Oak Leaves Expand

by Carl Strang

Last week I described the preference migrating songbirds were showing for an inferior woodland, rather than the high quality savannas at Mayslake Forest Preserve. I thought the security provided by the woodland’s buckthorn understory might be the significant factor. This week I found some support for that idea. The oaks have expanded their leaves.

Bur oak is the dominant tree in Mayslake’s savannas, followed by white oak, shagbark hickory, and Hill’s oak.

The migration is winding down, but there has been a clear shift of warblers, vireos and others into the savannas. The few remaining in the degraded woodland are species like yellow-bellied and alder flycatchers, which like low dense brush. Now that there are lots of hiding places in the oak canopy, it seems, that is the place to be.

Birds and Buckthorn

by Carl Strang

Birds eat bugs. That’s a 3-word description of the main action going on these days as migrant songbirds drop into our woodlands, refueling during the day before they continue on their way north at night.

Buckthorn provides no bugs, nor does honeysuckle. These Eurasian shrubs might as well be made of plastic, as far as our native insects are concerned, and so support none of the fuel needed by those feathered foragers.

So, why does it so often seem that more migrants can be found in woodlands with buckthorn and honeysuckle understories rather than restored woodlands with a diversity of herbaceous native plants beneath the trees?

This has been the hottest part of Mayslake Forest Preserve in recent days for diverse migrant songbirds. Its dominant understory plant is buckthorn. The nearby restored savanna, rich in native herbs, has some migrants, but not nearly so many species or individuals.

Some people who are excellent birders (but uninterested in ecology or any other aspect of natural history) have made similar observations, and so have a negative view of restoration.  It’s hard to blame them, given their data and focus.

So, what’s going on here? I have a hypothesis, but it needs testing (unless someone already has done so and I haven’t encountered the paper). I think the issue is security.

Here a Wilson’s warbler rests in the dense foliage of a buckthorn bush in the same area at Mayslake.

Both the savanna and the buckthorn-infested woodland have plenty of trees, and most of the insects these birds are after are feeding on the trees’ flowers and tender new leaves. The herbaceous plants in the savanna will provide abundant insects later in the season, but not much to speak of, this early. In other words, food availability probably is similar between the two kinds of places during this peak migration time (a test of my hypothesis would require measurements to confirm that statement, however).

I suspect that the buckthorn’s appeal is that it provides a ready hiding place for the migrants. They want a secure retreat if a hawk comes along, and the blanket of dense shrubbery beneath them has that quality. As dawn breaks, birds that have been flying all night are looking for a place to spend the day. Trees provide the food, and the dense patches of understory shrubs complete a clear target for weary, hungry, safety conscious birds.

Northern Cardinal Dossier

by Carl Strang

This time I share my dossier for a common and beloved species. As usual, it begins with the general account I wrote when I established the file in the 1980’s, then additional entries begin with my date codes.

Cardinal, Northern

The cardinal is the first bird I studied with any intensity, as a child mapping song perches of males in my neighborhood and connecting them into “territories.” Generally they selected highly exposed perches in treetops and on television antennas. The song is highly variable, but tonal qualities of voice and type of song pattern are distinctive. The alarm note is a sharp “teek,” again of a distinctive tonal quality and pitch. The female also sings, the songs following the same pattern as the male’s but sometimes lower in volume.

They nest usually in thick bushes within 10 feet of the ground. A nest at Boiling Springs, PA, was in a rain gutter closely overarched by spruce branches. Young birds in a brood observed in Lombard, IL, were kept together and off the ground by the parents.

Both sexes have bright red beaks surrounded by black feathers. When viewed head-on this has an imposing effect, the bird’s weapon thus being highlighted. No doubt this is of significance in agonistic display. Field guides, with their emphasis on lateral views, lead us away from this kind of discovery.

Cardinals feed in bushes, in trees, and on the ground. They are not acrobatic foragers. They consume large seeds at feeders in winter. Cardinals appear to show some territoriality through winter.

Songs vary among locations, individuals, and times. Each male has more than one song. Some rendered songs are: “chibone, chibone, chibone, chibone;” “What-cheer, wheet wheet wheet wheet;” they beging singing in late January (as early as 23JA83 in DuPage); “pul’see pul’see …” (~7 reps).

17JL84. Male foraging in black cherry tree spent 5-8 sec. on a perch, moving head to look at nearby leaves and twigs in small turning movements, moving 0.5-1m between perches (Willowbrook Back 40).

NO84 they were often feeding on ground, scratching in leaves.

12FE87. Heard first song of year.

5MY87. Nest with 3 eggs, of twigs (slightly loose structure) beside trail in riparian strip at Willowbrook. In honeysuckle, 5 feet up, in fork of branches. Deep cup. Eggs bluish with brown mottling. By a few days later only one egg left, nest apparently abandoned (too close to trail?).

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 streetside 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.

19JA89. First Cardinal song, on Willowbrook early morn. In an unusually warm January.

9MR89. Cardinals all singing today through midday (first warm day, 40 degrees F, after a long cold spell). There seem to be too many Cardinals singing, and I see 3 males chasing each other. In this year with such a mild January and no super-severe weather, unusually high survival?

17AP89. A cool, cloudy day. Cardinals all over the Back 40 are giving constant series of “alarm” (?) notes.

29JA90. First cardinal song of year, Willowbrook.

1990. The year of the 17-year cicadas, I caught some at Fullersburg and released them at Willowbrook. One of these flew across a small forest clearing, and a cardinal flew out and caught it with its beak, in mid-air.

26JA99. First cardinal song of year, Willowbrook.

4MR99. Many cardinals singing at Willowbrook, including a female near the Nature Trail head.

3MY99. Cardinals fighting in area of white cedars at Willowbrook.

13MY99. Cardinal nest at Willowbrook in honeysuckle shrub overhanging creek. May still be under construction, though birds agitated when someone is nearby. Female incubating 17MY, 27MY.

10AU99. Cardinal songs distinctly reduced in number, length. Only a few weak, partial songs this morning.

25AU99. Last cardinal song of year noted at Willowbrook.

26AU99. Cardinal fledgling, with rapid notes, similar in pitch to adult’s note but not as sharp, and rapidly repeated rather than separate.

1NO99. Cardinal eating buckthorn berries. 

14JA00. Cardinal sang a half song in afternoon, Willowbrook.

2FE00. First full cardinal song of year, Willowbrook.

21FE00. McKee Marsh, north Blackwell Forest Preserve. A male cardinal singing from a very exposed perch at the top of a 25-foot-tall cottonwood. Doesn’t change posture much when singing. Thrusts face forward a little, but keeps bill level. Sang back and forth with other audible cardinals, answering with full songs, “What-cheer, wheet wheet wheet wheet.” The others stopped singing, it paused for some seconds, then gave a “what-cheer,” paused, did so again, and gradually added “wheet” syllables until it was singing full songs again, even in the others’ absence. When not singing, turned head to look all around.

25FE00. Willowbrook. Several juncos and cardinals singing this morning. A display by a male cardinal that was singing at the service road junction with the Nature Trail. A female was in the same tree, and for a minute or two the male faced her, occasionally adopted an extended, stretched out body posture unlike the normal singing pose, moved with body held rigidly, and emitted a chattering dry trill between some of the songs, all the while facing the female. She stayed in place, he never approached within less than 5 feet, and he then turned away from her and resumed singing normally.

1JL00. A female yellow warbler feeding a cowbird fledgling near the south end of Silver Lake, Blackwell. Earlier this week a pair of scarlet tanagers were feeding a cowbird at Willowbrook, and half a dozen times this spring I have seen male cardinals feeding them (some were the same pair, but at least 3 different broods involved) also at Willowbrook.

2SE05. Had to re-learn fledgling call of rapid high notes lacking sharpness of adult alarm. May have been contact call rather than alarm, though adult nearby gave very occasional alarm, too.

7JA08. Fullersburg. A cardinal sang, briefly and uncertainly, but definitely. My earliest noted song (previous earliest 14JA00). Temperatures in the 50’sF past couple days.

15JA10. Culver. First cardinal song of the year.

5OC10. Mayslake. Singing: white-crowned sparrow, phoebe, cardinal, song sparrow.

7DE10. Mayslake. A cardinal singing, full strong song repeated a couple times. Sunny day but cold, teens F. (I have heard cardinals singing on occasion all through the middle of this winter, the first time I have observed such an extended singing period).

Another observation in recent years is that cardinals in our area seem to raise mainly cowbirds early in the season, but a final August nest nearly always produces only cardinals. If this is correct, it implies a strong selective pressure, at least locally, for shifting the nesting season later.

Cedar Waxwing Dossier

by Carl Strang

One delightful bird which can be seen in northeast Illinois throughout the year is the cedar waxwing. Today I share my dossier for the species, consisting entirely of my own observations. Though references are valuable it also is important, I think, to keep track of one’s own experiences with a species.

Cedar waxwings are smaller than robins but larger than sparrows, crested, soft brown and yellow in color with bright yellow follow-me bands on the tail tips.

Waxwing, Cedar

My principal childhood memory is of waxwings that nested around brushy thickets and willow clumps along the Tippecanoe River near Monterey, IN. Adults hunted insects in flycatcher fashion from bare twigs over the river. In DuPage County they are evident in wandering flocks through all parts of the year except the breeding season. They travel in flocks, staying one to many days in an area and feeding on berries in fall and winter. This also occurred in Cumberland County, PA. Mountain-ash berries were a favorite food in both places. Also consumed are dogwood, and buckthorn berries. Flock cohesion is aided by the bright-yellow tips of the tail feathers, and by the unique high-pitched thin contact call. First winter birds have breasts striped longitudinally with cream and the soft brown adults’ breast color. At the Willowbrook Wildlife Center clinic, waxwings frequently came in with broken wings and other injuries suffered in collisions with windows. In the cages they showed an open-mouthed threat display, possibly made more effective by the black facial markings. In mid-September at Herrick Lake, a single waxwing perched in an old-field treetop gave a single loud note and flew away into thicker trees. Several seconds later a sharp-shinned hawk flew by the waxwing’s original perch, heading in the same direction. (This first paragraph, written from memory, established the dossier in the early 1980’s. Subsequent additions begin with date codes.)

When not feeding, cedar waxwings typically perch high in trees.

30OC86. Willowbrook Back 40. Waxwings feeding heavily from honeysuckle (berries and leaves still on bushes).

16OC87. First autumn appearance of a flock at Willowbrook Back 40.

13JA88. Lots of waxwings in Back 40.

27OC88. Feeding on honeysuckle berries, Willowbrook Back 40.

13DE88. Waxwings abundant in Back 40, stuffing down rose hips.

3SE89. Mixed young and old waxwings eating honeysuckle berries, Island Park, Geneva.

JA99. Waxwing flocks frequently at Willowbrook. Eating, among other things, Asiatic bittersweet (Celastrus) berries.

11MR99. Last of winter waxwings noted. Not seen again at Willowbrook until 25MY. Then after 1JE another gap until 12&20JL. Became a frequent visitor again in early August.

These waxwings are drinking meltwater where snow is being warmed on a roof at Mayslake Forest Preserve. Much energy is saved by drinking, even if the water is cold, instead of eating snow.

7JA00. Waxwing eating buckthorn berries.

31JA00. Waxwing, again at Willowbrook, again eating buckthorn berries.

8FE00. Waxwings eating buckthorn berries at Willowbrook.

17FE00. Several waxwings on the ground eating snow (buckthorn berries available on bushes nearby).

19MY01. Many flocking waxwings spread out over a large area at the Arboretum, mainly in treetops in forest as well as more open areas.

12MR06. Cedar waxwings delicately picking anthers from silver maple flowers in the yard. [Note: studies have shown that waxwings use protein from pollen to render certain berries more digestible]

13JE06. Tri-County State Park. Cedar waxwing working on a nest in the topmost leaf cluster in a 25-30-foot box elder within 30 yards of Brewster Creek. Weaving, using long slender strands, at least some of which are stripped from grape vines. Spending considerable time with each strand. Mate perched in same cluster of trees. Bird completely concealed when weaving.

This is the tree where waxwings built a nest at (then) Tri-County State Park in 2006.

16JE06. The nest looks complete, a significant lump in the first branching of twigs about a foot from the tip.

22MY08. Fullersburg. An interesting display between 2 cedar waxwings, appears highly stereotyped. They were perched side by side well up in a tree in SW Butler Woods. They took turns quickly hopping away from the other bird a few inches, and returning, at which point the two birds touched or nearly touched beaks, which were angled up. Each of these cycles (or half-cycles, for each bird) took 1-2 seconds, and there were perhaps 20 reps that I observed (i.e. at least 10 per bird). At first they faced the same way, at some point one turned to face the other way and they continued. Eventually one moved to a different twig, but still was close. [Note: this is called the Side-hop display in the Stokes bird behavior guide, and is part of courtship].

6JL09 Mayslake. 14 cedar waxwings foraging like swallows out over May’s Lake. (This was repeated over several days.)

1JA10. Hidden Lake. Waxwings and robins feeding on buckthorn berries.

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.

 

robin-1b

 

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.

 

robin-b

 

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.

%d bloggers like this: