Lucky 19: Kirtland's Warbler Update in Wisconsin

(Above, a fledgiing Kirtland's Warbler in Adams County, Wisconsin. Copyright Joel Trick, Wisconsin DNR.)

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According to a Wisconsin DNR news release from July 6, 2009, 19 Kirtland's Warbler young have hatched in the state this breeding season.

(As background information for the uninitiated, historically and through 2006, Michigan was considered the endemic breeding range of this species. Only periodic, non-annual sightings were reported in Ontario (including one nesting record in 1945) and Wisconsin, with no documented nests ever found in Wisconsin. This scenario changed in 2007 when Kirtland's was confirmed as a nester for the first time in Wisconsin.)


Here's more information about the ongoing monitoring in 2009 of Kirtland's Warbler within two Wisconsin counties:

Adams County

Wisconsin Kirtland’s warblers have had an extremely successful nesting season in 2009, and have already surpassed the reproductive output of last year. As of today, at least five Adams County nests have fledged young, including two nests that each produced four young over the weekend. So far a biologist has determined that the nests that have fledged contained a total of 19 young when checked just prior to the young leaving the nest. Another nest that is currently being incubated is expected to hatch within the next week or so. This nest is the renesting effort of a pair that had previously been parasitized by cowbirds. One nest that was expected to fledge soon was empty today, and the behavior of the adults suggests it may have been lost to predation. The biologist has currently been unable to find the nest of one additional pair at the site, but he will continue to search in the days ahead.

Marinette County

Male Kirtland’s warblers are known to be present at two separate sites in Marinette County, and each has previously been observed with a female. On Thursday, a DNR volunteer monitor found a nest containing three eggs at one of these sites. Finding eggs at this late date suggests that this may be a renest after an early failure. If successful, this would be an important nesting record for Marinette County. We will continue to monitor this nest to determine its outcome.

Which wood-warblers are known to feed on fruits and nectar?

Many of North America’s wood-warblers consume fruit and nectar, especially during the non-breeding season.

Three of the most notorious species are Dendroica congeners Yellow-Rumped, Black-Throated Blue, and Cape May Warbler. (Some Vermivora genus members, too, are known for eating fruits/nectar, given they probe well with longer, thinner bills than Dendroica genus members’ that have bills primarily adapted for insect eating.)

Yellow-Rumped populations during the non-breeding season often remain in far northern latitudes in comparison to other wood-warbler species that are obligatory migrators forced to vacate areas where they breed. Yellow-Rumped is often able to remain in northern climes throughout the winter (e.g., Wisconsin and New England during some, but NOT all, non-breeding seasons) because, depending on its location, may subsist on foods such as poison ivy berries, wax myrtle berries, and/or privet berries – fruits, in fact, from which the majority of other songbirds are unable to derive much energy.

Black-Throated Blue, likewise, are documented to
eat small berries and fruits. They also feed at flowers, possibly for nectar or insects. During the non-breeding season in the Dominican Republic, this species feeds frequently on honeydew-like excretions from scale insects.

As for Cape May, non-breeders are often easily observed and are known to feed on nectar, among other things, taken up by means of a semi-tubular tongue. They also eat insects and fruit from Cecropia trees, grapes and grape juice, and tree sap. In some cases, this species has caused damage to commercial vineyards in Indiana, Pennsylvania, and W. Virginia by puncturing grapes, thereby damaging all grapes not bagged.

As a personal observation note, I remember several autumns in Wisconsin and Maryland when I watched transient Black-Throated Blue feeding on various berries. Staking out the same patch of shrubs each autumn invariably resulted in the presence of watching the berries disappear over a few days – while I enjoyed seeing female, male, and hatch year individuals of this species up close.

Can you name a common wood-warbler that migrates early throughout the USA?

If you said “Yellow Warbler,” then you’re correct.

Rather than merely identifying this species as among the earliest “fall migrants” within the wood-warbler family, it’s apt to state the Yellow Warbler is an early “summer migrant.”

Dispersal and/or migration begins by mid- to late July throughout the majority of its eastern USA breeding range.

Migration of Yellow Warbler on the West Coast is not as early, typically initiating in August and peaking later in the month and into early September.

In addition, note this species has protracted migration, as some tardy individuals have been noted in Pennsylvania as late as October 1st and into late October from sightings in South Carolina and Florida.

Earliest arriving transients from the north into Mexico have been detected by late July. Most individuals, however, arrive in non-breeding territory by August, with peak numbers returning in September and October.

Wisconsin Kirtland's Warbler Nesting Update

. . . largest total of nesting Kirtland's males is confirmed in latest report

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According to a Wisconsin Dept. of Natural Resources news release, bird monitors have confirmed the presence of six Kirtland's Warbler nests, with four hosting nestlings and two hosting eggs.

Eleven males in the state have been banded.

To read the news release, go to:

http://www.fws.gov/midwest/greenbay/kiwa/update22June2009.html

Of course, historically and through 2006, Michigan was considered the endemic breeding range of this species.
Only periodic, non-annual sightings were reported in Ontario and Wisconsin, with no documented nests found.
This scenario changed in 2007 when Kirtland's was confirmed as a nester in Wisconsin.

The presence of the aforementioned breeding individuals marks the third consecutive season of documented Kirtland's in Wisconsin.

Spring Confirmation: Wisconsin's Kirtland's Warbler Population Increases

. . . as many as 18 individuals seen this breeding season

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The Milwaukee Journal's Outdoor Writer Paul Smith features an update on this season's Kirtland's Warbler nesting confirmation.

It is the third consecutive breeding season that the normally Michigan endemic wood-warbler has been confirmed breeding in the state -- which historically was graced with only periodic sightings of this endangered species.

To read Smith's article, go to:

http://www.jsonline.com/sports/outdoors/47268492.html

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.