In a recent issue of Birding (January 2009), you comment that evolution moves faster than changes made by the AOU checklist committee. I see you are frustrated with the committee's turtle-like pace, what current subspecies do you think should be elevated to species rank?
This is a kind-of long question, and so here’s a kind-of long answer… If this subject doesn’t interest you, like me and chemistry in high school, then skip the answer and don’t worry about it. But I think taxonomy is interesting, if misunderstood.
In answer to your question, part of me is frustrated and part of me doesn’t give a damn. Every one of you reading this has a brain and can read papers, observe birds, and make informed decisions about their relationships. My first taxonomic memory goes back to when I was 16 and saw my first “Water Pipit” (a species which then included Rock Pipit, which I was familiar with, and our modern-day American Pipit). That Water Pipit looked and sounded so different from the Rock Pipits I knew so well, that I split it there and then in my mind – and in my notebook. And when I saw my first American Pipit some years later (when it was still called Water Pipit and was considered the same species as the Old World Water and Rock pipits) I couldn’t believe how on Earth they could be thought the same. Were people deaf, or what? So I split it, on the spot, in my own list. And then, lo and behold, they were “officially” split some years later. No great surprise there, but how could people not have realized earlier? I was puzzled. Since then I have encountered numerous other unrecognized species in the field, and quite a few I split in the Mexico guide – something I was criticized for at the time. Who was this kid with not even a biology degree coming along and splitting all these species? Well, since then, the AOU has split almost every one of those “new” species I split in the Mexico guide, and more. Taxonomy is an ever-changing field, and we’ll always be learning.
Having said all this, even a few years from now somebody writing a Mexico bird book might say “how come Howell didn’t split these 50 species? Was he deaf or blind or just simply stupid?” I can even say it myself, for if I wrote the Mexico guide again today, I would split a bunch more species based mainly on vocalizations. So why didn’t I do this before? Well, a) maybe I am stupid; and b) learning takes time, and you can’t learn everything no matter how hard you try. “Obvious” and “new” species now (if not when I wrote the Mexico guide) include, in no particular order, western and eastern Blue Buntings, western and eastern White-bellied Wrens, western and eastern White-collared Seedeaters, the Mexican population of Barred Owl (whose voice I finally recorded this year), the southern populations of Mountain Pygmy-Owl (Guatemalan Pygmy-Owl, whose voice I recorded a couple of years ago; note that the AOU doesn’t even split Mountain from Northern Pygmy-Owl!), western and eastern Vermiculated Screech-Owls, Ivory-billed Woodcreepers, Strong-billed Woodcreepers, Greenish Elaenias, Bananaquits, Tufted Flycatchers, and perhaps Northern Beardless Tyrannulets, Pine Flycatchers, Vaux’s Swifts, Squirrel Cuckoos, Rosy Thrush-Tanagers, Emerald Toucanets, Scaled Antpittas, and so on. There’s always more work to do, ever-shifting horizons.
Any one of you reading this could go out and do a “simple” study that might result in some North American species being “officially” split. You don’t have to be a taxonomist, all you need is the power of critical observation and some ability to write clearly. Ever heard a whip-poor-will in the East? How about in southeast Arizona? Sound the same? No way! Voice is really important in night-birds, and there are some plumage differences as well, so here are two good species just waiting to be “officially” split. My friend and colleague Jon Dunn, who sits on the AOU committee responsible for making such decisions, agrees with me that the whip-poor-wills are two species, so why aren’t they split? Well, it’s basically a matter of bureaucracy. Somebody has to write a paper, spell it out in words of one syllable (well, three, in the case of whip-poor-will), painfully elaborate the obvious, and propose the split. And then it will be officially accepted and published. But all this takes time.
As background digression, most checklists and taxonomic lists we use today are based on so-called Old-School museum taxonomists, who studied dead birds and divined their relationships from in-hand examination. Often, perhaps usually, these people knew little or nothing of the birds in life. Like any cross-section of people, some of these people were unburdened by awareness but a great many were brilliant and perceptive, and I have untold admiration for many of these people, such as Robert Ridgway and Alexander Wetmore among the more recent names. While today we constantly fuss and move families around in lists, it is amazing to me how much that generation of ornithologists got “right” and how observant they were. They provided a very solid foundation for modern-day ornithologists to build upon.
Many of their decisions, however, were subjective and based on intuition or colored by prevailing philosophies about how different a species should be in order to be recognized. The AOU’s current view is that even if we all know and agree that some of these old decisions are unrealistic and “wrong” they won’t be changed unless there is published evidence to support the change.
At some level it is difficult to argue with such a conservative, reason-based approach, but at the same time when it flies so blatantly in the face of reality, it is difficult not be frustrated. At some point, being in denial that, say, the whip-poor-wills represent two species, along with hundreds of other cases in North and South America, may be counterproductive to ornithology.
There really are no such things here as right and wrong, and if you want to follow the decisions made by a self-appointed committee of people just like you and me (or in many cases, less familiar with the birds in life than you and me!), then that’s fine. It’s part of the conforming that high school instills in us as card-carrying social members of the human species.
There is also the basic fact that evolution, or change, is constantly ongoing among birds and other organisms. Drawing a line at any one point in time and saying: “these are species, these are not” is unrealistic. There will always be cases that fall in the gray zone, and there is no right or wrong or easy decision. As Allan Phillips once said: it is the birds that decide their reproductive isolation, not the people. But, being humans, we have to draw lines and put things in boxes, so taxonomy will always be fraught with disagreements.
I’m guessing your question about elevating subspecies to species rank relates to North America north of Mexico? There are two different types of splits here: splits within North America (such as whip-poor-wills) and those between North America and other regions, such as Eurasia. It seems you can pick almost any page in the field guide and find examples of under-appreciated diversity. The following lists are just a sampling, but they should give an idea of how much there still is to learn, or to accept.
North American splits overdue are whip-poor-wills, northern pygmy-owls, Leach’s Storm-Petrel (a 3-way split that I bet the AOU will only make a 2-way split, which is a very common, conservative committee strategy), Xantus’ Murrelet (two very different species with striking vocalizations), Marsh Wrens, Winter Wrens, Warbling Vireos, Purple Finches, Fox Sparrows, White-breasted Nuthatches, and other possibilities include Black-capped Petrel (2 or 3 species, more work needed), Olive-sided Flycatcher, Curve-billed Thrasher, Red-winged Blackbird, and obviously Red Crossbill and juncos.
Overdue splits between North America and (parts of) Eurasia include Eared Grebe, Cattle Egret, Snowy Plover, Common Moorhen, and perhaps Black Tern, and several northern-breeding species such as Northern Harrier, Northern Shrike, White-winged Scoter, Common Merganser, Smithsonian (Herring) Gull, Vega Gull, and perhaps Bank and Barn swallows. Tropical splits include Mangrove Warbler and Ringed Kingfisher. Seabird splits include Trinidade Petrel, Scopoli’s Shearwater, band-rumped storm-petrels (if you haven’t seen the recent book, Petrels Night and Day, with CDs of all the amazing vocalizations, by Magnus Robb and colleagues, it should open your mind to the way of the future in seabird taxonomy – it’s a great book!), and perhaps Northern Fulmar, White-tailed Tropicbird, and Brown Booby. “OK, OK, Stop!” I hear you cry.
It’s almost overwhelming isn’t it? And that’s part of the problem. How can any committee, let alone any one person, keep up with, or be aware of, all of these cases? I hear rumors of Eastern Meadowlarks being split, but I’m not familiar enough with this case to have an opinion. So, while it’s easy to criticize taxonomic committees, they also require as much help as we want to give them, as well as some sympathy for the task they have taken upon themselves.