Monday, October 16, 2017

Warbler Guy, I'm planning an upcoming California birding tour and want to go with a San Francisco birding guide. As I prepare, where do I check for "rare" bird alerts that will reveal which rare California bird species are recent sightings?

Hi Davey:

Here's the answer to your question, above:

To see recent bird species sightings throughout California, feel free to check:

This link features a composite list of all California listserv sites.

Click on one or more as you please to see the latest bird sightings lists posted by


Glad to help:

One "strange but true" facet of California birding relates to how most of the state soon expresses a touch of spring (already!), given the courtship dance of male Anna's hummingbird individuals are often observed this time of year (and especially by November and December, annually).

Initial egg laying by this common, year-round resident hummingbird species occurs as early as December. Multiple broods may be tended by a female during one breeding season, with July and August the latest months each year when final active nests are observed.

As for wood-warblers typically occurring on listservs currently in the SF Bay Area where I often serve as birding guide to hot spots such as Point Reyes National Seashore (Marin Co.) and Bodega Bay (Sonoma Co.), the once abundant in-migration Yellow Warbler (late summer through September) is now a rare sighting, with only the rare individual detected on local San Francisco Bay Area Christmas Bird Count forays.

More typical, it's common to see Yellow-rumped Warbler individuals in many habitats this time of year through March (Audubon's Yellow-rumped Warbler subspecies — Setophaga cornonata auduboni) is the most abundant subspecies in this species to observe, though the West Coast also attracts the occasional to uncommon Myrtle Yellow-rumped Warbler subspecies (Setophaga coronata coronata).

Feel free to review my web site's "Warbler ID Charts," if you wish additional info. and/or see the "Birding Links" articles and my "2017 Nature Watch Calendar" where several wood-warbler articles appear, among other information elements.

Regards, Daniel Edelstein
Consulting Avian Biologist,
Birding Guide,
& Birding Instructor (Merritt College, Oakland, CA)

Tuesday, September 26, 2017

Warbler Guy, are Myrtle and Audubon Yellow-rumped Warbler their own species? Or subspecies?

Fine question, Jerry (in Chicago).

As brief background, in 2017 the American Ornithological Society (AOS) voted down a measure that would have split Yellow-Rumped Warbler into different species* (see two notes, below, for more details related to the aforementioned sentence).

Many of you already know the Yellow-rumped Warbler currently occurs as at least two, three, or four subspecies (varying among taxonomic organization plans). Among the current taxonomic plans, the “Myrtle” group (coronata), and the “Audubon’s” group (auduboni) are accepted in every one, with “Black-fronted” (nigrifrons), and “Goldman’s” (goldmani) also noted in at least one other taxonomic plan. 

NOTE  #1: In the N.A. Birds Online account for this species, the following additional subspecies is described in the "Myrtle group (below photo)":  D. c. hooveri McGregor, 1899: Breeds in central and s.-central Alaska, se. Alaska, Yukon Territory, Mackenzie, and nw. British Columbia; intergrades with auduboni known from Stikine River, AK (). Like nominate coronata, slightly larger, with longer wing (minimum wing length 73.5 mm in females, 75.5 mm in first-year males, and 78.0 mm in adult males); more streaked below (Alternate-plumaged males) or paler brown (females). Characters broadly clinal where range meets that of nominate coronata; for this reason, hooveri not recognized by Hubbard (). More recently, hooveri maintained as valid (, R. Dickerman and P. Unitt pers. comm.).

(Audubon's Yellow-rumped subspecies appears in photo, below.)

NOTE #2: The International Ornithological Congress (IOC) differs from the AOS assessment of this species. It ALREADY splits the Yellow-rumped Warbler, thereby recognizing Audubon's and Myrtle as two species).

(* = The recent AOS rejection vote against creating additional divisions of the Yellow-rumped complex was based, in part, by several committee members who suggested the need for further genetic analysis and determination of the extent of interbreeding in the subspecies’ contact zones where the “Myrtle” group (coronata), and the “Audubon’s” group (auduboni) mix in western Canada. The status of two other subspecies — “Black-fronted” (nigrifrons), and “Goldman’s” (goldmani) remain unchanged according to at least one taxonomic organization plan.

Black-fronted is a resident in Mexico, and Goldman’s occurs only in southernmost Mexico and Guatemala. Neither of these two subspecies has been observed in the American Birding Association geographical area.

As for why, the IOC considers the Myrtle and Audubon's to represent two distinct species, the following 10 naming rules appear to guide the IOC's reasons for adopting name choices, with one or more the reason why the IOC divides the Yellow-rumped Warbler into two species: Myrtle Yellow-rumped Warbler and Audubon's Yellow-rumped Warbler:

1.            - Each species should have one name only.
2.            - A species name must be unique.
3.            - Anglicized names are acceptable.
4.            - Established names should prevail.
5.            - Local names should not have priority.
6.            - Offensive names should be changed.
7.            - Patronyms are acceptable without bias for or against.
8.            - Simplicity and brevity are virtues.
9.            - Use of the word “island” will be limited.
10.          - Species in the same genus may have different group names.

       For more information, see: 

Tuesday, September 12, 2017

Warbler Guy, which warblers are the most confusing to identify because they look like other species? Any tips to identify look-alike warblers?

Jamie (in Boston), I like the pictorial guide to confusing look-alike species in The Warbler Guide
("Comparison Species" corresponding to each warbler account and, in addition, pages 512-519 within the "Similar Non-Warbler Species" section).

(Orange-crowned Warbler is shown above.)

In this section, photographs of these look-alike birds feature both Ruby-crowned and Golden-crowned Kinglet, Bushtit, Verdin, Blue-gray Gnatcatcher, Black-Capped Chickadee, Blue-headed (and Plumbeous and Cassin's) Vireo, Yellow-throated Vireo, Red-eyed Vireo, Warbler Vireo, Philadelphia Vireo, Bell's Vireo, Sparrow species, and Eastern Towhee.

This field guide is excellent and recommend it for many other outstanding features that few other field guides host.

Happy Birding On These Last (Precious) Days Of Summer (!), Daniel
(hosts my resume and my "Birding Tours" addition to
birding articles, etc. at the "Birding Links" tab-button)

Wednesday, August 30, 2017

Warbler Guy, last time I wrote you mentioned late summer is when the initial waves of wood-warblers start migrating, correct? Migrating warblers occur through which date in the Midwest? Warbler dispersal begins when, please?

Joey (in Chicago):

Interesting question that you pose given a recent report from Ryan Brady, an ornithologist/bird researcher/scientist for the Wisconsin DNR. See his list of 20 wood-warbler species that he detected on 8/29/17 near Bayfield/Washburn, WI (near Lake Superior): (Then see more of my commentary, below.)

From: Ryan Brady <>
Subject: [wisb] 20 warbler sp. - Bayfield County
Date: Wed, 30 Aug 2017 01:50:37 +0000

An excellent flight last night brought 20 species of warblers to the trails around my property this morning, including Golden-winged, Blackpolls, Bay-breasteds, Mournings, Palms, Pine, and more. Thrushes were on the move in the morning fog, yielding some Swainson's and my first Gray-cheekeds of the fall. Also had my first Lincoln's Sparrow and a nice push of 3 Yellow-bellied Flycatchers.

Full eBird checklist at

Ryan Brady
Washburn, Bayfield County, WI


Responding more to your questions, above:

Dispersal begins earlier than migration. Fledgings leave the nest and begin their independent lives while foraging BEFORE eventually migrating. So newborns may linger in an area near where they were born. By mid- to late-August at upper Midwest latitudes, some begin to migrate south while other species -- such as American Redstart, Palm Warbler, Yellow-rumped Warbler, among others — may have a protracted migration. These three species are among the latest to leave northern latitudes, with some Yellow-rumped and Palm remaining through November and December -- and, in recent years, some of both species persisting through Christmas Bird Count surveys in the upper Midwest (and even remaining throughout the winter in some cases). Pine Warbler may also persist late while sometimes feeding at seed feeders after an insect fauna is depleted with freezing temperatures.

A nice resource to read about breeding vs. non-breeding ground ranges of wood-warblers is in Warblers (the field guide from 1998 by Jon Dunn & Kimball Garrett). Its information is dated in spots, but most of the text remains valid. As a more updated complement, I also refer to the fantastic The Warbler Guide (Tom Stephenson & Scott Whittle, Princeton University Press, 2013). This guide's range maps for migration and breeding/non-breeding ranges more accurate in some cases than Warblers, with more comprehensive photos for each species. You won't be sorry for purchasing both books.

Enjoy the migration, everyone....and time for my raptor class at Merritt College to begin next week (BIOL 80A, Raptors Of The San Francisco Bay Area....via

Regards, Daniel (hosts my "Birding Tours" information)

Friday, August 11, 2017

Warbler Guy, did the proposal to split Yellow-rumped Warbler into three species pass? Or is the Yellow-rumped Warbler still considered three subspecies by the American Ornithological Society (AOS)?

No, sorry, Kristi (in Middleton, CA): The American Ornithological Society did NOT pass this proposal in 2017.Here's the comments from the AOS Committee on Classification and Nomenclature (North & Middle America committee members as to why this proposal did not pass: (Regards, Daniel Edelstein, Avian Biologist & Birding Guide,

Proposal: Split Yellow-rumped Warbler Setophaga coronata into three species
YES - 1 without comment.
YES. A side note – The Toews paper (published in The Auk) states in the introduction "….the complex is currently treated as a single species, Setophaga coronata, by the American Ornithologists' Union, but as 3 species by the International Ornithological Committee (IOC); we used the IOC taxonomy in this article." I think AOU publications should follow AOU taxonomy. This point should to be made to the editor, if it hasn't already.
YES to split of goldmani, given how well-differentiated genetically and morphologically it is. A weak YES to split of coronatus and auduboni (despite the hybrid zone), given the indirect evidence for post-mating isolating mechanisms (which are after all isolating mechanisms), their different calls, and their differing morphology.
YES. First, I think the level of plumage and genetic differentiation between goldmani and other coronata taxa is comparable to differences among species in other closely related species groups in Setophaga. Therefore goldmani should be treated as a species. In regards to coronata/auduboni, the lack of assortative mating is troublesome, but I think the proposal does an adequate job to show that selection against hybrids is operating at some scale, as is selection for traits that are differentiating these taxa. This selection appears to be stable or increasing, which will further barriers to introgression through time.
YES. A strong yes, in fact. I feel that the weight of the evidence is now strongly in favor of this re-split. The genomic evidence is very strong that (for example) auduboni and coronata are well-differentiated, and that some regions of their genomes are under differential selection. Within the hybrid zone there appears to be no assortative mating (= little prezygotic isolation), but there does appear to be only limited genetic introgression and some form of selection against hybrids (= substantial postzygotic isolation). This scenario is the one theoretically expected in the early stages of full speciation under the BSC, where the postzygotic fitness consequences of hybridization impose selection (aka reinforcement) that leads to the later evolution of pre-mating isolation. Moreover, the hybrid zone itself is narrow and apparently stable, despite the vast population sizes of these birds and their very high dispersal potential. And phenotypically they are very easily distinguished. On an aside: the evidence is even stronger for recognizing goldmani as a full species.
NO. The problem here as I see it is the hybrid zone between coronata and auduboni. There is no evidence that there is assortative mating where they come together, and they hybridize like crazy. The evidence of postzygotic selection against hybrids (Toews and Irwin 2009) is important, and I agree it is likely that "some form of selection impedes the fusion of the Myrtle and Audubon’s forms." (T & I 2009:3057). But this is a long way from species-level stuff. Evidence of adaptation is not evidence of speciation, and I think that may be being confused here: a lot of adaptation occurs between populations that are not species. Selection for particular alleles across geographic space and a shift in such a selection regime across subspecies boundaries and non-assortative (and extensive) mating at a contact zone screams "subspecies" to me.
Brelsford & Irwin (2009) said it well in their title "Incipient speciation despite little assortative mating," and in the abstract: "Pairing data indicate that assortative mating is either very weak or absent…"  and "…there is moderate reproductive isolation between these populations…" Adaptation to different selection regimes (probably natural and sexual in this case) is great, and while reinforcement does appear to be occurring, it is only able to apparently stabilize what are actually pretty high rates of gene flow at least away from the contact zones." Toews et al. (2016) included multiple samples from each subspecies, but did not sample birds from the contact zone between S. c. coronata and S. c. auduboni." This leads to their uncertainty over whether more homogenized regions of the genome are due to hybridization or gene flow. Let me tell you from the specimens: gene flow will be responsible for a lot of it. I agree that "Clearly, performing additional genomic assays from birds across regions of sympatry will be beneficial." (Toews et al. 2016:708).
These populations are a wonderful example of the speciation process, but the birds' behavior in contact shows that they fit the concept of subspecies rather than the closer-to-evolutionary-independence we expect from full biological species. In sum, I do not consider there to be enough reproductive isolation yet established to make these anything more than a subspecies pair headed perhaps at some distant date to become (nearly) fully reproductively isolated. Saying that they are so now (biological species) suggests that we’re guessing a long way into the future, and that the substantial levels of gene flow occurring now are somehow not consequential. They may be genomically diagnosable, but they are far from genomically independent, given levels of gene flow.
Genetic differentiation of goldmani is expected for an isolated population smaller than the others, simply through drift (as Toews et al. 2016:706 noted). So genetic distinctiveness and isolation are not good metrics of limits of biological species, in my view. Phenotype needs to be more rigorously assessed in relation to other closely related members, and coronata and auduboni suggest well-differentiated subspecies are still not reproductively isolated. So as to whether goldmani is a species, I think we will want to know a great deal more.
NO. Maintain as one species, for now. I'm sorry, but I just can't get past the issue "of little assortative mating in the hybrid zone." If you believe in the BSC as I do, that's pretty much it. And I'm not sure what the "indirect evidence for selection against hybrids in the contact zone" means. I can readily identify these two ssp. groups. They not only look different, both in alternate and basic plumage, their call notes sound different. I think songs differ too, but both have a variety of songs. Here in the West, "Myrtles" prefer more mesic habitats. The motion alludes to the NACC having merged various taxa in this complex, notably hooveri with nominate coronata and memorablis with auduboni. I don’t think the NACC has taken any position on ssp. since 1957. I believe memorablis is mainly a size ssp. (larger), but plumage differences have been described from hooveri, especially in basic plumage.
I look at lots of Yellow-rumped Warblers here in the West, and have only a few times been pretty sure of hybrids. On the other hand, I don't look that carefully at every bird, and identifying a basic plumaged bird would be pretty problematical. I did see several hybrids in summer along the Stikine River, southeast Alaska, and I believe there are pretty much all hybrids along one river, I think in northern BC.
One thing that interests me is the disgestive system of this species. "Myrtles" are well-studied and they are able to digest bayberries, wax myrtle berries, poison ivy and poison oak berries, something that other wood warblers can't do. That's why "Myrtles" winter so far north, as far north as the southern Great Lakes and Nova Scotia and they can be abundant in mid-winter on the Mid-Atlantic coast. Are Audubon's able to digest these berries as easily with comparable plants in the West?
Anyway, for now, I'm comfortable with a one species concept. As for nigrifrons I would be very surprised that they merit being treated as a separate species. I've seen them in Chihuahua and yes they did look blacker, but they sounded like "Audubon's" farther north. The distance isn't that far from the Sky Islands of the Southwest, where intergrades have been noted in southwest New Mexico and southeast Arizona. As for goldmani this is an interesting case that merits further study. I'm told that folks seeing them in Guatemala report them giving very different songs, but don't know if there are recordings (maybe some put on a web site?). I did not see them on the hike for the Horned Guans in southwest Chiapas, so guess they occur elsewhere in Chiapas. The BNA account (Hunt and Flaspohler 1998) state: "In this subspecies, Alternate and Basic plumages of adult males nearly identical; there may be no Prealternate molt (Hubbard 1970, 1980)."  If that's true, it certainly is suggestive for separate species status.
Hunt, P.D., and D.J. Flaspohler. 1998. Yellow-rumped Warbler (Dendroica coronate). In The Birds of North America, No. 376 (A. Poole and F. Gill, eds.).  The Birds of North America, Inc., Philadelphia, PA.
NO. At the outset, I would like to make it clear that I have always "disliked" the Myrtle-Audubon’s lump because in my tidy little worldview, if I can identify two taxa by call note as far away as I can see them, they "have to be" species.  In fact, to this day, I use "Myrtle" and "Audubon’s" in my field notes etc. Also at the outset, I find these genetic data interesting and important to understanding the history and process of diversification, and I applaud the authors of the recent papers for making substantial progress. But application of my tidy little worldview to real world situations is, predictably, not always tidy, and application of genetic data to taxonomy is not always straightforward.
Specifically, as confirmed by these recent papers, there is no evidence for assortative mating at the Audubon’s-Myrtle contact zone. Hubbard's original results based on phenotype are confirmed by genetic analyses. Despite the call note differences and fairly conspicuous plumage differences, they are not isolating mechanisms – the two taxa treat each other as "same" where given the chance to show us the relevance of these characters --- these differences evidently make no difference when it comes to mate choice. So, if these two taxa don’t treat each other as different species (my version of BSC), why should we? Perhaps rescuing my tidy worldview is that as far as is known songs of Audubon's and Myrtle are not readily distinguishable, although I don't think this has been adequately studied. Thus, perhaps it isn't a surprise that the two are not reproductively isolated. Toews et al. (2016) used song playback to capture individuals, and I wish they had reported on the details of this, i.e. whether responses were equivalent, etc.
The authors found evidence for selection against hybrids away from the contact zone and interpret that as evidence for reproductive isolation. This is the same interpretation of the BSC that, unfortunately, allowed the Scrub Jay split to pass, a result with which I strongly disagree. Neglected in this interpretation of the BSC is that there is presumably selection against intergrades away from the contact zone in EVERY parapatric subspecies pair. Otherwise, there would be a smooth cline between subspecies taxa and thus  …. they would not be treated as valid subspecies. Presumably natural selection favors the phenotype-genotype combination that characterizes the populations of diagnosable subspecies away from zones of intergradation. The only "escape clause" from this conclusion is that the situation is not in equilibrium. However, because most subspecies follow biogeographic patterns, selection favoring those phenotype-genotype plateaus is implied. Therefore, the phenotypic and genetic results of the recent studies favor ranking them as subspecies, not species, opposite of their published recommendations and those of the proposal. In other words, if Myrtle and Audubon’s are ranked as species under this interpretation of the BSC, then all parapatric, diagnosable subspecies with zones of introgression should also be elevated to species rank.
As for ranking the allotaxa goldmani and nigrifrons as separate species, this would require showing that these taxa have diverged from coronata and each other in song more so than coronata and auduboni have, preferably also with playback trials. Such trials and comparative analyses of vocalizations have obvious problems in interpretation … but so does every set of criteria for species delimitation. What song and playback trials have going for them is that they consistently predict absence or presence of free gene flow between parapatric and sympatric taxa --- thus, they work, empirically, for predicting the all-important process of gene flow (as in the Toews-Irwin study of Winter vs. Pacific wrens). As for the problems with use of song in oscines because it is "learned," this oversimplification should not be perpetuated. First, oscines are genetically hard-wired to learn there "own" songs --- otherwise, for example, in areas where multiple wood-warblers are syntopic, they would all just sing the same Esperanto song. Second, experiments show that some components of song are genetically determined: genetics constrains which components of song are learned vs. inherited. I look forward to seeing published results on song differences (as hinted in the proposal).
I end with a string of minor comments on the evidence. (1) Because as far as I can tell, no specimens were collected, all interpretations of phenotype are evidently based on in-hand inspection in the field; perhaps digging into some of the background studies would reveal that there are archived photos for each individual? (2) As for the finding that nigrifrons and goldmani are reciprocally monophyletic, although this has an awesome ring to it, keep in mind that it is based on a limited N of individuals and loci, and so in any such statements, one additional sample might erase such proclamations, i.e. all such proclamations should be accompanied with the qualifier "based on N individuals and loci." (3) As for the general finding that all four taxa are genetically defined, we "already know this" assuming that the plumage characters that define the four taxa have a genetic basis. That neutral loci also reflect the genetic differences underlying the phenotypic differences is interesting but taxonomically not particularly relevant. (4) That there is no gene flow between auduboni and nigrifrons despite nonbreeding sympatry is expected; the only wintering audubonithat might remain in the range of nigrifrons during the breeding season are probably defective individuals that would be unlikely to breed, and even if they did, the rarity of those events might make them difficult to detect without much larger N. (5) I really look forward to studies of the potential contact zones between auduboni and nigrifrons.
NO. After reading the commentary from both the pro-split and pro-lump camps, I think that leaving these taxa together best represents the admittedly complex and somewhat intermediate situation that these taxa represent. I am open to being persuaded otherwise, however.
NO. Like the other "No" votes here, I think that the lack of assortative mating in the contact zone between coronata and auduboni argues against recognizing them as biological species - along with the lack of known song differences. It's unfortunate that the genomic data didn't include sampling in/near the contact zone. I wonder why those samples were not included? I could possibly be convinced to split goldmani given genetic and morphologic differences, but would like to see the unpublished data on vocal differences.