Proposal (1) to South American Checklist Committee
Elevate Rhynchotus maculicollis
to species rank
Effect
on South American CL: this proposal would split the
Red-winged Tinamou, Rhynchotus rufescens, into two species, R.
rufescens and R. maculicollis.
Background: The subspecies of Rhynchotus rufescens
(Red-winged Tinamou) that inhabits the foothills of the Andes of Bolivia and NW
Argentina, R. m. maculicollis, has been treated at the subspecies
rank during this century by Peters (1931), Meyer de Schauensee (1966, 1970),
Blake (1977), Sibley and Monroe (1990), Handbook of the Birds of the World,
etc.
New
information: Maijer (1996: Auk 113: 695-697),
however, provided data on primary vocalizations that suggests that this taxon
merits species rank. His rationale was as follows: (1) songs of tinamou taxa currently
treated as species are surprisingly uniform (citing Hardy, Vielliard, and
Straneck ARA cassette); (2) songs of the three lowland subspecies of R.
rufescens are differ in only minor ways, perhaps only individual variation
(based on his limited experience); and (3) the difference between maculicollis
and lowland rufescens is substantial; to quote Maijer: "the song
differences between maculicollis and lowland populations of R.
rufescens are as great as between closely related species in other tinamou
genera (pers. obs.)". Maijer compared tape maculicollis from 5
individuals from 4 widely separated areas of Bolivia to single representative
recordings of lowland rufescens from the three named subspecies (from
Bahia, Huanchaca, and Entre Rios) to quantitatively demonstrate the
differences. Maijer noted that the foothills and lowlands populations are
probably allopatric, separated by unsuitable (forest) habitat.
Recommendation: We could easily fault Maijer for not having larger and
broader samples, for not evaluating whether the closest rufescens
populations approach maculicollis in voice, and for not quantifying his
statements on within-species vocal variation in other tinamous. However, such
criticisms could be leveled at almost any new data set, and if we set our
standards that high, we might as well endorse 99% of the status quo and all go
home. Furthermore, our current status-quo taxonomy is based on much less. For
example, Peters or whoever started treating maculicollis as a subspecies
probably lumped it into rufescens without so much as a comment. From my
experience on the AOU CLC, this example will be a typical dilemma for us:
retain a status quo often based on unstated rationale or opinions versus accept
a novel change backed by data that is often far below what we'd hope for.
Unfortunately, a dissertation-quality study cannot be undertaken on every
taxonomic problem.
Therefore,
I favor following Maijer for the following reasons: despite limited sampling in
terms of individuals, it is geographically fairly extensive, and I have no
reason to suspect that more complete sampling would alter the conclusions. The
sonograms indicate that indeed there is a major difference between the two
proposed species. I do not have sufficient direct experience to evaluate the
statement attributed to Hardy et al. concerning within-species variation in
other tinamous. Philosophically, my position is that if we recognize maculicollis,
then we at least have one pair of tinamou allospecies for which their taxonomic
rank is supported by a published, peer-reviewed paper ... which differs
strongly, for example, for the current status-quo taxonomy of that set of Crypturellus
species from duidae through kerriae and their Middle American
relatives.
English
names: Maijer recommended "Huayco
Tinamou" for R. maculicollis, the onomatopoetic local name for the
bird in Bolivia. I like this, but I do not think we should be constrained by
published preferences for novel taxa. Another possibility, less colorful but
perhaps more informative than the above, might be "Foothill Tinamou."
Some "common name" purists out there might insist that we use a
compound name, like "Huayco Red-winged Tinamou" and "Lowland
Red-winged Tinamou." On the AOU CLC, we tend to use these compound names,
or invent a new name for both taxa (reserving the old name for the
superspecies) when the taxonomic split divides the original species into two
major populations. However, when the split involves a peripheral isolate of a
widespread form, we tend to retain the "old" name for the widespread
one and invent a new one for the peripheral isolate (e.g., Red-winged and
Red-shouldered blackbirds). In my opinion, the Rhynchotus situation is a
better match for the latter. Therefore, I propose we go with "Red-winged
Tinamou" and "Huayco Tinamou."
Van Remsen, 4 Oct. 2000
Comments
from Stiles: "I have no experience with the
taxa involved. However, my experience
with several other tinamou taxa has been that voice, while not necessarily absolutely
invariant, is much more constant than
details of plumage over wide geographical
areas in several species. Hence, I would be more willing to split a tinamou species on
the basis of pronounced vocal differences than differences in plumage, all
other things being equal. How did Maijer identify his foothill birds? Did he
take specimens to serve as vouchers for the vocalizations? (in other words, is
there no doubt that what he recorded is maculicollis?) If this is the case, my
personal bias would be to recognize maculicollis as a separate species as per
Van's recommendation. Regarding English names, I have no strong preferences in
this case. It seems that, for consistency, if three-word names are to be
employed, the choices would be Foothill Red-winged T. and Lowland Red-winged
T.; with two-word names, Huayco and Red.-winged Ts would do . I don't care for
Foothill T. "a secas" as there are several other tinamou taxa that
are essentially foothill birds.
Comments
from Nores: "NO. Although Maijer reasons
seem valid, I think that the differences in song are not enough to elevate maculicollis to species rank to. In the
field the songs do not sound too different.”
Comments
from Jaramillo: "YES. My vote is to do so, elevate Rhynchotus
maculicollis to species rank and give it the English name Huayco Tinamou. I
have heard and seen many individuals of R. rufescens from southern
Buenos Aires province, to Santa Cruz Bolivia and at several sites in between.
Their vocalizations vary somewhat individually but there is no clear geographic
pattern that I have detected at least through casual observation/listening.
However, the shift in song from rufescens to maculicollis is
clear, unambiguous and distinct. Rhynchotus rufescens gives a melancholy
series of whistles, usually three, the first one longer and slurred the last
two shorter and descending: "Pheeew weeu weeu". In contrast, R.
maculicollis gives a sharp, quick two syllable whistle that is slurred
together the first part ascending the second more even in frequency:
"Wheee- cooo!" I have heard the two taxa only several days apart,
rufescens in the lowlands of Santa Cruz, Bolivia and maculicollis in the
highlands of Siberia, Bolivia. The differences in vocalization and habitat were
striking, furthermore there were no representatives of Rhynchotus in
intermediate elevations. Apparently the same distinction is seen in Argentina
in the Calilegua area highlands (maculicollis) and Salta/Jujuy lowlands
(rufescens) and Sierra de Aconquija (maculicollis) and Tucuman
lowlands (rufescens) without any intermediate populations. I do not like
the name Foothills Tinamou for maculicollis due to the fact that it
appears to inhabit areas above what I would term the foothills, being found in
clearings above moist Yungas/cloud forest, so really in the lower Temperate
zone, or perhaps upper subtropical. The grasslands I have heard maculicollis
in Bolivia are moist, often at the fog line, and very different from the dry
(or at least seasonally dry) grasslands one finds rufescens in. Based on
heard calls and responses to playback, maculicollis occurs in low
densities, while rufescens is often found in rather high densities. From
my perspective this split seems to be a very good one.”