SJF February Summary

by Carl Strang

Beginning in the middle of the month, I went through all of St. James Farm Forest Preserve seeking the great horned owl nest. I did not find it, but did create an inventory of 25 large tree cavities where an incubating owl might not be visible from the ground. An additional possibility would be a hawk nest in the dense top of one of the spruces. Twice I saw an owl, presumably the male if they are nesting this year, in the same north central portion of the main forest. In past observations elsewhere, the male usually perched in the vicinity of the nest. I will continue to monitor the suspect cavities, but may need to see branched young later in the season to narrow down possibilities further.

I was able to eliminate this cavity, as it was otherwise occupied.

I was able to eliminate this cavity, as it was otherwise occupied.

Some photo processing in the computer makes the raccoon easier to see.

Some photo processing in the computer makes the raccoon easier to see.

I had not seen or heard a pileated woodpecker on the preserve for more than 6 weeks (though occasionally I heard suspicious loud, spaced tapping sounds), but in the second half of February heard or saw one on three different days. The one close sighting was of a male.

The pileated’s tongue-spear in action.

The pileated’s tongue-spear in action.

American coots and large numbers of mallards were a continuing presence on the stream. For much of the month the Canada geese roosting at Blackwell frequently passed over St. James Farm in large numbers, occasionally stopping to graze the lawns and meadow areas. Geese began to break off into pairs as ponds opened up during the last third of February. Interesting bird sightings included a bald eagle flying over, and a hermit thrush on February 16. Migrating sandhill crane flocks began to pass over beginning on the 21st. A small group of white-throated sparrows in the eastern part of the main forest were the first observed on the preserve this year. The first red-winged blackbirds arrived, and eastern bluebirds became a more consistent presence in the last part of February.

This male eastern bluebird seemed to be staking a claim in a corner of the grounds adjacent to a pair of bluebird houses.

This male eastern bluebird seemed to be staking a claim in a corner of the grounds adjacent to a pair of bluebird houses.

Fox squirrels fed heavily from Norway spruce cones in the south forest, and on tree buds elsewhere. Skunk and deer activity was much as described for January. The preserve’s deer minimally are a group of 3 does, a group of 2 deer which occasionally associate with those does, and a single buck. The snow was never deep enough to discourage raccoons. A mink used a den off the south edge of the pond in the preserve’s northwest corner.

Along the way during the owl nest search I found this curiosity.

Along the way during the owl nest search I found this curiosity.

The deer pelvic bone was well gnawed by rodents.

The deer pelvic bone was well gnawed by rodents.

The bone has been on this buckthorn twig long enough for the twig to grow several long branches.

The bone has been on this buckthorn twig long enough for the twig to grow several long branches.

The large area of restoration brush clearing in the main forest was expanded greatly by District staff, generally following the route of the new trail mapped in the preserve’s master plan. Among the more interesting plants encountered during the owl nest search were two of the most massive black walnuts I have ever seen, and a prickly-stemmed greenbrier (Smilax tamnoides).

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Goings On at SJF

by Carl Strang

Winter is relatively slow and quiet in places like St. James Farm Forest Preserve, but plenty still is happening. Today’s sharing will proceed north to south.

American coots have been a constant presence in the stream.

American coots have been a constant presence in the stream.

Entrance to a mink den just above the edge of the north pond.

Entrance to a mink den just above the edge of the north pond.

In mid-February I begin the search for the preserve’s great horned owl nest. I wait until then so that the incubation is thoroughly committed and my potential disturbance is minimized. This is the first time I have conducted such a search at St. James Farm. That relatively large, old forest provides a handicap.

So far, with less than a quarter of the preserve covered, I have found more than ten cavities where an incubating owl could not be seen from the ground.

So far, with less than a quarter of the preserve covered, I have found more than ten cavities where an incubating owl could not be seen from the ground.

The south forest also hosts wildlife activity.

Fox squirrels have been exploiting the abundant Norway spruce cones in the plantation.

Fox squirrels have been exploiting the abundant Norway spruce cones in the plantation.

The ground beneath those trees is littered with gleaned cone cores.

The ground beneath those trees is littered with gleaned cone cores.

The south forest receives its share of attention from bark-foraging birds like this hairy woodpecker.

The south forest receives its share of attention from bark-foraging birds like this hairy woodpecker.

Each visit to the preserve brings highlights like these.

Skunk Surprise

by Carl Strang

Snow that fell around the turn of the year has provided good tracking opportunities at St. James Farm Forest Preserve. As I walk the new survey routes I established in December, I am beginning to assemble a sense of the general mammal presence and activities on the preserve. For instance, I found that cottontail rabbits are much more abundant and widely distributed than my earlier first impression indicated. The species list also is growing. For example, I ran across some mink tracks on New Year’s Day.

At first I was excited, because they seemed smaller and less round than mink tracks usually are, but they proved to be those of a mink rather than the locally rarer long-tailed weasel.

At first I was excited, because they seemed smaller and less round than mink tracks usually are, but they proved to be those of a mink rather than the locally rarer long-tailed weasel.

With minimal wandering the mink, possibly a female by the small size, came straight out of the forest and into the newly reconfigured stream.

With minimal wandering the mink, possibly a female by the small size, came straight out of the forest and into the newly reconfigured stream.

A new species record is welcome, but even more welcome was a bit of a mystery that came the next day.

Skunk tracks in the snow!

Skunk tracks in the snow!

This was surprising because, in my previous experience, skunks didn’t emerge from their dens in early January unless the temperature overnight was at least 30-40F. It had been in the mid-teens. As I followed my route I was able to trace the skunk’s course, roughly a straight line to the preserve’s boundary against a residential neighborhood. Later I backtracked this individual to a contorted tangle of footprints in a difficult to negotiate (for me) spot in the woods just north of Butterfield Road. I wasn’t able to cut this skunk’s entry into that area, so perhaps its den is there.

That wasn’t the end of it, though, as I soon crossed a second skunk’s trail. This was a different individual, larger and with a significantly wider straddle. Its feet were dragging significantly. Sorry, it didn’t occur to me at the time to photograph those tracks. I encountered them near where skunk #2 was exiting the preserve, again into the neighborhood to the east. As I continued my walk I was able to backtrack this second animal, occasionally cutting his trail and occasionally following it.

Here is the habitat map of northern St. James Farm. M shows where the mink was, S1 is the narrow-straddle skunk, and S2 is the wider-straddle individual. Solid lines show where I followed the tracks, dashed lines indicate areas between places where I cut the animals’ trails.

Here is the habitat map of northern St. James Farm. M shows where the mink was, S1 is the narrow-straddle skunk, and S2 is the wider-straddle individual. Solid lines show where I followed the tracks, dashed lines indicate areas between places where I cut the animals’ trails.

Ultimately I traced a good mile that skunk #2 had hiked. No wonder its feet were dragging at the end, and the foot drag gradually vanished as I backtracked it. It had crossed the parking lot after visits to the ranger residence and the round office building. Before that it had crossed the trail of skunk #1 (close enough in time that my skills are inadequate to say which individual passed that way first) after taking the Prairie Path tunnel under Butterfield Road. It had emerged from the woods south of Butterfield, still on the preserve, but a locked gate blocked my further progress.

This is the kind of traveling I expect in February, when the striped skunk mating season arrives. Then, they are much more likely to come out on the colder nights. As this winter progresses I look forward to learning whether St. James Farm’s skunks in the winter of 2015-16 habitually emerge to wander more often and in colder weather than skunks in other years in other places.

 

Mink in a Tree

by Carl Strang

I can’t pretend to know much about mink. Typically I’ll get 4-6 brief glimpses of our most common weasel in the course of a year, and I’ve accumulated a total of 6 or 7 hours of “dirt time” (mainly “snow time” in this case) tracking them. With that as background, I can’t truly say how odd this little story from last Friday is. It was a cold, overcast day, and I was returning to Mayslake Hall from a relatively uneventful lunchtime walk. As I approached the little stream that serves as the outlet for Mayslake Forest Preserve’s lakes, I caught the motion of a roughly squirrel-sized mammal. It had climbed onto the base of a severely tilted willow.

The tree in question.

The tree in question.

The animal was very dark.

Definitely not a squirrel.

Definitely not a squirrel.

As it climbed all the way to the topmost branches, 15 or so feet above the ground, I was thinking: could this be a mink? But it’s climbing a tree!

When it stopped and gave me a look, the identification was confirmed: a mink indeed. Here, the tail and hindquarters are visible to the left, the head to the right.

When it stopped and gave me a look, the identification was confirmed: a mink indeed. Here, the tail and hindquarters are visible to the left, the head to the right.

Fortunately for me, the critter held still and let me get enough photos that I ended up with a few that were reasonably in focus.

I had set the camera’s ISO to 2000 on that dull day. Note the white chin.

I had set the camera’s ISO to 2000 on that dull day. Note the white chin.

Eventually the mink climbed back down and sprinted through the woods to the safety of Mays’ Lake. Tree climbing is not typical behavior for this amphibious mammal, I am sure, but I certainly have a broader sense of the little carnivore’s capabilities after this episode.

 

Mayslake Catch-up

by Carl Strang

Now that we are getting autumnal weather, it’s a good moment to look back at the summer just past, and at the current hints of what is coming. Here are photos from the past month at Mayslake Forest Preserve.

This dorsal view of a black-legged meadow katydid doesn’t show off his colors, but as he pauses between songs we can see the sound-production structures in the bases of his wings.

This dorsal view of a black-legged meadow katydid doesn’t show off his colors, but as he pauses between songs we can see the sound-production structures in the bases of his wings.

Usually I’m good at spotting bee mimics, but this large syrphid fly had me calling it a common eastern bumblebee for several seconds before I realized my error.

Usually I’m good at spotting bee mimics, but this large syrphid fly had me calling it a common eastern bumblebee for several seconds before I realized my error.

According to BugGuide, “larvae are deposit filter-feeders in water-filled tree holes,” which explains why Mallota bautias don’t turn up very often.

When I spotted the scissor-grinder cicada on the horizontal branch I took advantage of the opportunity for an unobstructed telephoto. Only when I was cropping the picture in the computer did I notice the second individual on the vertical branch.

When I spotted the scissor-grinder cicada on the horizontal branch I took advantage of the opportunity for an unobstructed telephoto. Only when I was cropping the picture in the computer did I notice the second individual on the vertical branch.

So much for summer. Now for hints of the season to come.

This brown, probably male, nymph is a greenstriped grasshopper, the species that will kick off the singing insect season next spring. They get started early because they overwinter in this form rather than in eggs as do most of the species singing now.

This brown, probably male, nymph is a greenstriped grasshopper, the species that will kick off the singing insect season next spring. They get started early because they overwinter in this form rather than in eggs as do most of the species singing now.

This Henry’s marsh moth caterpillar was clambering over the tangled stems of a reed canary grass patch, probably seeking a pupation spot for its winter hibernation.

This Henry’s marsh moth caterpillar was clambering over the tangled stems of a reed canary grass patch, probably seeking a pupation spot for its winter hibernation.

These mink scats, freshly deposited on a path near the stream, are the first sign of that species I have seen in a while. Perhaps this mink will center its winter activities around Mayslake’s wetlands.

These mink scats, freshly deposited on a path near the stream, are the first sign of that species I have seen in a while. Perhaps this mink will center its winter activities around Mayslake’s wetlands.

Reptiles and amphibians are moving toward their hibernacula. Recently I spotted a garter snake that looked different from the usual Chicago version of the eastern garter snake.

It was paler around the head and neck.

It was paler around the head and neck.

The side stripe is on scale rows 3 and 4, and other details support the identification of plains garter snake, a new species for the Mayslake list.

The side stripe is on scale rows 3 and 4, and other details support the identification of plains garter snake, a new species for the Mayslake list.

Still Winter at Mayslake

by Carl Strang

The calendar claims that spring has arrived, but it’s still winter at Mayslake. A while back I mentioned my 6 seasons framework for northeast Illinois. The first of March brings the start of our sixth season, Late Winter. I once held too rigidly to the idea that Late Winter ends in mid-April, but especially after last year I feel the need to modify the framework and acknowledge that this season is variable in length. I have an idea of how to mark the end of Late Winter, which I will share later. For now, it is shaping up to be a relatively late spring. Consider the lake ice at Mayslake Forest Preserve. This year the ice was thick enough to support people, though few took advantage of the opportunity.

Forest Preserve District rangers placed these fish structures out on the Mays’ Lake ice early in March.

Forest Preserve District rangers placed these fish structures out on the Mays’ Lake ice early in March.

In my previous 4 springs at Mayslake, the latest there was ice on the lakes was March 18. This year it has been slow to depart.

Mays’ Lake was almost entirely ice covered on March 13.

Mays’ Lake was almost entirely ice covered on March 13.

By March 19 the fish structures had sunk, but the lake still was largely in ice. The previous late date for lake ice in my 5 years at Mayslake was March 18. The ice still was there through yesterday (the 21st).

By March 19 the fish structures had sunk, but the lake still was largely in ice. The previous late date for lake ice in my 5 years at Mayslake was March 18. The ice still was there through yesterday (the 21st).

Meanwhile the stream corridor marsh, though open and frozen in turns, has filled to capacity and beyond.

The marsh on March 6.

The marsh on March 6.

Snows have allowed the continued opportunity for tracking.

A mink has been passing through the preserve on a weekly basis.

A mink has been passing through the preserve on a weekly basis.

A pair of coyotes has been a more regular presence on the preserve as well, as have red-tailed hawks. I am thinking I should soon conduct a search for a new den and a new nest, respectively. It has become clear, though, that if the great horned owls are nesting this year, they are off the preserve to the south.

Literature Review: Muskrat Ups and Downs

by Carl Strang

One of the classical sources of data in vertebrate wildlife ecology is the Hudson Bay Company fur records in Canada. Those were used, for instance, to establish the dramatic cyclical pattern of lynx relative to showshoe hare populations, inspiring much subsequent research as to the underlying causes. There still are data to be mined from those records, as was demonstrated in a 2011 study [Estay SA, Albornoz AA, Lima M, Boyce MS, Stenseth NC. A Simultaneous Test of Synchrony Causal Factors in Muskrat and Mink Fur Returns at Different Scales across Canada. PLoS ONE 6(11): e27766. doi:10.1371/journal.pone.0027766].

The muskrat, primary focus of this study, is common across North America, including northeast Illinois.

The researchers examined Hudson Bay Company fur records from 81 posts across Canada, looking at muskrat numbers, mink numbers, and bringing in climate data. They concluded that mink had an important impact on muskrats all across Canada, but the greatest and most direct effect was in the west.

Mink, also common in our area, are predators of muskrats.

In the east, variation in winter precipitation also was important, with drought in particular affecting muskrats. Interactions among these factors could be important here. For instance, drought could force muskrats to disperse longer distances over land, reduce their watery escape space, and concentrate them, exposing them to greater mink predation.

Vertebrate Notes

by Carl Strang

Today I have a few observations on vertebrate animals to report from Mayslake Forest Preserve. The first was a personal nostalgia trip as I watched a green heron foraging in the stream corridor marsh.

While green herons sometimes wade, they more often hunt from a perch.

This brought back childhood memories of watching green herons hunt from the piers at Lake Maxinkuckee in north central Indiana.

Here the heron takes aim at a tadpole or other small animal.

Nearby, at May’s Lake, I found a log protruding from the water a few feet offshore that has become a marking station for a mink.

The mink at Mayslake typically travel in the water, seldom leaving tracks on shore, so such depositions of scats are the best clue to their presence.

In recent days we have been hearing the familiar incessant complaints of a fledgling red-tailed hawk.

It frequently perches in the top of a tree.

This probably is an offspring of the same pair that nested on Mayslake preserve last year. They decided to nest elsewhere this spring, but frequent sightings hinted that their nest was nearby, and the arrival of this youngster supports that idea.

Aquatic Mammal Scats

by Carl Strang

Soon after I started checking the amphibian traps I set in the marshes at Mayslake Forest Preserve I noticed signs that the traps were being used.

Mammal scats. The trap’s quarter-inch mesh gives a scale.

Other scats on nearby logs were drier, but about the same size.

They are composed of vegetable matter.

These are muskrat scats. Muskrats leave them on exposed surfaces just above the water, indicators to other muskrats that this marsh is occupied. I have known muskrats to construct rafts of cut plants when there were no readily available platforms.  This little marsh is showing itself to be home to quite a diversity of animal life.

Meanwhile, in the narrow stream nearby, I have noticed that a prominent rock likewise has been accumulating a mammal’s calling cards.

These are smaller in diameter than the muskrat’s scats, darker in color and in linear arrays.

A close look reveals what appear to be tiny fish bones.

The bones by themselves don’t rule out muskrat, but this is a narrow swift stream, and repeat visits here by a muskrat are unlikely. Also, other structural features in these droppings point to a different species.

These scats in fact reveal that the mink I tracked through the winter continues to pass this way frequently. I find it interesting that two aquatic mammals in different orders use similar behaviors to communicate their presence.

Fooled!

by Carl Strang

Yesterday I was gifted with a humbling lesson. On my lunchtime walk at Mayslake Forest Preserve I saw a string of fresh footprints in the shallow snow on the trail near the May’s Lake outlet.

My eye was drawn to the big, round-looking footprint lower left.

Mink, I thought: round looking, right size, 5 toes. The tracks led along the trail I was following. I was a little bothered by toenails that seemed a little too prominent, and the fact that this animal was following the trail rather than dropping down to the lake edge below. But I have followed mink over land before, and I kept seeing enough round looking footprints to shore up my mental image.

I decided to climb up and see if the local skunk had been out. Last week I found that the skunk-sized den entrance I first noticed last October near the friary (shown in this photo from a posting then)…

Freshly dug in October, the den entrance was around 5 inches in diameter: skunk sized.

…in fact was occupied by a skunk, which had begun to emerge in answer to February’s mating call. Yesterday the area around the den was well trampled, and there had been much coming out and going in.

Here is the same den, yesterday.

Some of the tracks looked suspiciously like the “mink” tracks I had been following. I went back down, and soon found these.

There was no denying that the footprints on the extreme left and right in this frame were those of a skunk.

As I returned to the place where I first had seen the tracks, I worried over how I had been fooled. Eventually I concluded that there were in fact several lessons. First impressions had been one factor. My eye had been drawn to the largest footprints, the round-looking ones. I failed to look closely at all the tracks. If I had done so, I would have noticed the unmistakable creviced, narrow heel markings characteristic of skunks.

I also learned about an unusual substrate. The footprints were in very shallow snow, much of it deposited over slick ice. Where the skunk had stepped on that ice, the toes had spread abnormally to produce those uncharacteristic, round-looking tracks.

Finally, I should have given more credence to those little doubts about the toenail marks and the animal’s following the trail rather than the lakeshore.

That’s the thing about tracking. There always is something new to learn. And it doesn’t hurt to be taken down a peg now and then, too.

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