November 6, 2020
HIDDEN SPECIES & SPLITTING
By Andrew Whittaker
Avian taxonomy is in a constant state of flux, particularly in the species-rich Neotropics, where many bird species remain relatively poorly known, especially when compared to those in Europe and North America, or even other tropical regions of the world with longer histories of ornithological exploration and study. Even within the US, new “splits” (in other words, when two or more subspecies of a single recognized species get “split,” resulting in those subspecies being elevated to full species status) are announced with some regularity by the American Ornithological Society (AOS) in its annual supplement to the check-list of North American Birds. Armchair birders are always happy to add the life birds resulting from such splits to their lists without leaving home, but since taxonomy is always a work in progress, the whole splitting and lumping process can prove more than a little confusing to birders.
Most often, the initial field detection of a probable split involves an important telltale pointer, more often than not, a distinct vocal difference. These vocal differences take on added significance if there are concordant morphological and genetic data sets, all of which can combine to make a strong case for recognizing two or more species, rather than just the original one. I would like to share with you a good example of a potential split in South America involving a conspicuous species, one that I am sure many of you who have visited South or Central America will quite possibly already have had experience.
My tale involves the Southern Lapwing (Vanellus chilensis), a shorebird that has fascinated me ever since my first trip to Patagonia in early November 1998. While in Ushuaia, in southern Argentina, I was amazed to find myself unable to recognize the voice of the local Lapwings despite being extremely familiar with Southern Lapwing vocalizations from Brazil. I had lived in Brazil for 11 years, and I knew Southern Lapwing as a widespread and abundant bird (away from the Amazon) that was noisy and very conspicuous. Throughout much of the country, it is well known, even to non-birders, as “quero-quero” (a transcription of its commonly heard voice), which translates into “I want-I want.”
I can still vividly remember that cold, early November morning, with a very strong wind blowing as I birded on foot out from the Ushuaia docks. I left the outskirts of town on a dirt road, which led me through rolling grasslands. Here I stood amid wind-swept fields, extremely frustrated, wondering why on earth I was unable to locate a flock of what I assumed to be Austral Parakeet (Enicognathus ferrugineus) noisily flying by me in a mostly treeless area.
These colorful parakeets would have been a lifer for me, so as you can imagine, I was both anxious and desperate to locate and observe them. Ten minutes passed before I heard the distinctive parakeet-like voice again. But a quick scan of the sky again failed to reveal any parakeets! With frustration mounting, I cupped my hands to my ears and moved my head from side to side in an effort to better localize the source of the sounds. To my sheer amazement, it sounded as though the voice was coming not from the sky but from the ground! I soon located a bird walking in the 3–4-inch grass some 75–100 m away in the field and was dumbfounded to find myself looking at a Southern Lapwing! My initial shock quickly turned to delight as I realized I was, in fact, looking at a vocally very different Southern Lapwing from the ones with which I was so familiar! Better still, the extent of the differences strongly suggested to me that more than one species was involved in what was currently known as “Southern Lapwing.” However, the next question was: which of the two distinct vocal forms I now knew represented the “true” (first described) Southern Lapwing, and which vocal type represented the potential “new split”?
Please check out the very distinct differences in the two voices by clicking on the links below.
“True” (chilensis) Southern Lapwing:
The “split” (cayennensis) Lapwing:
On my return to my ship’s cabin, I checked through all the pertinent literature I had available, including the ship’s extensive natural history library. Focused on Southern Lapwing, first and foremost, I found out that the first subspecies to be described (in taxonomic parlance, the “nominate subspecies”) was in fact from Chile (chilensis), whereas, by range, the subspecies fretensis was the subspecies I had just heard here for the first time. The only reference I could find to vocal differences within the Southern Lapwing complex was in Birds of the High Andes by Fjeldså & Krabbe (1990). They described the voice that I knew well from Brazil, and then added that “Sspp fretensis and chilensis give a distinctive, much harsher, and parakeet-like shrill tjirr-tjirr-tjirr…teree teree teree.” The authors further added: “Judging from different proportions and vocalizations 2 species might be involved (SOUTHERN LAPWING V. cayennensis, incl. lampronotus, and CHILEAN LAPWING V. chilensis, incl, frenatus).” But, Fjeldså & Krabbe also added a caveat that “intergradation is known from one (man-influenced) locality.” This strongly suggested that these odd-sounding Lapwings from Ushuaia were part of the same biological species as the nominate form from Chile, and, therefore, represented the “true” Southern Lapwing! The flip side to this revelation, courtesy of Fjeldså & Krabbe, was the recognition that the “Southern Lapwings” in Brazil that I had taken for granted over the past decade were not “true” Southern Lapwings at all, but actually represented a likely potential split!
Since my initial Southern Lapwing revelation, I have, whenever encountering Southern Lapwings over the past two decades of leading VENT tours, made sure to inform my groups of the potential of Southern Lapwing being split into two species, and I have been careful to point out which subspecies we have seen and explain if it is either part of the “true” Southern Lapwing or the impending split. I also take care to point out the subtle plumage differences that distinguish the two groups of these lapwings, and to emphasize that the vocal distinctions provide the strongest evidence for recognizing two species in the group instead of one. I also advise folks to place the northern birds in “escrow,” as they will almost certainly become countable as a distinct species once someone finally publishes a full analysis supporting a split.
Please take a careful look at the images below of the two types of Southern Lapwing and see for yourself. Although initially they may look the same, after careful comparison they clearly show several distinctly different plumage characteristics between them. Following is a quick rundown for anyone wanting to check up on exactly which “Southern Lapwing” they have, in fact, seen.
The “true” Southern Lapwing (what Fjeldså & Krabbe 1990 referred to as “Chilean Lapwing”) comprises two subspecies: nominate (Vanellus chilensis chilensis) described (Molina, 1782) from Chile; and the second form, described much later (Brodkorb, 1934), is Vanellus chilensis fretensis from southern Chile. The distribution of the “true” Southern Lapwing is basically the southern tier of South America, throughout the length of Chile and southern Argentina north through mostly Patagonia into the central area. Argentina is the only known country where both forms of this Southern Lapwing complex coexist. In the northern central region, both species can be seen side by side, and this occurs farther north into the pampas during the winter, sometimes even as far north as Buenos Aires. In the summer only the “split” can be found breeding around Buenos Aires.
This form also has two subspecies, the first of which, described by Gmelin, JF, (1789), was from Cayenne, French Guiana, and was described as the subspecies cayennensis. The other representative (with the same vocal type) is the more widespread subspecies lampronotus described from southern Brazil (Wagler, 1827). So, if split, the “new” Lapwing would bear the name (Vanellus cayennensis), with constituent subspecies cayennensis and lampronotus (cayennensis having priority because it is the oldest of the applicable names).
Interestingly, it’s the northern and eastern “split” of Southern Lapwing that has by far the larger distribution of the two. In fact, its range is expanding rapidly with deforestation into the Amazon of Brazil (as well as farther north), and it has now colonized parts of Costa Rica. Conversely, the “true” Southern Lapwing is found only from the southern tier of South America, being primarily a Patagonian species. Therefore, paradoxically, it is, more often than not, the incipient “split” in the Southern Lapwing complex that most people are familiar with, and it is the “true” Southern Lapwing that they have yet to see!
To summarize, despite the fact that it has been 30 years since Fjeldså & Krabbe first speculated in print about the possibility of two species of “Southern Lapwings” (a speculation that appears increasingly prescient), and more than 20 years since I first became aware of the vocal and morphological differences that they had already detailed, no quantified vocal, morphological, or genetic analysis of species-limits within “Southern Lapwing” has been published, and, therefore, no split has yet been adopted. Rumors abound that such an analysis may be forthcoming, and then, finally, we can have English names to go with the resulting “daughter” species from the split and, at last, happily, cash in on another lifer!
One more interesting feature in Southern Lapwings is that both of these forms present in both sexes an impressive pink wing-spur. This feature is mostly not visible, or it is just a tiny pink point sticking out of the black breast shield that is easily overlooked. However, as you can see below, they are very impressive and obvious when used in territorial battles!
Victor Emanuel Nature Tours | 2525 Wallingwood Drive, Suite 1003 | Austin, TX 78746
Follow us on
© 2020 Victor Emanuel Nature Tours. All rights reserved.