• Welcome to BirdForum, the internet's largest birding community with thousands of members from all over the world. The forums are dedicated to wild birds, birding, binoculars and equipment and all that goes with it.

    Please register for an account to take part in the discussions in the forum, post your pictures in the gallery and more.
ZEISS. Discover the fascinating world of birds, and win a birding trip to Columbia

Warbling Vireo (1 Viewer)

Richard Klim

-------------------------
Andrew Spencer, Earbirding.com, 30 Apr 2012: Identifying Eastern and Western Warbling Vireos.

Eastern Warbling Vireo Vireo [g] gilvus (monotypic) and Western Warbling Vireo V [g] swainsoni (sometimes 'swainsonii') are recognised as distinct species by Monroe & Sibley 1993.
[Cape Warbling Vireo V [g] victoriae has also been suggested as a species.]

Brewer 2010 (HBW 15).

Gardali & Ballard 2000 (BNA Online):
Systematics
More than 1 species may exist within Warbling Vireo as currently classified (Am. Ornithol. Union 1998). Two species (Sibley and Monroe 1990) or even 3 species (Sibley 1996) sometimes recognized. Differences in morphology (especially overall size and size of bill), possibly voice (J. Barlow and B. McGillivray unpubl.), genetics (Johnson et al. 1988, Murray et al. 1994), and ecology (differing Prebasic molt strategies described by Voelker and Rohwer [1998]; subtle differences in breeding habitat noted in Semenchuk 1992; and different wintering areas). More study needed, however, from across range, not just areas of potential overlap (Alberta), and from disjunct populations (s. Baja and some mainland Mexico breeders poorly known), and closely related taxa (e.g., Brown-capped Vireo). Studies where Vireo gilvus swainsoni and nominate V. g. gilvus co-occur in Alberta (J. C. Barlow pers. comm.) and Montana (A. J. Banks pers. comm.) are ongoing.

Geographic Variation
Populations in western North America (se. Alaska, s. Yukon Territory, n. Alberta south through Rocky Mtns.) have slighter bill that is less swollen (smaller average depth and width) and more extensively dark upper mandible than eastern populations (central Alberta south and east). Isolated breeding population in extreme s. Baja (V. g. victoriae), however, approaches eastern birds (nominate gilvus) in this swelling of bill. Western North American birds also average about 25% smaller in body size (but with relatively longer tail) and tend to show more contrast between crown and rest of upperparts, which tend to be more tinged olive green, and show less yellow on underparts than eastern populations. Song said to differ where eastern and western populations meet in central Alberta, western birds tending to have less musical, more choppy song (higher tones and more breaks and peaks; see Sounds: vocalizations, below); uncertain whether these differences consistent among all western and eastern birds, and variation exists within each region. In the West, Warbling Vireos of Rocky Mtns. largest, with darker crowns and duller upperparts, compared with those to the south and west, where crown sometimes not particularly dark. Some southern birds of eastern population (nominate gilvus) may have less swollen bills than those in north. Above mainly based on Phillips 1991 (see for details).
Information on genetic variation, based on very limited sample sizes, show differences across range. Allozyme data found Nei's genetic distances between 0.103 and 0.076 between samples of V. g. swainsoni, "V. g. leucopolius," and V. g. gilvus (Johnson et al. 1988). Analysis of mitochondrial DNA (cytochrome b gene) from Alberta of swainsonii and nominate gilvus showed about 3% sequence divergence (Murray et al. 1994).

Subspecies
Most recent treatment is by Phillips (1991), who recognized 5 subspecies tentatively divided into 2 species. Classification by Blake (1968) recognized 6 subspecies within Warbling Vireo (excluding Brown-capped Vireo taxa lumped by this author under Warbling Vireo). Subspecies divided into 2 groups by Am. Ornithol. Union (1998), and this arrangement followed here, using taxa recognized by Phillips (1991). Although there are differences between eastern and western groups, Phillips (1991) stated that swainsonii is dubiously distinct at the species level, noting evidence of hybridization (Banff, Alberta) and that no single morphological character distinguishes all gilvus group from swainsonii group.

Western Warbling-Vireo (Swainsoni Group).
Small-billed, more extensively dark on upper mandible, small body size (see Measurements, below), generally more olive green on upperparts and darker gray on crown, Prebasic molt completed after leaving breeding grounds; winters in Mexico. ...

Eastern Warbling-Vireo (Gilvus Group).
Bill averages wider and deeper (more swollen), upper mandible with more extensive pale area, body size larger, upperparts duller and grayer (including crown, which differs only slightly from back), completes Prebasic molt on breeding grounds; winters in Central America (south of Isthmus of Tehuantepec) from s.-central Chiapas south to Nicaragua. ...
 

mb1848

Well-known member
"Western Warbling Vireo V [g] swainsoni (sometimes 'swainsonii')"
The NACC in 2009-A-14 changed spelling from swainsonii to swainsoni based on ICZN Code 24.2.4. In the original description Baird used both spellings. The NACC picked as the first reviser Baird in 1866.
 

Jacana

Will Jones
Hungary

Cryptic speciation in the Warbling Vireo (Vireo gilvus)​

Scott F Lovell, M Ross Lein, Sean M Rogers
Ornithology, ukaa071, https://doi.org/10.1093/ornithology/ukaa071

Eastern (Vireo gilvus gilvus) and western (V. g. swainsoni) forms of the Warbling Vireo have essentially allopatric breeding ranges across north-central North America, but come into contact in central Alberta, Canada. In 1986, Jon Barlow presented preliminary morphological and song evidence suggesting that the Warbling Vireo complex might comprise more than one valid species. However, to date, Barlow’s suggestion is supported by only limited DNA evidence, demonstration of molt and migration differences between the taxa, and anecdotal accounts of differences in song, morphology, plumage, and ecology. We analyzed variation in both mitochondrial and nuclear DNA in birds from Alberta and surrounding areas to determine the levels of genetic differentiation and hybridization occurring in the contact zone, and whether the two taxa warrant recognition as separate biological species. Our analyses reveal that Warbling Vireos in Alberta and the surrounding areas are separated into two well-defined, genetically differentiated, and monophyletic clades corresponding to previously recognized taxonomic groups. The two taxa come into contact in a narrow (~85 km) zone in Barrhead County, northwest of Edmonton, Alberta. They show evidence of limited hybridization. The distinct genetic differences are maintained in the contact zone, where individuals of the two taxa may occupy neighboring territories. Differences in spring arrival dates, molt schedules, and migration routes indicate that a migratory divide may play an important role in reproductive isolation. We suggest that the two taxa are distinct cryptic species: an eastern form, Vireo gilvus, and a western form, Vireo swainsoni.
 

njlarsen

Gallery Moderator
Opus Editor
Supporter
Barbados
Bring it on, I am ready for the armchair tick! The one thing I am not sure about: how far south do western group members migrate? Are birds in Costa Rica identifiable by range?

Niels
 

pbjosh

missing the neotropics
Switzerland
Niels,

Suddenly the separation of Red-eyed and Chivi Vireo in S America is looking pretty trivial eh? 🤣
 

Jacana

Will Jones
Hungary
There's a potential fly in the ointment, as this study only looks at the Alberta contact zone, and doesn't take into account any samples from other populations, meaning that taxonomic bodies might want to hold off on making a decision until the other three species are better sampled.

Still, it's encouraging for the armchair tickers!
 

dantheman

Bah humbug

Cryptic speciation in the Warbling Vireo (Vireo gilvus)​

Scott F Lovell, M Ross Lein, Sean M Rogers
Ornithology, ukaa071, https://doi.org/10.1093/ornithology/ukaa071

Eastern (Vireo gilvus gilvus) and western (V. g. swainsoni) forms of the Warbling Vireo have essentially allopatric breeding ranges across north-central North America, but come into contact in central Alberta, Canada. In 1986, Jon Barlow presented preliminary morphological and song evidence suggesting that the Warbling Vireo complex might comprise more than one valid species. However, to date, Barlow’s suggestion is supported by only limited DNA evidence, demonstration of molt and migration differences between the taxa, and anecdotal accounts of differences in song, morphology, plumage, and ecology. We analyzed variation in both mitochondrial and nuclear DNA in birds from Alberta and surrounding areas to determine the levels of genetic differentiation and hybridization occurring in the contact zone, and whether the two taxa warrant recognition as separate biological species. Our analyses reveal that Warbling Vireos in Alberta and the surrounding areas are separated into two well-defined, genetically differentiated, and monophyletic clades corresponding to previously recognized taxonomic groups. The two taxa come into contact in a narrow (~85 km) zone in Barrhead County, northwest of Edmonton, Alberta. They show evidence of limited hybridization. The distinct genetic differences are maintained in the contact zone, where individuals of the two taxa may occupy neighboring territories. Differences in spring arrival dates, molt schedules, and migration routes indicate that a migratory divide may play an important role in reproductive isolation. We suggest that the two taxa are distinct cryptic species: an eastern form, Vireo gilvus, and a western form, Vireo swainsoni.
Presume they'll all be hoping to get a medal if this happens?
 
Last edited:

Mysticete

Well-known member
United States
Long-awaited and not a huge surprise. Wonder if this will show up in this year's AOS proposals, or if is too late in the year.

Now we just need someone to publish on the Western vs Eastern Marsh Wren situation...
 

Xenospiza

Distracted
Supporter
I don't think I have ever heard or read the English word "dun". It doesn't differentiate between the two either: they are really not that different at all... They're boring-looking vireos and I see no issues with a boring set of names such as Eastern and Western Warbling Vireo.
(Funnily this mimics E and W Orphean Warbler in the Palearctic, where the lumped species was also named after its singing qualities).
 

Paul Clapham

Well-known member
Canada
Clements/eBird already uses "Eastern" and "Western" for the sub-specific forms, as did HBW when it was still online. So I don't think those are going to be controversial choices if the split is accepted.
 

Kirk Roth

Well-known member
I don't think I have ever heard or read the English word "dun". It doesn't differentiate between the two either: they are really not that different at all... They're boring-looking vireos and I see no issues with a boring set of names such as Eastern and Western Warbling Vireo.
(Funnily this mimics E and W Orphean Warbler in the Palearctic, where the lumped species was also named after its singing qualities).

But you've heard of a Dunlin, right?

In addition to the shorebird, the word hangs on well enough in equestrian circles.

Aside from the description of a very neutral brownish gray, a secondary meaning of the word is along the lines of "dull or drab." So perhaps this is perfect for a "boring-looking vireo!" I have significant doubts that anyone will adopt "Dun Vireo" as a name, but I do like the suggestion.
 

Mysticete

Well-known member
United States
I think western and eastern are fine. It's hard to find many other creative ways to name them, given how similar the morphology is. The only other thing I could think of is maybe referencing the song, since that is the most distinct feature separating the two forms.
 
ZEISS. Discover the fascinating world of birds, and win a birding trip to Columbia
ZEISS. Discover the fascinating world of birds, and win a birding trip to Colombia
ZEISS. Discover the fascinating world of birds, and win a birding trip to Colombia

Users who are viewing this thread

Top