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Red-tail Dark Morph… what subspecies?


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24 minutes ago, Trevor L. said:

I thought this was a dark-morph calurus/alascensis, but someone commented that it was an abeitcola. I am now unsure. Help.

Photo

I don't envy you guys out west when it comes to RTHA.  I've never seen an abieticola in person, or in any identification literature that had the underwing coverts be dark.  They still have the very visible patagial bar, but much darker than Eastern.  

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I only have experience with light morph abeiticola, and zero with calarus/alascensis birds, so I can’t add anything useful. If anyone has access to Birds of the World (I got my college to get access, coming soon) maybe they have something?

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9 minutes ago, chipperatl said:

I don't envy you guys out west when it comes to RTHA.  I've never seen an abieticola in person, or in any identification literature that had the underwing coverts be dark.  They still have the very visible patagial bar, but much darker than Eastern.  

RTHA identification is much more fun out here.  Instead of lumping them all as "just Red-tails", we can go through different subspecies and morphs before lumping almost all as "just Red-tails".

By the way, abieticola is seen at least as much in the east, if I'm not mistaken.

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1 hour ago, Jerry Friedman said:

RTHA identification is much more fun out here.  Instead of lumping them all as "just Red-tails", we can go through different subspecies and morphs before lumping almost all as "just Red-tails".

By the way, abieticola is seen at least as much in the east, if I'm not mistaken.

In the northeast at least, it’s probably 5:1 eastern to northern

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11 hours ago, Avery said:

I only have experience with light morph abeiticola, and zero with calarus/alascensis birds, so I can’t add anything useful. If anyone has access to Birds of the World (I got my college to get access, coming soon) maybe they have something?

There are “light” and “dark” morphs of abieticola now?

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2 hours ago, chipperatl said:

There are “light” and “dark” morphs of abieticola now?

Well, since this is a dark one, then I’d assume the ones I’ve seen (which looked similar to light morph eastern) would be considered light morphs

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12 hours ago, Avery said:

In the northeast at least, it’s probably 5:1 eastern to northern

EBird reports of abieticola seem to tail off around the 100th meridian.  Part of the reason, of course, might be that the Great Plains, especially the northern plains, aren't heavily birded, especially in winter.  I don't know how to get a ratio.  But Whatbirders in Kansas and Nebraska might consider looking for Northern to add to their collection of Eastern, Krider's, three morphs of Western, and three morphs of Harlan's.

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10 minutes ago, Jerry Friedman said:

Raptor experts talk about dark morphs of abieticola on the Raptor ID group on Facebook.  They're apparently fantastically rare, if they exist.  See this article.

Wow!!!  I had not seen this anywhere, and thought I was caught up on these.  Finding one during the winter is one of the best parts about driving around here in SC Michigan.  

Now I’m wondering if I had one with this calurus/alascensis.  It has the dark sub-terminal band on the tail.  Never mind has bands on tail, so not an abieticola.  

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1 minute ago, Jerry Friedman said:

EBird reports of abieticola seem to tail off around the 100th meridian.  Part of the reason, of course, might be that the Great Plains, especially the northern plains, aren't heavily birded, especially in winter.  I don't know how to get a ratio.  But Whatbirders in Kansas and Nebraska might consider looking for Northern to add to their collection of Eastern, Krider's, three morphs of Western, and three morphs of Harlan's.

There isn't a written ratio, I was just going off of personal experience

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10 minutes ago, chipperatl said:

Wow!!!  I had not seen this anywhere, and thought I was caught up on these.  Finding one during the winter is one of the best parts about driving around here in SC Michigan.  

Now I’m wondering if I had one with this calurus/alascensis.  It has the dark sub-terminal band on the tail.  

Based on what @DLecysaid, which agrees with what Jean Iron said in that article, I'd say you were right to call yours calurus/alascensis.  It has the barred tail and a narrower subterminal band.

That would certainly be something to look for in Michigan in winter, but as far as I can tell, you could never prove that it was an abieticola and not an unusual Western.

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This is an email that raptor expert Brian Sullivan (one of the developers of the Raptor ID app) sent out to all of us eBird reviewers back in 2018 regarding abieticola and non-Harlan's dark morph Red-tails in the eastern United States:

Red-tailed Hawk subspecies are a quagmire, but we do our best to try to allow people to report distinctive individuals in eBird. The subspecies abieticola was described in 1950 by W. E. Todd and further supported by a peer-reviewed paper from Dickerman and Parkes (1987). Jerry Liguori and I published an article in Birding recently about this taxon, the introduction of which is pasted below:
 
"During migration and winter across the central and eastern Lower 48, heavily marked Red-tailed Hawks cause confusion for many birders. In most cases these birds are identified as Western Red-tailed Hawks (Buteo jamaicensis calurus). But in 1950, W. E. Clyde Todd described a new subspecies of the Red-tailed Hawk in his paper “A Northern Race of Red-tailed Hawk”, which differed from typical Eastern Red-tailed Hawk (B. j. borealis) in having more richly colored underparts, a dark throat, and a heavy bellyband. Todd named this subspecies abieticola (ab-i-et-i-ko-la), reportedly meaning “dweller of the firs”. Despite a well-researched paper, the subspecies did not receive wide recognition. A follow-up paper by Dickerman and Parkes (1987) supported the validity of Todd’s research, and provided a more comprehensive comparison between abieticola, Eastern, and Western Red-tailed Hawks. Dickerman and Parkes stated: “This is the breeding race of the spruce-fir belt of Canada west to Alberta.”  Dickerman and Parkes reviewed claims of Western Red-tailed Hawks from the Northeast and found that all purported calurus were actually well marked examples of abieticola. Likewise, we propose that most heavily marked Red-tailed Hawks occurring from the Great Lakes through the Northeast region in migration and winter are abieticola."
 
For what it's worth, I am currently reworking Systematics section of Red-tailed Hawk in BNA, and it will recognize abieticola moving forward. If one recognizes any subspecies of Red-tailed Hawk, one must recognize abieticola. Characters mix across all races, and there are many intermediates, but typical abieticola individuals are fairly straightforward. We also suspect now that dark/rufous morphs occur in this northern race, and that most (all) reported calurus dark/rufous morphs east of the Great Plains pertain to this form. We've added a 'Slash' option to eBird to accommodate this uncertainty, so birders can report these as 'calurus/abieticola' for now. They can do that too for heavily marked light morphs, if they wish.
 
Here's an article on the subspecies in general:
 
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6 hours ago, Jerry Friedman said:

Based on what @DLecysaid, which agrees with what Jean Iron said in that article, I'd say you were right to call yours calurus/alascensis.  It has the barred tail and a narrower subterminal band.

That would certainly be something to look for in Michigan in winter, but as far as I can tell, you could never prove that it was an abieticola and not an unusual Western.

I just had someone on iNat label one of my borealis as a "light morph".  😆  Guess there are light and darks there now.  

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7 minutes ago, Greenesnake said:

 

 
For what it's worth, I am currently reworking Systematics section of Red-tailed Hawk in BNA, and it will recognize abieticola moving forward. If one recognizes any subspecies of Red-tailed Hawk, one must recognize abieticola. Characters mix across all races, and there are many intermediates, but typical abieticola individuals are fairly straightforward. We also suspect now that dark/rufous morphs occur in this northern race, and that most (all) reported calurus dark/rufous morphs east of the Great Plains pertain to this form. We've added a 'Slash' option to eBird to accommodate this uncertainty, so birders can report these as 'calurus/abieticola' for now. They can do that too for heavily marked light morphs, if they wish.
 
Here's an article on the subspecies in general:
 

This will at least give me a reason to go back through my abieticola pics for a closer look.  

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In West Tennessee we have found that abieticola is the 2nd most encountered subspecies of Red-tailed Hawk, behind only borealis. I have researched the photos in eBird reported as calurus or calurus/alscensis here and have found no legit records of light morph individuals of those here. It certainly stands to reason that the dark and dark rufous morph Red-tails that we get that are not Harlan's would be abieticola instead of calurus and we are now encouraging the birders here that encounter dark, dark rufous morph, and intermediate morph Red-tails as calurus/abieticola instead of calurus or calurus/alascensis, based on that email from Brian. I don't think that it's that dark morphs of abieticola are exceptionally rare, it's just that we've always assumed that they were calurus until recent years.

As in Red-tails in general, even within abieticola there appears to be a great deal of variability and we encounter some light morphs of that subspecies that are heavily marked with white breasts, some that are heavily marked with a rufous wash on the breast, some that are moderately marked with white breasts, some that are moderately marked with rufous washed breasts and everything in between.

Edited by Greenesnake
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2 hours ago, Jerry Friedman said:

Welcome to Whatbird, @Greenesnake!

I'm sure you're busy, but if you have the chance, I'll bet @Trevor L. and @chipperatlwould be grateful for advice on how to report their Red-tails in this thread.

Or maybe it's obvious that they both should report them as calurus/abieticola.  Anyway, it's great to have the benefit of your expertise here!

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On 10/21/2021 at 3:43 PM, Greenesnake said:

In West Tennessee we have found that abieticola is the 2nd most encountered subspecies of Red-tailed Hawk, behind only borealis. I have researched the photos in eBird reported as calurus or calurus/alscensis here and have found no legit records of light morph individuals of those here. It certainly stands to reason that the dark and dark rufous morph Red-tails that we get that are not Harlan's would be abieticola instead of calurus and we are now encouraging the birders here that encounter dark, dark rufous morph, and intermediate morph Red-tails as calurus/abieticola instead of calurus or calurus/alascensis, based on that email from Brian. I don't think that it's that dark morphs of abieticola are exceptionally rare, it's just that we've always assumed that they were calurus until recent years.

As in Red-tails in general, even within abieticola there appears to be a great deal of variability and we encounter some light morphs of that subspecies that are heavily marked with white breasts, some that are heavily marked with a rufous wash on the breast, some that are moderately marked with white breasts, some that are moderately marked with rufous washed breasts and everything in between.

Very interesting blog posts by people fitting dark-morph Red-tails with GPS transmitters.  The post I linked to found that their three "non-Harlan's" birds captured in Kansas summered in Harlan's territory in Alaska.  Could birds like that be wintering farther east?  The previous post found that a bird captured in Minnesota, very non-Harlan's-looking, summered but probably didn't breed in northern Manitoba.  Maybe that's a dark abieticola?  I don't calurus is supposed to summer that far east.

The Alaska birds have weird migration routes too--east, then south.  If I were leaving Alaska in fall, I'd be heading south as soon as I could.

Anyway, @chipperatland @Trevor L.clearly need to capture dark Red-tails and put GPS on them 🙂

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