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

Returning Wood-Warblers In The Bay Area

Birders are reporting the initial appearance of northbound migrating wood-warblers to the Bay Area this week.

Newly-arrived ORANGE-CROWNED WARBLERS are currently joining brave over-wintering populations, with Oak-Bay woodlands one of the best habitats to hear and seem them.

Note the annual date range of first-returning migrants for this species in Marin County (the initial county north of the Golden Gate Bridge) is 2/18 (earliest detection) through 3/16 (latest detection), according to Dave Shuford’s “The Marin County Breeding Bird Atlas.”

Soon, other nesting wood-warblers of the Bay Area shall also appear, with their identities and date range of arrivals in parentheses below:

- WILSON’S (3/10 – 4/8) (shown above)

- BLACK-THROATED GRAY (3/31- 4/27)

- YELLOW (4/8 – 4/23)

- MACGILLIVRAY’S (4/3 – 4/30)

For a comprehensive list of arrival dates for Marin County landbirds, feel free to visit my Web site (www.warblerwatch.com) where there’s a button that provides access to the Atlas’ chart (page 39).

Who’s ready for a brief wood-warbler quiz?

It’s the Q and A portion of the day, so feel free to satisfy your wonderment with the following questions (answers appear far below):

1. To which family do some taxonomists believe is most closely related to wood-warblers?

2. If you include North, Central, and South America, and the West Indies, how many wood-warblers exist?

3. Although most wood-warblers possess small bills, which two species have more robust ones?

4. Which common wood-warbler has rictal bristles (like flycatchers) to help it sense prey while pursuing insects?

5. Although most songbirds have ten functional primary flight feathers on each wing, how many do wood-warblers possess?

6. Among the 53 typical annual breeding North American wood-warblers, what’s typical about their breeding behavior in contrast to Central and South American wood-warbler species?

ANSWERS:

1. Some taxonomists place wood-warblers closest in relation to the tanager family, Thraupidae (sometimes treated as a subfamily, Thraupinae, of Emberizidae). Other researchers believe they are nearest to the New World finches family, Emberizidae.

2. 126 species amidst 28 genera.

3. Yellow-breasted Chat and Yellow-Rumped Warbler.

4. American Redstart.

5. Nine.

6. North American wood warblers remain monogamous for the breeding season, while Central and South American pairs may persist together for longer periods.