Proposal (558) to South American Classification Committee
Treat Thalurania
fannyi and Thalurania colombica
as conspecific
Proposal: This
proposal, if it passes, would result in T.
colombica being removed from the AOU-SACC list and lumped, a prevailing
treatment in publications before the 1990s.
Discussion:
The split of fannyi
from colombica by Escalante-Pliego
& Peterson (1992) was based on differences in crown coloration and under a
phylogenetic species concept.
Recent data shows that the distribution of Thalurania morphotypes in Colombia is a rather more complex matter
than would have been evident from materials available in the mid-1990s. As
hinted by some comments in proposal 137
(http://www.museum.lsu.edu/~Remsen/SACCprop137.html), this proposed split,
which is currently accepted by SACC, requires reconsideration.
Donegan (2012) recently summarised the situation of these
species in Colombia, the only country in which Escalante-Pliego & Peterson
(1992)'s two species supposedly co-occur.
[Localities mentioned in the first two sentences are from Serranía de
San Lucas, an isolated massif north of the Central Andes. Anorí and Samaná are in the north of
the adjacent main Central Andes range.]:
""WOODNYMPHS
Thalurania sp.
Trapped
previously by Salaman et al.
(2002a) at La Punta (5) and La Teta Resort (12) and
others mist-netted at
Santa Cecilia (11, 2†) where sound-recorded in the hand or on release
(XC99512-13, 104416-17) and while foraging (XC104452). All males at Santa
Cecilia had a spot of purple feathers slightly behind the centre of the
otherwise green crown (Fig. 5). In
this feature, they are intermediate between Purple-crowned Woodnymph T.
colombica of the East Andes and Green-crowned
Woodnymph T. fannyi hypochlora of the
West Andes and adjacent lowlands, which were previously treated together as 'Crowned Woodnymph'. ICN specimens collected at Anorí
similarly possess a small purple forehead spot. Escalante-Pliego & Peterson
(1992) noted that 'One to several violet
feathers at the rear edge of the forecrown are
observed in most Panamanian specimens'. To this should now be added
specimens from San Lucas and the northern Central Andes (F. G. Stiles in Remsen et al. 2012,
proposal 137). T. fannyi and T.
colombica were split largely on the basis of crown
coloration in males (Escalante-Pliego & Peterson 1992). In the latter
study, purple-crowned birds were considered restricted to the Santa Marta
Mountains and Central Andes of Colombia, with green-crowned birds in the West
Andes and adjacent lowlands. We now know that purple-crowned birds occur in the
East Andes (Donegan et al. 2007),
with green-crowned birds in the West Andes and purple-and-green-crowned birds
in the northern Central Andes and San Lucas. At río Samaná, Caldas (05°25'39"N,
75°01'07"W), purple-and-green crowned males also occur, as do males with
almost no purple in the crown (M. Slaymaker in litt. 2012). Green-and-purple-crowned males from Panama
are generally assigned to T. f. fannyi, with pure green-crowned hypochlora in
the Colombian Chocó and West Andes. Treatment of T. colombica and T. fannyi as separate species requires revision in light of the
known distribution of morphotypes in Colombia, identical female plumages and
similar vocalisations throughout the Colombian Andes."
We have more recently seen the description (recently
rejected by this committee) of Thalurania
nigricapilla (see proposal 472:
http://www.museum.lsu.edu/~Remsen/SACCprop472.html). The main distinguishing feature cited in the diagnosis
section for the nigricapilla
description was also in crown coloration.
Most committee members accepted the proposition in the proposal that
individual variation in this feature should be investigated further before
recognising this species.
These two proposed woodnymph species' calls sound pretty
similar (click on below links, then on "Sonograms", if these do not
immediately come up on your browser):
http://www.xeno-canto.org/browse.php?query=Green-crowned
Woodnymph (Thalurania fannyi) 8&pagenumber=&order=taxonomy&view=3
http://www.xeno-canto.org/browse.php?query=Violet-crowned
Woodnymph (Thalurania colombica)
9&pagenumber=&order=taxonomy&view=3
Females are indistinguishable. In biometrics and plumage features other than adult male
crown coloration, they are also similar, based on my data and experience from
mist-netting populations in all three Andean cordilleras of Colombia. Mostly green-crowned birds now seem to
be replaced by purple-crowned birds at some point in the mid-Central Andes
(rather than this being between-Cordillera variation). Some "good" species show
North/South distribution splits in the Central Andes, but they tend to be of
higher elevation than Thalurania.
It bears note in terms of assessing this proposal that although
Escalante-Pliego & Peterson (1992) was published some time ago, many
birders active in Colombia were unaware of the split until relatively recently,
due to near-universal use of Hilty & Brown (1986)'s field guide until the
mid-2000s at least. The Restall
and McMullan field guides split these, but they were published in 2006 and
2010/2011 respectively. The status quo versus novel nature of a
split treatment is therefore somewhat moot in the country where the two occur
together.
Now arguing against a change in treatment, one could adopt a
similar viewpoint here to that of some committee members in proposal 173
(http://www.museum.lsu.edu/~Remsen/SACCprop173.html) on Zimmerius chrysops.
There, new distributional data were thought by some not to be sufficient
to show current species-level taxonomy to be misled, but just to demonstrate
that previous assumptions as to the distributions of species required
reconsidering. An
approach against lumping these two species would regard the SACC baseline as
only to be amended following a detailed peer-reviewed publication including a
detailed vocal and/or molecular study specifically on topic, refuting the
current treatment. No such study
post- Escalante-Pliego & Peterson (1992) is available and a detailed
molecular and vocal investigation would indeed be helpful and welcomed.
Although they were described very close
together in time, the name colombica (Bourcier,
1843) apparently has priority over the name fannyi
(Delattre & Bourcier 1846).
The vernacular name of this hummingbird if lumped would revert to
"Crowned Woodnymph". Vernacular
names for this group were previously discussed in Proposal 303 (http://www.museum.lsu.edu/~Remsen/SACCprop303.html).
Finally, I'd like to stress that
Escalante-Pliego & Peterson (1992)'s study includes a lot of extremely
valuable data and analysis on this genus, especially as regards plumage
variation and the Central American populations. The doubts expressed here as to their proposed treatment for
the Colombian taxa are based in part on recent data not available to these
authors and perhaps in part on a different approach to species limits. This proposal should therefore not be
taken as a criticism of their work overall, which is a valuable and appreciated
contribution to the ornithological literature.
References:
Donegan, T.M. 2012. Range extensions and other notes on the birds and
conservation of the Serranía de San Lucas, an isolated mountain range in
northern Colombia. Bull Brit. Orn. Cl. 132: 140-161.
Escalante-Pliego, P. &
Peterson, A. T. 1992. Geographic variation and species limits in Middle
American woodnymphs (Thalurania).
Wilson Bull. 104: 205–219.
Other papers mentioned are cited in the above.
Thomas
Donegan, October 2012
Comments from Stiles: “YES.
Although I haven’t really gotten serious (yet?) about putting all my Thalurania data together, I am firmly
convinced that there is no solid basis for splitting fannyi from colombica. To
begin with, I should note that the original separation by Peterson et al.
involved a bit of
circular reasoning:
they started out with the question of whether the green- and
purple-crowned male birds were separable in multivariate space, then concluded
from a PCA that they were - but mostly on the basis of crown color! They effectively negated Zimmer’s
statement that blue feathering at the rear of the crown in fannyi decreased southwards from the zone of closest approach to colombica; in this I find that they were
correct. However, the small blue
feathers bordering the crown are not the feathers of interest here: Thomas (and
I) refer to the larger, more brilliant display feathers of the crown itself,
and among these occurs the mixture of green and purple feathers in the N end of
the Cordillera Central (Antioquia; Andrés Cuervo specimens) and the Serranía de
San Lucas (Bolívar); males of the Magdalena Valley and the Cordillera Oriental
are purple-crowned. Thus, a
considerable zone of intermediacy exists between colombica and fannyi based
on male crown color. Even more convincing
is the situation in females, in which geographic trends in coloration exist but
do not support a split along the lines of male crown color. Had Peterson et al. looked at females
(notably features like unicolored vs. bicolored grey underparts, blue vs. green
shoulders, etc.) they might well have reached a different conclusion.
Comments from Remsen: “YES. I am convinced by Donegan’s proposal
and by Gary’s comments.”
Comments from Pacheco: “YES. Pelas mesmas razões acima.”
Comments from Nores: “YES. I find Donegan’s proposal very
convincing and Gary’s comments very useful. By coloration and especially
by distribution with a zone of hybridization
it appears evident that they are
subspecies.”
Comments from Robbins: “YES, based on both Thomas Donegan and Gary Stiles’s
comments.”