Nashville Warbler Dossier

by Carl Strang

How do we “know” what we “know?” It occurred to me back in the 1980’s that much of what I “knew” about most species of animals and plants was information I had gained from reading or from talking with others. I made the decision to assemble a dossier for each animal species, based entirely on my own experience. This was humbling, as the resulting files were small even for common species. From then on I made a point of adding notes as I focused on accumulating more such experience. In recent years my attention has been focused more on singing insects, and so I have added fewer notes to the vertebrate dossiers, but such as I have I continue to share here from time to time in the winter. Today’s focus species, the Nashville warbler, is one we see in the Chicago area only during migration, so at least I have a ready excuse for its small dossier. The odd prefixes for each entry are my date codes.

Nashville Warbler

Nashville Warbler

Nashville Warbler

Observed as a migrant in Lafayette, IN, and at Willowbrook Forest Preserve, DuPage County. Song close to Tennessee warbler’s. First part of song identical, with loud “se-bit’, se-bit’, se-bit’” then instead of emphatic “tee’s” has fewer, slurred, robin-like notes (usually 3). The Willowbrook birds hung around the taller thick shrubs at the edge of the riparian strip.

1MY87. At Willowbrook, a Nashville warbler hopped along and between twigs, 8-15 feet up in riparian woodland. At times very frenetic impression, jerking head around to look in all directions and not pausing long. At other times paused for several seconds and looked all around. Caught 2 small caterpillars within 3 minutes, both by reaching into expanding leaf tufts in box elders. Killed with pecks before swallowing. Not observed to hover-glean or sally.

4MY87. Abundant. In addition to song, a “bick” call, loud and sharp. Another one observed feeding in same way as the one above: much looking between short frenetic hops, and stretching to reach prey from leaf-clusters. Feeding in box elder.

5MY87. Has a chunky body and shows fluttering-hopping advances like a kinglet.

2MY88. First of year singing. Also 7MY at Fulton County Museum property.

19MY88. Female seen at Willowbrook.

31AU88. One observed in Willowbrook riparian area, feeding among low shrubs. Acrobatic, and an aerial pursuit. Reached a lot, too.

29AP89. Heard singing at Von Oven Scout Camp, Naperville.

8MY89. Last noted of spring.

29AP99. First of season noted at Willowbrook. Last noted 14MY there that spring.

3MY99. At Willowbrook, foraging 20 feet up in a box elder. Deliberate, making 1-2-inch hops with much looking around and reaching but no acrobatics. No long jumps, except when moving from tree to tree. Sang infrequently. Slow motion not conspicuous.

2SE99. First migrant of fall noted at Willowbrook. Last seen there 17SE.

1MY00. First migrant heard at Willowbrook.

24SE00. A couple in the Sparrow Hedge, Fermilab.

13OC00. A single, clearly marked adult among Tennessee warblers feeding in tall goldenrods, etc., at McKee Marsh.

14SE02. A single individual at Elsen’s Hill (there were mixed flocks elsewhere) systematically moving from one tall goldenrod to another along a wooded trail edge, perching in or adjacent to the flower heads and searching them closely.

8MY11. Elsen’s Hill. One foraging among the twig tips of a small rosaceous tree in which leaves were expanding. It cranked and twisted its neck so as to peer into and all around the tips while remaining perched in place.

American Tree Sparrow Dossier

by Carl Strang

Today’s feature is my dossier of the American tree sparrow, a wintering bird that still is with us but soon will head back to the northern nesting grounds. The following notes reveal my interest in the complex range of this species’ vocalizations.

American tree sparrow. The black spot in the clear chest is a helpful identification feature.

American tree sparrow. The black spot in the clear chest is a helpful identification feature.

Sparrow, American Tree

This songbird is a common winter resident in old fields and residential areas with some bushes, in Culver, around Lafayette, in south central Pennsylvania and in DuPage County, IL. Usually they occur in loose flocks, often mixed with juncos. They feed on the ground, especially, taking seeds. Note: “tsew,” “tsoo” or “tsee” in a slightly melancholy minor key, hint of downward slurring. Has a 3-syllable call, a hair slower and more flowing than junco’s, very musical and pleasant in contrast. Single-note call has a descending tail, is much like white-throated sparrow’s.

26FE87. Song heard in Willowbrook Back 40: “Tsoo-too-doo-doo-dee-chew-chew-chew-chew.” Song loud and clear, of water thrush quality.

7MR87. Another song: “tsee-tsoo-bye-tsee-tsoo-tsoo.” First note held longer than others. Tsee syllables highest pitched, tsoo’s lowest. Sang from perch in top of willow clump, 6 feet up, at West Chicago Prairie.

13MR87. Still hearing them singing.

22MR87. Still present and singing at Culver Fish Hatchery.

15OC99. First tree sparrow of the season at Willowbrook.

20DE99. Tree sparrows eating Indian grass seeds at Fermilab. Sometimes their call notes are simple and flat, but sometimes they add a trailer that so far I cannot tell from white-throated sparrow’s. In conflicts they have beautiful, musical clusters of notes.

29JA00. A flock of 30 tree sparrows and 2 juncos feeding on the gravel berm edge of Swenson Road, Fermilab.

5MR00. A single still at Fermilab, in thick grass area with a few shrubs, beside trail.

The red on the top of the head, the white wing features and yellow lower bill mandible are additional distinctions.

The red on the top of the head, the white wing features and yellow lower bill mandible are additional distinctions.

23NO04. Willowbrook. A flock of tree sparrows in tall prairie vegetation using a call I don’t remember hearing before, a pardalote-like “wee’dah.”

16NO10. Mayslake. Many tree sparrows are in the west stream corridor along the southern edge of the mansion grounds. Giving an unusual call, less than a second long, beginning at a high pitch, slurring to a lower one, and quickly back up to the starting pitch.

6JA11. The more complex tree sparrow call can be difficult to pick out when many birds are producing it at once. When a single bird is isolated, the call has the rhythm of a quick, “tit willow,” i.e., three dominant syllables with the last two close together and a little more separated from the first.

2FE12. American tree sparrow call: dedjidu, quickly pronounced.

15NO12. Mayslake. Tree sparrows eating seeds of Canada goldenrod and annuals.

25JA13. Mayslake. On the ground in the off-leash dog area, an enormous flock of at least 100 tree sparrows, 30 juncos with at least one white-throated sparrow mixed in, doing the double-foot scratching to get through the snow and then reach, presumably for seeds.

A Cricket’s Adventure

by Carl Strang

At mid-day on Friday, a tree cricket sang from a Canada goldenrod plant near the eastern edge of Mayslake Forest Preserve.

The central character in today’s story.

At this point in the season, the long-trilling meadow-dwelling tree crickets are mainly members of the sibling species pair of black-horned tree cricket and Forbes’s tree cricket. The two species cannot be distinguished except through an analysis of their recorded songs. The critical feature of the song, the pulse rate, varies with temperature, and in the field the temperature can vary significantly with microsite at this time of year. So, I caught him and installed him in a cage. Back home, in the quiet of the evening, he began to sing and I got my recording.

The next day I wanted good photos for documentary purposes. I put the cricket in a jar, and the jar in the freezer for 10 minutes. This immobilized the little guy long enough for me to get photos.

The dorsal view shows that this individual is very pale. The antennae and tarsi are dark, but not the black typical of the two species. There is no stripe on the pronotum.

There is some dusky pigmentation on the underside of the abdomen, but this too can be much darker in black-horned/Forbes’s tree crickets. He looks dead, but he fully revived within 15 minutes or so.

The spots on the first two antennal segments are very helpful in tree cricket characterization. Here the spots are large, dark and close together.

The cricket’s adventure was nearly complete. I had a public night hike Saturday night, and I took him in a jar, releasing him with an explanation of his story and the reason I put him through it.

It was only later, when I studied the photos closely, that I began to have some doubts. The heavy, close-together markings correspond more closely to those of a third species, the prairie tree cricket, which I had been seeking but not found. The literature and on-line information seem to suggest that, nevertheless, this could be a black-horned/Forbes’s. The critical question seems to be, how wide is the space between the two bars on the second antennal segment? If it is less than a third the width of the inner bar, then this is a prairie tree cricket. If more, it’s a black-horned/Forbes’s. As best I can tell, it is very close to this critical width. I will continue to pursue the question for this individual, but all of these species show some variability, and my best response is to find more crickets in Mayslake’s meadows, and see what they tell me.

Assorted Photos 2

by Carl Strang

Today I’ll share photos of some colorful insects. Fiery skippers are described in references as a southern species that sometimes appears in the North. It seems to me, though, that a year seldom goes by when I fail to see them.

I have seen fiery skippers several times at Mayslake Forest Preserve this year. This one’s on sneezeweed.

With summer waning away, it’s appropriate to begin seeing autumn meadowhawks.

AKA yellow-legged meadowhawks, for obvious reasons.

Finally I want to focus on some very small insects. They are tiny, but so abundant this year that it’s been impossible to overlook them. The shiny black beetles, each at most a couple millimeters long, first showed up in sweep nets the kids were swinging at the Forest Preserve District’s employee parent-child event at Mayslake in August. Then they were mainly in Queen Anne’s lace flowers. Lately they have shifted to goldenrods.

They plunge their heads into the little florets of this Canada goldenrod.

Their simple hump-backed oval shape, shiny elytra, and abundance all made it seem likely they should be common enough to find in references. I tried probing them, and they showed no jumping talent, so I ruled out flea beetles. I found a likely match while scanning photos representing the various families of beetles in the BugGuide website. They appear to be members of the shining flower beetle family, Phalacridae. One common genus is Olibrus.

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