Split Ortalis columbiana from O. guttata
Effect of Proposal: If it passes, this proposal would result in one of Colombia‚Äôs most charismatic and distinctive endemic species, Ortalis columbiana (Colombian Chachalaca), being instated as separate from O. guttata (Speckled Chachalaca).¬† This treatment is already reflected in much modern literature and is a treatment that would now also be supported by vocal differences, recently analysed by Donegan et al. (2010).
Discussion: In Donegan et al. (2010), we reviewed the literature on this species and studied a good sample of sound recordings from across the range of the greater guttata group.¬† We stated as follows:
‚ÄúIn Salaman et al. (2001) but not in Salaman et al. (2007, 2008a, 2009), we recognised the split of Colombian Chachalaca Ortalis columbiana of the Cauca and Magdalena valley slopes from Speckled Chachalaca Ortalis guttata of the Amazonian basin and eastern Andean foothills. Many other authors have adopted a similar approach in splitting these species (e.g. Peters 1934, Pinto 1938, Meyer de Schauensee 1964, Hilty & Brown 1986, Sick 1993, Ridgely & Greenfield 2001, Restall et al. 2006, Gill & Donsker 2010). However, in some publications, they are lumped (e.g. Dunning 1987, Dickinson 2003, Rodriguez et al. 2005, Erize et al. 2006; Brooks 2006, Remsen et al. 2010). In the case of Brooks (2006) a research and conservation priority was highlighted for Ortalis guttata columbiana to ‚Äúverify its status as a subspecies of O. guttata or its validity as a separate species‚Äù. Votes on the Colombian checklist forum were 13-3 in favor of treating this as a separate species.
‚ÄúAs is well known, columbiana differs considerably from eastern populations in plumage characters. O. columbiana has more extensive pale scaling on the breast and belly, compared to stippled white marks in guttata (Figure 1).
‚ÄúPrevious opinions on the rank of these taxa have been based largely on subjective interpretations of plumage and biometrics (e.g. Sick 1993). Molecular studies of the group (e.g. Pereira et al. 2002, Frank-Hoeflich et al. 2007) have not addressed the issue of relations between members of the Ortalis guttata group to date. In this section, we consider vocal differences, which have not been subject to detailed study before now. Notably, vocal differences are comparable to those between other Ortalis ranked as species.
‚ÄúThere are considerable interspecific differences in the rhythm of phrases of Ortalis songs. For example, the song of Ortalis garrula is a repeated three-syllable ‚ÄúGuachara‚Äù whilst that of O. ruficauda is a repeated ‚ÄúGuacharac√°‚Äù (four syllables with emphasis on final note). Differences in these aspects of the vocal signature have impacts on acoustic variables such as number of notes, total song length and the relative length of different notes in a song. Recordings of columbiana (n=7) involve an initial ‚Äòcha‚Äô followed by a gap, then a longer phrase, in all song bouts. The full repeated phrase could be transcribed as ‚ÄúCha, chachalaca‚Äù. The final two notes are sometimes delivered closely together and merge in some recordings into: ‚ÄúCha, Chachalac‚Äù. In contrast, all recordings studied of the song of other O. guttata populations lack the initial note in their main song bouts (n=21). The songs of the subspecies guttata and subaffinis of Amazonia (n=16), auracan of northern Brazil (n=2) and squamata of southern Brazil (n=3) are instead a repeated three or four note refrain with no initial note or gap, which could be transcribed as ‚ÄúChachala‚Äù or ‚ÄúChachalaca". In recordings where more than one individual is calling, one must listen carefully to identify particular individuals so as to discern the rhythm of the song, particularly at the start of a song, when many individuals tend to vocalize in duets. Sick (1993)‚Äôs transcriptions of some songs are based on the sound of more than one individual vocalizing, for example. Fieldwork by the first author in Colombia and Bolivia with both columbiana and guttata groups revealed that these more complex appearing songs are due to several individuals vocalising at the same time.¬†
‚ÄúThere is variation in songs across the range of the eastern populations. Recordings of the northern Brazilian populations auracan examined are all of a three-syllable refrain. Recordings had different relative lengths of the three syllables compared to Amazonian populations (Figure 2). These two Brazilian populations also have different plumage from guttata, leading some authorities to split them (e.g. Sick 1993). However, the Comit√© Brasileiro de Registros Ornit√≥logicos does not recognize this split and vocal differences are not so marked as for columbiana.
‚ÄúRufous-headed Chachalaca Ortalis erythroptera also has a three-syllable song (as for a narrower Ortalis guttata) but the song is lower pitched and slower (Figure 2). This difference is comparable to that shown between O. guttata group and O. columbiana.
‚ÄúTurning to calls, various one-note honks and whistles, often repeated, are given by both guttata and columbiana groups. Insufficient materials were available to carry out a detailed comparison.
‚ÄúIn light of vocal and morphological differences, a better approach for these birds for the time being under a biological species concept (Helbig et al. 2002) would be to recognize Ortalis columbiana as a species, and we therefore adopt this approach, reverting to the position in Salaman et al. (2001).‚Äù
A list of sound recordings inspected, some sonograms and photographs were also published.
Recommendation: A ‚ÄúYES‚Äù vote.¬† This is an old chestnut of allopatric populations on which various authorities have taken different views over the years.¬† SACC has had this issue down as requiring a proposal for many years.¬† There has now also been a study of voice that supports one of the two approaches, i.e. splitting columbiana.¬† If anyone wants to do a separate proposal on splitting the vocally more similar Brazilian taxa, then that would be a separate matter.
Comments from Dan Brooks (chair of Cracid Specialist Group): ‚ÄúI‚Äôm happy to endorse this proposal and hope it will be given consideration for ratification by SACC.‚Äù
Donegan, T., Salaman, P., Caro, D. & McMullan, M. 2010. Revision of the status of bird species occurring in Colombia 2010. Conservaci√≥n Colombiana 13: 25-54.
Other references are cited in this paper.
Thomas Donegan, May 2010.
Comments from Robbins: ‚ÄúNO.¬† The plumage differences are well documented, but after listening to the poor quality recordings of columbiana on xenocanto, it is difficult to know how different the vocalizations are. At this point, I‚Äôd like to see genetic data added before making a decision. Thus, for now, I vote ‚Äúno‚Äù.
Comment from Thomas Donegan: ‚ÄúSubsequent to the above comment, Andrew Spencer has uploaded some nice recordings of columbiana to xeno-canto which show the phraseology discussed above and in the paper, which should help committee members with this one. http://www.xeno-canto.org/america/browse.php?query=guttata+rec%3Aspencer
Please note that this and the other two proposals on Colombian splits in this series are based on a large number of other published recordings in addition to those on xeno-canto (all of which are listed and cited in the paper) and that sonograms are also set out in the paper."
Comments from Stotz: ‚ÄúYES¬† I think that the widespread guttata needs splitting up, and columbiana is the most distinctive of the taxa deserving of species rank.‚Äù