I was recently looking at turkey vulture subspecies and found that here on iNat, many vultures have been IDed as Cathartes aura aura, while being within the range of the subspecies Cathartes aura meridionalis and well past any possible range of overlap. My source for subspecies range is here: https://birdsoftheworld.org/bow/species/turvul/cur/systematics#subsp
Could someone with some more knowledge help me understand this or offer any solutions?
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Part of the confusion undoubtably comes from the two subspecies having the same common name (an argument for not attaching common names to subspecies, but that’s a different topic). There is mention in the BOW account of the two subspecies being considered synonymous by some, so that might also be part of the confusion.
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If you’re interested, try tagging the most prolific identifier of that subspecies in an observation with your question. Since they are a curator, they should be able to shed some light on the topic, or correct the subspecies IDs, if needed.
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This looks to be a known and unresolved issue as far as I can tell. It seems to stem from the fact that iNat typically follows Clements for avian subspecies. Clements made a number of changes back in October of 2024 with a new update that included the splitting of Cathartes aura meridionalis from C. a. aura (which was previously treated as synonomous as David mentioned). Prior to the update, Cathartes aura meridionalis wasn’t even an option that could be entered if I recall correctly - hence why all existing observations occur fairly recently. There’s a flag for the taxon which better explains the issue here: https://www.inaturalist.org/flags/704753
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I’m not seeing turkey vulture attached to Cathartes aura aura? Either way, the Curator Guide explicitly says that an infraspecies should not have the same common name as its parent species:
Do not add common names for infraspecies that are identical to the common name of the parent species, e.g. if the species is Cola coke and it has the subspecies Cola coke ssp. classic and Cola coke ssp. zero, don’t add the common name “Coke” for the subspecies. That will just confuse people who are trying to add an ID for the species Cola coke and make it harder for people who actually want to choose the subspecies. Instead, try to choose unique common names like “Coke Classic” and “Coke Zero.”
So in cases where someone has added an infraspecies common name that matches that of its parent species, the name should be removed from the infraspecies.
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The common names of the two subspecies don’t match the parent species, but they match each other. Both C.a. aura and C.a. meridionalis are labeled as “Western Turkey Vulture”
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I was DM-ed to participate in this thread since I’m the top identifier for Turkey Vultures, and yes, it is a mess, and it might be from my doing. Here’s a collective history of what’s going on.
- October 13 2024: Clements (2024) adds meridionalis to the checklist and pulls it out of synonym from aura (based on Kirk et. al. 2023), essentially making most of the western US vultures meridionalis.
- October 29, 2024: I added meridionalis as a taxon for iNaturalist.
- October 29, 2024: I flagged aura saying that the taxon likely needs to be split, but I wasn’t sure how the split should go; specifically, bump all obs to species level, or atlas them by breeding distributions. Flag for Taxon: Western Turkey Vulture (Subspecies Cathartes aura aura) · iNaturalist
- March 27, 2025: User “beedleborm” added the name “Western Turkey Vulture” to meridionalis with the note:
This is the “Western race” that Wetmore described. Not to be confused with C. aura aura [also called Western Turkey Vulture in iNat] which this subspecies was split from by Wetmore
The Issue
The reason why I haven’t done anything with this, even though I started the curating process is that I really despise the fact that Clements accepted this subspecies. Though some refuted Wetmore’s (1964) assessment, at least four articles published in the last 20 years have used meridionalis, and I think that’s what influenced Clements to recognize it. These are listed below:
- Blidstein et. al. 2007: Mentions meridionalis 6 times but only stated that they “presumed” South American migrants belonged to this subspecies. No systematic research done. SEASONAL ABUNDANCES AND DISTRIBUTIONS OF BLACK VULTURES (Coragyps atratus) AND TURKEY VULTURES (Cathartes aura) IN COSTA RICA
- Dodge et. al. 2014: Mentions meridionalis 2 times, only to state that they’re from western US. No systematic research done, but did prove through geotagging that western US vultures do indeed migrate to Colombia and the Guinean region. Environmental drivers of variability in the movement ecology of turkey vultures (Cathartes aura) in North and South America
- Grana Grilli et. al 2017: Mentions meridionalis 2 times, when referring to a specimen they geotagged in Patagonia, AZ (which should be aura by breeding distribution) and central Canada, and how they migrated to Panama and Venezuela. They claim wing measurements dictate migratory patterns, which meridionalis is diagnosed on, but no data is presented on if there’s overlap between aura and meridionalis. Wing size but not wing shape is related to migratory behavior in a soaring bird
- Kirk et. al 2023: Mentions meridionalis 40 times, but their study only discusses the relationships between meridionalis and resident ruficollis in Venezuela. No mention of aura or distinction from them. Foraging shifts in Neotropical Turkey Vultures (Cathartes… - Google Scholar
Summary
Four recent papers have used meridionalis as a valid taxon in their research, but to date, no paper has actually compared aura and meridionalis, but rather what would be meridionalis compared to Central and South American Cathartes vultures. Wetmore (1964) claims that meridionalis is larger with longer wings than aura, but his data doesn’t appear to be statistically significant, and there is overlap in wing chord length.
As such, I have refrained from identifying Turkey Vulture subspecies in the US, simply because I think recognizing meridionalis is a step backwards, and it certainly doesn’t help iNat since most of us can’t measure the vultures we see.
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How about other parts of the world? The Caribbean, for example, where ssp. aura as currently circumscribed is the expected one? And what to do about ssp. aura also being called “Western” Turkey Vulture?
I’ve just negated subspecies diagnosis in the US. Subspecies ruficollis and jota are pretty easy to id. I just call everything in the Caribbean and Central America as aura based on phenotypic traits of the Northern group (aura/meridionalis/septentrionalis).
What, if anything, should be done about the issue then? I’d be happy to help if there is a solution I can participate in.