Sunday, December 27, 2009

#1: WOOD-WARBLER Photo Quiz (Quiz Yourself, If You Please)

Can you identify the wood-warbler species in the five (5) photos, above?

(Hint: There only four total species among the five photos.)

Answers will be posted here in my next article that will appear no later than 1/5/10. Please check back, in addition to noting my NEW 2010 "Daniel's Nature Watch Calendar/Phenology Calendar" that will be posted at my regular web site by the first week of 1/2010:

Happy New Year, Daniel

(Photo credits from top to bottom: Kevin Stockman, Martin Meyers, Martin Meyers, WI DNR, and WI DNR)

Saturday, December 12, 2009

Warbler Guy, have wood-warblers shifted their winter distribution as warmer winter temperatures have become more common in recent years?

(Above, thanks to Martin Meyers for submitting a Common Yellowthroat male photo (taken in Nevada) )

That’s a fine question, Howie (in Minneapolis).

Turns out the answer is “yes,” if you agree with a recent technical report titled “Birds and Climate Technical Report (Niven, Bucher, and Bancroft, 2009;

This report tracked the locations of 305 species by using Audubon Christmas Bird Count (CBC) data collected in the past 40 years throughout the lower 48 states (and s. Alaska and s. Canada).

Among these species, researchers suggest 58% of them shifted farther north in the past 40 years. They include many non-warblers such as Fox Sparrow, Pileated Woodpecker, Pine Siskin, Purple Finch, Ring-Billed Gull, and Fox Sparrow, among others.

Which wood-warbler species has shifted father northward during winter? It’s the Common Yellowthroat. Seeing this moisture-centric species on CBCs is not uncommon during the breeding season, especially because they are found throughout all of the lower 48 continental states. In addition, even seeing them throughout the winter in southern states is regular occurrence.

More eyebrow-raising: Seeing them increase their presence in northern USA states when the December/January CBC surveys occur. By this time, insect resources should have ebbed. Resources are few and far between. The pantry is empty for most insect-dependent bird species, such as Yellowthroats.

In other words, a sighting of a Common Yellowthroat on an Illinois or Indiana (or Wisconsin) CBC used to be much more rare. But the current report suggests the shift northward has made a winter-time Yellowthroat observation less rare.

The authors of the report cite four lines of evidence as verification of warming climate being a major factor in why bird species’ (including the Yellowthroat’s) have shifted north during the last 40 winters.

Time and space doesn’t allow me to discuss these four areas. But it’s worth noting that the birds’ movement north is consistent with computer model predictions based on a hypothesis of global warming/climate-change effects, according to the authors’ contention.

To read more about this report, see:

Sunday, November 22, 2009

Warbler Guy: We've missed you since your 11/7 post? What's up? When will you return? Inquiring warbler fans wish to know (!)

OK, OK, I'm guilty as charged.

My college class that I'm teaching ("Ornithology") has been my child to babysit for lately -- and I'm not complaining.

The field trips are fun as a complement to the Powerpoint slide shows I present during class (Merritt College).

BUT I'm on my next article that you'll soon see here:

How the Old World warblers (the Sylvids) have been split and re-organized.

It's an interesting development.

Yet it also requires a reading length almost equal to scanning every name in the NY City phone book.

In other words, it's a time drag and, tongue in cheek intended, a near Master's Degree in descriptive research to learn about the Old World Warbler taxonomy changes.

I'll be back at you soon.....and, meanwhile, enjoy the birding and our wood-warbler friends.

Regards, Daniel

Saturday, November 7, 2009

Warbler Guy, which warblers are the most common to see at the upcoming Christmas Bird Count (CBC) events?

Oh, “yes,” Floyd D. in Davenport, IA. . . Wood-warblers are often detected in non-warm weather areas where the 2009-2010 CBC events will soon happen. (Given Floyd also wonders if "seeing warblers during a northern USA CBC is even possible?" I'll answer that phase, too, below.)

Before I mention the highest wood-warbler species totals for the most recent (2008) CBCs, consider how cold weather-challenged states such as Minnesota, Wisconsin, Michigan, New York, and others routinely report Yellow-Rumped Warbler for selected CBCs.

As you may already know, upon moving south from the aforementioned states, it’s increasingly likely that your CBC experience will include sightings of winter-challenged-weather songbirds such as wood-warblers.

As a result, CBCs occurring in, for example, southeastern USA states typically document more total Yellow-Rumped individuals (i.e, Yellow-Rumped Warbler may and can be found annually during CBC viewing periods (mid-Dec.-early Jan.) in almost every eastern state east of the Mississipi River except for Minnesota and some to many New England states.

Other COMMONLY detected wood-warbler species seen during CBCs include Orange-Crowned, Yellow-Breasted Chat, Palm, Northern Waterthrush, Northern Parula, Yellow-Throated, Black-and-White, and Ovenbird.

Now, Warbler Guy presents a strange brew of wood-warbler totals from the 2008 CBC season and for various North American “Tally Rally” totals:

- 17 Painted Redstart (Arizona’s Green Valley-Madera Canyon CBC);
- 15 American Redstart (Florida’s Coot Bay-Everglades CBC);
- 70 Black-and-White (Florida’s Coot Bay-Everglades)
- 524 Common Yellowthroat (Texas’ Guadulupe River Delta-McFaddin Family Ranches CBC)
- 17 Wilson’s Warbler at the coastal Orange Co., CA CBC

Monday, November 2, 2009

Three Brief Warbler Questions......(BELOW)

(Drawing of Bachman's Warbler, left*)

(* = My monologue and one-liners about Bachman's Warbler and other topics follow.)

Here’s three brief questions that I’ve received recently. My humble apologies, but I’m hyper-uber busy with deadlines this week for field survey/biological work and teaching (i.e., I’m preparing to teach an Ornithology class at Merritt College that begins soon), so I’ve got a monologue of “one-liners” for answers, below.

1. Warbler Guy: How many wood-warbler (Parulidae Family) members are there within the A.O.U. checklist area (A.O.U = American Ornithological Union)?

Answer: 78 species, including some of the coolest names that even the best namers of cars would likely not have the ingenuity to produce: Fan-tailed Warbler, Buff-rumped Warbler, and Elfin-woods Warbler.

2. Why is Bachman’s Warbler still featured in some field guides (see nearby drawing)?

Answer: I don’t know and I remain puzzled – given that the most recent specimen was collected in 1949 in Mississippi and the last probable breeding pair was seen that same year in South Carolina. Note the last confirmed sightings were near Charleston, South Carolina from 1958 to 1961.

Therefore, if you wish to enliven a boring dinner cocktail party's conversation, then speak louder than normal while mentioning your sighting of this wood-warbler....(smile).

3. Warbler Guy, I know the “Old World” warblers are classified into the family Sylviidae, a different one (among 228 worldwide) than the “New World” wood-warblers family (Parulidae). Given the Sylviidae members primarily occur in a different hemisphere (e.g., where Europe is located), do some ALSO live in the “New World” (North, Central, South America)?

Answer: Yes, the A.O.U. checklist area (see #1 question, above)
includes 12 species, with your best chance for viewing a Sylvid member in Alaska during the summer when the Arctic Warbler is present (Note: A vagrant sighting of Dusky Warbler, a Sylviidae family member, occurred recently in the Santa Cruz, CA area.

Otherwise, good luck finding "Old World" warblers in the lower 48.

No worries, however. Most of our 114 or so wood-warblers in the Americas are prettier than their Old World classmates. We got lucky on the avian spin of the dice there. To wit, you don't hear about too many birders going to see warblers in Europe, correct? On the other hand, wood-warbler watching in the USA is peaking with the piqued interest of millions. Go to Point Pelee or Magee Marsh in the Midwest during the initial two weeks of May and you'll get my drift.

Wednesday, October 21, 2009

Hey, Mr. Warbler Guy: Is a Yellow-Breasted Chat truly a wood-warbler? C’mon, they don’t look like one, act like one, or sound like one.

Answer: Good question, Rob, in Cordelia, CA.

At seven inches from bill tip to tail tip, the Yellow-Breasted Chat (YBCH) is EASILY our largest North American wood-warbler family member. All the other warblers in our area range from 4.25 to 5.5 inches in length. Equally vexing, unlike YBCH, most other wood-warblers have an insect-catching small bill. Consequently, seeing a YBCH’s oversized one — it looks more like a tanager’s in shape and size — leaves you scratching your head.

So does hearing its Northern Mockingbird/Brown Thrasher-like song. Even the YBCH’s skulking, secretive behavior is somewhat strange for a wood-warbler, given many (especially among the 27 Dendroica genus members in North America north of Mexico) are extroverts in fast-forward mode during the breeding season while displaying “hover and glean” foraging behavior in search of insects amidst the tips of branches.

So why is a YBCH considered a wood-warbler? Primarily because researchers use more than birds’ songs, their behavior, their skeletal structure, and their general appearance to define a species (as well as the genera, families and orders of birds that constitute the 9,800 or so species in the world). They also employ blood analysis (i.e., DNA/DNA hybridization techniques) techniques. All of these aforementioned distinguishing techniques form the “Phylogenetic Species Concept” that is broadly accepted by most taxonomical scientists (but only SOME biologists) as an accurate way to determine a species.

Of course, molecular analysis of blood is a somewhat recent development technique for distinguishing birds at the species level. Hearken to pre-DNA analysis, and you stumble upon the studies of one E. Eisenmann. In1962, he called into question the then generally accepted placement of the YBCH in the wood-warblers by pointing out how it is missing jaw muscle, thereby suggesting an affinity with tanagers (Thraupidae family). Eisenmann also argued that the YBCH’s hyoid apparatus (a specialized system of bones and muscles within the avian tongue) differs from that of design present in many songbirds. No matter. Eisenmann lost his tug of war with other experts. Various conscientious objectors in the birding community have similarly raised their voice (and ire) to question the inclusion of YBCH in the wood-warbler family.

Adding fuel to the debate is the American Ornithological Union's checklist of birds where an you an asterisk appears after YBCH's name, denoting that this species is "probably misplaced in the current phylogenetic listing, but data indicating proper placement are not yet available" (see

Nonetheless, YBCH holds tight. It officially remains a wood-warbler.

Stay tuned.

Saturday, October 10, 2009

Warbler Guy: What does Myrtle vs. Audubon's Warbler mean? Are not they both Yellow-Rumped Warbler?

Thanks, Jill in Ocala, Fl.......No worries, Jill —
as even the experts have trouble figuring out how Audubon's and Myrtle fit into the systematic scheme by which Yellow-Rumped Warbler occurs in the majority of states, including Alaska.

Living in a vast range that stretches from our 49th state to Guatemala, consider how this common to abundant species has confounded taxonomic researchers over the years. In turn, it's not surprising that some birders are, likewise, challenged as to what to call a Yellow-Rumped when they see it. Myrtle? Audubon’s? Hooveri? Intergrade (i.e., Hybrid)? — if you’re in Alberta or British Columbia during the breeding season and note a Yellow-Rumped that shares field marks of both Myrtle and Audubon's).

So, given space limitations here, and based on the need to oversimplify the reasons for the split of this species into subspecies (and what a subspecies means in terms of its definition), here’s the current organizatonal "flow-chart" that the experts (e.g., citing approval from the American Ornithological Union that is the ultimate soothsayer in deciding this bird's classification nomenclature) have established for the Yellow-Rumped Warbler:

Five subspecies occur in the Yellow-Rumped Warbler species:


1) Dendroica coronata coronata = Myrtle (Yellow-Rumped) Warbler; 2) D.c. hooveri = Hoover's (Yellow-Rumped) Warbler (not recognized by Jon Dunn and Kimball Garrett's 1997 "Warbler" Field Guide, but this subspecies is acknowledged within the Birds of North American Online). (See if you have a subscription to this $40 per year service; if you need to join, please go to

(#3-#5 among the five subspecies in the species)

3) D.c. auduboni = Audubon's (Yellow-Rumped) Warbler;
4) D.c. nigrifrons = Northwest Mexican Black-fronted (Yellow-Rumped) Warbler) (non-migratory); and
5) D.c. goldmani = Guatemalan Goldman's (Yellow-Rumped Warbler) (non-migratory).

Such an update in the taxonomy of Yellow-Rumped means
my earlier post from 2009 on this “wood-warbler” blog is now outdated.

Previously, Jon Dunn & Kimball Garrett split Yellow-Rumped into six subspecies: two subpecies formed the Myrtle Yellow-Rumped Warbler and four subspecies living in different geographical areas qualified within the Audubon's group.

Got all that? Your eyes are plowing through the snow drifts of words, above, but have not yet resorted to wearing snow tires?

If so, then consider one final thought related to Yellow-Rumps:

It's the word "impressive" -- as in suggesting this term is even too modest a way to describe the Yellow-Rump’s amazing BraveHeart survival ability, given its presence throughout the winter during many years within higher latitudes (i.e., upper Midwest and southern New England) where chilly winters prevail.

On the other hand, where I live in the mild Bay Area of northern California, the over-wintering bar is not as high for Yellow-Rumps whose presence during the non-breeding season includes both visiting populations of Audubon's and Myrtle's. Here, they are a common to abundant sight amid various habitats, including Eucalyptus, Monterey Cypress, and Monterey Pine groves within urban, suburban, and rural habitats.

Talented, refined “birding by ear” listeners are able to determine the Myrtle vs. Audubon's subspecies by each's diagnostic, yet sound-alike call note — a challenging feat, to say the least. In fact, I opine that the difficulty of distinguishing the two subspecies from one another by call is for many birders on par with identifying by sight a week-old Twinkie from one that has aged for two weeks. Not too easy, correct? Notice that I’m mentioning “call note” here because the songs of Myrtle vs. Audubon's are indistinguishable, according to Dunn & Garrett.

As for the multiple drawings devoted to this species on the color plates featured in Dunn and Garrett's Warbler field guide (as drawn by the fine artist and birder Tom Schultz), it exhibits excellent views of the diagnostic field marks germane to each subspecies.

In short, to tell them apart, note how Myrtle is the only subspecies of the four adults to exhibit white in the throat compared to the faint to brilliant yellow sheen seen in the other three subspecies: Audubon's, Black-fronted, and Goldman's.

Tuesday, September 29, 2009

Warbler Guy: Do warblers migrate over the ocean or was this bird (below photo) confused and lost?

Thanks for the question, Kevin.

Here's my answer, though it's a simplified one to your question that deserves more ink than this digital retorte provides.


Given your interesting photo of the Black-Throated Gray Warbler that landed on your boat’s deck while amid the Pacific Ocean, it’s 100% certain that your unfortunate friend is lost and wayward from its normal southern migration route. More exact, no wood-warbler species on the West Coast have yet been discovered to migrate to non-breeding/wintering grounds via an oceanic route.

On the West Coast, only disoriented and/or wind blown wood-warblers show up on offshore islands, such as those often seen by bird banders/researchers stationed at the central California chain of islands called the Farallones. Here, banders have captured in their nets various species of so-called eastern wood-warblers. Others, like the Black-Throated Gray in the photo, below, are wayward sojourners desperate for a wayside to rest upon while fighting to survive in a pelagic habitat that offers no food resources.

Unfortunately, the vast majority of wood-warblers seen resting on boat decks, buoys, and rip-rap along coastal and deep water habitats typically are hatch year birds. Most will either perish while traveling over the Pacific ocean before reaching island refugia such as the Farallones or incur high mortality after being set free by banders that discover them. Some researchers suggest eastern wood-warblers found on the West Coast (including Farallone Island individuals") are inherently "dyslexic" in the sense they do not have the orientation design necessary to complete the classic migration routes that their brethren successfully negotiate each spring and autumn on their north and south peregrinations.

Beyond the West Coast, trans-oceanic migration by songbirds is rare -- and, in the wood-warblers seen in N. America north of Mexico, it is only documented to occur in a few species.

One of them, for example, the Blackpoll is known to contain populations that in autumn perform the high-octane feat of an ocean migration route that totals more than 2,150 miles (NE USA/Maritime Provinces to northern South America).

How do researchers know the Blackpoll performs such a magician's stunt annually?

It's because bird bander's in Bermuda (an island east-southeast of the southeastern USA) band birds in the autumn, and, thereby, sometimes catch Blackpoll in their nets. Evidently, Bermuda is in line with the route over which Blackpoll travel during their southbound migration and this small island serves as a stopover wayside area for Blackpoll that wish to stop and "refuel" before leaving to migrate south again at night.

High-octane is an apt description of the Blackpoll's Herculean task because many leave their "staging" grounds en masse with other Blackpolls and fly en route together as heavyweight butterballs while weighing as much as 26 grams (nearly an ounce) at the beginning of their air treks.

By the end of the Blackpolls' long-distance trip, however, they have been documented to have lost half their starting weights. Emaciated and Twiggy-Thin Blackpoll, therefore, in some cases, are known to digest their muscle to serve as a last resort energy source.

While winging south, researchers have figured Blackpolls burn .08 grams per hour during their three to four days of travel, a process that is a non-stop direct flight, if the Blackpoll does not stop at island refugia such as Bermuda. In comparison, such a weight loss program for club members and gym rats on two legs would mean a 20-pound or more evaporation of girth per day (for the typical weight of 6' tall male or 5'6" female).

Now there's a weight loss program that would attract headlines and lead to a manic panic for (I imagine) a best-selling book titled: "Migrating With a TailWind To A Fat-Free Lifestyle." :-)

Friday, September 18, 2009

Warbler Guy: To help me with my warbler identification skills, can you tell me which warblers look the same year-round and don’t seem to become drab?

Among the 52 wood-warbler species typically seen annually in North America (north of Mexico), only 11 wear their flashy, bright, high-definition (alternate) plumage year-round. The vast majority — the other 41 species — undergo a molt before they migrate, so the males turn drab and less colorful after the breeding season.

Which11 warbler species look similar year-round?:
According to two sources I carefully checked — “Field Guide to Warblers,” (Jon Dunn & Kimball Garrett) and “Identification Guide to North American Birds (Part 1)” (Peter Pyle) — the answer is Golden-Winged, Yellow-Throated, Pine, Prothonotary, Worm-Eating, Swainson’s, Ovenbird, Louisiana Waterthrush, Red-Faced, Painted, and Yellow-Breasted Chat.

Expanding upon the basic facts presented above, most North American birds replace all their feathers during a complete molt that occurs in late summer or fall. The new feathers that develop before the birds leave on migration create an appearance that will be present throughout the fall and into winter. The technical word for this appearance is “basic plumage” because it usually persists longer throughout the year than the breeding (or alternate) plumage stage.

As indicated above, the majority of wood-warblers undergo a second molt that may occur progressively throughout the winter on the non-breeding grounds or as a more rapid molt before they leave to migrate north. This molt is called the peralternate molt and results in alternate plumage (or breeding plumage). In simple terms, think of this molt as providing birds the ability to “alter” their appearance to be colorfully attractive for the breeding season.

Of course, it is the males that most benefit from shedding their basic, non-breeding, drab (basic) plumage and transform into a brighter façade. That’s because the females pick their male partners when nesting occurs on the breeding grounds, a process that begins after migrating males arrive and preceded by the prealternate molt that occurred for them in their non-breeding grounds.

If you’re lucky enough to see warblers performing breeding and courtship displays, then you’ll see first-hand how the pretty males attempt to catch the eye of their female suitors (that are typically slightly more drab in appearance). Courtship poses include various wing gyrations and diving/hovering displays, among other behaviors.

As a closing note, it’s a good idea to remember that not all prealternate molts result in a prettier, more colorful appearance among male birds. Consider three ptarmigan species in the western USA and Alaska that molt from a majestic snow white basic plumage appearance to a more mottled, camouflaged expression that matches their tundra (and other habitat) surroundings and is, thus, more suitable for the ptarmigans’ survival in their summer environs.

Thursday, September 3, 2009

Wisconsin Kirtland's Warbler Nesting Update

(Above, Kirtland’s warbler male at a new Adams County site, June 12 2009.
Photo by USFWS; Joel Trick)


Want to know how many Kirtland's Warbler individuals were seen in WI this past 2009 breeding season?

Which counties?

How the Kirtland's third consecutive year of documented nesting in the state suggests this federally endangered songbird is now an annual nester in Wisconsin? -- in addition to, of course, nesting yearly in at least 12 Michigan counties (where at least 1,803 individuals were confirmed in 2009).

If so, please feel free to visit the following WI DNR link:

Tuesday, August 25, 2009

Warbler Guy, do you know when the warblers begin their autumn migration?

Good question, Neal in the “Midwest,” per your question in the “comments” section of the 8/7/09 article I authored here.

Wood-warbler migration actually begins in the summer by July or August for many species, if you also add in their initial travel in various directions away from breeding grounds (i.e., a behavior that is called “dispersal”). That is to say, unlike the more direct, dawdle-free behavior wood-warblers exhibit as they travel north on favorable tail-winds during spring migration, their post-breeding migration south is often a stuttering, stop-and-start, protracted itinerary.

Weather patterns in August through early October are a principal factor as to when many bird species (including wood-warblers) initiate migration and, subsequently, how far they travel on each segment of their southward night-time journeys. With north and northwest winds at their backs, wood-warblers may travel as many as 100 to 150 miles during a night’s journey.

Then again, feeding layovers for one or more days may occur where wood-warblers find abundant food resources. Likewise, binge eating sessions may be required when their body fat reserves deplete. Excess rain and unfavorable wind conditions also force wood-warblers into holding patterns until conditions improve.

Given the background information mentioned above, note it’s merely a brief and general summary of autumn bird migration patterns. More exact, consider that post-breeding season migration is an obligatory behavior most wood-warblers perform following dispersal from their breeding grounds.

Greeting the season’s initial freezing low temperatures, wood-warblers rudely discover their primary food source — insects, during the breeding season — rapidly disappear from the landscape. Consequently, migration emerges as an imperative survival behavior.

How many warblers migrate? For the majority of North America’s (north of Mexico) 52 annually present warbler species, their journeys begin by mid- to late summer (at the earliest) and no later than early to late autumn. So, for example, “early birds” such Yellow Warbler may begin dispersing/migrating in July, while other populations of the same species may wait until early October to leave for southern latitudes where they’ll spend the non-breeding season.

Other late summer, early-to-leave migrants include Tennessee Warbler, American Redstart, and Louisiana Waterthrush, all of which begin dispersing from northern breeding territories in July. True, uninterrupted migration toward “winter” habitat may not occur for these species (and many other North American wood-warblers) until beyond July and as late as October (and, more rarely, November and December) for some populations.

Only a handful of warbler species either do not migrate or remain annually (or periodically) throughout the winter in higher latitudes as far north as southern Wisconsin, Ohio, New York, and some New England states. This select club of bravehearts includes at least one subspecies of the Common Yellowthroat (among its 13 subspecies that live in North America), Yellow-Rumped Warbler, Palm Warbler, Orange-Crowned Warbler, and Yellow-Breasted Chat.

Which wood-warbler is the earliest to leave its breeding grounds? A leading contender is a subspecies of Orange-Crowned Warbler populations that breeds on the West Coast. Where it breeds in the San Francisco Bay Area, for example, Orange-Crowned often leave its dry and dormant environs by June, retreating to foothill and Sierra Madre mountainous habitat as intermediary “staging ground” habitats where cooler and moister conditions dominate and, thus, host abundant insect food resources.

For more details about the typical annual dates when each North American breeding wood-warbler disperses and/or migrates, see Jon Dunn and Kimball Garrett’s “Warbler” field guide (A list of the best warbler field guides and resources appears in a 10/21/08 article on this blog, so please feel free to scroll down the page and click multiple times on "older posts" to find it.).

More simplified information relating to autumn migration times for most USA-breeding wood-warbler species appears in a “Warbler Tips ID Chart” at my Web site: (After arriving at this site’s home page, click on the button title “Warbler Tips ID Chart.”)

Friday, August 7, 2009

Can you please share the answers to your latest quizzes?

Yes, Jeremy S. (Tucson, AZ). Here’s the answers:

1. Can you name the two hybrid forms that sometimes result when Golden-Winged and Blue-Winged Warbler mate?


Lawrence’s and Brewster’s

2. Can you name two wood-warbler species that are breeding endemics to one USA state?

Tropical Parula and Golden-Cheeked

3. On the West Coast, which wood-warbler is one of the earliest dispersing species after nesting?


Orange-Crowned Warbler, given many disperse and/or migrate from the Bay Area by June.

4. Among the species listed in the 5/29/09 article, which one is considered extinct?


Bachman’s Warbler

5. Common Yellowthroat was often previously named differently in many field guides as XXXXXX Yellowthroat?


Maryland Yellowthroat

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


Wisconsin (as only one documented nest has been found in Ontario during the 1945 breeding season), while Kirtland’s has bred from 2007 through 2009 in Wisconsin.

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


Nashville Warbler, as its two USA subspecies are split into separated (allopatric) populations while nine Yellow Warbler species occur in the USA among the 43 total subspecies within North, Central and South America.

Warbler Guy, do you know why New World warblers are usually more colorful than Old World warblers?

(Townsend's Warbler, above)

Good question, Antoine (in Richmond, VA).

The answer is not obvious nor proven in scientific research.

My explanation relates to how birds evolved and new species became established throughout North America (i.e., a portion of the New World) over eons of time.

As a first step, think about the geographic spot or “epicenter” where our North America wood-warblers originated. That area is the Appalachian Mountain region that served as breeding areas to which tropical species of wood-warblers (such as the colorful Yellow and Black-Throated Green Warbler, to name just two of many species) began migrating and breeding within the distant past.

In turn, new, evolving wood-warbler species spread throughout North America as they colonized habitat when the glaciers melted within northern latitudes 12,000-18,000 years ago. Generation after generation of breeding isolation of these new, pioneering populations from one another allowed distinct appearances to flourish as new species.

So, for instance, “sister,” look-alike, colorful species such as the Black-Throated Green, Hermit, Townsend’s, Golden-Cheeked, and Black-Throated Gray Warbler are considered close first-cousin relatives – though all primarily breed in distinct geographical areas throughout North America that do not overlap.

In fact, experts consider these five warblers a “super species,” with the Black-Throated Green the initial precursor from which the other four look-alike species evolved and spread west and north throughout North America from their Appalachian origins.

As for the generally drab, uncolorful appearance of Old World warbler species (Sylviidae family) that primarily breed in Eurasia, their evolution occurred in a similar fashion to the aforementioned progression of our New World North American wood-warblers (the majority of which occur in the Parulidae family). That is to say, one or more drab, uncolorful original warbler species in the far past were the root species of the evolutionary tree from which other multiple species evolved and spread throughout Europe and Asia.

In short, it’s mere geographical luck that the USA’s location is within the latitudinal migration pathway that colorful neotropical/equatorial New World species chose as they evolved their migrational routes from the south in search of northern breeding territories.

Wednesday, August 5, 2009

Best Buys: Warbler Books

Which are two of the best wood-warbler books?

Here's two covers of publications I own and use often:

- Warblers, Jon Dunn & Kimball Garrett

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

Tuesday, July 28, 2009

Difficult Decisions: Identifying Female Warbler Species

Which are the most difficult wood-warbler female species to identify from one another?

All rise and bow to the Lord of Warbler Identification, as how doth one begin to compile such a lengthy list?

It includes such opponents as Wilson’s vs. Hooded; Yellow-Rumped vs. Cape May; Common Yellowthroat vs. Wilson’s; Wilson’s vs. Yellow; Bay-Breasted vs. Blackpoll (in late summer/autumn) – and I’ve just begun to scratch the surface of this identification game conundrum.

An interesting treatise on this topic appears at the following web site address:

Here, the author (Larry Liese) explores how to distinguish female Yellow, Wilson’s, and Common-Yellowthroat from each other.

(The illustrator of the above graphic is George C. West.)

Tuesday, July 21, 2009

Which wood-warbler populations have fallen precipitously in recent years?

If your answer included "Cerulean Warbler," then you're correct.

Based on information at Cornell of Ornithology's web site (, this Neotropical migratory bird species continues to experience population declines in parts of its range. However, given the Ceruleans low population density and patchy distributions, accurate population trends are difficult to estimate. One ongoing, annual monitoring program -- the Breeding Bird Survey, coordinated by the US Geological Survey -- has compiled data that suggest a 3.8 percent annual decline in populations of Ceruleans since 1966. To adequately protect this species more information is needed about its habitat requirements, breeding biology, and population status, the Cornell web site suggests.

To determine the number of breeding pairs and productivity, describe nesting habitat, and identify potential threats to the population and its habitat, the Cerulean Warbler Atlas Project (CEWAP) employed enthusiastic birders and biologists to survey known and potential Cerulean Warbler breeding sites from 1997 to 2000.

Results from CEWAP will be used to produce management guidelines for Cerulean Warblers. As of December 2000 you can download the final report, "An Atlas of Cerulean Warbler Populations," by conducting a Google search with the aforementioned title in quote marks.

Saturday, July 11, 2009

Lucky 19: Kirtland's Warbler Update in Wisconsin

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


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.

Wednesday, July 8, 2009

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.

Tuesday, June 30, 2009

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.

Wednesday, June 24, 2009

Wisconsin Kirtland's Warbler Nesting Update

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


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:

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.

Tuesday, June 9, 2009

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

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


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:

Friday, May 29, 2009

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.


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

Wednesday, May 13, 2009

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.

Monday, April 27, 2009

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


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

Answer: Nashville


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.


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

Answer: Tanager family

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

Answer: Yellow


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

Answer: Common Yellowthroat

Tuesday, April 21, 2009

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


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:

Wednesday, April 8, 2009

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

Excellent question, Don Y. of Houston, TX.


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.

Tuesday, March 31, 2009

How did the Hermit Warbler get its name?

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


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.

Monday, March 16, 2009

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

Friday, March 6, 2009

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 ( where there’s a button that provides access to the Atlas’ chart (page 39).

Wednesday, February 11, 2009

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?


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.

Tuesday, February 3, 2009

Wilson’s Warbler: Abundant, Yet Vulnerable

You might think the Wilson’s Warbler is one of the most abundant warbler species while traveling through Alaska, most of Canada, and south through the western USA to southern California and New Mexico. Your supposition would largely be correct.

But long-term trend analysis indicate recent population declines, especially in the western portion of the species’ range. The most likely problem is large-scale destruction of riparian habitat.

Nesting on or near the ground at elevations that vary from sea level to the alpine zone, the three subspecies of Wilson’s Warbler encompass a wide geographical area that spans from eastern Canada to Alaska and portions south into Utah, New Mexico and central California.

Interestingly, the subspecies may occur together in non-breeding range, with all three subspecies possible in Panama.

Although it shares its genus name – Wilsonia -- with other wood-warbler species – (Canada and Hooded), Wilson’s is by far the most common. All three species possess rectal bristles (small , highly-sensitive feathers at the base of the bill) that are utilized during “flycatching,” a foraging behavior that can sometimes help with field identification.

Wednesday, January 28, 2009

Mr. Warbler, what’s the difference between “New World” and “Old World” warblers?

Thanks for the question, Barbara S. in Spokane.

Noting the New World is a geographic designation corresponding to the Western Hemisphere, Old World warbler species live within the Eastern Hemisphere areas of Europe, Asia, and Australia – with only a few species (e.g., gnatcatchers) existing in the New World/Americas.

Approximately 350 Old World warblers occur in the Sylviide family. New World warbler species total around 120 species and most of them are in the Parulidae family.
(Approximately 52 are annually seen in the USA north of Mexico, with the most common being Yellow, Common Yellow-throat (above photo), Yellow-Rumped, among others.)

In fact, the Olive Warbler (the sole Peucudramidae family member) is the only non-Parulidae family species among North American wood-warblers to occur north of Mexico.

Note there’s also the Australasian warblers in the Acanthizidae family that include gerygones, thornbills, and scrubwrens,.

This family is native to Australia, Indonesia, New Zealand, and the south-west Pacific. Australia hosts 35 endemic Acanthizidae family members and New Guinea 15. A single species is found in Vanuatu, New Caledonia and the Solomon Islands, and three species occur in the New Zealand region, including endemic species in the Chatham Islands and Norfolk Island. In Asia two species are restricted to Indonesia and another is found in the Philippines and on mainland Asia. Most species are not migratory, with the exception of the gerygones.

Thursday, January 8, 2009

Which wood-warbler travels the longest migration route?

Thanks for the question, David in Studwell, MN.

The answer: Blackpoll

Autumn studies of the routes south-traveling Blackpoll take have been extensive. Through banding at stations where the same individual has been studied, researchers have determined some Blackpolls travel more than 5,000 miles one way from Alaska to Brazil.

For many Blackpoll migrating populations, migration occurs over the Atlantic Ocean from the northeastern United States to Puerto Rico, the Lesser Antilles, or northern South America.

This route averages 1,500-2,000 miles over water, necessitating a potentially non-stop flight of up to 88 hours. To complete this migration feat, many Blackpolls nearly double their body mass and prefer to take advantage of a shift in prevailing wind direction to direct them to their destination.