Bluebird Hope

by Carl Strang

I was taking a walk at the Morton Arboretum a couple days ago when a male bluebird landed in a small tree nearby.

He allowed a close approach.

Soon his mate appeared.

Females look similar, but their colors are not as bright.

They were going in and out of a natural tree cavity.

The cavity was big enough that the bird completely disappeared when entering.

This was exciting, for me. I have been concerned that bluebirds may be going the way of purple martins, recognizing only bird houses provided by people as suitable nest sites. This pair may or may not use that cavity in the end, but the fact that they are considering it is a positive sign. They, at least, have not irreversibly imprinted on nest boxes as candidate nest sites.

Nesting Accelerates

by Carl Strang

Last week, Mayslake Forest Preserve’s restoration volunteers found a killdeer nest on one of the meadows that had been burned earlier in the season.

The burn removed dead vegetation tops in an area, rendering it suitable for the shorebirds’ nest.

Killdeers have been present for a few weeks, so this was not a big surprise.

Here one forages at the edge of May’s Lake.

I have seen a robin incubating, as well. The red-tailed hawks should be on eggs by now. One regularly hunts the preserve, but they did not nest there as I speculated they might, earlier. I suspect that the nest is in the residential neighborhood north of Mayslake.

Goose Broods

by Carl Strang

Canada goose eggs have been hatching, and broods are appearing in our area. I was especially interested in this family that showed up at May’s Lake on Monday.

They have four goslings.

One adult has a band on the left leg. It seems likely that this is the same pair that nested in the parking lot marsh at Mayslake Forest Preserve last year and brought two goslings to fledging. They nested off preserve this year, but apparently not too far away, and brought their brood to last year’s successful rearing grounds.

Meanwhile, the pair nesting in the parking lot marsh this year has left the nest, and I waded out to assess its success.

The egg never pipped, and the gosling in the nest is dead.

In addition to the dead egg and gosling, there were shells indicating at least two more goslings that apparently left the nest with the parents.

Here is an example of a hatched egg.

As neither parent was banded, and I couldn’t be sure of the exact total of hatched eggs, I won’t be able to know if any brood I see is this one. I simply will record brood sizes I see on the preserve as the summer proceeds.

Swami Predicts

by Carl Strang

We are at the point in the season where Mayslake Forest Preserve’s red-tailed hawks began to build their nest last year. This is the nest that was taken over by the great horned owls in this year’s ill-fated nesting attempt. Looking over my notes, I see that the red-tails telegraphed their eventual nesting area by spending a lot of time in its vicinity in February and early March.

Red-tail perched in the 31st Street Woods, near where the pair built their nest last year.

This year the red-tails were closed out by the owls, or so it seemed. Now that the owls have abandoned the old nest the hawks could take it back and build it up for re-use. I don’t think that’s going to happen, however. This year the hawks have been hanging out around Mayslake’s savannas, especially the south savanna. That area remained their focus several days after the owls moved out, so I think that if the hawks nest on the preserve they will build a new nest in the south savanna.

Normally I would guard a raptor nest location, but there is no nest, yet. If they do build where I anticipate, it’s a relatively high-activity area. Furthermore, there is going to be a lot of noise later in the spring when the friary demolition site is graded, topsoil is spread, and seeds planted. If the hawks are to succeed they will have to tolerate some ruckus.

American Robin Dossier

by Carl Strang

 

Today’s post is another in my series of species dossiers. It begins with the summary paragraph written when I established the dossier in late 1986 or early 1987. I have edited out some less informative entries.

 

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American Robin. Familiar bird of natural and artificial savannas. Primarily a summer resident, although small numbers remain in northern IN and IL around fruit-rich areas as long as winter weather is not too severe. Waves of migrants seen each spring and fall. Nest typically on branches of broadleaf trees, or in shrubs. Nest of grasses and mud, with deep inner cup. Sometimes grasses dipped in mud before delivery to nest. Eggs deep sky-blue. Young may get out of nest a short distance a couple of days before fledging, but after early-morning departure from nest they tend to travel some distance and do not return. Young scattered, tended individually by parents, who swoop and may peck at people or mammals which approach the young. Fledglings have dark spots on breast. Worms and insects hunted on ground in summer; fruit the winter food. Mulberries eaten by both adults and young in early summer. Winter berries include buckthorn, mountain ash. Song dominates habitat in early morning and dusk. A musical series of phrases, each composed of 2-3 clear, slurred whistling notes sung from mid to high perches in trees, on aerials, etc. Alarm call “cheet’-der-der-der-der.” Occasional battles, presumably territorial, take place. Striking white spots on tips of tail feathers may be “follow-me” signals. Preyed upon by cats, on occasion. When hunting worms, run 2-20 feet over the ground, stop, then may move a short distance, lean down with side of head turned toward Earth, then possibly reach down and pull up worm with beak.

26AP80. Pennsylvania. Robins, when startled into flight across the path of an approaching car, appear to use body-twisting and turning tactics more appropriate to flight from a hawk.

14JE87. Young-of-year eating mulberries at Culver Fish Hatchery.

9SE87. Large flock in Willowbrook Back 40. One ate grapes.

16SE87. In the evening, within a half-hour before sunset, robins were migrating south over Willowbrook. They flew just above treetop level, in flocks of 3-30, occasionally perching to rest for a time in the treetops, then moving on. The birds occasionally called to one another in flight, alternately flapping in short bursts, and gliding.

29AP88. A robin on a nest at Pratts Wayne Woods Forest Preserve, 6 feet up in crotch of a 15-foot, 3″dbh fencerow box elder.

7AU88. Young robin, apparently independent but still with spots, eating black cherries in Willowbrook Back 40.

30AU88. Lots in Back 40, mostly on ground but 1 in black cherry going after fruit.

5OC88. Robins eating grapes, Back 40.

6OC88. Robins eating gray dogwood fruits, Back 40.

12OC88. Robins eating honeysuckle fruits, Back 40.

17JE89. A broad-wing calling repeatedly, in north end of Maple Grove Forest Preserve. Robins definitely disturbed, with nervous dee-dee-dee’s every 20 seconds or so.

28AU89. Robins eating gray dogwood fruit, Back 40.

21OC89. Robins eating buckthorn berries, West DuPage Woods Forest Preserve.

3JA90. A robin singing very softly at Herrick Lake Forest Preserve. Temperature ~40F, sun.

 

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14JA90. A large robin flock, scattered in woods on ground, moving as they do when hunting worms. Ground frozen. Saw occasional reaches to turn over a leaf, but no feeding.

7AP90. Robins in forest at Winfield Mounds Forest Preserve, throwing leaves with beaks to find food.

2JE90. Culver. A robin foraging on lawn (20 feet from nearest shrub) singing, 7:30am.

14SE90. Willowbrook, robin ate a couple small grapes, swallowing them whole.

JA99. Robins present on Willowbrook preserve all winter. Heavily fruiting asiatic bittersweet (Celastrus vine) a particular attraction.

6FE99. At Morton Arboretum, in an area thick with honeysuckle beneath a mesic forest, many robins feeding on the ground, vigorously throwing leaves aside and eating very small things too quickly to identify. I dug, found a mix of insects and fruit-like items.

9SE99. 2 robins eating buckthorn berries at Willowbrook.

13OC99. Robin occasionally singing at Willowbrook.

8FE00. Robin eating buckthorn berries at Willowbrook. They are fewer and more intermittent than last winter, 1 or 2 at most at any time.

13AP00. Willowbrook. One robin chasing another in the savanna. Could robins have nested in prairie savannas in years when fire burned off the tall plants beneath the trees? They might have fledged an early brood before the new plants got too tall for them.

16AP00. Willowbrook. A robin carrying nesting material.

1JE00. Arboretum. Along the Joy Path, a robin was perched in the lower branches of a maple, well concealed from above by leaves, sitting absolutely still and barely opening its beak at intervals to give a high-pitched note, somewhat waxwing-like but louder, better defined, that was difficult to locate.

15JE00. 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.

5JL00. Willowbrook. Many robins, adult and first‑year, on the preserve today. A young one, and also a red‑bellied woodpecker, sally‑foraging for insects, possibly flying ants, from the top of a tall dead tree near the stream. (One passing insect was observed for a few seconds before the robin flew out and caught it).

11MR01. A robin singing loudly, Timber Ridge Forest Preserve.

28JL01. A newly on-its-own robin chased a cicada through the air, the insect giving its predator-discouraging call, but broke off the chase and flew back the way it came. The robin was never close to the cicada during the part of the chase I saw.

13MR02. First morning of robin (or any) dawn chorus at my house.

Rookery Trees

by Carl Strang

 

The great blue heron was the bird that first inspired my interest in learning about nature when I was a 7-year-old, watching several of them in a small lake one calm summer evening. A few years later a number of great blue herons established a new nesting colony near my hometown of Culver, Indiana, among the large branches of a grove of sycamore trees  in a swampy woodland.

 

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An interesting development over the past decade has been the proliferation of great blue heron rookeries in DuPage County. One on Danada Forest Preserve near the center of the county had 25 nests or so by 2001. Another large colony has been growing for several years at Pratts Wayne Woods. Close to there, at James Pate Phillips (Tri-County) State Park, an offshoot of the Pratts Wayne rookery existed for a few years in a group of dead trees, but this experiment is on the verge of ending as the trees lose branches. There is another small rookery at Churchill Forest Preserve, and a final one strung out along the Des Plaines River in and adjacent to southeast DuPage County.

 

Remembering the Indiana rookery, I was curious about what species of trees were supporting the Danada colony. On a recent frigid weekend morning I went there to find out. It had to be done in mid-winter, both to avoid disturbing the birds (which could begin to return by the end of February), and to take advantage of frozen ground and water for easy travel.

 

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I found the colony to be situated in swampy woodland surrounding a large pond. Most of the 15-20 nest trees were living cottonwoods, and 90% of the nests were in these.

 

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Two of the nest trees were dead, and three were willows. One cottonwood had 16 nests, a couple had 13, and one had 11.

 

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I counted a total of 142 nests. There may have been more; we have had some strong wind storms since the nesting season which could have dismantled some nests. Like sycamores, cottonwoods have open canopies and thick branches capable of supporting the relatively large stick nests herons construct. Most of the trees in the colony woods were cottonwoods, so a statistical examination limited to that bit of woodland would not reveal much about heron preferences. It appeared likely that the other trees there simply lacked the necessary support structure. A few willows were used, but each had the capacity for fewer nests. The better question is how the birds choose the rookery site in the first place. Trying to answer that would require a longer-term examination of many colonies.

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