Proposal (59) to South American Classification 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 138-153 mm
Tail:
C. s.
obrieni 95 mm
C. s. spectabilis (n = 2) 92 mm, 101 mm
C. s. exsul (n = 9) range 99-108
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 22.1-24.2
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, semi-deciduous 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."