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.

Some Recent FOYs

“FOY,” meaning first-of-the-year observation, appears frequently in my notes about my visits to Eliza Howell Park at this time of the year. There is something new to be seen every day.

Here are a few selected FOYs from recent walks, each of which seems noteworthy in its own way.

1.FOY Wild Lupine.

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Lupine tends to be the first to bloom each year among the flowers in native wildflower field at Eliza Howell. It is starting to bloom now and I always note it both because of its attractiveness and as a herald of all that is to come.

2.FOY Baltimore Oriole Nest

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Photo by Kevin Murphy

The nesting Baltimore Orioles are one of the highlights of the Detroit Audubon-sponsored field trip to Eliza Howell each June. (This year it is Saturday, June 8, at 8:00 a.m. – free and open to all.)

These orioles typically arrive in the first week of May and begin building nests in the third week of the month. The picture here was taken on May 18; the female was weaving.

3.FOY Burrowing Crayfish Hole

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Crayfish (also called crawfish and sometimes crawdads) are gilled and clawed crustaceans, related to lobsters. Some are terrestrial, spending most of their lives away from bodies of water. They burrow down to groundwater and come up at night to eat on land. They are nocturnal and I have no pictures from Eliza Howell, but this hole is evidence that they remain present in the park. This one will probably continue to remove mud as it digs deeper, piling it up near the entrance in the shape of a chimney (or volcano).

4.FOY Common Milkweed

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The common milkweed is a wildflower made famous as a host plant for Monarch butterfly eggs and larvae. Right after I saw the FOY Monarch on May 15, I checked a spot where I have found early milkweeds in other years. They are up and growing and will be ready any time the Monarchs are ready to lay eggs.

5.FOY Fledgling Robins

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The day after I took this picture of 4 young robins filling the nest, they left it. While I have been observing a number of different bird nests this spring, this is the first that I have watched successful fledging.

6.FOY Opossum Encounter

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On a recent walk in the EHP woods, I met this opossum along the path. “Possums” are nocturnal mammals and this daytime encounter reminds me that they are sometimes visible during the day. Maybe someday I see a mother opossum with several young on her back. That would be a great lifetime first (designated in my notes by “L” for “lifer.”)

7.FOY Honeysuckle Blossoms

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The redbuds and the crabapples have already been blooming for some time, but one of my favorite blossoms, honeysuckle, is just beginning. Most of the honeysuckle in the park have white blossoms, but a few, like this one, tend toward pink. The picture was taken on May 21.

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This list of recent FOYs could be considerably longer, but it is time to get away from the desk and back to the park to see what is new today!

Raccoons in Winter

Though Raccoons are nocturnal mammals, I see them quite often during my daytime walks in Eliza Howell Park, especially in late Fall and in Winter. They are usually sleeping and, from all appearances, sleeping very soundly. I realized how just how soundly when I came across one that had selected an open space on the ground for its daytime resting site.

I walked right up to the sleeping animal. It didn’t raise its tucked-in head or move any other part of the body; it seemed totally unaware of me. The only way I was sure it was alive was by the slight rise and fall of its body as it breathed.

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Raccoons do not typically take their daytime rest out in the open like this; I usually see them sleeping in large cavities of trees. Often they select a tree in the bottomland, along the Upper Rouge branch shortly before it reaches the Main branch, where the old willow trees provide many places to crawl into. Their sleeping pattern allows us to see them only from the rear, head hidden, just like the one on the ground.

This tree is used frequently, though not every day.

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Raccoons do not hibernate, but they may sleep away much of the coldest weather, day and night. They add a lot of body weight in the fall and do not really need to eat much in the winter. In milder winter weather, however, they are more active at night, evidenced by their changing day-to-day sleep locations and by their tracks in the mud and snow.

A good place to look for tracks is along the edge of the river, where this picture was taken.

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Raccoon tracks are among the easiest mammal tracks to identify. Both the fore print and the hind print show five toes and might be compared to human prints. The fore print resembles a small human hand and the hind print looks somewhat like a small human foot with very long toes.

The daytime sleeping spots are more like roosts than dens, just some place to curl up for a long winter nap.

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Photo by Kevin Murphy

It is in the winter, however, that Raccoons also select real dens for nesting, deeper cavities in trees or perhaps in a log or a burrow in the ground. They mate in late winter and females give birth to (usually) 2 – 5 kits in the spring.

Occasionally, a Raccoon is seen with its eyes open in daytime in the winter, as in this picture. This location may possibly be a nesting den.

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Photo by Kevin Murphy

There is much that happens in Eliza Howell Park that those of us who visit only in daytime miss. I sometimes follow mammal trails like this one and wonder how many different species and individuals are foraging along the river at night.

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Thanks to the Raccoon practice of daytime resting that allows it to be visible, I know that it is definitely one common Eliza Howell nocturnal species.