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 Serran’a de San Lucas, an isolated massif north of the Central Andes.  Anor’ and Saman‡ 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 Anor’ 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 r’o Saman‡, Caldas (05ˇ25'39"N, 75ˇ01'07"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 Choc— 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 Serran’a 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: ŇYES. Although I havenŐt 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 ZimmerŐs 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; AndrŽs Cuervo specimens) and the Serran’a de San Lucas (Bol’var); 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:  ŇYES.  I am convinced by DoneganŐs proposal and by GaryŐs comments.Ó

 

Comments from Pacheco: ŇYES.  Pelas mesmas raz›es acima.Ó

 

Comments from Nores: ŇYES.  I find DoneganŐs proposal very convincing and GaryŐs comments very useful. By coloration and especially by distribution with a zone of hybridization it appears evident that they are subspecies

 

Comments from Robbins: ŇYES, based on both Thomas Donegan and Gary StilesŐs comments.Ó