Proposal (#59) to South American Checklist Committee:
Split Celeus obrieni from C. spectabilis
Effect on South American CL: This proposal would elevate a taxon to species
rank that we currently treat as a subspecies on our baseline list.
Background: Prior to 1973, Celeus spectabilis (Rufous-headed Woodpecker) was
considered to be a single polytypic species consisting of two described
subspecies:
C. s. spectabilis Sclater & Salvin, 1880 E Ecuador & NE Peru.
C. s. exsul Bond & Meyer de Schauensee, 1941 -- SE Peru, extreme W Brazil &
N. Bolivia.
In 1973, Short described a new subspecies, C. s. obrieni, from a single
unidentified specimen (pointed out to him by Charles O'Brien) in the AMNH: an
adult female, collected 16 August 1926 by E. Kaempfer at Iruçui, state of Piauí,
Brazil, elevation 124 m, on the Rio Parnaiba. Short refers only generally to the
habitat in which obrieni was collected, saying that it was from "dry forested
country", and speculating that it was probably widespread in the Piauí-Maranhão
region.
Short's diagnosis of the specimen follows: "Differs from C. s. spectabilis and C. s.
exsul in its smaller size (wings, tail, bill, tarsus), and in several color features,
especially the greatly reduced barring dorsally, and reduced markings ventrally.
Also whiter above and below; small outer rectrices mainly cinnamon (nearly all
black in exsul and spectabilis); and secondaries paler, more buffy (less chestnut),
especially on tertial feathers. The bill appears yellower, less white, compared
with both older and more recently collected specimens of other races."
Measurements given by Short (1973) are as follows:
Wing Chord:
C. s. obrieni 136 mm
C. s. spectabilis (n = 2) 150 mm, 147 mm
C. s. exsul (n = 9) range of 138153 mm
Tail:
C. s. obrieni 95 mm
C. s. spectabilis (n = 2) 92 mm, 101 mm
C. s. exsul (n = 9) range 99108
Exposed Culmen:
C. s. obrieni 24.3 mm
C. s. spectabilis (n = 2) 28.3
C. s. exsul (n = 9) range 28.7 31.2
Tarsus:
C. s. obrieni 21.1 mm
C. s. spectabilis (n = 2) 23.4 mm, 23.1 mm
C. s. exsul (n = 9) range 22.124.2
Short concluded that the "new form clearly represents a race of C. spectabilis,
rather than some other species of Celeus, by virtue of its fully rufous head, its
black, shield-like breast patch, it mainly clear rufous secondaries, and its black,
unbanded tail. Its bill, although small, matches spectabilis in the slight curvature
of the culmen, and in the breadth across the nostrils. In its reduced markings
obrieni bears the same relation to other races of C. spectabilis that C. torquatus
torquatus does to other races of C. torquatus, and that C. flavescens ochraceus
does to other races of C. flavescens."
Subsequent authors have followed Short's lead in treating obrieni as a
subspecies of spectabilis: Sibley & Monroe (1990), Sick (1993), Winkler et al
(1995), Parker et al (1996), Clements (2000) and Winkler & Christie (2002).
F. C. Novaes conducted surveys in Piauí in the region of Uruçui-una close to the
type locality of obrieni in 1980, but was unsuccessful in relocating the taxon
(Novaes 1992). Novaes described the dominant habitat of the area as cerrado
intermixed with caatinga, but with other kinds of vegetation, such as dry scrub
forest, low riverine scrub forest, and swamp vegetation dominated by burití palms
(Mauritia flexuosa).
The holotype (and lone specimen) of obrieni remained the sole basis for the
inclusion of C. spectabilis on the Brazilian list, until 1995, when A. Whittaker, as
part of a Goeldi Museum expedition, located and tape-recorded several
individuals fitting the plumage characters of C. s. exsul at various localities in the
upper Rio Juruá drainage in Acre (Whittaker & Oren 1999). All of the Acre birds
were found either in stands of bamboo, or in humid second-growth (Cecropia
dominated) bordering rivers; the typical habitats in which the species is found in
Peru and Ecuador (e.g. Winkler et al 1995, Parker et al 1996, Ridgely &
Greenfield 2001, Winkler & Christie 2002). Whittaker & Oren (1999), commenting
on the distinctiveness of obrieni, combined with the huge range disjunction from
other populations of C. spectabilis, and its very different habitat, suggested that
obrieni should be accorded full species status. They also suggested the English
name of "Caatinga Woodpecker" for obrieni, to highlight its fairly unique habitat
(among Celeus). Winkler and Christie (2002), noted that "obrieni differs
significantly in plumage, and data on habitat indicate major distinction from other
races; possibly a separate species, but no further information available." These
authors later go on to say "it has to be assumed either that the taxon is extinct or
that it represents a highly aberrant form of another species."
Analysis: This is a difficult case, primarily because of lack of information. The
taxon obrieni is described from a single specimen, there are no tape recordings
of voice, and habitat preference is essentially inferred from the general habitat
surrounding the type locality. In general, obrieni appears to be smaller than other
Rufous-headed Woodpeckers, although I am largely unimpressed by the degree
of difference (except possibly for culmen length) given a sample size of N = 1. On
the other hand, plumage distinctions between obrieni and the other two
subspecies of C. spectabilis are striking (as illustrated by dorsal and ventral
photos in Short 1973). Short's comments that the differences, although major,
are in order of magnitude similar to those found between various subspecies in
the C. torquatus and C. flavescens complexes are well-taken. However, in both
torquatus and flavescens, the different subspecies, although strongly divergent in
plumage, have intergrading populations that are known to be vocally similar or
identical to one another. With obrieni, we are talking about a highly distinctively
plumaged bird that is separated from the nearest known population of spectabilis
by ca. 3,150 km, and which occurs in a dry forest-caatinga-cerrado biome,
whereas both spectabilis and exsul are birds of humid forest habitats. Whittaker
and I searched for obrieni near the type locality in February of this year (without
luck): we saw no habitat approaching the habitats in which we have seen C.
spectabilis in Peru or w. Brazil. Aside from a few remnant patches of humid
(semi-deciduous) terra firme forest (which were occupied by C. flavescens
ochraceus), the habitats encountered were notably xeric. It seems safe to
assume that regardless of the precise habitat in which obrieni was collected, it
was not even remotely similar to that occupied by C. spectabilis in the remainder
of its range. Given the extreme range disjunction, very different habitat types,
and quantum plumage differences of the taxa involved, I am somewhat surprised
that obrieni was not described as a separate species in the first place, but Short
(1973) makes no mention that this was even under consideration.
Recommendation: In spite of my general reluctance to describe anything on the
basis of a single specimen (especially lacking vocal data), I recommend splitting
obrieni as a separate species from C. spectabilis on the basis of a hugely
disjunct range, occupation of a different biome, and quantum differences in
morphology. The caatinga region of northeast Brazil is a noted region of
endemism, and recognition of obrieni as a separate species-level taxon would fit
an established biogeographic pattern. Although I don't believe that conservation
considerations should drive taxonomic decisions, elevation of this obscure form
as a species-level taxon would have the added benefit of focusing more attention
on locating an extant population, and on conservation initiatives for the caatinga
region of Piauí in general.
Literature Cited:
CLEMENTS, J. F. 2000. Birds of the world: A checklist. Ibis Publishing Company,
Vista, California.
NOVAES, F. C. 1992. Bird observations in the state of Piauí, Brazil, Goeldiana
Zool. 17:15.
PARKER, T. A., III, D. F. STOTZ, AND J. W. FITZPATRICK. 1996. Ecological
and distributional databases. Pp. 132436 in: STOTZ, D. F., J. W. FITZPATRICK,
T. A. PARKER III, AND D. K. MOSKOVITS. Neotropical birds: Ecology and
conservation. University of Chicago Press, Chicago, Illinois.
RIDGELY, R.S., AND P. J. GREENFIELD. 2001. The birds of Ecuador. Vol. 1.
Status, distribution, and taxonomy. Cornell University Press, Ithaca, New York.
SHORT, L. S. 1973. A new race of Celeus spectabilis from eastern Brazil. Wilson
Bulletin 85:465467.
SIBLEY, C. G., AND B. L. MONROE, JR. 1990. Distribution and taxonomy of
birds of the World. Yale University Press, New Haven, Connecticut.
SICK, H. 1993. Birds in Brazil. Princeton University Press, Princeton, New
Jersey.
WHITTAKER, A., AND D. C. OREN. 1999. Important ornithological records from
the Rio Juruá, western Amazonia, including twelve additions to the Brazilian
avifauna. Bull. B. O. C. 119:235260.
WINKLER, H., D. A. CHRISTIE, AND D. NURNEY. 1995. Woodpeckers: An
identification guide to woodpeckers of the world. Houghton-Mifflin, Boston,
Massachusetts.
WINKLER, H., AND D. A. CHRISTIE. 2002. Family Picidae (Woodpeckers). Pp.
296558 in: DEL HOYO, J., A. ELLIOTT AND J. SARGATAL eds. Handbook of
birds of the world. Vol. 7. Jacamars to Woodpeckers.
Kevin J. Zimmer, August 2003
P.S.: If the proposal passes, then I'll follow up with another one on the English
names.
==========================
Comments from Robbins: "Although it seems likely that obrieni is a valid species
given the distinct plumage and the large distributional disjunction from Celeus
spectabilis, I'm against elevating it to species status based solely on a single
specimen. I'd even support this if Kevin and Andy had seen birds that matched
the description of obrieni, but at this point we can't rule out the possibility,
however unlikely, that the holotype is an aberrant or hybrid individual."
Comments from Jaramillo: "YES The great difference in plumage, habitat, and
massive range disjunction all suggest that this is a good species. It is unfortunate
that we have only one specimen to work from, and no recent sightings of this
taxon. However, the hybrid theory for this specimen is exceedingly unlikely in my
opinion. The question would be hybrid of what? Particularly with respect to the
place it is known from. I don't know that part of the world but is Celeus flavescens
the only possibility there? Is there any other Celeus there which could be the
potential other parent? I think that in this case the possibility that this single
specimen is a hybrid is so remote that at least for me it becomes a non-issue."
Comments from Silva: "YES. obrieni remains as a big problem. I have a student
(Marcos Pérsio Santos) living in Piauí. He spent lots of time looking for this taxon
and did not find anything, Certainly, it is a distinctive taxon and I do not think that
it represents a case of hybridization. The type-locality is a mosaic composed by
cerrado, caatinga and dry forests. Unfortunately, most of the tall (25 m) dry
forests that once was widespread in this region has been already completely
modified. If obrieni is associated with this kind of habitat, it is certainly under very
strong threat. I agree with Kevin that obrieni does not belong to Celeus
spectabilis, a completely different species. Although the weak evidence (one
specimen and no recent record) I will vote yes in this proposal."
Comments from Stotz: "YES. Celeus obrieni is clearly related to spectabilis.
Given that spectabilis doesn't occur anywhere close to the type locality of obrieni
and the very distinctive plumage of obrieni, it seems essentially impossible to me
that obrieni could be explained as a hybrid or aberrant spectabilis. Although the
published justification is not very strong, I think it is sufficient to hang our hat on,
and recognize obrieni."
Comments from Stiles: "[YES] Somewhat reluctantly, I will recommend species
status. Reluctantly, because I dislike recognizing taxa from single specimens,
especially when no reliable field observations are available. However, to my
knowledge Kaempfer was a reliable collector and the data on the label are
specific as to date and locality. The morphological differences in combination
with the wide range disjunction and presumably very different habitat (here is
where I am least content with the lack of field data, but if the locality is accurate
the habitat must be different from spectabilis) all point to obrieni being something
different."
Comments from Schulenberg: "My vote is NO. But that is a vote on principle,
pure principle.
Kevin Zimmer does a good job of convincing me that obrieni deserves species
rank. My only concern is that Kevin's well reasoned arguments are not published.
I don't see any substantive difference between Peters, or a field guide author,
publishing a taxonomic decision with little or no available rationale; and our
committee publishing or reaching a taxonomic decision on the basis of "inside"
information, with little or no available (to anyone outside of SACC) rationale. In
both cases, from the perspective of anyone on the outside, the decision is made
inside of a "black box."
Admittedly, outsiders might stumble across our SACC proposal website, or we
might even direct people to it. But what is the long term prospect of the website?
To the greatest extent possible, I'd prefer for our decisions to be based on
published information and published rationales. Kevin's proposal looks to me to
be a great first draft of a short note for publication on this taxonomic change; if
such a manuscript had been submitted already, then I would vote in favor of this
proposal in a heartbeat.
I too am uncomfortable, of course, with species known from only a single
specimen. Hybridization seems very unlikely to me in the instance, however:
what would the parent combination be? And outside of some well known
instances of secondary contact (e.g., Colaptes), so far as I know woodpeckers
are not particularly prone to hybridization anyway.
It would be interesting to know what other specimens were collected the same
day and place as the type of obrieni, to see whether this might give some clues
as to what habitat the bird might be found in (or once occupied?)."
Comments from Whitney: "Celeus spectabilis obrieni is known only from the type
at AMNH. That proposal in the literature to split it as a species is ludicrous
(nothing more than a statement that it should be elevated to species rank
because it's apparently unique). This question deserves careful analysis, which
Kevin should do and publish before the SACC accepts it as a species.
I looked at the specimen a few years ago, and I wish I could lay may hands on
the video and notes I made, but it's late and this may be a done deal now.
Anyway, it's a very strange specimen, I think. I was not convinced, on looking at
it, that it could not be a mutant individual showing a combination of characters
that are all individually present across the genus, or perhaps a cross or
backcross between C. flavus and another species (flavescens, even torquatus
potentially involved). C. flavus has a lot of rufous in the wing up in that region.
Finally, I went to Uruçuí back in about March 1999. If the bird is at all like
spectabilis, it is almost certainly going to be in a river-created habitat. I saw no
sign anywhere near (above or below) Uruçuí of patches of Gynerium, bamboo,
other primitive grasses, other river-edge veg that looked like it might be OK for
something similar to C. spectabilis. Who knows what the river looked like when
Kaempfer was there -- but I can report that the entire region is basically cerrado,
often right down to the bank of the river, and it's in amazingly good shape, I
imagine very much like it was back then. All of this means next to nothing, of
course -- but I do believe that obrieni is best left alone until someone finds it alive
or gets a molecular analysis of it done. At least find out what its mother was. If
she was not any of the species we have on the books, then that's enough to
convince me that it can be elevated to species rank. (Not that this info is
recoverable from this specimen, but it certainly could be tried).
What's the point of elevating it without clear reason? Feel free to forward this
message to others if you think appropriate."
Comments from Remsen: "NO. In view of tom and Bret's comments above, I
change my vote from YES to NO. When someone with Bret's experience and
instincts has actually handled the type specimen and has his doubts, that's
enough for me, and Tom's philosophical points are on target."
New comments from Zimmer: "Both Tom and Bret's points are well-taken, and
indeed, I think I conveyed my own general reluctance to recognize anything
based on only a single specimen. I also want to state that I respect Bret's
informed views on this particular situation. However, I think a few of his points
call for clarification. I don't think that proposals in the literature to elevate obrieni
to species status are "ludicrous". Rather, they seem natural given the uniqueness
of the type specimen and the huge range disjunction from any known population
of Celeus spectabilis, the species with which obrieni was lumped by Short. Short
also examined the type of obrieni, and compared it with all other Celeus at
AMNH. He obviously thought the specimen was different enough (i.e. not clearly
a mutant or hybrid) to warrant the creation of a new subspecies. Given the range
disjunction and the biome from which the specimen originated, I'm surprised that
he decided to describe obrieni as a subspecies rather than as a distinct species,
but my point is the same: an experienced taxonomist looking at the specimen
against a backdrop of all other Celeus still decided it represented a distinctive
taxon rather than a hybrid or mutant of some type.
“I think that all too often we tend to invoke the hybrid theory when confronted with
single specimens of distinctive taxa. For some groups, in which hybridization is a
proven frequent phenomenon, such speculation may be justified. But for most
other birds, I think it is less likely that someone collected the ultra-rare hybrid
than that the specimen is of a valid taxon whose range and/or microhabitat we
simply haven't managed to pin down. The validity of Pithys castanea was
constantly questioned until it was rediscovered by LSU personnel. Ditto for
Hemitriccus inornatus, Hemitriccus (Todirostrum) senex and Pipra vilasboasi.
What about Conothraupis mesoleuca? It remains known from a single specimen
(less distinctive than Celeus obrieni). Is it ludicrous that we continue to recognize
it as a distinct species? Had Short described obrieni as a distinct species rather
than as a distinct subspecies, it would be in the same boat as the Conothraupis --
an enigma that no one has been able to refind despite much searching in the
vicinity of the type locality.
“We also have to ask what are the likely parents that would produce this hybrid.
The only Celeus that we found in the region was Celeus flavescens ochraceus.
The other Celeus species that Bret mentions (torquatus, flavus) are humid forest
or gallery forest bird, and this habitat is lacking from the region. To accept the
hybrid theory, we must not only accept that this rare occurrence (i.e. two Celeus
species interbreeding and producing a spectabilis-looking hybrid) took place, but
that the resulting hybrid was some sort of vagrant that made its way out into
inhospitable habitat that was inconsistent with the habitat occupied by its parent
forms.
While Bret found the type specimen of obrieni odd (i.e. possibly a mutant, hybrid,
or backcross), his examination of it obviously wasn't enough to deter him from
making the effort to search extensively for the bird near the type locality (which
isn't exactly on your way to anywhere). Based on my own time in that region, I
agree with Bret's assessment that there is no habitat typical of Celeus
spectabilis. This proves nothing, because we don't have any real reason to think
that obrieni would be ecologically similar to spectabilis anyway. Short placed
obrieni with spectabilis on the basis of plumage characters alone. I don't agree
with Bret regarding the lack of any real alteration to the native habitat since the
time of Kaempfer. As Jose Maria has noted, much of the tall forest from Piauí
has disappeared. A similar assumption that habitat loss could not explain the
disappearance of Spix's Macaw predominated for some time, based on the
abundance of caatinga extant within its former range. It is now known that the
macaw was intimately tied to a critical abundance of caraiba trees; a microhabitat
within a habitat. For a big woodpecker, for which potential nest trees could be a
limiting factor, it seems entirely conceivable that destruction of tall, semideciduous forest or systematic removal of larger trees from remaining stands of
such forest could explain a massive decline in a specialized species. I found
caatinga and dry forest to be present over large areas of Piauí. At the same time,
I found only remnant stands of taller forest, which supports Jose Maria's
observations.
“None of this proves that obrieni is a distinct species, but I do think that the only
reason we are having this conversation is because of the "accident" that Short
described it as only a subspecies in the first place. If the hybrid/mutant argument
prevails, then I see no more justification for recognizing obrieni as a subspecies
of spectabilis than I do for recognizing it as a distinct species. To subscribe to the
hybrid/mutant theory or the "can't recognize anything based on a single
specimen argument" would invalidate recognition of obrieni at any level. If the
bird is a legitimate taxon, I don't see how it can possibly belong with spectabilis.
To maintain the status quo until the bird is discovered in life, is to essentially
validate Short's description of the bird as a distinct taxon. Once you've accepted
that part, the elevation of obrieni to species-level is not such a leap.”
New comments from Silva: "After reading carefully all new comments, I think I will
keep my vote on
obrieni."
More comments from Bret: "I guess I'll add a few more thoughts on the Celeus
obrieni proposal, especially since Kevin called for some clarification of my
comments. First, I apologize for the word "ludicrous". When I saw it written back
at me, it did look harsh.
Hey, I don't know what this specimen represents. Without a molecular analysis
of it, I doubt we are going to "find out". Now, if someone does manage to prove
that it exists in the wild, that's great. But that hasn't happened despite some
good observers looking at the single known locality of occurrence (and
Kaempfer's locality *can be trusted*; as I recall, his notes showed that he was at
the end of an extended stay at Uruçuí when he collected it, and it looked to me
like he must have been close to town). For sure, Kevin, I thought it was worth
going to the type locality to look for the bird. It is a distinctive looking bird. And
Celeus woodpeckers, especially those in relatively open habitats, are almost
certainly going to be heard or seen within three days. (However, I wouldn't call
that specimen, or most other Celeus, a "big woodpecker").
Where does this leave us? Well, someone could write a paper actually
evaluating the specimen and all associated data and reasoning. The conclusion
could be that it is a species-level taxon, or that it is a mutant/hybrid. I think that's
it for possibilities (unless the conclusion is that it's not possible to pin it down on
present knowledge, surprise). Short decided it was a lot like spectabilis and
called it a subspecies; nobody seems very happy with that. But Tom's got it quite
right when he says that elevating it to species level without anything more than
"it's disjunct and looks distinctive" is too arbitrary (not that we can't be a little
arbitrary in some cases). So, I continue to think that if anyone wants to elevate
obrieni to species level, then they should publish a well-balanced, objective
argument for it. That argument will have nothing to do with whether or not it was
originally described as a species or subspecies.
Some points to be considered, among many others: Yes, if it is a simple F1
hybrid, it cannot be explained. I don't think it could be this kind of hybrid, and I'm
not arguing that it is a more complicated (and infinitely rarer) type of hybrid. I will
comment, however, that a wandering individual torquatus or flavus in this region
is not too far-fetched. There is a mosaic of habitats, and I suspect that
populations of these species could be found not terribly far away. Should such
an individual end up mating with a "resident" flavescens, and if this were to
happen again with another species... dream on. At least this can be checked!
So, let's see *who it's mother was* -- if it is clearly a named species, then the
case for obrieni as a valid taxon at any level is out... with one exception. If the
mother was especially close to spectabilis, there is a good argument for either
splitting obrieni as a species [disjunct, distinctive sounds good now] or leaving it
as a well-marked subspecies, depending on where one draws that line (and it
looks like most/all of us, including me, would call it a species). I am not arguing
that it is a mutant displaying an odd combination of Celeus-like characters,
though I think that is possible. I *am* arguing that we cannot be sure what it is,
*especially in the absence of a good, detailed analysis of the situation*.
It should be noted that there is no caatinga anywhere near the type locality.
There is no "transition to caatinga" anywhere near the type locality. This entire
region of Piauí and Maranhão is a mosaic of cerrado, cerradão, palms, and
somewhat more mesic woodland. This is reflected clearly on vegetation maps
and in the avifauna present there -- right, Kevin (or am I missing something)? In
1999 (I think that's when I was there), it was all in pretty darned good shape, with
extensive cleared areas only around Uruçuí itself (along with some nice habitat):
basically, I was impressed. The area was on the verge of massive alteration,
however. The tractors were already at work. Farmers from Paraná, in particular,
had bought up vast tracts of land and were planning to level it all for soybeans
within the next few years; highly mechanized operations. I talked with several of
these guys, independently, always by accident, always without really wanting to.
(Never stop for a beer where there are 0 women present. Or only 1 woman. And
certainly don't do it more than once.) Thus, aligning this locality with caatinga
areas of endemism and suggesting that obrieni could be a species that fits some
caatinga-related pattern, calling it "Caatinga Woodpecker" is inappropriate at
best.
The idea that we are worried about this at all is due to it being described as a
subspecies doesn't look at the other side of the coin: One might well have
submitted a proposal to suggest that there are some reasonably good points in
favor of C. obrieni not being a good species. Lumping? Yes, that's always right
there besides splitting.
Finally, somewhat sheepishly: I saw a female Conothraupis mesoleuca at P. N.
Noel Kempff Mercado back in about March 1993. It sat in good view for more
than a minute. This was not far from the type locality, and I feel confident that it
couldn't have been a speculigera though it sure looked a lot like it, mostly being
grayer, less greenish as I recall. Since the female is undescribed, and I've been
meaning to get back for a more careful look at the area, I've just let it slide. I am
a strong proponent of getting documentation for stuff like this; I still don't have it.
No further excuse.
Thanks to all for considered opinions, but this is the last from me on this one."
Comments from Nores: "[YES] Si. Las razones para reconocer a un nuevo taxa
son similares, ya sea para especies o subespecies. Si uno acepta que el único
ejemplar conocido tiene características diferentes como para aceptarlo, y estas
características son a nivel de especies, me parece que lo lógico es considerarlo
como especie."