Bark Birds Big and Small

by Carl Strang

As the season progresses, numbers of passing migrant birds at St. James Farm Forest Preserve have diminished. Residents, augmented by winter additions from the North, increasingly dominate the avian communities. Prominent among these hangers-on are the birds that forage on tree bark. Downy, hairy and red-bellied woodpeckers are year-round residents covering three body sizes and the particular foraging advantages of each. Nuthatches are still smaller, songbirds that have the ability to crawl sideways or upside down on the tree bark, finding hiding insects the woodpeckers might miss. Red-breasted nuthatches have become common in the coniferous forest this fall, while resident white-breasted nuthatches are scattered through the deciduous woodlands.

On Saturday this white-breasted nuthatch caught a harvestman that did not find a sufficiently secure bark crevice.

On Saturday this white-breasted nuthatch caught a harvestman that did not find a sufficiently secure bark crevice.

While photographing the nuthatch I heard in the distance a loud call which was entirely unexpected. Eventually my monitoring route took me into that part of the forest, and the calling resumed close by.

A pileated woodpecker!

A pileated woodpecker!

This huge bird is not one we encounter very often in DuPage County. I know of two resident pairs in the eastern half of the county. Others occasionally wander through, and this male at St. James Farm qualifies as one such traveler.

Continuing to call frequently, he actually flew closer to me. Here he cries from just above.

Continuing to call frequently, he actually flew closer to me. Here he cries from just above.

On Sunday I was in a different part of the same forest, but it was calm. I did not hear a pileated calling in the distance. I hope he moved on, rather than becoming dinner that night for the great horned owl I saw being harassed by crows not far from the woodpecker’s attention-drawing display. On the other hand, it would be nice if the pileated decided to hang around for the winter. As the largest block of old trees in the western half of DuPage County, the forest at St. James Farm is the place most likely to host our largest woodpecker species. Pileateds need lots of big old trees harboring carpenter ant colonies. In any case this was exciting, the highlight to date of my young monitoring program at St. James Farm.

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.

 

Mourning Dove Species Dossier

by Carl Strang

This week’s species dossier features a bird that is familiar and common. Over the course of my developing this dossier (established in the mid-1980’s) there seems to have been a change, with mourning doves wintering this far north with increasing frequency.

Dove, Mourning

Mourning dove

Mourning dove

Mourning doves usually live in open areas with some trees. In winter, they sometimes roost in thick evergreen plantations. They feed on the ground, picking up seeds. Nesting begins early in spring (March), with adults’ walking around, picking up sticks the first sign. Usually the first nest is in the branches of a conifer; subsequent nests may be in deciduous trees. The nest is a flimsy, loose platform of sticks. Two eggs almost always complete the clutch. Both adults incubate; early morning is a common switching time. The call is a mournful “cooweeoo, coo, coo-coo” (“bachelor song,” after literature). They produce a loud whistling of wings in flight. Generally they are not seen in northeast Illinois in winter, though occasional adults stick it out around feeders in Culver, Indiana. (Some were present all winter of 1998-9 at Willowbrook). There is a distinctive pumping of the head while walking. Mourning doves were very common in Texas, in brushlands, mountains and desert.

Mourning dove fledglings. This species lays 2 eggs per clutch.

Mourning dove fledglings. This species lays 2 eggs per clutch.

Late MY90, Hartz Lake. A mourning dove singing his bachelor song low in a tree flew off in a startle as a female sharp-shin landed in the same tree. The dove stayed within tree canopies as it flew.

27JA97. Morning. Snow fairly deep. A red-tailed hawk flew over the College of DuPage parking lot with something in its talons, pursued by half a dozen crows. The hawk perched on a flat-topped, wooden light pole and began plucking prey while crows sporadically left nearby perches and swooped at it. After 10-15 minutes it flew away, and I checked the feathers, which were scattered in singles and small clumps over a 20×30 foot area: mourning dove. Crow calls resembled owl mobbing, but smaller number of birds and less sustained.

MODO DE 3b

11MR99. First “bachelor calls” of the season at Willowbrook.

31OC01. At least 20 mourning doves, more than I have seen together in months in northeast Illinois, at a savanna area in the Nelson Lake property, Kane Co.

MODO DE 1b

18FE05. First bachelor calls of the season, Winfield Mounds.

Mourning dove incubating its nest

Mourning dove incubating its nest

30MR09. Mayslake. A pair of mourning doves has a nest in a spruce in front of the mansion. (This nest later was abandoned, possibly because of the heavy human traffic that was passing close by).

Crow Question

by Carl Strang

Lately I have been seeing the occasional crow flying around in central DuPage County. It may not mean much. Maybe they’ve been lucky and not been bitten. Maybe they are recent arrivals from a rural area. But my hope is that, at last, we may be starting to see some crows with a resistance to West Nile virus.

American crow

This has been an uptick year for the virus in Illinois, thanks to the drought, which favors the mosquitos that spread the disease. According to the Illinois Department of Public Health, 179 people have been diagnosed with West Nile this year, and 6 have died in the state. This compares to the corresponding numbers of 34 and 3 last year. In DuPage County, survey traps monitored by forest preserve district staff have found at least 23 infected mosquitos in locations scattered all over the county. My memory is that in years like this, crows are absent from late summer until well into the winter, when dispersing or migrant crows move in. That is why seeing a crow in early autumn, as I have done lately, is cause for at least a meager hope.

Red-tailed Hawk Species Dossier

by Carl Strang

I have heard reports that red-tailed hawks are starting to carry sticks, and March is the month when they begin to nest in DuPage County, so today I am sharing my species dossier on that raptor. As usual, the rule is that the dossier is limited to what I have observed personally rather than second-hand reports or through the literature.

Hawk, Red-tailed

Red-tailed hawk

This hawk is common in the eastern U.S. They nest in treetops in woodlots, sometimes on utility poles, and forage over nearby fields, soaring, or perching on trees or poles. Unless winter weather is severe, they remain all year round.

28MR87. Hawk carried a snake by the head, body dangling beneath, to treetop.

16JA88. McDowell. A great horned owl flew to a tree on the west bank of the river, just north of where trees thin to a thread of willows, and where a housing development comes down to the river. There’s a top-blown tree nearby, also several large oaks. Then crows began raising a ruckus nearby in another direction, as though pestering a great horned owl. From that direction a red-tailed hawk soared, but they paid it no heed. It circled an adjacent riparian strip, but when the owl finally broke and flew with a flock of 10 crows in pursuit, the hawk fell in between, and also began to chase the owl. Once it got above the owl and swooped at it, brushing the owl’s back with its feet, but about then the crows caught up and chased both raptors down toward where I had seen the first owl perched, now out of my sight.

1MY88. Call a wheezing “preeyarrrr.”

7FE89. A red-tail “visited” Willowbrook’s outdoor animal exhibit. The captive red-tails called, caged crows gave short, uninflected (flat) caws with somewhat sharp beginnings but open ends. These were fairly rapid, but not chattering, and not clearly strung together.

Soaring red-tails usually seem to be patrolling territory rather than hunting.

12JA92. Hidden Lake Forest Preserve. A soaring red-tail gave the k-yer call, over woods. Moments later a second passed over, going in the same direction. Is that call given only when another hawk is in sight?

2DE95. West DuPage Woods. A red-tail called frequently. After 10 minutes I saw a second one, also flying. It seems likely that if one calls, another is in its view.

27JA97. Morning. Snow fairly deep. A red-tail flew over the College of DuPage parking lot with something in its talons, pursued by half a dozen crows. The hawk perched on a flat-topped, wooden light pole, and began plucking its prey while crows sporadically left nearby perches and swooped at it. After 10-15 minutes the hawk flew away, and I checked the feathers, which were scattered in singles and small clumps over a 20×30-foot area: mourning dove. The crow calls resembled the ones they use in owl mobbing, but there were fewer birds and the mobbing was less sustained.

Red-tail fledgling at Mayslake, July 2011.

9DE99. Crows pursued a red-tailed hawk in the northeast part of Willowbrook preserve.

18JL00. Willowbrook. In the early afternoon, a Cooper’s hawk soared low above the marsh and areas east and west of it, while 3 red‑tails soared high. One of the visiting red‑tails called once, but the Cooper’s, which has been resident all summer, called repeatedly.

22AU04. Canadian side of Lake Superior. On a driving journey around the lake I passed through an area where there had been a big fire, and saw there both the first kestrel and the first red-tail of the trip, showing them to be associated with relatively early successional, extensive areas in this part of the northern forest.

20NO09. Mayslake. A pair of adult red-tails circled the west end of the savanna calling frequently, and a third call was coming from within the canopy. Eventually one of the adults flushed out a young red-tail, perched in one of the oaks, and it flew low out of the savanna and south across the lake. This could be the same bird that was perched near the dog parking lot yesterday. Clearly this was a defense of winter territory by the pair. It was not clear whether the young bird called, or whether that was mimicry by a blue jay that was nearby. Last winter a pair of adult red-tails stayed around Mayslake the entire season. They seemed to be investigating nesting possibilities, but ultimately vanished for the summer.

The 2010 red-tail nest at Mayslake

16MR10. A red-tail pair is building a nest at Mayslake, in the stream corridor woods adjacent to the parking lot marsh. They carried small sticks in their beaks while flying. (This pair fledged one youngster from this nest, and it stayed around the mansion grounds area for some weeks in the summer, calling loudly and frequently. In 2011 they did not nest on the preserve; their 2010 nest was used by the great horned owl pair. Apparently they nested nearby, however, as a fledgling came onto the preserve occasionally in the summer, and displayed the same loud calling behavior. The pair has been present on the preserve through February of this year, and I will be watching for nesting activity.)

The noisy fledgling from 2010

19JA11. Mayslake. A red-tail flushed from one of the trees near the chapel was carrying a dead gray squirrel and accompanied by its mate. They flew toward the S stream corridor.

Great Horned Owl Species Dossier

by Carl Strang

Today’s species dossier is one of my largest. Great horned owls simply attract my attention and interest more than most other animals, and so I have accumulated more notes on them. Great horned owls haven’t been as easy to follow in the years since West Nile virus came into our area. Formerly the crows were reliable blabbermouths as to where the owls were. If our local crows develop resistance to the disease, those days will return.

Owl, Great Horned

Great horned owl

My earliest memory of young great horned owls was in a forest near Purdue, after they had branched one spring [branching is the term for owlets leaving the nest; it is different from fledging, because they reportedly climb down to the ground, walk to another tree, and climb up it]. I know this species primarily from observations in DuPage County, IL, where it is the common large owl, occurring in forests, even small ones. A pair nested annually in the Willowbrook riparian strip for many years, staying as year-round residents. They nested in large willows, 20-30 feet up, first in a nest on branches, then after a storm dislodged the nest, on a provided platform until that tree fell. Incubation begins January or February. The non-incubating male bird usually perches nearby in the daytime, flying away apparently to draw off people or mobbing crows. Owlets (usually 2) branch in May as trees are leafing out, can fly between trees by late May. Young have a distinctive begging call, a rising squeaky-scraping or -grating loud “scaip!” Young disperse usually by the end of October. Before then, they fly all over their parents’ territory, usually staying fairly close together. Branched young mostly sit still, observing all that goes on around them. November brings frequent late afternoon and evening territorial calls: the female’s call is a higher-pitched “WHO-whowhowho-whowhowho-who.” The male’s call has fewer syllables and a lower pitch.  Deep, booming voice. Willowbrook’s territorial birds had a running, never-ending conflict with the caged birds. I also heard calls during childhood campouts on the Tippecanoe River, Indiana, in summer, and later in the woods near the Boiling Springs, Pennsylvania, house in spring.

Pellets and food remains in late winter 1986 at Willowbrook were heavy in rabbit fur and bones in February, meadow voles in March. There were feathers of a gull in May. They covered a territory that included Willowbrook, adjacent residential neighborhoods, and much of the College of DuPage campus, for a total of perhaps 100 acres.

In the Basin of the Chisos Mountains, Big Bend National Park in Texas, they were calling around 5:30am in late July. We saw others there on the road in early evening in the upper desert. They were a bit paler than Midwestern birds.

Some contents of owl pellets at Mayslake, 2009. Prey species are meadow voles, white-footed mice, and a short-tailed shrew.

12FE87. Lots of recently molted breast feathers in Willowbrook Back 40.

8AP87. Photos of branching young owls.

Great horned owl, soon after leaving the nest.

29AP87. Crow remains found under nest area.

5MY87. The pair’s own nestlings now branching, in a willow 50m from nest tree.

6MY87. Remains of a consumed pigeon.

7MY87. The young are in another willow, closer to the nest tree, the one used most by last year’s young when branching. The third (foster, added by Willowbrook staff) youngster is on another branch of the same tree.

8MY87. Another tree change.

1JE87. The young are flying.

5OC87. Adult male beginning to hoot, in afternoon, Willowbrook Back 40.

9JA88. McDowell. Owl flushed from pine grove at south end of north field.

16JA88. McDowell. A great horned owl flew to tree on the west bank of the river, just north of where trees thin to a thread of willows, and where a housing development comes down to the river. There’s a top-blown tree nearby, also several large oaks. Then crows began raising a ruckus nearby in another direction, as though pestering a great horned owl. From that direction a red-tailed hawk soared, but they paid it no heed. It circled an adjacent riparian strip, but when the owl finally broke and flew with a flock of 10 crows in pursuit, the hawk fell in between, and also began to chase the owl. Once it got above the owl and swooped at it, brushing the owl’s back with its feet, but about then the crows caught up and chased both raptors down toward where I had seen the first owl perched, now out of my sight.

30MR88. Willowbrook. Fresh pellet with remains of 2 meadow voles.

25AP88. Both great horned owls off the nest, though in nearby trees.

17MY88. I hadn’t seen great horned owls of Willowbrook Back 40, or heard harassment by crows, in some days. Today I saw 2, upstream of their nest. Crows didn’t harass them for long or in numbers (2-3), apparently too occupied with their own nesting activity.

18JE88. Harassment of owls by crows gradually has increased this month at Willowbrook. Today I observed heavy harassment of a great horned owl by a large number of crows at McDowell Grove F.P. Owls branch at the same time crows are starting to nest, and becoming too busy to harass owls.

22FE89. Owl on a nest at Willowbrook (started incubating within the past 10 days).

26AP89. For the first day since February, there is no adult owl in the nest tree at Willowbrook (have been brooding several days, then a few days of adult perched beside nest with a youngster visible. 2 young. A fox squirrel climbed the nest tree. When it was just below the nest, the adult female flew from a nearby willow, and landed on the nest. The squirrel turned around and began to climb down as she flew in, but was not panicked.

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

30NO89. Great horned owl flying, viewed from behind. Wingbeat of remarkably little amplitude, compensated by its more rapid rate. A fluttering sort of appearance. Wings kept straight. (A behavioral quieting of flight?)

14DE89. Willowbrook nature trail. The owl caught a mouse, according to tracks. Slight blood drops in snow. Many steps trampled snow just beyond the mouse burrow. Then the owl walked, either having swallowed mouse or transferred it to bill. Tracks: landed on mouse tunnel, then walked 5m. Noticeable straddle, up to 1 inch. Track 4 inches long, 3.5 wide, right angle toe pointing to outside distinctive for species. 8 inches center to center for length of step between tracks.

Sketch of great horned owl tracks.

3JA90. The Willowbrook owl pair perching near nest platform.

29JA95. Following a tip, I found a great horned owl on a nest at Maple Grove F.P. Stick nest was built last year by Cooper’s Hawks, according to informant. Nest solidly based in a main crotch 15-20 feet up. Owl had head and ear-tufts up, very noticeable but only from the front. Nest tree right beside a regularly used trail, but not a main trail, less than 200 yards from Maple Ave. and less than 100 yd. from the private school on the east border of the preserve. The owl reportedly has been on the nest less than a week.

18FE99. At Willowbrook, I found this year’s great horned owl nest (they probably have used this site before; not easy to find) in the top of a dead tree trunk, with most of branches gone, a large hollow with little in the way of a roof. Only part of the owl’s head is visible, and only from certain angles. A single fuzzy feather tuft was the give-away. Once while I watched, the bird appeared to stand and turn or shift eggs by moving feet, stepping from one to the other. The owls had been advertising consistently in the area around this tree in the early winter. Crows mobbing nearby earlier in the day (presumably after the non-incubating bird nearby) drew my attention to this area. Only one other candidate tree is nearby.

A sketch I made after finding the nest on February 18.

11MR99. The great horned owl was standing in the Willowbrook nest in the morning.

15MR99. A young bird was seen on the afternoon of the 12th. Today at least 2 young are visible. They were being fed between 3 and 3:30pm.

18MR99. The 2 young owls frequently are standing in the sun in the nest.

12AP99. The Willowbrook great horned young have branched.

A pair of branched young.

16AP99. One of the owl young somehow crossed the rain-swollen Glen Crest Creek to perch between it and the Nature Trail. Flew?

4MY99. At mid-day, a flock of 8 crows pursuing an adult great horned owl over much of Willowbrook Preserve.

27MY99. Both Willowbrook owl young still alive.

11AU99. Only one of the Willowbrook owl young remains.

18AU99. The young owl calling at mid-morning.

8MR00. A neighbor near the north edge of the Willowbrook preserve reported that the pair of great horned owls have been calling in his yard nightly since late January. He gave us permission to look for a nest, and we found it, in the top of a large blue spruce, built on an old crow or squirrel nest. 20 minutes were required to find a small hole through which to confirm the bird’s presence. The tree, perhaps 40 feet tall, is close to a dead‑end side street, in between his house and garage (the 2 buildings less than 20 feet apart), with no other tall trees right there though several others were in the yard. The bird appeared still to be incubating, occasionally turning eggs. We did not see the non‑incubating owl, but numerous potential roosting sites are nearby.

30MR00. We checked the nest again. After a few minutes the brooding bird flew away (sunny, warm afternoon). We could see one young bird clearly; there may have been more. Development seems behind last year at this date by at least a week. Still all white down, as far as we could see.

14AP00. In central Kane County, in a bur oak woodlot of perhaps 10 acres, a great horned owl nest. The nest is an appropriated crow or hawk nest in the top of a large oak. At least one young bird still is inside. The presence of the owls was made clear when the adult male flew past us, pursued by crows. He was small, appearing no larger than the crows. Later I found the nest when walking through the woods. The female flew a short distance, and a few crows called, but she settled in against the trunk of an oak, well camouflaged, and they left her alone.

17JL00. No sounds of great horned owl adults or young at Willowbrook in the evening.

2001: No signs of nest or young around Willowbrook this year, though in the spring an adult seemed to be decoying crows.

Great horned owl tracks. Owl tracks are distinctive in having one of the toes protruding out to the side at an odd angle.

14SE01. An owl called several times in the early dusk at Herrick Lake, south of the former youth campground. I see that this is my earliest record of territorial behavior, by about 3 weeks.

3NO01. Saw an owl, probably a male, at Herrick Lake F.P. in the forest behind a house, north of the big trail loop and south of the former youth group camp. That was in the morning. In the late afternoon, heard one hooting along the Fox River somewhere around Red Oak NC.

27SE02. While walking after a run at Herrick Lake, heard both members of the pair duetting strongly for at least 5 minutes (same area as previous 2 entries).

13FE07. At mid-day in the middle of a winter storm with heavy blowing snow, a great horned owl at Fullersburg holding a recently caught gray squirrel.

3AU08. Great horneds called for a long period, early morning, in my neighborhood. This continued into the dawn hour and overlapped with a cardinal’s singing, past 5 a.m.

21JA09. Mayslake. An elm branch, apparently broken from tree by storm, with bark being consumed by cottontails. Near there, one of the rabbits caught and consumed on the spot last night by a great horned owl (impressions of wing and tail feathers in the snow). Head, feet, a couple bones, and fur all that remain.

29JA09. Mayslake. I found where a great horned owl had walked on the frozen stream surface, heading S out of the woods, taking off before reaching the bridge. The tracks led back to a feeding site, with much cottontail fur and a bone, but no rabbit tracks. Continuing downstream 20 yards I found another area against the bank with fur and blood, and a couple great horned owl footprints again from last night, but again no rabbit tracks. On downstream another 30 yards I found yet a third such site, but again no rabbit tracks. Here there was no feeding, mainly just the impression of the rabbit in the snow. As the owl had walked a few steps before that impression, it must have had the rabbit in its beak. The owl had come from the N or NW. I searched all around but did not find a clear kill site. All of this was under trees with moderately thick brush that makes it seem unlikely the owl would carry prey in there from outside. The shift of location twice would seem to reflect a sense of vulnerability. I wonder if the owl would have removed the head and feet at the actual kill site. The body impression where it first landed on the stream ice was bloody.

Here is one of the stops made by the great horned owl described in the January 29 entry. There is an oval depression where the rabbit’s body was placed.

14FE09. Fullersburg. This year the great horned owls are nesting in last year’s Coopers hawk nest, just west of the Amphitheater. That nest has been available both the past two years, but the owls have chosen to use other hawk nests close to 31st Street in all of the previous 4 years but 1. In that year there were reports of a nest well south of the preserve, but I could not find one on the preserve.

19FE09 Mayslake. I found the great horned owl nest in a hollow willow near the west boundary of the preserve close to May’s Lake. It is not high up, and exposed thanks to the brush clearing, but facing away from the lake may limit its discovery by fishermen.

Great horned owl incubating nest in tree cavity, Mayslake, February 2009.

6MR09. Mayslake. Great horned owl is standing in the nest cavity, apparently brooding.

13MR09. Mayslake. The great horned owl nest tree snapped off at the point of the nest cavity, presumably in the wind storm 3 nights ago (gusts reached 45mph). A dead owlet at the base of the tree, none others nor adult seen, no sign of hurt adult but nest apparently abandoned (cold enough today that an adult would be brooding). There has been enough time that scavengers could have removed other young.

Dead nestling beneath storm-broken nest tree.

10DE10. Neighborhood. I heard a great horned owl calling early this morning.

27JA11. Mayslake. Great horned owl incubating on last year’s red-tailed hawk nest. It was not there yesterday.

Great horned owl incubating nest, Mayslake, January 2011.

10MR11. Mayslake. The owls have abandoned the nest. No sign of disturbance or dead nestling beneath, best guess is the eggs didn’t hatch, either infertile or perhaps the female was forced to abandon during the fierce blizzard at the beginning of February.

18MR11. Mayslake. At a bright mid-day, the great horned owl pair duetted for more than 15 minutes, the male in the west end and the female in the east end of the area 9 hilltop pines.

29MR11. Mayslake. A single hoot from GHO in pines, mid-day, the first I’ve heard since the 20th.  (In September I heard the pair duetting at Mayslake, so they remain at the preserve.)

What’s with the Crows?

by Carl Strang

Ever since the arrival of West Nile virus several years ago I have grown accustomed to seeing few crows in DuPage County. Urban and suburban areas supply plenty of habitat for the species of mosquitoes that most often carry the virus, as opposed to rural areas, which do not. Consequently I have come to think of the suburbs as a population sink for crows. The mosquitoes carry death to crows in the late summer. New crows appear in the winter or spring, apparently having immigrated from rural areas. Some of these may nest, though most apparently are young birds not quite ready to do so. Thanks to the virus, they don’t get a chance.

This fall has been different. I am seeing crows regularly. The most remarkable case came on one of the very windy days we experienced last week (cue wind shot).

As I stopped by forest preserve district headquarters in the afternoon, I saw a flock of at least 30 crows. They perched on the HQ roof, but spread out before I could get the camera untangled.

A few remained on the roof.

Others went to the lawn, or to nearby trees.

I was away from the county for most of the crow nesting season, so now I am asking myself: are these locally raised birds? Have they at last evolved a resistance to the virus to match that in our other avian species? Can we look forward again to easily finding great horned owls?

Species Dossier: American Kestrel

by Carl Strang

This week’s species dossier focuses on a species which seems to have become less common locally than it once was. Certainly I don’t see them as often as I did along the same roads in years past.

American Kestrel

Typically I have seen this small falcon along the road or at a field with few or no shrubs. They catch voles by diving from the air and pinning with their feet. They sometimes hunt from a perch, sometimes from the air, and often can be seen hovering over an open field before diving to the ground. They can be seen year round in DuPage County IL, Marshall County IN or Cumberland County PA, though they leave if the weather becomes severe in winter. The male’s courtship display consists of high altitude flight and steep dives accompanied by a “killee killee killee killee” call slightly reminiscent of a killdeer’s. Male has red tail, black round spots on breast, bright-colored head. Larger female has brown and black barred tail, no breast spots, duller head colors.

10JA80. Boiling Springs, PA.In the afternoon I watched a crow chasing a kestrel. The birds flew high, and the crow stayed right with the little falcon’s twists, turns and dives. Finally, the crow broke off after the chase had carried the two a couple of hundred meters from the starting point. The crow flew back there, and the kestrel flew a parallel course 50m away, but continued out of my field of view.

16NO86. Herrick Lake Forest Preserve, IL. Late afternoon. Female kestrel carrying small brown mammal in talons (prey looked all brown, but maybe had long tail). In sparse fencerow beside tall grass field.

(Date not recorded). DuPage County, IL. At the edge of a construction site a kestrel perched, its attention focused on a small isolated patch of tall grass.

18AU89. Willowbrook Forest Preserve marsh. Blue jays were mobbing a kestrel, making strange, harsh, parrot-like calls and sometimes chasing the falcon. The kestrel stooped at the jays a couple times, but the jays kept mobbing until the kestrel left.

17OC92. Vicinity of Cantigny (Winfield, IL). While driving I saw a kestrel carrying a house sparrow low across the road. It was a heavy load for the kestrel, which lost its grip, perhaps distracted by my car’s close proximity. The sparrow flew away. Many times I’ve seen kestrels searching vole habitat, carrying or eating mice. This, I believe, is the first bird capture I’ve witnessed.

8MR00. Willowbrook. In the afternoon, a kestrel calling above the Wildlife Center buildings and outdoor exhibits, perched briefly.

22AU04. Canadian side of Lake Superior. I passed through an area where there had been a big fire, and saw there both the first kestrel and the first red-tail of the trip, showing them to be associated with relatively early successional, extensive areas in this part of the northern forest.

American Crow Dossier

by Carl Strang

Here is another, relatively long, entry in my series of species dossiers, accounts of what I have learned of various species from my own experience. In sharing these I am less interested in transmitting information than in encouraging you to think about what you know about these animals from what you have observed. When I started these records in the 1980’s I was embarrassed by how little I could say, and developing them was a good exercise in paying better attention when in the field.

Crow, American

Abundant around Culver, Indiana, in Cumberland County, PA, and [formerly] in DuPage County, IL. Strictly rural in the Culver area when I was a child, staying out of town [though this no longer is the case]. In PA, occurred in and out of town, but more typical of drier uplands and agricultural areas (the fish crow was more common in town and around rivers). In DuPage County, IL, American crows were abundant in both town and rural areas. They spend times in all habitats, though they stay up in trees when in the forest, usually. They spend more time in open, drier habitats than in others.

Their diet is equally diverse. I’ve seen them take corn sprouts, insects, young birds and rabbits, and carrion. In DuPage County they were the principal avian scavengers; vultures are practically nonexistent except during migration. Road kills are the most commonly observed food there. In late winter 1986 I saw a group of crows feeding on smooth sumac fruits, along the road at Warrenville, IL.

Crows nest solitarily, in the highest levels of forest trees. Vocalizations include a feeding call of young, a whining sound with somewhat the quality of a played sawblade: ree ree ree reereereereeree. This call accelerates and becomes slightly higher pitched and squeakier toward the end. Adults’ single “caws” appear to be contact calls. Harsher, sharper rapid clusters of caws are signals that rally crows to mob hawks or owls. This is a social, flocking species for most of the year, though spreading out when foraging for widely scattered foods like insects in short grass.

In DuPage County, crows mob great horned owls most frequently. Usually a mobbing begins with a single crow spotting the perched owl, and giving the rallying call. As more crows gather and add their voices, they perch all around the owl and the noise gets very loud. Usually the owl just sits stoically, but if it flies the crows give chase, sometimes one or two so bold as to peck the owl on the back. Eventually they lose interest, and silently fly off in one’s and two’s. Crows themselves are the objects of aerial harassment attacks by red-winged blackbirds.

Tall dead treetops with many branches in woods often are congregation sites.

10JA80. Boiling Springs, PA. In the afternoon I watched a crow chasing a kestrel. The birds flew high, and the crow stayed right with the little falcon’s twists, turns and dives. Finally, the crow broke off after the chase had carried the two a couple of hundred meters from the starting point. The crow flew back there, and the Kestrel flew a parallel course 50m away, but continued out of my field of view.

22FE87. Flock of 15 crows, flying. Cawing a lot, caws a little short though they aren’t chasing anything. Occasionally one utters a low, dry rattle. Later a loose group of four flew, taking turns making sets of 3-4 connected sharp caws. When calling, an individual folded his wings slightly and glided at a slight angle downwards.

14MR87. Signs of breeding. One, after cawing as though after an owl (none right there) broke off a twig from a treetop and flew away with it. Later a crow closely chased another out of that part of the woods. The chase went for at least 100m.

15MR87. Crow flying with beakful of soft material.

29AP87. Remains of a crow beneath great horned owl nest area.

16JA88. (McDowell?) Great horned owl flew to tree on west bank, just north of where trees thin to a thread of willows, where a housing development comes down. There’s a top-blown tree nearby, also several large oaks. Crows raising a ruckus, as though pestering a g.h. owl. From that direction a red-tailed hawk soared, but they paid it no heed. It circled an adjacent riparian strip, but when the owl finally broke and flew with a flock of 10 crows in pursuit, the hawk fell in between, and began to chase the owl, itself. Once it got above the owl and swooped at it, brushing the owl’s back with its feet, but about then the crows caught up and chased both raptors down toward where I had seen another owl perched, now out of my sight.

21MR88. Crows have been molting wing and tail feathers. Still chasing each other.

10AP88. 3-5 harsh, medium-fast caws apparently means “human here.” Several circled me at Hidden Lake F.P. woods, some perched in treetops above me and peered down, making that signal.

14AP88. Spotted 2 crow nests along Butterfield Rd., one beside construction site in a small grove of 30-40-foot-tall trees, the other well up in one of a grove of large oaks.

7MY88. Culver, IN. 2 nests high in oaks of “Indian Trails” area between town and Culver Military Academy. Adults flew off silently.

17MY88. I hadn’t seen the great horned owls of Willowbrook’s Back 40, or heard harassment by crows, since the restorational clearing of the marsh and fill area. Finally I saw 2, upstream of nest. Crows didn’t harass them for long or in numbers (2-3), apparently too occupied with their own nesting activity.

Harassment picked up, gradually, in June. On 18JE88 I observed heavy harassment of a great horned owl by a large number of crows at McDowell Grove F.P. Owl’s branching comes at the same time crows are starting to nest, and becoming too busy to harass owls.

18AP(MY?)88. The notes of a crow’s “human” call may be uttered rapidly when given as a warning. I walked into a riparian strip, one crow gave that fast version as I approached, and another immediately flew up from the streambed where it could not have seen me.

23MY88. Crow carrying medium-sized ear of dried corn, with about half of corn still attached, in beak.

29JA89. The crow mobbing call is a drawn out, often slurred, slightly burred caw, but retaining the abrupt start. (Another crow flying in, when still at a distance, gave a single note of this type but lazier, more drawled sounding, because it lacked the abrupt start and because it was more drawn out.)

7FE89. Permanently disabled crows in the exhibit cage at Willowbrook Wildlife Center responded to a “visiting” red-tail with short, uninflected (flat) caws with somewhat sharp beginnings but open ends. Fairly rapid, but not chattering-like, not clearly strung together. Many notes, long-continuing.

12MR89. A crow near Hartz Lake (Indiana) carrying a twig.

13MR89. DuPage County. Crow nest, same cluster of trees but farther back from busy Butterfield Road, as last year.

21AP89. A crow nest in downtown Chicago, in the little park across from the Newberry Library. I seldom have seen crows in the city. One bird visited the nest while I watched, but did not switch with the incubating crow.

25AP89. At end of a brief chase between 2 crows, one (I believe the pursued) gave a rattle-call. But I’ve recently heard the call from a bird perched for a long time.

10MR90. Crow with twig in beak, flying straight and parallel to road at 25mph.

30AP90. Crow chasing crow: a rattle call by the pursuing bird, with an emphatic inflection within.

12MR92, McDowell Forest Preserve. A Cooper’s hawk flew, northerly, high above woods. Pursued by a crow that occasionally swooped at it, but the hawk itself was nearly crow-sized, and it often turned and flew at the crow. Flight faster and more twisty then, but the crow turned to pursue the hawk when the latter resumed its path. Three such cycles observed.

20AU92. Cooper’s chased a couple crows at Herrick Lake F.P., not seriously. They rattle-called afterwards.

24JA93. Warrenville Grove Forest Preserve, IL. In late morning on a cold, sunny day, a goshawk flew past as I crossed a brushy opening in the forest. The bird was low, perhaps 10 feet up, and abruptly dipped, then flew up to a 15-20-foot-high perch on a large branch of a tree at the edge of the clearing. I came within 40 yards or so; the bird watched me but did not fly as I turned and skirted its position. Crows passing over gave several sets of quick, paired caws: “caw-caw, caw-caw, caw-caw,” merging in some cases into a fairly rapid series of cawing notes. This was not a response to me. Long after I left the site, I heard the same paired caws and looked back to see that the crows emitting them were circling above the goshawk’s position. The crows stayed at an altitude of ~1.5 tree-heights; the hawk was perched between 1/3 and ½ the trees’ height.

27JA97. Morning. Snow fairly deep. A red-tailed hawk flew over the College of DuPage parking lot with something in its talons, pursued by half a dozen crows. The hawk perched on a flat-topped, wooden light pole, began plucking prey while crows sporadically left nearby perches and swooped at it. After 10-15 minutes it flew away, and I checked the feathers, which were scattered in singles and small clumps over a 20×30 foot area: mourning dove. Crow calls resembled owl mobbing, but smaller number of birds and less sustained.

1997-98. I occasionally see a white crow as I drive to work at Willowbrook Forest Preserve, the bird on either side of Park Boulevard a short distance north of Butterfield Road.

15MR99. Crow flew across Butterfield Road near Naperville Road crossing, north to south, with sticks.

14AP99. Willowbrook. Crows seen chasing one another several times.

4MY99. At mid-day, a flock of 8 crows pursuing an adult great horned owl over much of Willowbrook Preserve.

25MY99. Blue jay mobbing a perched crow in top of dead willow, Willowbrook.

9DE99. Crows pursuing a red-tailed hawk in NE part of Willowbrook preserve.

2010. In recent years, crows have become scarce in DuPage County, apparently because of a lack of immunological resistance to West Nile Virus. The pattern seems to be that new birds disperse into the area in winter, and may attempt to nest (but this isn’t common as far as I can tell, supporting the idea that these are young, dispersing individuals). When conditions support the emergence of West-Nile-carrying mosquitoes in late summer, the crows vanish, apparently victims of the disease. Supporting this notion is the observation that in the cooler wetter summer of 2009, more crows persisted into the fall.

Cooper’s Hawk Dossier

by Carl Strang

It has been a while since I have shared one of my species dossiers. One of my practices is to keep records of what I have learned from my own observations of various species, as opposed to reading about them in other sources. Today I bring out my dossier on the Cooper’s hawk. In reviewing it I see that I have left out a lot of observations of this species, which has become common in the Chicago suburbs over the past decade or two, but those other observations would be much like the ones below. The observations begin with my date codes.

Cooper's hawk b

13SE85. Spring Valley Nature Center, Schaumburg. A Cooper’s Hawk pursued a frantic, cheeping young thrush in and out among the trees, in sharp twists, turns, and vertical climbs and plunges, for a good 15 seconds. Then the hawk broke off, and the thrush escaped. This took place in an old field between stands of trees. Could the cheeping have been a signal to the hawk that the thrush had plenty of wind? As soon as the hawk turned back into the woods, the thrush continued its flight over an open field.

2AP88. One passed through woods at Hartz Lake (in Indiana), occasionally calling “kip.” Flew and perched, flew and perched its way across woods.

12MR92, McDowell Forest Preserve. A Cooper’s flew, northerly, high above woods. Pursued by a crow that occasionally swooped at it, but the hawk itself was nearly crow-sized, and it often turned and flew at the crow. Flight faster and more twisty then, but the crow turned to pursue the hawk when the latter resumed its path. Three such cycles observed.

18AP92. Hartz Lake. Pair of Cooper’s hawks hanging around a clearing in the woods, often calling: a wild-sounding, almost woodpecker-like “eh-eh-eh-…” (15-20 repeated syllables).

20AU92. Cooper’s chased a couple crows at Herrick Lake F.P., not seriously. They rattle-called afterwards.

18MR99. An immature plumaged Coopers appeared, hung around the Willowbrook riparian area (SE corner of preserve) for the rest of March, calling frequently, but vanished in early April.

1SE99. Cooper’s hawk soared above Nature Trail area of Willowbrook, moving north to south. They soar from time to time.

15JE00. Morton Arboretum. Near Parking Lot 7, when I arrived around 8am, 3 robins were giving the high‑pitched thin call repeatedly, and the forest otherwise was relatively quiet. After 10 minutes, a Cooper’s hawk started calling nearby, then flew out away from the forest edge until an eastern kingbird started to chase it. It immediately turned around and flew back the way it had come, and kept going. The robins then were quiet.

16JE00. Willowbrook. In the afternoon, a Cooper’s hawk perched near the west edge of the prairie, drawing alarm calls from a robin (the hawk‑whistle warning call) and a cardinal, and a chorus of 7 loudly mobbing jays.

18JL00. Willowbrook. In the early afternoon, a Cooper’s hawk soared low above the marsh and areas east and west of it, while 3 red‑tails soared high. One of the visiting red‑tails called once, but the Cooper’s, which has been resident all summer, called repeatedly.

26FE01. A Cooper’s called for a long time from the top of a tree near the islands in the river at McDowell Grove. A harrier was flying overhead, but the Cooper’s did not appear to be looking at it while calling.

14AP01. 2 Cooper’s, possibly a pair, at West DuPage Woods. One made an unusual flight through the open air, with exaggerated, moth-like wingbeats reminding me very much of a short-eared owl.

5MY01. A Cooper’s hawk incubating a stick nest high in a tree at Wayne Grove Forest Preserve. Tail visible from below.

10JA02. Two jays newly arrived at Willowbrook (for weeks there had been one, at most, and these were in addition to that one). They were mimicking crow caws, with lower volume and a brighter tone that made the mimicry clear, but an interesting sound. One of them also repeatedly imitated a Cooper’s hawk’s calls, both the string of notes and the isolated single notes. Again the volume was lower than in the hawk, but tonal fidelity was very good. They were in brush, low to the ground and close to me (the Cooper’s imitator was within 20 feet and clearly knew I was there). Before long I saw a Cooper’s hawk, almost certainly the same one that we saw hunting the day before by sitting and waiting on a tree branch for a minute or 2, then moving to a new perch. Today the hawk was perched about 100 yards from the jays.

12MR02. As 2 Cooper’s hawks began to call in the woods at Willowbrook, a jay flew to the treetops above them and began the bobbing “teakettle” call. Another jay arrived and began to “jay” call as the first continued on away in the direction it had been going.

26OC07. A Cooper’s hawk still calling at Fullersburg.

2006-2008. Cooper’s hawks nested at Fullersburg. The great horned owls there prefer to use a hawk nest from the previous year. In at least one year the Cooper’s were successful, as fledglings frequently were to be seen. In at least one year, and perhaps two, the hawks started to incubate but then abandoned. In one case this happened shortly after a pair of broad-winged hawks arrived and began to advertise their territory nearby.

24MR09. Mayslake. Scattered feathers of a Cooper’s hawk in the prairie south of the stream corridor marsh. The location, and nature of feather damage pointed to great horned owl as the predator.

Coopers kill 2b

 Late summer 09. Mayslake. One day a Cooper’s hawk caught a young-of-the-year robin in the woodland east of the mansion.

 Autumn 09, Mayslake. A Cooper’s hawk, flying low, could see through the windows of the library wing, and attempted to fly through as it would a space within a forest canopy. Unfortunately the windows were closed. It was not flying fast, and after bouncing off flew away, apparently unharmed.

With the winter’s slower season arriving, I expect to be sharing more dossiers. I encourage any student of natural history to be careful in separating what you know out of personal experience from what you have heard second hand.

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