Mr. WarblerWatch, are the recent Dusky Warbler sightings in California rare ones?

(Photo © Brian L. Sullivan)

Simon Frazer, Eugene, OR

No need to be so formal, Simon. WarblerGuy is fine.

The answer to your question is “yes.”

Normally a breeder in East Asia, Dusky Warbler (Phylloscopus fuscatus) has been spotted in North America just 10 times since the 1970s, most commonly in Alaska, according to Joseph Morlan, an ornithology instructor at the City College of San Francisco. Morlan also told the Santa Cruz Sentinel — see: http://www.santacruzsentinel.com/ci_10814091 — his theory as to why the four and a half inch songbird found itself thousands of miles wayward from its normal environs:
“Weather is the most likely culprit, but it's untested," Morlan said.

Morlan, who is a member of California Bird Records Committee, provided a list of Dusky Warbler sightings in California below.

Who initially planted the proverbial flag on the moon and took the Giant Step for Birding Humankind by spotting the Dusky Warbler at Antonelli's Pond in Santa Cruz (Santa Cruz County)? That would be one Steve Gerow, followed by Rick Rournier, who apparently alerted master birder Don Roberson. By then, the digital airwaves were bathed in the typical alert system birders use to exclaim their discoveries. The resulting throng of binocular-toting enthusiasts lining the banks of the diminutive pond quickly climaxed. Meanwhile, the sudden spike of incoming revenue for local Santa Cruz motels and restaurants had proprietors scratching their head.

Coincidentally, lightning strikes twice. Dusky Warbler appeared in California’s Bay Area, as “. . .another dusky warbler was spotted last week next to a Costco parking lot in Richmond (just north of Oakland)," Matthew Dodder told the Santa Cruz Sentinel in the same article. Dodder, a birding instructor, brought his students from Palo Alto to capitalize upon the anomaly. To say the least, the appreciative witnesses may have enshrined their mentor for the viewing thrill, while ticking off another species on their burgeoning life lists.

Given all the excitement occurred nearby — basically in my backyard because I live nearby — you’d think I’d be around to skedaddle quickly over to watch the fun, correct? You’d be wrong. I was 750 miles away when this so-called Super Nova of a birding phenomenon occurred. My gazes were instead fixated on distant horizons while conducting raptor surveys in the Nevada wilderness since early September.

Such a tragedy, I’m sure you’re thinking. Relegated to raptors instead of vagrant warblers. Life is so cruel. Oh well, there’s always Alaska, as this Old World warbler (Sylviidae family member) sometimes occurs in Alaska.

Otherwise, I've got the toll-free number for Singapore Airlines to share with you because your better bet is to head to the Dusky's primary breeding area: southeast Asia.

As for the moral of this (rare) birding story: “Wait ‘till next time" or "the early bird gets the worm" (substitute "birder" for "bird" and "Dusky Warbler" for "worm."

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Accepted Dusky Warbler Sightings (County in parentheses):
1. 27 Sep 1980, SE Farallon Island. SF
2. 28-29 Sep 1984, Hayward Regional Shoreline
3. 14 Oct 1987, SE Farallon Island. SF
4. 22-23 Oct 1993, Goleta SBA
5. 31 Oct-3 Nov 1995, Vandenburg Air Force Base
In addition there has been one documented record from Kern County on October 4-5, 2008; and a sighting of a bird believed to possibly be this species in San Joaquin County on October 3rd of this year.

Which are the best wood-warbler field guides/books?

. . . and thanks to Joseph C. of Lake Forest, IL for the question.

My favorite wood-warbler field guides/resources follow: (Note the final resource is the only non-book, yet an amazing treasure: an award-winning video that highlights the lives of wood-warblers in North America.)

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WOOD-WARBLER RESOURCES:

# = First wood-warbler field guide I would buy
* = Best photos I’ve seen in wood-warbler guide
& = Best field guide for ecological information

# A Field Guide to Warblers of North America
Jon Dunn, Kimball Garrett, Sue A. Tackett, Larry O. Rosche, Cynthia House, Thomas R. Schultz, Roger Tory Peterson

Warblers of the Americas: An Identification Guide,
Jon Curson, David Quinn, David Beadle

& American Warblers: An Ecological and Behavioral Perspective, Douglass H. Morse

Life Histories of the North American Wood Warblers: Part 1, Arthur Cleveland Bent

New World Warblers, Jon Curson

* Warblers of the Great Lakes Region and Eastern North America
Chris Earley

Vanishing Songbirds: The Sixth Order, Wood Warblers and Other Passerine Birds, Elliot Porter and Kenn Kaufman

Stokes Field Guide to Warblers, Lillian and Donald Stokes

The Warblers of North America, Alexander Jr. Griscom and John Henry Dick

Wood Warblers' World, Hal H. Harrison

Handbook of the Birds of the World, Volume 11: Old World Flycatcher's to the Old World Warblers (Handbook of the Birds of the World), Joseph Del Hoyo, Andy Elliott, and David Christie

DVD/VHS wood-warbler resource:
Watching Warblers, Michael Male and Judy Fieth

Why are Yellow-Rumped Warblers so common?

Thanks for the question, Lori V. in Menlo Park, CA.

(UPDATE: The answer below is outdated, given recent name classification changes. Thus, see the 3/7/11 article here at this blog for an update in relation to the Yellow-rumped Warbler split into various subspecies.)

Here's why you see Yellow-Rumped Warbler in many different habitats and, especially, en masse during a prolonged spring and autumn migration (in the Midwest and East):

1. Among the six subspecies in the Yellow-Rumped Warbler (YRWA) species, four are Audubon subspecies (including the male Audubon YRWA seen in the above photo) and two are Myrtle subspecies.

2. YRWA exploit multiple feeding niches within the profile of the forest. That is, you are as apt to see them in the interior branches near the main trunk as you are to notice them near the ground. As a “hover and gleaner” feeder (like many Dendroica genus wood-warbler members of which the YRWA is enrolled), you can expect to see YRWA in a forest profile, but they also might be at the seashore (finding invertebrates near the surf) or, even, on grassy lawns (where insects may provide food resources).

3. In turn, given YRWA is able to exploit multiple environments and feed on diverse food resources – from insects, to fruit (such as poison oak and poison ivy berries, in addition to privet and wax myrtle berries – the species is well-adapted to sustaining its populations in times of food scarcity. That is to say, the YRWA has a diversified portfolio – a perfect tactic to ensure that the boom and bust of food resources does not impact the species’ numbers.

4. The hydrochloric acid content within YRWA individuals appears to be more potent than the digesting apparatus contained within most other wood-warblers. In fact, the wax myrtle berries that help YRWA survive harsh conditions in winter along the mid-Atlantic are not digestible by most birds, including the 51 other wood-warbler family members typically found annually in North America north of Mexico. Given the abundance of wax myrtle, YRWA are able to survive into the deep fall (and sometimes throughout the winter) in states that often encounter harsh winter conditions: WI, MI, OH and, in the East, MD, VI, NY (and in some New England states during some winters).

Seeing YRWA in November and December, thus, is not uncommon in the states mentioned immediately above. Increasingly warmer winter seasons, too, provide succor to YRWA that do not need to vacate northern latitudes as is the custom in the vast majority of other songbirds.