A Favorite Pin Oak Tree: 19th Century Origins

The Pin Oak tree at the edge of the road in Eliza Howell Park is one of my favorite trees. It stands alone, with enough room for its branches to spread. 

At this time of the year, the leaves are fallen and the branches are bare.

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I first started paying close attention to this oak because the birds are attracted to it. Warbling Vireos have nested here twice in recent springs and both Red-bellied Woodpeckers and Blue Jays are all over it in late September and early October, collecting acorns.

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Photo by Margaret Weber

This is a quite large – and old – Pin Oak, a species that does not live as long as some other oaks. After having been asked several times how old it is, I decided to try to find the answer. There is no exact method of knowing the age of a living tree, but there is a widely used method of estimating the age.

The steps in estimating tree age are these:

  1. Measure the circumference of the tree at 4 ½ feet from the ground.
  2. Divide the circumference by pi (3.14) to get the diameter.
  3. Multiply the diameter (in inches) by the “growth factor” that has been identified for the specific species, based on how fast growing it is. (Different organizations have published the growth factors for different species.)
  4. The resulting number is the approximate age of the tree, in years.

Pin Oaks are moderately fast growing and have been given a growth factor of 3.0.

It is difficult to measure the circumference of a large tree by oneself so recently, when accompanied by Charon, another Eliza Howell enthusiast, we undertook the measurement.

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At 4 ½ feet high, the tree measured exactly 12 feet in diameter (144 inches).

144 divided by 3.14 = 45.86.

45.86 times 3.0 = 137.58

Using this method to estimate age, the tree is about 137 or 138 years old.

137 years ago was 1883. This is just an estimate, but it is probably safe to say that this tree began to grow before the twentieth century, long before this property was donated to Detroit for parkland.

It was already over 100 years old when I started enjoying it, appreciating it in all seasons. On hot summer days, when someone else has not claimed the spot, I park the car in its welcome shade as I take my walk.

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Across the road is the prairie flower field and the Pin Oak sometimes makes a lovely background for a flower picture — Joe Pye Weed in this case.

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Pin Oak leaves turn late in the Fall, in November in Eliza Howell. The bronze (?) shade is not as striking as the leaves on some other trees, but there is something very attractive about it.

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As oak trees go, Pin Oak trees do not have a long lifespan. This one is perhaps older than average. I hope it continues to provide beauty, food, shade, and nesting habitat long after my nature walk days are over.

Golden-crowned Kinglet and Eastern Bluebird: Two Occasional Early December Birds

The completion this month of 15 years of bird watching in Eliza Howell Park (180 consecutive months and over 1370 different records) Park makes this a good time to review the seasonal presence of different bird species. Based on experience, I know fairly well which species I can expect to see in the park at any given time of the year, in any particular 2-week period. These can be considered Common for that particular “season.”

And I know the species that I do not usually see on my outings at a particular time of the year, but am not surprised when I do see them. These are Occasional birds, birds that I can expect to observe some years during this season, but not most years.

The current “season” is the first two weeks of December, a period of time characterized by cloudy days, with leaves on the ground but very few remaining on trees.

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At this time of the year there are no flowers blooming, no developing seeds or fruit, little evident insect activity; I tend to concentrate my observations on mammals and, especially, on birds.

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Recent sightings of two occasional bird species led me back to my records. The first is a Golden-crowned Kinglet, only the fourth time in the last 15 years that I have seen this bird in the park in December.

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Photo by Margaret Weber

In my listing of Eliza Howell birds, Golden-crowned Kinglet is identified as a Migrant, a bird that passes through the park in the spring and fall each year, but is not present in either the summer or the winter. It is a late fall migrant, usually seen well into November.

As can be seen from the range map below (from the Cornell Lab of Ornithology), the southern part of Michigan is within its winter (nonbreeding) range. Some Golden-crowned Kinglets can be seen in southern Michigan in winter every year, but my interest here is specific to Eliza Howell, the habitats in this particular location at this specific time of the year. Here it is occasional.

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The second occasional December bird recently seen is Eastern Bluebird. Bluebirds are Summer Residents, breeding in the park. They have become more common in recent years.

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Photo by Margaret Weber

This is only the third December I have seen a Bluebird in Eliza Howell. However, two of these three years are 2018 and 2019. As the species becomes more common during the breeding season, it may also show up on more occasions during the winter.
Similar to Golden-crowned Kinglet, the winter range of Eastern Bluebird includes southern Michigan, though most individuals migrate further south. (This map is also from Cornell.)

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I typically see about 24-25 different species in the park in December, most of which are the usual Eliza Howell birds of winter: Northern Cardinal, Red-tailed Hawk, Red-bellied Woodpecker, Dark-eyed Junco, Black-capped Chickadee, Mourning Dove, etc. They brighten the gray days.

The occasional appearance of a different species adds to the brightness and adds to my knowledge about what to expect when.

A Tiny Patch of Cattails: Over the Seasons

About a year ago, I commented on the way the seed clusters of Staghorn Sumac persist into and through the winter (December 14, 2017). Another perennial plant in Eliza Howell Park that holds its seeds well into the winter is Cattail.

Now, in mid-December, most Cattail seed clusters look like this.

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It is likely that many visitors to Eliza Howell Park never see cattails. There is only one small patch that I am aware of, at the edge of a wooded area, with only about 10 – 12 seed stalks a year.

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Cattails thrive in wet soil and are usually found in or by wetlands. The Eliza Howell patch is in area that I would not call a marsh or wetland (or even a vernal pool), but does tend to be a wet spot in the spring.

Cattails spread by rhizomes (creeping roots) and by seeds. Since this patch is isolated, it probably started from seeds.

Last February, most of the seed clusters were still tightly closed, not yet dispersing seed.

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In late winter, shortly before it is warm enough for the seeds to sprout, they finally open and the seeds are released, relying mostly on the wind for dispersal. The next picture is from March 22, 2018.

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It would be interesting to know the source of the seeds that started the Eliza Howell patch.

The new growth on the established plants appears in April, and a couple months later seed stalks are evident. In July, they look like this.

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By mid-August, the seed clusters look quite mature.

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There are a number of plant species in the park that I check on regularly around the calendar year. Cattails are one, in part because of the manner and annual timing of seed dispersal. And they are a species that has observable change in winter.

 

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.

 

Green in December: Winter Creeper

While I normally use the common name, rather than the scientific name, of the plants I observe in Eliza Howell Park, I have for some reason long thought of this plant as “euonymus” and have only this year begun to call it “winter creeper.” While walking in the park recently, I was reflecting on how well chosen the “winter creeper” name is.

Except for a few lingering leaves on some honeysuckle bushes, by early December the green has left the Eliza Howell woods until spring. It is gone, that is, except for one small area along the river where the evergreen winter creeper grows.

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These green leaves on the tree may look like the tree’s leaves, but they are the leaves of the climbing vine that grows up the trunk and covers the branches. Winter creeper can grow up to 70 feet high, capable of reaching the tops of trees.

The vines are large and strong, sometimes several on the same tree.

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Winter creeper was introduced in the U. S. about a century ago, imported from the Orient as an ornamental. Some have escaped into the wild. These Eliza Howell vines are very mature looking and have probably been here a long time.

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In addition to having green leaves in December, winter creeper now also has fruit  on the vines. The berries are a lot like bittersweet berries (see “Bright Berries, Bright Birds on Gray Days,” November 8, 2018), but they mature even later. They are just opening now.

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There is a second location in the park, outside the wooded area, where these evergreen vines are found. In this spot, the vines are much smaller, probably younger, and are not producing fruit.

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Some published reports indicate that winter creeper flowers and fruits only in more mature plants. Based on the very limited examples I have seen in the park, this may be the case, but my experience is much too limited to confirm it. 

What I can confirm is that a December walk in the woods mostly means brown leaves on the ground (when not covered with snow) and bare branches on the trees…

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… except for the small patch of winter creeper found some distance along the path that goes to the right after crossing the footbridge. Winter creeper is one big reason I take this particular path frequently in winter.