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.

Mayslake Birds Update

by Carl Strang

The birds have completed their nesting for the year, and some already have departed for the South.

It has been a while since Mayslake Forest Preserve’s eastern kingbirds have filled the air with their distinctive chattering.

Mayslake is not a migrant mecca, but we get a few. The mixed flocks usually build themselves around the local black-capped chickadees, whose frequent calling and local knowledge make flock cohesion possible and worth maintaining. One recent flock contained 2 chickadees, a redstart, 2 magnolia warblers, a black-and-white warbler, a black-throated green warbler, and a chestnut-sided warbler.

The black-and-white warbler crawled the tree bark, while the other species hunted insect prey in their various other specialized ways.

Another flock on the same day included a chickadee, a redstart, a house finch, a downy woodpecker, a white-breasted nuthatch, and a house wren. Resident birds like the woodpecker and nuthatch often join these flocks. A final grouping that day included 3 chickadees, a Nashville warbler, and a warbling vireo.

The Nashville warbler

September birders know to key on the chickadee calls. The migrants certainly do.

P.S., this is the 900th post of this blog.

Kirtland’s Warbler Tour

by Carl Strang

Last Thursday and Friday I drove into the northern part of Michigan’s Lower Peninsula. I had two goals, the first of which I’ll detail tomorrow. My secondary goal was to take the Kirtland’s warbler tour. This is a seasonal education opportunity offered by the U.S. Fish & Wildlife Service and Michigan Audubon (nearly done for this year). The tours begin with a video introduction at the Ramada in Grayling, and then the guide leads participants in a car caravan to the tour site. We drove to an area where the current crop of jack pines was mainly 3-5 feet tall.

The pines are on a harvest rotation, with large areas clear-cut and replanted, so that there always are large areas covered with the small pines the warblers favor.

Kirtland’s warbler is a federally endangered species, but the population trend is upward and the range is expanding thanks to the intense management efforts. Now some are breeding in Wisconsin and Ontario as well as both peninsulas of Michigan. The rarity of the species draws birders to the area, and about 15 of us were on the Friday morning tour.

Allison, our guide, was knowledgeable, and there were plenty of competent birders in the group to assist with the spotting.

The area appears to be structurally and botanically fairly simple. The pines were dominant in the area, with scattered oaks and cherries the other large woody plants.

Jack pine has short needles and small, curved cones.

Between the pines were a few shrubs, mainly huckleberries or blueberries, as well as sweetfern, one of my favorites.

The wonderful odor of sweetfern leaves I associate with wild places. Sadly it does not occur in DuPage County, as it is a sandy soil species.

Among the herbaceous plants were scattered hairy puccoons.

This is another sandy soil plant.

The puccoons frequently threw off some of the more anxious birders whose search image was tuned to the color yellow. Kirtland’s warbler males were singing loudly at all times, but for a while they stayed out of sight. In the meantime we enjoyed a surprising diversity of birds for such a simple ecosystem: four sparrows (field, vesper, clay-colored, Lincoln’s), 3 warblers (Kirtland’s, Nashville, palm), nighthawk, upland sandpiper, brown thrasher, towhee, Brewer’s blackbird, and rose-breasted grosbeak were notable ones. Eventually a male Kirtland’s warbler perched and sang on an exposed branch.

This is an expanded view of the dot on my photo that represented the warbler. We had good spotting scope views.

The tour was highly satisfying. However, it did not allow me to further my primary goal, which was to find Roesel’s katydids in the Lower Peninsula. More on that tomorrow.

Goldfinch Song Mimicry?

by Carl Strang

In past posts on starlings and catbirds I have described well known song mimics. These are birds that include imitations of other birds’ songs in their own vocalizations. Blue jays and mockingbirds also are well known for mimicry. Sometimes, though, I think I hear mimicry in other birds. One of these is the American goldfinch.

Male goldfinches have two singing periods. Now, early in the season, they are advertising for mates. There will be a quiet time through June, then in July they will start up again to establish their nesting territories. Their songs often are distinctive, chattering jumbles with rising “zips” and “potato-chip” phrases that are unlike those of other birds. Many is the time, however, when I have heard what at first sounded like another species but proved to be a goldfinch. I don’t know if this is mimicry, or just a coincidence in phrasing and timing that momentarily sidetracks me into an erroneous identification. I think, though, that I may start a list of other birds whose songs can seem to appear in the goldfinch’s repertoire. Recently I started the list with Tennessee and Nashville warblers. Such a project can focus attention on a problem and lead to new insights.

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