Mammals in an Urban Park: Herbivores, Omnivores, and Carnivores

During my many walks in Eliza Howell Park in Detroit in recent years, I have confirmed the presence of 15 different mammals (not including smaller mammals like voles, deer mice, and bats).

When animals are classified by what they eat, they are usually identified as herbivores, omnivores, or carnivores. Among the Eliza Howell herbivores is the Groundhog. In this picture, an adult is on the left, an immature on the right.

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Herbivores eat plants and only plants, many having digestive systems that are able to digest many different kinds of plants, including grasses.

Of the 5 herbivores that I am aware of in the park, the White-tailed Deer is the most common. In the winter, when they are sometimes in herds, I have seen as many as 10 together. Here is a stag, watching me as I watched him.

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I do not (yet) have any pictures of the two aquatic herbivores found in EHP: Muskrat and American Beaver. Beaver is the mammal most recently added to the list of those found in Eliza Howell and their practice of eating the stems, bark, and twigs of trees is evidenced by the many small trees they cut down and remove along the river.

The Eastern Cottontail is a fairly common herbivore in the park.

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Omnivores are animals that eat both other animals and (parts of) plants. They may be primarily animal eaters or primarily plant eaters and omnivores make up the largest number of Eliza Howell mammal species.

The Virginia Opossum is largely nocturnal, but I do encounter one during the day from time to time. It is often slow moving and may allow one to get quite close.

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Many omnivores are opportunistic feeders, eating whatever food is convenient. These include the various squirrels found in Eliza Howell. Tree squirrels are Fox Squirrel, Gray Squirrel (black variation in the picture below), and Red Squirrel. The ground squirrel is the Eastern Chipmunk.  Squirrels eat seeds and nuts and fruit, but they may also eat eggs, insects, baby birds.

(Clockwise from top left: Fox Squirrel, Red Squirrel, black Gray Squirrel, and Eastern Chipmunk)

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Raccoons will eat almost anything, but they especially like small animals found in water, such as clams, crayfish, and frogs. I have seen them – and their tracks – most frequently by the river. They are also primarily nocturnal, sometimes seen resting in trees during the day. They also den in trees.

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Photo by Kevin Murphy

Striped Skunk, another omnivore found in Eliza Howell, is mostly active at night and rarely seen.

Red Fox and Coyote are two mammals that are often considered carnivores, but perhaps should more accurately be considered omnivores. They eat mostly animals and carrion, but also eat fruit and berries.

In the last few years, I have seen Coyote more frequently than Red Fox in Eliza Howell. This picture of a Coyote was taken in nearby Rouge Park in Detroit.

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Photo by Kevin Murphy

Carnivores are animals whose diet consists of other animals. The one mammal that I have seen in EHP that is strictly carnivore is Mink. It is semiaquatic (I have seen them only by the river) and eats fish, crayfish, mice, muskrats, birds, etc. I see it only occasionally.

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As noted above, these 15 species are not the only mammals in the park. There are some smaller species that I am aware of and, without a doubt, other species that I have not yet found. One example: I think the habitat is perfect for flying squirrels, but I have not yet seen any evidence of these nocturnal mammals.

There is much more to learn about my favorite urban park.

Nature Discovery Day Is July 13

On Saturday, July 13,  there is a great opportunity for visitors to the park to become more familiar with the wildflowers, butterflies, birds, mammals, trees — and more – of Eliza Howell Park: 9:00 – noon. Free and open to everyone.

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There will be exhibits, activities, and options of guided walks designed to point out some of the natural wealth of this Detroit park. The park entrance is on Fenkell east of Telegraph. The event also includes an opportunity to learn more about the U-M wildlife motion-activated camera project (which includes Eliza Howell Park).

Among the highlights of mid-July are the meadow/prairie wildflowers. Among those catching my attention recently are these.

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Clockwise from top left: Foxglove Beardtongue, Black-eyed Susan, Butterfly Weed, Common Milkweed

The event is organized by Eliza Howell Park Partnership (EHPP), a coalition of persons with different organizational affiliations and a common interest in highlighting Eliza Howell as a place for observing and enjoying nature in an urban environment.

Guides will be present to assist in identifying the varieties of flowers, as well as the specific species of butterflies they attract. These are among the common butterflies at this time of the year.

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Clockwise from top left: Monarch, Common Ringlet, Red Admiral, Pearl Crescent.

While I am often unable to get a picture of a butterfly I see, it is never difficult to find flowers waiting to be photographed.

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Clockwise from top left: Staghorn Sumac, Chicory, Wild Bergamot, St John’s Wort.

Eliza Howell is the kind of nature park it is, in significant part, because the Rouge River runs through it. For those who wish to take it on Saturday, a short walk to the footbridge provides a good view of the shaded river.

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Back in the field, one flower not to be missed is Wild Bergamot, a mint family flower, sometimes called beebalm, that has only recently begun its summer blooming season. It is a magnet for a variety of insects. In this picture, the visitor is a Hummingbird Moth.

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Many mammals are more active at night than during the day. The cameras used in the UM wildlife camera project have located and identified some of the mammals of the night, as will be reported on July 13.

Two that I have recently seen during the day are White-tailed Deer and Groundhog.

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I thank EHPP for providing this opportunity to witness and enjoy the natural wealth of the park.

 

Six Hibernating Animals: See You in April

Animals have different ways of surviving winter in locations like Michigan where temperatures fall below freezing and the usual food sources are scarce or absent. Some (especially birds and mammals) find sufficient food options and remain active all winter. Some (especially insect-eating birds) migrate to a warmer climate for the season. Some (especially insects) survive only in the egg or pupa stage that will grow into the next generation of adults in the spring. And some hibernate.

I am using the term “hibernation” here to mean an adult remaining in an inactive or dormant condition, in the same sheltered location, all or most of the winter. Mammals (such as bears or groundhogs) may be the hibernators that we think of first, but many “cold-blooded” animals like reptiles, amphibians, insects, and crustaceans also hibernate.

On a recent walk, I started thinking of species that I find every year in Eliza Howell Park that are now hibernating. They include these six.

1.Eastern Chipmunk

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While tree squirrels remain active all winter, often relying on the food (especially nuts) that they stored in the fall, the chipmunk, the only ground squirrel in EHP, hibernates. It stores some food for the winter in its winter burrow and eats when it awakens from time to time during the winter, before returning to its dormant winter condition.  It will emerge in the spring, when I often see the first of the year near the path by the river on a sunny day.

2. Common Garter Snake

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I was walking in the park in the afternoon on December 2 this year when I was surprised to see a Garter Snake. My first thought was “I thought you would be hibernating.” They usually are in their den well before December, but this was a warm day (68 degrees), so it may not have been quite ready to settle down for the winter.

The non-venomous Garter Snake, with its three stripes along its roughly 2 feet length, is the only snake species that I encounter with any regularity in Eliza Howell Park.

3.Mourning Cloak

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Photo by Margaret Weber

The Mourning Cloak is the first butterfly species I expect to see in the spring. Different from almost all other butterflies in our region, it overwinters as an adult rather than in a developing stage or by migrating – and this is the explanation for its early emergence. It finds a hidden location, such as under bark, seeking protection from the birds that forage for insect life all winter. The location may not protect it from freezing temperatures, but it can survive them.

4.Land Snail

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In early October, these (Brown-lipped?) land snails were common in the wild flowers, climbing plants to consume dying leaves. Around first frost they settle down for the winter. They use their mucus to close the shell mouth and protect themselves from the cold. Before they seal themselves in, they find a location under rocks or ground litter protected from the cold and stay there until it is time to emerge in the spring. (Note “The Snails Have Returned,” April 18, 2018.)

5.Groundhog

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This picture, taken in June, is of a half-grown immature Groundhog. Adults mate shortly after they emerge from hibernation in the spring. Groundhogs use burrows throughout the year, but they sometimes dig a separate one for the winter. They settle in below the frost line, rely upon their stored body fat, and sometimes lose half their weight during the months of winter. I don’t know if any of the Eliza Howell groundhogs check the weather on February 2, but, if one does, no one is there watching.

6.American Toad

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Except for gathering at the breeding pond for an intense couple of days in April (See “American Toad Breeding Pond,” July 23, 2018), adult American Toads live quite solidary and nocturnal lives. In the Fall, they dig winter burrows with their feet, sometimes up to three feet deep. When the weather begins to warm and the insects become more active, they emerge and soon after, when the air temperature and the body temperature are right, the males will head to the breeding pond and call the females. (Some of us toad watchers will be listening.)

While the dates vary somewhat, I usually see each of these species for the first time in April. Until then, I wish them a peaceful winter.