“Northern Flicker subspecies should definitely be different species.”
The birder I had just met presented his epiphany with conviction to the rest of the group. A can of worms had been spilled. The following squabble was deemed inevitable from the moment the birder had opened his foolish mouth. Tempers were high, and voices were raised, and in the midst of it all, several good points were brought up. Finally, someone delivered the fatal blow by mentioning that Yellow-shafted and Red-shafted Flickers might not even be subspecies, and the birder piped down and quickly changed the topic to life lists and the latest gross mis-ID on the eBird Rare Bird Alerts.
The birder who had brought up the subspecies point had presented it confidently, and with the perfect amount of patronization, to prevent further questioning by everyone else. We all pretended to think about his proposal for a few seconds, then nodded in pretend approval as we moved onto the next topic.
But, as always, the best questions came up long after the debate. On second thought, what even was a subspecies?
After a few minutes of existential pondering of this question without finding answers, it was time to find out the answer the Millennial way and hit Google to find the answers. First, off Wikipedia:
According to Wikipedia, “A common way to decide is that organisms belonging to different subspecies of the same species are capable of interbreeding and producing fertile offspring, but they do not usually interbreed in nature due to geographic isolation, sexual selection, or other factors.”
Wait, isn’t that just a species? you may ask. But just wait, don't give up on Wikipedia yet! It has this vastly clarifying detail:
“The differences between subspecies are usually less distinct than the differences between species.”
Gee, thanks, Wikipedia, so specific.
However, as I was to find over the course of the next few months, Wikipedia (writers) had tried their best. No one at all really knew what a subspecies was.* There could be no subspecies for a species, or forty-two hundred. It also seems that some people want to “discover” another subspecies so they can niftily name it after themselves -- so next time Joe Bloe says there’s a Northern Cardinal subspecies named after him, take him with a grain of salt (and preferably reply by asking if it’s C. c. igneus.). The subspecies playing field is therefore a mess of gore and taxonomic claim jumpers.
*To be fair, I didn’t ask any actual taxonomists, although I did ask some people who study the work of taxonomists (aka. taxonomistmists).
It seems that some notable people agree with this verdict.
In the abstract of the article “Subspecies Are For Convenience", Cornell researcher John Fitzpatrick states that in regard to solid definitions for subspecies, “trinomial epithets will inevitably be applied to a heterogeneous mix of evolutionary phenomena, thereby precluding genuine standardization of the concept.“
Thankfully, Fitzpatrick picked an especially apt and descriptive title to sum up his article for those who don't know what he was talking about in that last sentence. Subspecies are for convenience. The line between subspecies and normal population variations is hard to draw, and rather arbitrary.
The implications are dear to my chaparral-hugging, sagebrush loving heart. Among the article's many discussions is one on how arbitrary subspecies concepts led to the rejection of Coastal Cactus Wrens for federal protection. For any Californian birder who has personally witnessed the struggle of Coastal Cactus Wrens against the terrible forces of fire, hearing this is enough to burn down the AOU headquarters that made the decision (which might be counterproductive if the AOU headquarters were in Cactus Wren habitat, but they're not, so burn away).
Here’s a little background. The high at-risk “San Diego” Cactus Wren is the more unassuming sister of its loud and charismatic sibling, the interior Cactus Wrens. Recent genetic evidence suggests additional breeding isolation of the San Diego Wren from its more northerly cousin, C .b. anthonyi.**
** C.b. anthonyi could also be called 2-3 other names. Like I said, it's a messy playing field.
Although there are some morphological differences as well, the AOU decided, after the deep and contemplative intense examination of dozens of specimens in a few hours, that there wasn’t enough to designate the bird as a subspecies. They just don’t use the same level of in-depth inspection when it comes to the Willets or Redpolls, do they?
And Californian birders all joined in a mutual screech of protest upon the announcement of this decision--except there was no mutual screech of protest. As far as I know, very few people knew or cared. Few birders realized that the “San Diego” Cactus Wren not being listed as a subspecies would also mean the “San Diego” Cactus Wren could not be federally listed as endangered.
This is more than just an one-person (me) outrage. And more importantly, this isn't really the AOU's fault. This is a deep flaw in the system: using an arbitrary definition that no one fully agrees on to determine something so important as federal protections. Nowhere is this more evident than recent developers efforts to de-list the federal listed Alta California Gnatcatcher by hiring "scientists" to proclaim that Alta California Gnatcatchers are not a separate subspecies.
As the title of the article I just paraphrased half of this from says, “Subspecies Are For Convenience.” Truly. Whether you're a conservationist or a developer, subspecies can be yours to manipulate.
(Moving to the next topic now - read the article here)\
Even if birder's borders between subspecies are AOU-burning-worthy blurry, that’s not to say that subspecies are invalid--just like species, some subspecies are more obvious than others, or to put it in more accurate terms, a few subspecies are obvious. The rest, however. are in fact AOU-burn-worthy.
On one hand, contemplating these topics and reading these articles ruined the pristine concept of taxonomic perfection I had always seen certain authorities as. On the other hand, arming myself with this background on subspecies debate allowed me to assess the earlier Northern Flicker claim a little better. After going through the abstracts of a dozen papers for a few hours, I felt as qualified as the AOU to determine if Northern Flicker subspecies were truly distinct or not. ***
***In all honesty, no hate on the AOU. I like what they do. Actually, I like them a lot more than most birders, who seem to think the AOU is the second coming of the European Starling or something.
Also, I'm sad to say I did not conduct my investigation with an unbiased mind. I thought (and still think ) that they are distinct enough to be a subspecies. My goal was more to find out about how distinct these subspecies really are.
A little background first. Chances are, you're familiar with Red-shafted and Yellow-shafted Flickers. Perhaps you've had some extensive encounters with their integrate, the aptly named Orange-shafted Flicker. And that's the key word: extensive. Orange-shafted Flickers are exceedingly common, and what's more, they may fill a gap in a smooth cline from the color spectrum of red to yellow.
My goal was to find, not by my incapable self, but by Google Scholar-ing and J-Storing the work of others, any papers that could be sacrificed to the horrors of being read by a high school student for the higher cause of determining how distinct Northern Flicker subspecies were.
The answer? There is no answer!*
I found that there was a complete lack of direct concern about Yellow-shafted and Red-shafted Flickers' distinctness and an overwhelming focus on the hybrid zone itself between the two. In other words, the subspecific distinctness of Yellow-shafted and Red-shafted Flickers seemed to be a given.
At this point, it could get philosophical. Even if the two flickers aren't distinct enough entities to be considered subspecies, should this lack of concern matter? If subspecies are truly for convenience, what does it matter that the two flicker population groups are not really as well-defined or clear as we would like them to be? The dubbing of the two groups certainly makes it easier for researchers to describe and study the unique flicker hybrid zone. In the end, a subspecies is like an emo or a prep -- it's just a label.
*Cue evil 8th grade science teacher laugh
But enough of the Socratic rambling. Let's get back to the research. The only thing research cemented for sure is that Yellow-shafted and Red-shafted Flickers are not separate species. Not by any 21st century definition of species, anyway. And not that there's much advocates for a Northern Flicker split anyway -- who knows? Maybe this post will bring out an army of Flicker separatists, marching with their 1940 field guides and proudly proclaiming their Northern Orioles and Plain Titmice.
In any case, unless you're trying to be a hipster in birding, the consensus that Northern Flicker is one species is undebatable. There's no intergrade breakdown, most intergrade areas seem to have random selection, zygotic barriers seem to be largely lacking, and the main mystery of the species lies not in its definition of species but its unexplained unchanging hybrid zone.
So given all of this, why the difference in morphology? The differing coloration on the under wings and shaft comes from different caretenoid processes, making them possibly geography-related.
Intrasexual rather than intersexual selection also might be the cause of these genetic shifts. Key words: might be. In the end, it always, always, ALWAYS comes back to these three words : need more research (I'm not complaining. That's what's providing future jobs for my generation of aspiring ornithologists).
Whether these findings can trickle down to flicker subspecies as well is an entirely different question.
The only tenet I can still safely hold on to anymore is that the two subspecies/whatchamicallits have vast morphological differences and exhibit at some degree of breeding isolation, blurry morphological cline or not, which many would say defines the two as separate subspecies regardless of whatever shady hybrid business goes on backstage. In other words, although subspecies lines can be difficult to draw, the Northern Flicker subspecies line is not one of them.
But I'm no AOU, and I'm going to throw the reader under the taxonomical bus by allowing them to make the decision. After reviewing the whole incident, Mr. Northern-Flickers-Are-Not-A-Subspecies was just looking to shut down the argument once and for all, and may have or may not have believed in his own blurted words. But his simple statement took me on a long journey of learning.
Only one thing at the end of this mind-boggling mess is clear: a subspecies is a subspecies is a subspecies. Whatever that means.
Also----subspecies are a form of taxonomical colonialism, and you should try and get a subspecies named after myself while you can.
INTERESTED IN NORTHERN FLICKERS? Click on these links!
P.S. I predict noone who reads this will actually click on these links.
Some of the zillion papers on which hybrid zone hypothesis fits the NOFL hybrid zone and NOFL subspecies selection habits.
Paper on hybrid zone
OKAS Paper on morphology
Jstor paper 1
Jstor paper 2
Jstor paper 3
Jstor paper 4
Jstor paper 5