Which wood-warbler species are members of the “Watch List?"

(As a Watch List member, Hermit Warbler (above photo) populations are stressed by ongoing habitat loss in both their breeding and non-breeding range.)

Thanks for the question, Kerry W. from Polesville, PN.

Answer:

Coordinated by the Audubon Society and the America Bird Conservancy, the Watch List aims to rally conservationists around America's most imperiled birds. In so doing, the Watch List employs the latest available research from the bird conservation community along with citizen science data from the Christmas Bird Count and the annual Breeding Bird Survey to identify species in the continental U.S. and Hawaii that are in need of immediate conservation help. It is a call to action to save species fighting for survival amid a convergence of environmental challenges, including habitat loss, invasive species and global warming.

The current wood-warbler family members on the Watch List:

Bachman's Warbler
Blue-winged Warbler
Golden-winged Warbler
Virginia's Warbler
Colima Warbler
Lucy's Warbler
Golden-cheeked Warbler
Hermit Warbler
Grace's Warbler
Kirtland's Warbler
Prairie Warbler
Bay-breasted Warbler
Cerulean Warbler
Prothonotary Warbler
Worm-eating Warbler
Swainson's Warbler
Kentucky Warbler
Canada Warbler
Red-faced Warbler

What “strange” common names were previously designated for some of our wood-warblers?

(The above Black-Throated Blue female's vastly different appearance in comparison to a definitive male of the species is suggested to be the reason John James Audubon named it a different common name, the Pine Swamp Warbler.)

Common Yellowthroat was once often referred to as Maryland Yellowthroat. John James Audubon mistakenly named two Yellow Warblers as Children’s Warbler. In another instance, Audubon misnamed two juvenile Yellow Warblers as Rathbone’s Warbler.

Audubon was not alone in his naming confusion. Beyond Audubon, naturalist/painter Alexander Wilson also made his share of identification mistakes. Both of these luminaries – as well as other contemporary birding experts in bygone eras – are to be excused because during their tenures little was known about the relationship between plumage changes and corresponding definitive field characteristics.

Audubon’s failed nomenclature decisions periodically continued to surface as he gathered specimens for his paintings. Originally calling a bird specimen he collected in Pennsylvania the Pine Swamp Warbler, he later realized his subject was truly a Black-Throated Blue Warbler.

Later, Audubon was misled by Wilson’s naming procedure into thinking a Blackburnian Warbler was worthy of being designated a new species, the Hemlock Warbler. Audubon, in fact, was never able to correct this misnaming mistake. Another misplay hearkens to May 1812, when Audubon caught a wood-warbler specimen that he named Vigor’s Warbler in honor of Nicholas Vigor, an English naturalist. More correctly, Audubon’s find was an immature Pine Warbler. His confusion was probably the result of the collected individual being in vastly different habitat than its usual pine/needle tree haunts.

Even the Canada Warbler was originally misnamed by Audubon. When he first drew the bird as it perched on the fruiting branch of a magnolia, Audubon suggested it be named the Cypress Swamp Flycatcher. Later he changed his mind, renaming the bird as Bonaparte’s Flycatcher only to again change its designation to Bonaparte’s Flycatching Warbler.

Eventually, it was confirmed that Audubon’s specimen was instead a young female Canada Warbler. Eight years later, Audubon painted the same species and mistakenly called it a Canada Flycatcher.

What are the answers to the most recent quizzes appearing on the right side of this home page as you scroll from top to bottom?

Beyond Michigan's breeding population, where else do researchers believe the Kirtland's Warbler regularly to periodically breeds?

Answer: WI & Ontario

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Which common wood-warbler's breeding range is split into an eastern and western subspecies breeding population?

Answer: Nashville

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Which sequence of weather conditions typically result in a "fallout" of wood-warblers during the spring on the Gulf Coast?

Answer: Warm, southerly breezes followed by a cold front/northerly winds.

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If it's not a wood-warbler, then into which taxonomic placement has Yellow-breasted Chat previously been proposed?

Answer: Tanager family

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Which "New World" wood-warbler species has the most extensive breeding area?

Answer: Yellow

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Unlike Blackpoll that undertake a long migration (see 1/8/09 article), which wood-warbler has populations that do NOT migrate?

Answer: Common Yellowthroat

Where in Michigan might I see Kirtland’s Warbler and what are the best dates to go?

Thanks for the question, Laurie in Detroit, MI

Answer:

Given the good news (from a Michigan DNR news release from September, 2008) that Kirtland’s Warbler populations are at an all-time high of 1,791 singing males, your chances of detecting them are excellent. Most of the population nests in 12 lower Michigan counties within central-northcentral Michigan (Alcona, Clare, Crawford, Grand Traverse, Iosco, Kalkaska, Montmorency, Ogemaw, Oscoda, Otsego, Presque Isle, and Roscommon) and five upper Michigan counties (Chippewa, Delta, Luce, Marquette, and Schoolcraft). (However, nine individuals were detected in WI in 2008 and one in Ontario.).

The initial two weeks of June are the ideal time to visit the Kirtland’s breeding grounds, but a later visit through the first week of July could also yield viewing results.

Note that guided tours to view the Kirtland’s Warbler leave from various locations. To find out the schedule, contact the DNR Wildlife Division, Natural Heritage Program, Box 30180, Lansing, MI 48909, or visit the DNR Web site: www.michigan.gov/dnr.

Why is the diversity of wood-warblers greater in eastern than western USA forests?

Excellent question, Don Y. of Houston, TX.

Answer:

Although different perspectives for this phenomenon have been initiated by researchers, a summary of the leading ones follow:

1. The epicenter of wood-warbler colonization occurred initially in eastern USA forests, so over time more wood-warbler species have evolved in this area in comparison to western habitats.

The above statement is an oversimplification of a theory that is based on two million years of bird movement/migration in North America since the Pleistocene glaciation episodes occurred. In this regard, theorists believe the eastern wood-warbler species were present before the most recent four glacial advances. As the ice sheets advanced, separation of some species may have occurred or movement was enhanced, so that the splitting off of sibling wood-warbler species occurred. However, this process is slow and, thus, colonization of western USA areas has occurred with less diversity of species than those remaining (and continuing to evolve) in eastern habitats areas.

2. Moisture is generally far more abundant during the breeding season in eastern forests than western ones. As a result, more insect prey resources occur in eastern than western foliage where many species of wood-warblers forage.

3. Related to the above, #2, the foraging method called “foliage-gleaning” is specific to the largest quantity of wood-warblers occurring in North America, namely the Dendroica genus of wood-warblers. More than half of this area’s 52 annually occurring wood-warblers in North America (north of Mexico) are members of this genus. Given the far greater opportunity for “foliage gleaning” to occur in eastern forests than western ones (due to the composition of forests and the tree species they host), more wood-warbler species were able to establish themselves and evolve in eastern USA habitats.

How did the Hermit Warbler get its name?

Thanks for the question, Jim D. in Delvan, WI.

Answer:

Perhaps the reason relates to how it’s often easier to hear than see them, as Hermit Warblers typically forage individually high in the tree tops — hence, the common name that John Kirk Townsend first described when collecting this species in 1837 near Fort Vancouver (now Vancouver, WA).

Considered part of the Black-Throated Green “super species” — along with Black-throated Green (Dendroica virens), Golden-cheeked (D. chrysoparia), Black-Throated Grey (D. nigrescens) and Townsend’s (D. townsendi) warbler — the Hermit Warbler breeds in coniferous forests of the Coast, Cascade, and Sierra Nevada mountain ranges of southern Washington, Oregon, and central and northern California.

Where it occurs with Townsend’s Warbler within the s. Washington Cascade Mtns., Olympic Mtns., and central Oregon Cascade Mtns., Hermit Warbler may be losing populations as it is replaced and outcompeted by its first cousin. Studies by S. Rowher and C. Wood from 1994 to 1996 in this region indicate that 80 percent of adult Townsend’s and only 53 percent of adult Hermit paired and maintained their territories long enough to reproduce successfully. Other data relating to aggression behavior and hybrid zone analyses further supports Rohwer and Wood’s conclusions. Another reason for the reduced local populations of Hermit’s may be the result of reduced suitable breeding habitat in portions of its home range.

Nonetheless, in other portions of its range where Townsend’s Warbler does not breed, Hermit Warbler population densities appear to be stable, according to Breeding Bird Surveys (BBS) conducted in the last 30 years. However, it’s important note that BBS surveys are limited to routes where roads occur, so more comprehensive surveys of the Hermit’s total abundance do not exist. In addition, given the Hermit Warbler’s inherent small population worldwide and narrow geographic distribution, it is not considered abundant or common in most portions of its home breeding range.

Latest Warbler Quiz Answers

Below, you’ll see correct answers to recent quizzes that appear on the right side of this page (in order, from the most recent quiz to older ones):

Which "New World" wood-warbler species has the most extensive breeding area?

Answer: Yellow Warbler

Unlike Blackpoll that undertake a long migration (see 1/8/09 article), which wood-warbler has populations that do NOT migrate?

Answer: Common Yellowthroat

What behavior displayed by American Redstart is different than most other songbirds?

Answer: Some females sing

Which wood-warbler species spends the winter in large numbers in higher latitudes than any other wood-warbler?der members?

Answer: Yellow-rumped Warbler