The next 10 ABA (North American) splits - 2022 (1 Viewer)

[Mysticete]

I've tried to find additional references for this as well, and have largely come up empty, especially as there doesn't appear to be much vocal differentiation?

Another one I have heard mentioned, I think by David Sibley in a blog post? Was Golden-crowned Kinglet. Which biogeographically would make sense, but I haven't seen much work suggesting this.

For what it's worth, the recent Costa Rica/Belize Field Guides that Steve Howell was involved with discuss the Olive-sided Flycatcher possible split, describing the Western vs Boreal forms as having different vocalizations. However they are certainly cryptic and from description it doesn't sound like it's possible to tell the two species apart based on morphology.

My list for top ten is mostly the same, although I would add a three-way split of White-breasted Nuthatch given the most recent paper, which presents at least as solid as argument as the Steller's Jay split.

Steller's Jay
White-breasted Nuthatch
Yellow-rumped Warbler
Fox Sparrow
Spruce Grouse
Savannah Sparrow
Canada Jay
Warbling Vireo
Great Blue Heron
Black Noddy

 

[Jacana]

For what it's worth, the recent Costa Rica/Belize Field Guides that Steve Howell was involved with discuss the Olive-sided Flycatcher possible split, describing the Western vs Boreal forms as having different vocalizations. However they are certainly cryptic and from description it doesn't sound like it's possible to tell the two species apart based on morphology.

My list for top ten is mostly the same, although I would add a three-way split of White-breasted Nuthatch given the most recent paper, which presents at least as solid as argument as the Steller's Jay split.

Steller's Jay
White-breasted Nuthatch
Yellow-rumped Warbler
Fox Sparrow
Spruce Grouse
Savannah Sparrow
Canada Jay
Warbling Vireo
Great Blue Heron
Black Noddy

Why have you discarded Willet, as opposed to one of the others?

 

[Mysticete]

Willet would be number 11: It doesn't have the advantage of being split by any other checklist (I don't think...unless Birdlife split it and I am forgetting about it), and hence WGAC is not likely to assess it. There are also AFAIK no new studies published since the last AOS proposal that would cause the NACC to change their mind. So while I think it will be split someday, I think its further off than other birds in the list.

Of course, one new study could easily change things, and for all I know someone is currently writing up that paper as we speak.

 

[pbjosh]

Forgive my poor memory but was there good genetic sampling in prior studies of Willet? It’s an interesting case. Two populations that can be told apart but how much do they behave like good species in terms of genetic separation / haplotype networks, and is there any estimated time of separation? There are plenty of other species out there with varied habitat use and subtle vocal differences. For me the most striking thing about the Willet is the strong difference in habitats, but I guess that could either be really old and they’ve not separated in obvious ways, or really recent and they’re incipient species.

I won’t try to play the game of trying to guess what’s next based on WGAC and NACC and whatnot, though it’s fun to read this discussion.

Also, I would suggest that some of the most overdue / obvious splits that would affect ABA birds though not add species to the ABA list are island forms of House Wren (Cozumel + Caribbean forms), Sumichrast’s / Oaxacan / whatever it would be called Scrub-Jay, Guatemalan Pymgy-Owl (if not further splits there, comment below), and Goldman’s (or new name) Warbler, Sharp-shinned Hawk (Birds S to Cen Mexico vs Chiaps/GT vs Andes vs SE S America), Cuban Meadowlark, and I’m certain I’m forgetting a few.

Band-rumped Storm-Petrel seems overdue, there is a pretty good paper on it and that would result in a new bird for the ABA area (Hawaiian birds would be distinct from nominate and Monteiro’s in the N Atlantic). But I don’t think even HBW splits it beyond Monteiro’s?

Speaking of the Glaucidiums, I’m also surprised that there seems to be little discussion and no studies of N Pymgy-Owl in general, just the odd anecdotal comments both in support of splitting up to 4 ways vs comments of “meh there is a lot of voice overlap” (which I’ve not experienced but don’t claim to be any sort of expert).

There’s actually quite a laundry list of unstudied / little discussed birds in Middle America… San Lucas Robin, Chiapas/GT Plumbeous Vireo, Rock Wren populations from Chiapas S, etc…

 

[pbjosh]

Another fun question is what is the next lump? Cassia Crossbill or Redpoll or ??

 

[njlarsen]

For the almost ABA species: Red-legged Thrush into two species (three-way split less likely).
Niels

 

[Mysticete]

Another fun question is what is the next lump? Cassia Crossbill or Redpoll or ??

Bicknell's Thrush could be a contender as well.

 

[Mysticete]

Forgive my poor memory but was there good genetic sampling in prior studies of Willet? It’s an interesting case. Two populations that can be told apart but how much do they behave like good species in terms of genetic separation / haplotype networks, and is there any estimated time of separation? There are plenty of other species out there with varied habitat use and subtle vocal differences. For me the most striking thing about the Willet is the strong difference in habitats, but I guess that could either be really old and they’ve not separated in obvious ways, or really recent and they’re incipient species.

There is a genetics paper on the Willet from 2016, and a proposal the following year. There were 6 in favor and 5 against, but because NACC uses a supermajority voting system, the proposal failed. The arguments against seem to center on sample size, desire for more playback, and some members being uncomfortable with splitting something that acoustically, morphologically, and genetically were so similar, at least compared to other shorebird sister species.

 

[cajanuma]

For what it's worth, the recent Costa Rica/Belize Field Guides that Steve Howell was involved with discuss the Olive-sided Flycatcher possible split, describing the Western vs Boreal forms as having different vocalizations. However they are certainly cryptic and from description it doesn't sound like it's possible to tell the two species apart based on morphology.

I was surprised that the new Lee & Birch Flycatcher guide makes no mention of this. Still in a quick comparison of recordings on xeno-canto the differences seem real to my ear, and Howell's descriptions in his Costa Rica guides are very good renditions.

A Western bird from Colorado: XC13845 Olive-sided Flycatcher (Contopus cooperi) ("wot! peeves you" is how Howell describes it)
An Eastern bird from Quebec: XC186316 Olive-sided Flycatcher (Contopus cooperi) ("whit free beeh")

I guess the name majorinus is available for this Western population? It's the subspecies from California and based on xc recordings it sounds like the other Western ones, which are currently included in nominate cooperi.

 

[awiner]

Forgive my poor memory but was there good genetic sampling in prior studies of Willet? It’s an interesting case. Two populations that can be told apart but how much do they behave like good species in terms of genetic separation / haplotype networks, and is there any estimated time of separation? There are plenty of other species out there with varied habitat use and subtle vocal differences. For me the most striking thing about the Willet is the strong difference in habitats, but I guess that could either be really old and they’ve not separated in obvious ways, or really recent and they’re incipient species.

I won’t try to play the game of trying to guess what’s next based on WGAC and NACC and whatnot, though it’s fun to read this discussion.

Also, I would suggest that some of the most overdue / obvious splits that would affect ABA birds though not add species to the ABA list are island forms of House Wren (Cozumel + Caribbean forms), Sumichrast’s / Oaxacan / whatever it would be called Scrub-Jay, Guatemalan Pymgy-Owl (if not further splits there, comment below), and Goldman’s (or new name) Warbler, Sharp-shinned Hawk (Birds S to Cen Mexico vs Chiaps/GT vs Andes vs SE S America), Cuban Meadowlark, and I’m certain I’m forgetting a few.

Band-rumped Storm-Petrel seems overdue, there is a pretty good paper on it and that would result in a new bird for the ABA area (Hawaiian birds would be distinct from nominate and Monteiro’s in the N Atlantic). But I don’t think even HBW splits it beyond Monteiro’s?

Speaking of the Glaucidiums, I’m also surprised that there seems to be little discussion and no studies of N Pymgy-Owl in general, just the odd anecdotal comments both in support of splitting up to 4 ways vs comments of “meh there is a lot of voice overlap” (which I’ve not experienced but don’t claim to be any sort of expert).

There’s actually quite a laundry list of unstudied / little discussed birds in Middle America… San Lucas Robin, Chiapas/GT Plumbeous Vireo, Rock Wren populations from Chiapas S, etc…

Sharp-shinned Hawk - yes, but also or especially the forms in the Caribbean.

 

[raymie]

My list for top ten is mostly the same, although I would add a three-way split of White-breasted Nuthatch given the most recent paper, which presents at least as solid as argument as the Steller's Jay split.

Is there a recent paper on the nuthatch split?

 

[l_raty]

Is there a recent paper on the nuthatch split?

I've not seen the actual thing, but : https://doi.org/10.1111/mec.17169

What are the recent papers on black noddies ?

 

[Mysticete]

I've not seen the actual thing, but : https://doi.org/10.1111/mec.17169

What are the recent papers on black noddies ?

Apparently so far unpublished, but I have heard that Pyle (I think) and co are working on a manuscript on the situation. I can't now find any of the sources for this unfortunately.

 

[Paul Clapham]

Willet would be number 11: It doesn't have the advantage of being split by any other checklist (I don't think...unless Birdlife split it and I am forgetting about it), and hence WGAC is not likely to assess it.

TiF has split it, but no, WGAC isn't paying any attention to that as far as I know. And yes, nobody else has split it.

 

[pbjosh]

Sharp-shinned Hawk - yes, but also or especially the forms in the Caribbean.

Already split I thought? Given that you are the one commenting though I suspect not and I am misremembering, hah If they’re not already split then yes absolutely!

 

[Mysticete]

Already split I thought? Given that you are the one commenting though I suspect not and I am misremembering, hah If they’re not already split then yes absolutely!

A recent paper argued they should be split, but no one has acted upon it. Honestly I suspect the next year or two to be a really slow year for completely new splits, what with the nacc chaos and WGAC busy just with the reconciliation process.