Burn Season

by Carl Strang

The end of winter brings with it the prairie and savanna controlled burn season. Mayslake Forest Preserve got some of that attention, but it was more limited than the almost complete coverage of two years ago.

Only half of the north stream corridor prairie was burned, for instance.

Only half of the north stream corridor prairie was burned, for instance.

A thread of fire reached into the edge of the stream corridor woodland and ignited the tall stump which I regarded as the most likely nest site for the great horned owls last year. It continued to smolder for days.

Several feet of one side burned away, showing that the cavity had been wide open and quite deep.

Several feet of one side burned away, showing that the cavity had been wide open and quite deep.

I don’t know if any owl eggshell fragments could be found in the former base of the cavity, but it’s a moot point now as they won’t be able to use this platform again.

I don’t know if any owl eggshell fragments could be found in the former base of the cavity, but it’s a moot point now as they won’t be able to use this platform again.

It’s a moot point personally, too, as I will be retired next year and plan to shift my preserve monitoring to St. James Farm, a preserve closer to home.

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Return to the Platform

by Carl Strang

One of my annual rituals is to go out in mid-February and seek the nest of the great horned owl on the preserve that I am monitoring (Mayslake for the past several years). This year that task proved to be much too easy, as the birds returned to the location of their nest in 2012. That was when they made the arguably poor choice of laying their eggs on top of a squirrel nest. It worked as long as the female was incubating quietly, but after the eggs hatched the nest began to fall apart from all the comings and goings. One of the babies fell to the ground and we rescued it. After it was checked out and cleaned up at the Willowbrook Wildlife Center, it was returned and its dubious home was placed on a more solid platform.

Mike Wiseman did the honors.

Mike Wiseman did the honors.

Ultimately one youngster branched.

Ultimately one youngster branched.

The platform remained, and we hoped the owls would use it, but they apparently did not nest in 2013, and last year they nested in an unknown location not far from the stream corridor marsh. Maybe a couple years’ accumulation of fallen leaves was needed to make a suitable foundation. Hard to say. In any case, on January 28 I found this:

Just enough of her peeks out to reveal that glare so typical of an incubating owl.

Just enough of her peeks out to reveal that glare so typical of an incubating owl.

That was as much as she showed. Sometimes it was less.

Those feather tufts are a good image to plant in your mind if you are going hunting for a great horned owl nest. Sometimes they are all you will see.

Those feather tufts are a good image to plant in your mind if you are going hunting for a great horned owl nest. Sometimes they are all you will see.

We had a blizzard a few days after I found the nest. She seemed well protected in that platform, so I hoped the storm didn’t drive her off the nest. That was what I believed happened in 2011 when the Groundhog Day Stormageddon blizzard brought in a couple feet of snow in short order. After around 40 days the owls abandoned the nest that year. This year I was counting the days. Last Friday she was on the nest. On Monday she was gone. I checked a couple times through this week, but sadly we appear to have a repeat of the 2011 failure. This is why great horned owls live so long, so as to have multiple opportunities to produce the young that will replace them in the population.

 

Blue Jay Species Dossier

by Carl Strang

This week’s species dossier contains my observations of the blue jay, a bird I regard as the Forest Crier, who lets everybody know what is going on.

Blue jay

Blue jay

Jay, Blue

Lives in forests and old, tree-filled residential areas. Nested in the yard at Culver (15′ up in silver maple), riparian strip at Willowbrook Forest Preserve, IL (8′ up in small tree) and Maple Grove F.P. (10′ up in hawthorn at forest edge, incubating 31MY86). Bird reluctant to move when on nest. Eats mainly insects in summer, a lot of nuts and seeds in fall and winter. Forages from ground to top of canopy. Very vocal. “Eeth! Eeth!” sharp alarm call; rising, accelerating “a-a-a-ee-ee-ee-ee” (long a’s and ee’s) begging/feeding call of young (much like crows’); “ool-ool” and “teekle-teekle” calls accompanied by peculiar bobbing of body. Captive reared birds at the Willowbrook Wildlife Center often used this latter movement in concert with vocal mimicries (whistles, telephone ringing). Low, highly musical, conversation-like vocalizations among Willowbrook’s caged birds. Wild birds mimic calls of various hawks. They travel in loosely organized flocks much of the year. Mob crows in spring. Courtship feeding observed in a treetop at Maple Grove F.P. on 10MY86. Tend to take over feeders, other birds stay away until they leave.

15JE86. As a broad-winged hawk flew past, pursued by a couple of starlings at Maple Grove, a blue jay uttered a single “eeth!” call.

Late summer 86. As a flock of ground-feeding grackles flushed at the approach of people, jays and downy woodpeckers at Meacham Grove emitted contact calls, apparently as a final check of location and status before possible flight.

11MY88. Responded to deer breaking twig loudly with “thief” call, Hartz Lake.

12MY88. Jay on nest in 20′ box elder, nest 15′ up, riparian strip of Willowbrook Back 40.

5JE88. In the middle of Geneva I stood under a tree in which a pair of cardinals suddenly began to alarm-call rapidly. They were close to me, but not paying attention to me. The calls were directed at a blue jay which the cardinals chased from the isolated street-side tree to a clump of trees and brush, and continued the alarm calling and chasing until the jay left. The jay resisted some, was not driven off easily.

29MY88. Hartz Lake, in woods. A chipmunk saw me move my arm laterally, gave 3 chips increasing in speed, and ran. Immediately 2 jays feeding on the ground flew up. They were 40-50 feet away.

13JL88. Blue jay young still following, begging from parent, though they look full grown.

18OC88. Cactus Camp, IN. A blue jay yelling at me with repeated, energetic “jay jay” (“thief thief,” “eeth eeth”) calls.

24DE88. Cactus Camp. Jays doing a lot of “jay” mobbing; information about animals moving away from me?

4JE89. Elsen’s Hill Forest Preserve, IL. Teekettle call used as a warning to an intruding jay, given as the intruder landed. After several repetitions the intruder hadn’t left, and so the calling bird flew into the same oak and began to displace it (flights of 10-20 feet). It “jay”ed once, then resumed “teakettles,” continuing displacements and increasing their frequency, until the intruder left.

11JE89. Cactus Camp. Pair of jays mobbed me with loud “jay” calls.

17JE89. A broad-wing called repeatedly, in north end of Maple Grove. Jays, flickers and grackles highly agitated, flickers the most continuously vocal with “keels” every 2 seconds (2 birds). Grackles gacking frequently, too. A great crested flycatcher near, also vocal, but not clearly in response to the hawk; same with chickadees. Robins definitely disturbed, with nervous dee-dee-dee’s every 20 seconds or so. Jays in bursts, with several birds mobbing.

18AU89. Willowbrook marsh. Kestrel and jays. Latter making a strange, harsh, parrot-like call. Chasing, mobbing. Kestrel seemed to stoop at the jays a couple times, but the jays kept mobbing until the kestrel left.

31AU89. Jays vigorously “jay”-ing at a great horned owl well hidden among leaves in a willow top. Chipmunks chucking nearby, below.

3SE89. Jays maintain contacts with a-a calls (long a’s) and a variety of squeaky notes.

14OC89. Cactus Camp. Jays “jay”ing at a hawk, landing on branches nearby. Hawk appeared to be a red-tail, but was down inside forest. Jays stayed with it as it flew.

Late MY90. Cactus Camp. Jays foraged in accumulated oak leaves in the open among short brush by perching on tree or sapling branches, searching the ground, and making short flights out.

 

GHO Surprise

by Carl Strang

This year the snow was too deep in mid-February for me to cover Mayslake Forest Preserve thoroughly in a search for the great horned owl pair’s nest. As far as I could tell there was no nest on the preserve, at least in places where I could go with my skis.

Last Wednesday evening, as I left a photography class I am taking at Mayslake, I was pleasantly surprised to hear the distinctive, grating-yelping contact call of a fledgling great horned owl. I approached the sound, and eventually realized there were two youngsters.

The next day I searched the vicinity, and found one of them.

The young owl was perched in a weeping willow.

The young owl was perched in a weeping willow.

One of the adults snoozed in another willow nearby.

Note the white collar and developed feather tufts, in contrast to the immature owl’s.

Note the white collar and developed feather tufts, in contrast to the immature owl’s.

This is a portion of the preserve where my ability to move on the skis was limited by dense shrubbery. Next year I will begin the search in this area, hoping that the nest platform, whatever it was, will be good for another season.

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.

Mourning Dove Post Mortem

by Carl Strang

Last week I found a pile of feathers beside the trail at Mayslake Forest Preserve.

The distinctive tail feathers indicated that the prey was a mourning dove.

The distinctive tail feathers indicated that the prey was a mourning dove.

At first I was inclined to think the predator was mammalian. A raptor plucking its dinner from an elevated perch would scatter the feathers more widely. The feathers were pulled cleanly, however, and without the tooth marks and salivary gumming up of barbs that might accompany a mammal’s work. Furthermore, there was no blood and there were no bones.

One of the quill feathers showed a distinct cut or crease across the barbs.

One of the quill feathers showed a distinct cut or crease across the barbs.

That kind of mark could have been made by the edge of a raptor’s bill, biting the feather to pull it out. I compared the crease to a great horned owl skull, and the match was perfect, furthermore pointing precisely to a less visible mark made closer to the feather’s attachment point by the other bill edge. The location of the feather pile was well within the woods, and not far from a favorite daytime roost of the local owls. It appears that after removing a bunch of feathers, the owl carried its meal to a more secure, elevated location.

One Less Red-bellied

by Carl Strang

Birds don’t molt feathers in clumps. When you find a bunch of feathers together, you can take it as a sign of predation.

This group of feathers on the mansion lawn at Mayslake Forest Preserve last week is an example.

The black and white barring all across the feathers, and their size, identify the vic as a red-bellied woodpecker. The perp? My vote goes to one of the preserve’s great horned owls. The feathers appeared plucked rather than pulled out and mangled as teeth would have done. Red-tailed hawks can take birds of this size, but woodpeckers are so nervous and alert that a nighttime hit seems more likely. A migrating Cooper’s hawk is another possibility to consider. They are predators of birds, and have a variety of sneaky tactics that might catch even a woodpecker off guard. In any case there is one less red-bellied on the preserve, but others still are around. This year’s resident pair at Mayslake raised two broods successfully, for example, so even if one of those adults was the prey, there will be a new generation ready to take its place.

Some Bird Notes

by Carl Strang

There had been no sightings of Mayslake Forest Preserve’s great horned owl fledgling since the day after it left the nest tree.

One of my last views of it, on May 3.

On Saturday evening I was at Mayslake to see First Folio Theater’s production of Shakespeare’s Merchant of Venice on the outdoor stage. During the intermission I took a quick walk to the east end of the preserve, and was rewarded by the peculiar screeching whining contact calls of a juvenile great horned owl. Still flapping!

Another owl update was this newly molted feather I found during last week’s creek walk.

Proof that the barred owls are in their usual territory at Waterfall Glen Forest Preserve.

Earlier in the season one of Mayslake’s willow flycatchers gave me a photo op.

This is a bird of open fields with scattered shrubs. Usually one pair nests at Mayslake.

Birds are much quieter now that the breeding season is nearly done.

Owlet Branched

by Carl Strang

The great horned owl nestling at Mayslake Forest Preserve branched on Wednesday of last week. That verb is applied to that species when they leave the nest because they are not fledging, still being flightless. Typically they climb out of the nest, climb down to the ground, walk some distance great or small to another tree, and climb up it. The Mayslake bird wasn’t quite so venturesome at first, simply going up two branches above the nest platform. That night, however, it traveled to another tree about 30 feet away from the nest tree.

It was in the very top of a tall oak.

A series of thunderstorms came through the night after I took that photo. The following day, Friday, the owlet was in the same tree but well below its previous perch. I had a night hike on Saturday, but by then the youngster had moved again and I did not find it. I hope to see it from time to time through the summer. There was only one youngster in the end. I say this with some certainty because when there are multiple nestlings they generally stick together when branching.

Here is an example from the Red Oak Nature Center a few years ago.

There is no way of knowing whether the surviving owlet is the one that spent some time at the Willowbrook Wildlife Center, or the one that stayed in the nest throughout. Even if the rescued bird eventually succumbed, the effort resulted in the installation of a solid nest platform that benefited the surviving nestling, and may well provide a base the parents will use again in coming years.

Nesting Update

by Carl Strang

Earlier this spring I reported on a failed Canada goose nest, coyotes having reached the vulnerable site chosen by a pair that evidently was young and inexperienced. Soon after, I noticed another nest under incubation in Mayslake Forest Preserve’s parking lot marsh.

They chose one of the lower muskrat houses, well buried in cattails off shore.

Late last week I found the nest empty. When my back is healed I will be able to wade out and confirm what appears from a distance to be a successful nest. I will be interested in the number of eggshells, because the next day I spotted two Canada goose broods on May’s Lake, one with 3 and one with 6 small goslings.

Yesterday the broods were still together, but one appeared to be down to two goslings, one in the frame here.

Apparently one gosling jumped ship, for the other brood was up to 7.

On the other hand, with the two families hanging together there could be shifting back and forth.

Meanwhile, I have kept an eye on the great horned owl nest. Over the past three weeks only one owlet has been visible.

In this first photo the baby clearly is bigger than it was when the platform was installed.

I didn’t give up hope that both survived. On cooler or windy days no owlet could be seen, so they can hide beneath the platform’s sides.

Here, a little larger, the owlet strikes a Kilroy Was Here pose.

I will be happy to be proven wrong, but I suspect that one of the two babies didn’t make it.

In this photo from Friday, the still larger youngster sports developing head tufts.

On Monday the owlet had left the nest and was perched a couple branches above it. Yesterday I could find no owlet, which probably means it hiked to a distant tree and climbed up. From this point I will be able to track it only by encountering it happenstance, or by hearing its distinctive calls in the evening.

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