grasses. The habitat is very
narrow and is closely encroached upon by shrubs and trees, such as
sumac, cherry, white pine, jack pine, oaks, aspens, and paper birch.
Signs of fox were noted at the edge of the cliff, but no trapping was
carried on here.
_Air_
_Aerial habitat:_ The only aerial mammals are the bats, of which four
species were taken during the summer. The flying squirrel is not
considered to be a true aerial form.
_Burns and Clearings_
Fires have been numerous throughout northern Michigan and a large part
of the region is covered by various stages in the succession following
fires or clearings. The areas studied were selected as representative
of the natural conditions of the peninsula, but even in these districts
there are many burned areas.
Many large areas have been heavily logged over, sometimes followed by
fire, with a result similar to that of a fire. In the region studied
there are numerous small clearings, some of which are in use as the
residences of settlers, but most have been allowed to revert to a wild
condition. The stages in succession on an abandoned clearing seem to be
similar to those following a fire, and they are here considered
together.
_Herbaceous stage:_ After a fire in a forest in this region the first
vegetation to spring up seems to be the herbs, of which the fireweed
(_Chamaenerion angustifolium_) is most prominent. A number of areas
dominated by this type of vegetation were seen, but the type seems to
be short-lived, and is probably quickly replaced by shrubs and tree
seedlings. The stages in succession following a fire in swampy areas
may be somewhat different from that in a hardwood region, but no data
was obtained. No opportunity presented itself to study the mammals of
the herbaceous stage, and I have no records for the species found
there.
_Shrub stage:_ Following a fire or clearing in a hardwood area the
herbaceous stage is apparently quickly followed by a thick growth of
shrubs and young trees. The characters of the shrub growth vary
considerably with the texture of the soil, amount of soil moisture,
slope, and completeness of burning. The growth is usually quite thick,
though in some clearings where the growth has been kept down for some
time there may be open grassy patches. In small clearings near
Fish-hawk Lake the raspberry (_Rubus strigosus_) is a characteristic
species, but near Little Girl's Point it is much less common. A large
area of shrub studied near Little Girl's Point is on a rather steep
slope facing to the north, though part is at the bottom of the hill on
a very gentle slope. There are no large trees, but saplings up to
2-1/2-inch trunks occur; most, however, are smaller. The quaking and
large-toothed aspens (_Populus tremuloides_ and _P. grandidentata_),
paper and yellow birches (_Betula papyrifera_ and _B. lutea_), sugar
maple, and linden are common seedlings. Shrubs, such as the sumac
(_Rhus hirta_), wild cherry (_Prunus pennsylvanica_), raspberry,
willows (Salix spp.), mountain maple, red-berried elder (_Sambucus
racemosa_), and hazel are common. A few herbs, like the fireweed,
golden-rod, and pearly everlasting, occur in open places.
A number of mammals are found in the shrub stage, but they are far less
abundant than in mature hardwood forest.
_Paper birch--aspen stage:_ The continued growth of the young trees in
the shrub stage leads to the production of a sapling forest of the more
quickly growing species, the paper birches and aspens. Often one or
other of these species becomes dominant to the practical exclusion of
the other, but sometimes both occur together. On the slopes near the
lakes of the Cisco Lake chain aspens are rare, and the sapling forests
on the clearings and burns are almost a pure stand of paper birch. Near
Watersmeet, however, the aspen seems to be the dominant form, and few
paper birches were seen. Near Gogebic Lake, also, the quaking aspen is
the dominant form, though paper birches are common in the sapling
forests. The growth in these sapling forests is very thick, and the
ground is nearly bare of vegetation, though it is heavily covered with
dead sticks and small logs. In a thick growth of quaking aspens, on wet
ground studied near Gogebic Lake, a number of alders and paper birches,
a few young trees of sugar maple and arbor-vitae, and a rare elm occur.
A scanty undergrowth of mountain maple and numerous sugar maple
seedlings is present. Few mammals are found in this stage of the
forest.
On the western slope of Birch Point on Cisco Lake there is a good stand
of paper birches, growing in an open stand with much grass in the
spaces between the trees. This place has been much used for camping and
it may be that the development of the grass is the result of opening
the forest by clearing out some of the trees. Among the birches are
numerous young firs and white pines, with a few young sugar maples, and
a rare arbor-vitae. The birches show many signs of age, and would
evidently, if undisturbed, soon give way to a forest dominated by the
pines and firs. In the grass among these trees deer-mice, red-backed
voles, and jumping mice (Zapus) were taken. Signs of snowshoe hare were
seen.
_Young hardwood forest stage:_ On the eastern slope of a low ridge at
Birch Point, Cisco Lake, a young hardwood forest is rapidly replacing a
former growth of paper birches which has followed a fire. In this
growth numerous old paper birches still persist, but they are being
strongly crowded by a thick growth of vigorous young sugar maples, some
of which have trunk diameters up to about eight inches, and which form
a dense shade. Among the maples are numerous young firs and a few young
hemlocks and arbor-vitae. The ground is mostly bare, being scantily
covered by leaves. The soil is moist, but there is no grass and little
brush. In this habitat deer-mice were taken, and one red squirrel was
seen.
_Artificial Conditions_
_Overflow swamp habitat:_ Due to the rise in water-level of the lakes
of the Cisco Lake chain many low areas of forest have been flooded and
killed. Many of the dead trunks of these trees still remain standing,
mixed with fallen and decaying logs in the water. Locally these
habitats are called "overflow swamps," a name here adopted for the
habitat. There is little living vegetation in these swamps, an
occasional water lily being almost the only plant present. Porcupines
commonly walk out on the logs of the swamp to secure the water lily
leaves, and probably the mink occasionally runs over the logs in its
movements along the waterways.
_Cultivated-field habitat:_ Cleared fields occur only sparingly in the
regions visited, and these fields are small in size. No study of their
inhabitants was made, though silver-haired bats were collected while
they were flying over a small clearing in the Little Girl's Point
Region.
_Edificarian habitat:_ Towns and buildings are not very common in
northern Michigan. In and around a cabin on Lindsley Lake a number of
deer-mice were trapped, and signs that porcupines had invaded the cabin
were noted.