Mammals

Elizabeth Osborne
2013

06 April
1:00 PM

Ashland Nature Center, Hockessin, DE

On the 6th of April, 2013, the Naturalist Certification class went for its first walk at the Ashland Nature Center. The focus of this walk was mammals.

We set off from the parking lot at 1:00 pm. Before we left, Derek showed us some antlers from a White-tailed Deer (Odocoileus virginianus)  and explained their function and appearance. The antlers may be stained different colors depending on the type of tree the deer rubs against.

The first mammal we saw was an Eastern gray squirrel (Sciurus carolinensus). It was in a mature large Sugar Maple (Acer saccharum) that was budding. Squirrels eat both the buds and the sap from the trees. Derek told us that any mature tree is likely to house some squirrels--when a branch falls off, a the hole left behind is a good place for them to nest.

(Both the scientific name and the common English name--"squirrel"--come from the Greek sciouros, which means "shadow-tail.")

Here's an Eastern gray squirrel on my balcony the day after the walk.

American red squirrels (Tamiasciurus hudsonicus), unlike grey squirrels, eat cones and walnuts. Later in the walk, we would see a walnut that had been chewed by either a red squirrel or an Eastern flying squirrel (Glaucomys volans).

As we got to the bog, we saw clusters of wood frog (Lithobates sylvatica) eggs in the water.

We were also on the lookout for signs of muskrats (Ondatra zibethicus). Because these animals are nocturnal, we wouldn't see them, but we could spot the grasses they had clipped.

Muskrats are the only animals in their genus, but they are sometimes confused with American Beavers (Castor canadensis). According to http://articles.washingtonpost.com/2012-05-21/lifestyle/35457231_1_beaver-dams-muskrats-adult-beavers, "Muskrats often move into beaver lodges, even while the beavers are there. Kevin Munroe, park manager at Huntley Meadows, said, 'Muskrats may provide another set of eyes looking out for predators.'"

At one time, muskrats were an important part of Delaware's economy. They were hunted for food and fur in the state well into the twentieth century. The interpretive trail in Port Penn, Delaware still has a muskrat-drying shack and some signs explaining how the hunting was done.
Some pictures are also at http://www.portpenn.org/photos/people/index.html

Yellow flowers were blooming along the path. I think these were Mossy Stonecrop (sedum acre).

As we walked along the boardwalk beside the bog, we looked for muskrat skat, which looks like shiny gray jellybeans. Although we did not find the scat, we saw the telltale cut grasses and a hind footprint. The thumbs of the muskrat separate more than those of a raccoon (Procyon lotor), which helps distinguish the footprints.

A green frog (lithobates clamitans) called from the bog.

We found scat containing long, stiff gray hair. This was evidence that a coyote (Canis latrans) had eaten a deer. In the summer, their diet changes, so the composition of their scat is also different, containing more fruits, such as cherries and persimmons.

The eating habits of coyotes are different from other animals. Vultures, for instance, start with the eyes or anus of a dead animal; coyotes tear large chunks out of the carcass.

Along the boardwalk, we also found red fox (vulpes vulpes) scat. At this time of year, fox scat is all gray--they eat mice and voles. There may be small bones in the scat. The fox was probably walking along the boardwalk when it spotted something down in the bog and hopped down to catch it.

Another gray squirrel ran by on the opposite bank.  Someone spotted the front paw track of a raccoon.
Older frog eggs had visible tadpoles inside them.

Tufts of cattail seeds had landed in the bog. Across the boardwalk from them swam a red-spotted newt (notopthalmus viridescens).

A skunk (mephitis mephitis) had left behind a mound of dirt after it dug for grubs. Skunks have small, dainty paws that they use to excavate worms and other invertebrates.

Across the bog, on a small promontory, we saw two saplings that had been cut by beavers. The bark on the saplings had been chewed, and the cuts were clean--both of these were signs of  beaver (castor canadensis)

Snowdrops (galanthus nivalis) were also blooming along the path.

As we neared the end of the first part of the walk, someone spotted a nest high in a tree. Derek told us that this was probably a flying squirrel nest because of the way it was small and densely packed.

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Part II

Coverdale Farm Nature Preserve

The next area we visited was the far side of the Coverdale Farm Nature Preserve. It consisted of rolling hills covered in dry grass. This is a managed habitat with controlled burns every once in a while. Late in the summer, milkweed will grow in this meadow, along with warm-season grasses.

An old tree in the middle of the meadow formed an island where different birds and small mammals could take shelter.

Along the edges of the meadow is what is called "hedgerow habitat"--mature woodland, plus marshy and riparian areas. These border areas provide shelter for a number or different organisms.

In a tree far across the meadow sat a kestrel. We had also seen one as we were driving over to the preserve. The kestrels eat meadow voles (microtus pennsylvanicus), which are a story unto themselves: a vole can produce a dozen litters a year, with anywhere from one to eleven babies successfully surviving to adulthood (http://www.fcps.edu/islandcreekes/ecology/meadow_vole.htm). If each surviving baby then repeats the process, the voles (also called field mice) can quickly populate an area like the Coverdale Farm Preserve.

The voles tunnel not far underground, making the field bumpy and hard to walk across. They also leave soft nests of chewed grass behind them.

We set off across the meadow looking for skulls and bird feathers.

About a hundred and fifty feet from us, on the rise of a hill, a red fox with some gray in its coat appeared and paused to look at us, then went on its way.

We found coyote (canis latrans) scat that had settled into the grass and been bleached by the sun--a sign it had been there for some time. Coyotes and foxes are both highly territorial.

The feathers of a mourning dove (Zenaida macroura) were spread across another small area of the meadow as we walked south. The shafts of the feathers were intact, which was evidence the bird had been eaten by a raptor rather than a fox. Foxes tear at their prey and break the feather shafts of a bird.

A hole about two inches in diameter was that of a meadow vole. Next to it was long, dark scat with thin, pointed ends--a fox had been digging at the vole's hole.

At a large burrow in the middle of the field, we found feathers from a bluebird's left wing. This time, the ends of the shafts were broken off. Near the entrance of the hole was soft fur from the underbelly of a fox. We also found scat containing deer skin and some of the bones of a young deer. A coyote had bitten through the bone to get at some of the nutritious material inside.

Away from the burrow, near the tree island in the middle of the meadow, we found the tracks of white-tailed deer (Odocoileus virginianus). Their cloven hooves help them travel over all kinds of terrain--the cupped hooves help them gain purchase on uneven ground like that formed by vole tunnels. You can tell the age of the deer by the tracks--young deer have sharp hooves, not yet worn down by a lot of walking.

As we rounded the tree island, someone found the skull of a small mammal. It was longer than that of a rabbit and had large eye sockets--a groundhog (Marmota monax).

Walnuts chewed in a particular way that resulted in a pattern like the face of an owl were signs of red or flying squirrels. Grey squirrels have bigger teeth and hands and have to tear at the nuts more.

Another kestrel flew over. One of the members of the class who is doing work with birds told us about a project that discovered certain birds of prey have the ability to perceive light on the UV spectrum, which allows them to follow trails of urine left behind by small mammals.

In an owl pellet, we saw the complete skull of a meadow vole. As we walked up the hill, we could also make out the path taken by deer from the way the grass had been trampled.

Another island of trees was made up of Osage Orange (Maclura pomifera), also called hedge-apple. These trees make up a "living fence" in the meadow. Their wood was considered the best for making bows by Native Americans.

In a shelter at the top of the hill, another class member found an entire mummified white-footed deer mouse. You can tell that these mice are arboreal because they have long tails, unlike house mice.

A roadkill deer had been left on the top of the next hill to attract predators. Its femur had been chewed, but its brainpan was intact. Having no pedicle for antlers, it was a female rather than a buck.

Witch hazel (genus Hamamelis) was in bloom along the hedge.

As we got back to the parking lot, Derek told us about an upcoming controlled burn. When the meadow is burned, the voles driven out and/or killed by the fire attract many different predators--birds of prey, coyotes, foxes, and others.

Here are the mammals we saw in the (living or dead) flesh or saw signs of on this walk:

red fox
coyote
muskrat
raccoon
gray squirrel
skunk
flying squirrel
beaver
meadow vole
white-footed deer mouse
groundhog
white-tailed deer

In addition, we saw, heard, or found evidence of the following birds and amphibians:

kestrel
owl
bluebird
mourning dove
red spotted newt
wood frog
green frog