Proposal (439) to South American Classification Committee
Split Ortalis
columbiana from O. guttata
Effect of Proposal: If it passes, this proposal would result in one of
Colombia’s 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:
“In 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
“verify its status as a subspecies of O.
guttata or its validity as a separate species”. Votes on the Colombian
checklist forum were 13-3 in favor of treating this as a separate species.
“As 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).
“Previous 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.
“There are considerable interspecific differences
in the rhythm of phrases of Ortalis songs.
For example, the song of Ortalis garrula
is a repeated three-syllable “Guachara”
whilst that of O. ruficauda is a
repeated “Guacharacá” (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
‘cha’ followed by a gap, then a longer phrase, in all song bouts. The full
repeated phrase could be transcribed as “Cha,
chachalaca”. The final two notes are sometimes delivered closely together
and merge in some recordings into: “Cha,
Chachalac”. 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 “Chachala” or “Chachalaca". 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)’s 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.
“There 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 Comité Brasileiro de Registros Ornitólogicos does not
recognize this split and vocal differences are not so marked as for columbiana.
“Rufous-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.
“Turning 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.
“In 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).”
A
list of sound recordings inspected, some sonograms and photographs were also
published.
Recommendation: A “YES” 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): “I’m happy to endorse this proposal and hope it will be
given consideration for ratification by SACC.”
References:
Donegan, T., Salaman, P., Caro, D. & McMullan, M. 2010.
Revision of the status of bird species occurring in Colombia 2010. Conservación Colombiana 13: 25-54.
Other references are cited in this paper.
Thomas Donegan, May 2010.
Comments from Robbins:
“NO. The plumage
differences are well documented, but after listening to the poor-quality
recordings of columbiana on xeno-canto,
it is difficult to know how different the vocalizations are. At this
point, I’d like to see genetic data added before making a decision. Thus,
for now, I vote “no”.
Comment
from Thomas Donegan:
“Subsequent 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:
“YES. I think that the widespread guttata needs splitting up, and columbiana is the most distinctive of the taxa
deserving of species rank.”