Another Flood – and Historic Crests

About 2 inches of rain fell in the Detroit area on Saturday, January 11, 2020, and the Rouge River again flooded in Eliza Howell Park. On 9:45 on the morning of January 12, when I walked toward the footbridge, I saw acres and acres of flooded woodland. This was the only the third time, in my many visits, that I saw water flowing over the bridge.

As those familiar with the park know, the water level varies a lot, but the footbridge is usually many feet above the water level. Here is a picture from November of 2019.

Unable to cross the footbridge, I left and re-entered the park from the end of Lyndon Street on the east side of the park. Before long, as soon as I left the higher ground, I again came to water as far as I could see.

The flood stage for the Rouge River in Detroit is 15 feet. I have not yet seen an official report on the height of the crest on this flood, but it was probably over 17 feet. That would mean that it is among the top 12 highest in the many years that the National Weather Service has been keeping records. Below is a list of the highest historical crests (those over 17 feet, according to NWS. It is noteworthy that, including this one, three of the 12 are in the last 2 years.

Floods have consequences and it will be interesting to see any significant impact on the habitat and on the plants and animals that live near the river. As soon as the water receded sufficiently, I took a walk in the woods. The leaves, branches, and other material on the forest floor had been swept along until they were caught by logs, tree trunks/limbs, and shrubs.

Beaver have recently arrived in Eliza Howell and their residence is, in all probability, in a burrow dug into the bank of the river. Such burrows start under water and angle up to a dry “nest” where the beaver rest during the day and where they have their kits. What impact is there when the water is feet over the bank, and over the resting area, for a day or two? I will be looking for indications of their continuing presence.

Nature is quite adaptable and, in my post-flood walk, I was noting how birds, including Black-capped Chickadees, were attracted to the new concentrations of potential food brought together by the water. Chickadees were finding many smaller seeds among the nuts in piles like this.

There are new “mudflats” where the water moved the leaves and, in the mud, track evidence that mammals are active. These tracks look like the prints of Coyote (left), Raccoon, and Deer.

Nature is adaptable, but having three floods cresting at over 17 feet in 2 years is not normal. I hope I don’t witness another one anytime soon.

 

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.

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.

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.

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.

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)

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.

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.

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.

Beaver!

For the first time in the years that I have been engaged in nature study in Eliza Howell Park, I am now seeing signs of beaver activity. There are some 20 small trees near the river (the largest are about 4 inches in diameter) that have recently been cut down and removed.

Beaver were an important part of Michigan’s history; the pursuit of their pelts was a major factor in the movement of Europeans into this part of the country. Unlimited trapping resulted in their being extirpated from this area some 150 years ago.

Some are now returning. In the last decade, they have been found along the Detroit River (including on Belle Isle) and a few have appeared in the Rouge River system. Until now, to my knowledge, none has been reported this far upstream on the Main branch of the Rouge.

I have not yet actually seen a beaver in the park (they are largely nocturnal), but I know of nothing else that cuts down trees and leaves these teeth marks.

Young beaver stay with their parents until 2 years old or so, when they leave to find a mate and establish their own lodge and colony. Perhaps the signs of beaver activity in Eliza Howell mean that a new pair is taking up residence here, for the first time since long before this area was established as a park.

There is a lot I do not know about beaver from personal observation. They were not in the various areas I have walked regularly during my life and my observations of them when visiting other locations were limited. There is much for me to learn.

While most descriptions of beaver lodges are of conical lodges in a pond formed by a dam, they also make lodges in banks, with under water entrances, especially along rivers where the water is deep enough for them to swim under water/ice. The water level in the Rouge in the park varies throughout the year and I do not know whether it sufficiently deep to meet beaver needs. This is what it looked like on my last visit in the area where the beaver had cut trees.

If they stay here, my guess is that they will be “bank beaver,” but one of the things I will be watching to see is whether they act to raise the water level, perhaps by using a current logjam as the start of a dam.

Beaver are able to change the environment in which they live and this has sometimes led to them being considered by some as a nuisance or a pest (for example, when their dams lead to flooded roads). Their overall impact on ecosystems and on sustainability has, however, been viewed by most researchers as very positive, as evidenced in a widely-endorsed, and very readable, book published last year.

I will also be looking for additional signs of their presence and of their behavior. So far I have not seen clear tracks in the mud, perhaps because most of the mud along the river is currently covered with leaves. The hind track (webbed) is reported to be about 6 inches long and the front about 3 inches. These drawings are from The Peterson Guide to Animal Tracks.

I cannot say definitely that beaver have taken up residence in Eliza Howell Park, but I will now have a different answer when asked whether any beaver live here.

I have been saying “not yet,” hoping that they would show up one of these years. Now I can say “there are definite signs; let me show you.” Perhaps soon I will be able to give an unqualified “yes.”