 If
you were to fly over Chippewa Nature Center, the most striking aspects of the land below would be the
Pine and Chippewa Rivers. The Chippewa River
runs the entire length (3.2 miles) of our property from west
to east. The
Center is dissected by the
PineRiver, which flows from the southwest to converge with the
Chippewa River
halfway into our property. The Oxbow (a pond that was the main channel of the
Chippewa River
prior to 1912) and man-made ponds dot the rest of the
property.
Because rivers are a major feature, many trails are
located close to them to give you the opportunity to enjoy
their plants, animals and scenic views. A river’s open corridor is a natural wildlife viewing
area, and vegetation along the shore creates an equally
natural wildlife blind. If
a white-tailed deer crosses 50 yards ahead of you in the
woods, it is hard to observe. But a deer crossing the river even 100 yards ahead is
quite visible.
Not only are animals more visible on and along the
river, but a tremendous variety use this special habitat.
Eagles, gulls, ducks, swallows, and a multitude of
other birds use rivers both for feeding and as a navigational
roadmap. Raccoons,
mink, muskrat, beaver, and otter find food in and along
rivers, and other mammals can be seen getting a drink or
swimming to the opposite bank as squirrels sometimes do.
What
you can see and how to get there
The
River Trail begins at the Visitor
Center, runs along the Pine and Chippewa
Rivers and loops back to the Visitor
Center via the bank of an ancient river. Other trails
with river views are the Arbury, Meadow Mouse and Woodland
Trails. From many observation points such as along the
Meadow Mouse,
Woodland and part of the River Trail, your “vista” includes
privately-owned houses on the opposite shore. In other
areas, the only houses you will see are the bank burrows, leaf
nests, hollow logs and other shelters used by wildlife.
 In addition to the plants and animals you can see and
hear along the rivers, look closely at each waterway. The difference between the two is especially apparent at the
convergence just downstream of the Visitor Center, where the Pine flows into the Chippewa.
The Pine
drains mostly farmland, and therefore carries a great deal of
silt. Its bottom and water have a muddy appearance. The Chippewa drains more sandy areas and carries less
suspended material, so its water is clearer. Where the
rivers come together, you can see a line of demarcation, as
though someone lowered a piece of Plexiglas vertically into
the water to keep the two rivers from touching. Dozens
of yards downstream the waters of both rivers finally mix
enough to become indistinguishable.
The suspended material in the Pine
River has several impacts on the river’s ecology.
These
materials readily absorb sunlight, which causes the
temperature of the river to rise. The Pine has much
warmer water than the Chippewa, resulting in fauna adapted to
warm water and the exclusion of cold-water animals such as
trout. The silt load is also dangerous to fish and
bottom-dwelling invertebrates in the river, as it makes it
more difficult for them to absorb oxygen through their gills,
and because when the water flow lessens, the silt load drops
to the bottom of the river, burying their eggs.
Part
of the Puzzle
The
Pine and Chippewa
Rivers don’t begin and end their influence of this region at the
boundaries of Chippewa
Nature Center.Both are major rivers in the Saginaw Bay Watershed.
The
Pine River
begins its journey 100 miles upstream of the Center, at PineLakein Mecosta
County.
It drains 370 square miles before emptying into the Chippewa River
, which also begins in Mecosta County, at
Chippewa Lake in the northern part of the county.
It is larger than
the
Pine River and drains nearly three times the area -- over 1,000 square
miles -- before joining the Tittabawassee River
at downtown Midland. The Tittabawassee
River, then flows 24 miles to join the Saginaw
River, as do the other rivers of this watershed: the Cass, Flint and Shiawassee.
The combined influence of all of these
rivers make the Saginaw Bay
watershed the largest in Michigan, as well as one of the biggest in
North America
, draining over 8,700 square miles!
Rivers
of Time
 The
courses of the Pine and Chippewa Rivers
have been altered every season of every year since these
rivers first formed. The channels have moved, become
narrower, moved again, and widened, over and over. These
changes over the last several thousand years all give evidence
of the power of moving water to cut through soil, carry it
downstream, and deposit it when the water’s movement slows
enough for the silt or sand to settle to the bottom.
The rivers first formed here nearly 13,000 years ago.
Mastodons, giant beaver and other prehistoric wildlife used
them. The first human inhabitants of this area also
arrived about this time, surviving on the same plants used by
the beaver and mastodons, as well as on the animals
themselves. Over thousands of years, Native Americans of
this region used the rivers as both highways and hunting
grounds. The first missionaries and fur trappers to
arrive here from Europe, in the late 17th century, also depended on the rivers to
make their way through the uncharted forests that covered this
region. In the 1800s, early settlers built farms along
these rivers, and, as Midlandgrew, it also stretched along the river corridors.
What does the future hold for rivers at Chippewa
Nature Center?
Many experts predict flooding will worsen nationwide
in the decades to come, because developments such as paved
driveways, asphalt parking lots, drainage ditches and sewage
lines all direct water to the river without allowing it to
sink into the soil. The result is more surface water
that is flowing faster to downstream locations, rather than
gradually percolating into the ground. After a heavy
rain, water moves quickly into ditches, streams and rivers,
creating “flash” rises in water levels.
Floods may actually reduce the amount of land at the
Center. These fast-rising waters are literally carrying
our land downstream. Riverbanks are already eroding rapidly. For
example, the River Trail has had to be
moved in a few places because the trail was dangerously close
to the eroding bank. Floods are also likely to
eventually create another oxbow here. A peninsula
of land on the Chippewa River, west of where the Chippewa and Pine
rivers converge, is shaping up to be another oxbow pond within the
next hundred years or so.
Rivers
in Winter
 The
restless nature of rivers is evident even in winter. There is a sharp contrast between areas where ripples in the
water created rough-looking ice, where shards of ice turned on
end by the jostling current froze in a vertical position, to
smooth-as-glass areas where a freshly frozen spot is still
nearly see-through.
Watching ice form over the course of a day or two is
just as fascinating as watching it break-up, though the pace
of activity is slower. As the water gets colder, a thin
layer of ice begins to form along the shore where the current
is slowest. In the faster part of the river ice crystals
collect and form floating “pancakes” of ice several feet
in diameter in the center of the river. As these become
more numerous, they bump into each other more and more
frequently, like bumper cars all traveling in the same direction. These
pancakes finally become concentrated
enough to mold together, and a solid, unbroken covering of ice
appears, seemingly overnight.
In milder winters, the rivers don’t freeze until the
end of December or even early January, and the waters are free
of ice again as early as late February. At the Visitor
Center, the Pine River usually freezes in late December,
though records range from November 13 (1986) to as late as
January 18 (1992).
Ice on the river affects plants and animals along the
shores, of course, but its major impact is on life below the ice. Aquatic
insects, mussels, fish and other riverine
life are as dependent on oxygen as are terrestrial animals. When
the river freezes over, the ice acts as a valve, shutting
off the supply of oxygen normally absorbed by the river water
from the air. In a cold winter, when the river may be
frozen for four months, there is very little oxygen entering
the river system for that four-month period.
When snow covers the ice, it resembles the
tundra. Tracks of squirrel, deer, raccoon, opossum and even birds are
visible in the snow, crisscrossing the rivers and inspiring
many unanswerable questions. What made the animal take a
sudden right-turn, or backtrack across the river completely? Did
it sense the ice was too thin, or did some other animal
startle it? How many of those same animals cross the
river when it is not frozen? Do they sleep on the other
side of the river all year, and swim across in the summer, or
does the frozen river extend the boundaries of their
territory, allowing them to explore an area they don’t
venture into in the warmer months? What about the tracks
coming to the edge of the river? Was the animal simply
getting a drink, or in the case of a raccoon or mink, perhaps
hoping to find an opening to hunt in? Another track on
the frozen rivers is that of snowmobiles, which are common on
the rivers even in warmer winters when there are frequent
patches of open water.
Rivers
in Summer
 If
you take the challenge of visiting the Nature Center
to observe the rivers once a week throughout the year, you may
find it hard in the summer to believe you are looking at the
same river that ripped at the bank so powerfully in the spring! Both
the Pine andChippewaRiversflow more slowly and are shallower in
summer. In dry
summers, you can walk across some areas of the
PineRiverwithout getting your knees
wet. And while the water
level drops, plant growth explodes. Emergent plants such
as arrowhead and sedges take hold near the shore, while long
strings of pondweed begin their chokehold in shallow areas. Such
changes interest us terrestrial observers on the
riverbank little, but to organisms that live 24/7 in that
water, these changes are critical and sometimes life threatening. How
does an ectothermic animal such as a
fish adapt? Once inappropriately called
“cold-blooded,” ectotherms aren’t necessarily cold, they
just derive their heat from their environment.) For instance, water rises from barely above freezing in the winter
to 80+ degrees just three months later. Many species are
obviously well adapted to these changes, as attested to by the
dozens of fish, mussel, reptile, and amphibian species found
in local rivers.
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