Happy Halloween!

by Carl Strang

Last weekend, Fullersburg Woods Forest Preserve was the site of the annual Halloween nature walks. In both the roles I played, as Carl the Coroner-back

and as Dr. Helmut Frankenstein, President of Notre Dead University,

as well as myself, I wish you a spooky, but safe, Halloween weekend.

Great Blue Heron Dossier

by Carl Strang

It has been a while since I posted one of my species dossiers. The idea is to make a record of what I know of a species from my own experience rather than what I have learned from others. This is a valuable exercise. When I got the idea and started it, I was embarrassed by how little I could write even for common species. It has forced me to pay more attention, to observe more, to be more discriminating in what I can claim to know about natural history. Even books and, yes, Internet sources like this blog need to be read skeptically. Today I choose the great blue heron, a species that played an important role in inspiring my interest in natural history studies. Records are dated with my code that begins with the day of the month, followed by a two-letter month code (usually the first two letters of the month’s name) and a two-numeral year. The code 16JE99 would indicate June 16, 1999.

Great Blue Heron

First observed at Hawk Lake, where several fished along the east side each evening in summer during my childhood. These were an early inspiration for my bird watching interest. Also observed in PA, along the Tippecanoe River in IN, in DuPage County, in Florida. Seek food usually in relatively deep water, sit-and-wait foraging. They quickly extend the neck to seize or spear fish or other prey. On rare occasions I have seen them briefly swimming on the surface of water too deep to wade. One in FL waited for fishermen to catch fish, then ran up in hope of getting the catch.

They have loud raucous squawking calls, a brief one in flight (often when disturbed) and a longer more rattling one when handled (i.e. at Willowbrook’s wildlife hospital).

Rookery established around 1967 south of Culver, Indiana, near the Tippecanoe River, in several large sycamores at the edge of a small woodlot near S.R. 17. That site still was used through 1986. Birds appear standing in nests in mid-March, radiate out in many directions to feed. Great blue herons then also reached all parts of DuPage County, IL, despite no rookeries there (a large rookery south of the county at Plainfield).

24JA89. A great blue heron flying east of Lake Maxinkuckee, IN.

10MR00. Several herons have returned to the new, small (10-nest) colony at Danada Forest Preserve.

7MY00. Great blue herons croaking in flight, traveling above West DuPage Woods Forest Preserve. An extended string of them, so the calls may be communication between flying birds.

13NO01. I count 25 nests, now, in the Danada rookery. The trees are at the edge of a pond. They are not sycamores, but I didn’t get close enough to ID. Elm shape.

21FE02. A single heron was standing on a nest in the Danada rookery at 4p.m. The winter has been mild, and it’s not inconceivable that a GBH could have survived the winter locally.

1SE02. At 10:30 p.m., a great blue heron in Geneva, standing in shallow water in the Fox River, apparently fishing in the street lights.

16JE03. This year I know of 2 large nesting colonies in DuPage County, both established in recent years. One is at Danada Forest Preserve, the other at Pratts Wayne Woods, near the intersection of Rt. 59 and Stearns Road and visible from both.

8AU03. I kayaked between Willow Springs Road in Cook County and Route 83 in DuPage on the Des Plaines River. There is a strung-out colony of great blue herons nesting over a 2-mile stretch of river that spans the county line. The nests are in scattered dead trees close to the riverbank, taller than the surrounding trees, 2-5 nests in half a dozen trees total. Though separated sometimes by more than a hundred yards, the trees each seem to have one of the others in view.

28MR06. At Tri-County State Park, the 2 nests from last year (a new satellite of the Pratts Wayne colony) gradually had lost most of their sticks. On the 23rd, herons returned (later than in the larger colonies), and now are building the nests back up. One seen carrying a long thin stick in its beak, flying up to a perch beside the nest and giving it to its mate standing in the nest, who then added it. Two additional pairs perching in those trees, but no new nest starts yet.

18JA09. Danada. Checked great blue heron rookery. Most of the 15-20 nest trees were living cottonwoods, and 90% of the nests were in these. Two were dead trees, and three were willows. One cottonwood had 16 nests, a couple had 13, one had 11. Total nests counted 142. The rookery is in a swampy area around a large pond. Last summer I also learned of a rookery at Churchill Forest Preserve, on the islands in the East Branch of the DuPage River.

11OC10. During a dragonfly monitoring run on the Des Plaines River I noticed that, in addition to the scattered great blue heron nests in tree tops along the shore, there is at least one group of trees with a number of nests in a more concentrated colony. There are more than a dozen nests in at least 3 adjacent trees. This cluster is on the river’s south bank, east of Route 83.

Here They Are!

by Carl Strang

In a recent post I mentioned that I have not seen many meadowhawks at Mayslake Forest Preserve. Two days ago I finally found a bunch there, around the edge of the stream corridor marsh. I saw several white-faced meadowhawks.

There also were a number of autumn meadowhawks.

These latter males were, I suspect, hanging around waiting for a heavy rainstorm. On several occasions I have seen pairs of this species laying their eggs on days after late season rains, the females depositing their prospective offspring on the mud just above the waterline, instinctively trusting that spring downpours will raise the pond level enough to submerge the eggs and stimulate hatching.

That same day, up near the friary demolition site I saw a late-flying shadow darner.

And, as a non-odonate bonus, near the off-leash dog fence I spotted a persisting female fiery skipper.

I treasure these last colorful insects. Soon we enter the long season of quiet.

Chorus Frog Mystery

by Carl Strang

Yesterday was warm, and as I enjoyed my lunch break walk I heard 3 different chorus frogs calling in 3 different places. One was on top of one of Mayslake Forest Preserve’s hilltops.

One was in the middle of a meadow, far from water.

The third was close to the stream corridor marsh, where most of the preserve’s chorus frogs gathered last spring.

Their calling reminded me of the spring peeper mystery I described in an earlier post. The circumstances are a little different, in that chorus frogs’ fall voices are much closer to their sound when advertising for mates in spring. Also, instead of calling over a period of weeks to months, they have a more abbreviated period of autumnal calling. A year ago I heard just one at Mayslake, also calling from an elevated spot late in the season. As was the case with the spring peepers, I have not encountered an explanation for this behavior. The only possibility that has come to mind so far is that this might have something to do with finding a safe place to hibernate. The calling frog may be advertising the discovery of such a spot, or announcing the need for help in finding one. I’m not a theoretical evolutionary ecologist, but I don’t think kin selection needs to be invoked here. If these males help females survive the winter they are helping themselves, even if other males also respond. That’s the best speculative stab I’ve been able to come up with so far.

Spots of Color

by Carl Strang

Familiar landscapes become delightfully transformed in this season. Some eye-grabs of color are planned; here is an example from my garden.

An additional element of enjoyable surprise comes in finding such changes in an area one is monitoring through the year. Mayslake Forest Preserve’s savanna had a couple early color explosions. One was in the sumac colony.

The Hill’s oaks also are turning up the red (or, if you prefer, turning down the green).

Now is the time. Get out and enjoy it. Soon it will be gone for another year.

Dead Vole Mystery

by Carl Strang

Perhaps a minute after leaving the snake I described yesterday, I encountered a small dead mammal lying on the trail.

What makes this finding of a deceased meadow vole surprising is that Mayslake Forest Preserve has no shortage of predators who include these little guys on their menu. Typically all that would be left would be bones in a raptor pellet or fur in a scat. I saw no signs of damage on the vole. Two most likely scenarios come to mind. First is that a well fed neighbor’s cat killed the vole and left it, the needle-like toenails and canines producing no obvious trace of their work. I haven’t seen any cats or their signs around lately, but I’ve known cats that were very good at staying out of sight. The other possibility is that the vole was victim of a short-tailed shrew’s poisonous bite, but some circumstance separated the shrew from its prey. Though I have no solution to this mystery, it’s enjoyable nevertheless to find such things and think about them.

Chicago Garter Snake

by Carl Strang

After nearly two years at Mayslake Forest Preserve I finally saw my first snake yesterday. I had heard reports of 4 or 5 sightings over the two years, and a staff member showed me photos of a Chicago garter snake that appeared in front of the mansion one day last summer, but given the amount of time I have spent out on the preserve I feel that I can safely say the preserve’s snake populations are small. I used the plural there because one description was of a probable fox snake. The reptile I saw yesterday was a Chicago garter snake.

This is a subspecies of the eastern garter snake that occurs in northeast Illinois. It is characterized by black spots that interrupt and cut across the pale side stripes in the front part of the body. Those side stripes are on the second and third scale rows up from the belly scales.

At this time of year it is likely that this 2-foot-long male was not far from a hibernaculum he has used in the past. There are several human structures nearby that might give access through the morainal clay to a space below the frost line. He was missing the tip of his tail, which gives me hope that I will be able to recognize him if I encounter him again.


by Carl Strang

Recently I found two relatively new burrows at Mayslake Forest Preserve.

This one, not far from the entrance drive, was excavated this past season. Its size is consistent with woodchuck or skunk. I haven’t seen the former species in that area, but I suppose one could have dug it and then moved on. The second, similar in size, is just outside the friary demolition exclusion fence.

It is in the same location as the coyote den that was covered in the run-up to the fence’s construction, and may access the same underground chamber.

I will be interested in learning what animals may be using these shelters in future months.


by Carl Strang

I have been watching with interest the demolition of the old friary at Mayslake Forest Preserve. In part I am looking forward to documenting the transformation of the new bit of vegetated landscape that will follow. But the demolition process is interesting, too. They started by removing the outbuildings. Now only the basements and foundations of those remain.

The main building is starting to come down.

I had imagined a wrecking ball, but no.

The crane’s bucket simply takes out large-bite-sized chunks of wall. It’s not haphazard destruction. Materials are piled according to type.

They took out the south wall first, exposing the courtyard. I was impressed that they had lifted a tractor onto the roof to move and sort materials there.

It seems like it might be hazardous to the operator, but given how competently they seem to be operating, I doubt that they would take unnecessary risks. I’ll continue to post updates as the demolition progresses.

October Monitoring Run

by Carl Strang

Last weekend’s warm weather allowed me to make a late dragonfly monitoring run on the Des Plaines River at Waterfall Glen Forest Preserve. Looking back through my records, I find that in all the monitoring I have done since 2003, I never have made a formal outing in October. It was worth trying for that reason, if no other. Besides, it was a nice day to be on the river in my sea kayak. There isn’t a lot to report as far as dragonflies and damselflies go. The only dragonflies were a pair of common whitetails, the female laying some last ditch eggs. I saw a couple familiar bluets,

a few orange bluets,

a stream bluet, 3 eastern forktails and 7 American rubyspots.

The last confirmed that this species is active late in the season, supporting my sighting at Fullersburg (which at first I thought was a smoky rubyspot). I also made some singing insect observations, the best of which were jumping bush crickets singing in the early afternoon on both sides of the river. This adds to my local range for this species, which clearly has shifted north of where you will find it mapped in references. The shallow lagoon at the downstream end of my monitoring area was hosting a gathering of great egrets.

The gorilla in the room, however, was a major construction project underway on the south side of the river. A fence was being built.

With much machinery, much shouting and an impressively speedy progress (I saw no sign of this when I last was there in late August), a metal framework is being erected and filled with fine-meshed screening.

The fence is parallel to the Centennial Trail, which has been closed for this project. The fence is only 6 feet tall or so, enough to disrupt the view of trail users but not enough to be a significant barricade to wildlife, I thought. A little research on the Internet revealed the purpose of this structure. It is a fish barrier. That may seem strange, but high water levels could lift the river high enough to reach the fence. The target fish are Asian carp, a group of 4 species which have been much in the news because of concerns that they might cross from the Mississippi River drainage (which includes the Des Plaines) and the Great Lakes. The Des Plaines River is paralleled by a canal, so the fence apparently is intended to keep the carp from going between the two. Would tiny baby carp be stopped, though? I’m not enough of a fisheries biologist to judge. For more information on the fish species and other information, here is a link.

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