Proposal (412) to South American Classification Committee

Split Momotus momota into five species

This proposal would reverse the decision of Proposal no. 117 which favored lumping the highland form aequatorialis (considered a separate species in the baseline list) into a broad M. momota due to the lack of published evidence supporting the split, and in view of the fact that other taxa currently included in M. momota would probably deserve species rank were a comprehensive analysis to be performed. I have attempted such an analysis (Stiles 2009), now published in Ornitología Colombiana, the online journal of the Asociación Colombiana de Ornitología. Hopefully by now the members of SACC have received from Van a pdf of this study; if not, it can be downloaded from the web page of the journal Ornitología Colombiana: www.ornitologiacolombiana.org/revista/htm.

Basically, I drew my data from three sources: plumage patterns, biometrics and vocalizations, supplemented by information on geographic distributions and ecology. I examined a total of 512 specimens of ten “focal” taxa occurring in the area between southern Central America, northern and western South America from Colombia east to the Guianas and south to northern Peru, and Trinidad-Tobago. I also examined ca. 30 specimens from areas slightly to the south and east to further check for intraspecific variation. I defined 14 characters of plumage pattern and took six 6 measurements of bill, wing and tail. For vocalizations, I restricted the main analysis to the ‘hooting’ “primary song”; motmots have a much broader vocal repertoire but other vocalizations had not been recorded consistently for all taxa. From sonograms, I measured five parameters of frequency and duration for those taxa in which this song consisted of a single note, and six additional parameters for taxa in which the song consisted of two notes. Data were analyzed with t-tests, ANOVA, discriminant analysis and principal components analysis. I defined species limits in this complex on the basis of two general criteria: diagnosability and the probability that the differences observed would assure maintenance of reproductive isolation should currently allopatric groups enter into contact. My results support recognition of five species-level taxa in this complex: lessonii Lesson 1842 (including 2-3 additional subspecies in Mexico beyond the scope of this study), momota Linnaeus 1766 (including the nominate, microstephanus Sclater 1855 and several other subspecies of eastern and southern South America beyond the scope of this study); M. aequatorialis Gould 1857 (including the subspecies chlorolaemus Berlepsch and Stolzmann 1902); bahamensis Swainson 1837 and subrufescens Sclater 1853. In the latter species I recognize as subspecies osgoodi Cory 1913, argenticinctus Sharpe 1892 and spatha Wetmore 1946, but find the following taxa not adequately diagnosable and recommend lumping them into nominate subrufescens: conexus Thayer & Bangs 1906, reconditus Nelson 1912 and olivaresi Hernandez & Romero 1978.

For the purposes of SACC, my analysis would recognize four species in our area (lessonii being restricted to Central America): cis-Andean momota, Andean aequatorialis, northwestern, trans-Andean subrufescens and Trinidad-Tobago bahamensis. My conclusions are congruent with a phylogeographic analysis of the Momotidae (as yet unpublished) by Chris Witt, save that bahamensis is nested within the subrufescens clade; I present arguments, mainly from plumage and biometrics, in support of species status for bahamensis. Regarding English names, I propose Amazonian Motmot for momota since the Amazon basin includes the vast majority of its distribution (and because of the great variation among the named subspecies, I could devise no adequately descriptive name suitable for all of them); Whooping Motmot for subrufescens because its rather long-drawn-out single-note song does indeed sound like a whoop; Andean Motmot for aequatorialis because it is indeed restricted to the Andes and because other species of motmot are also “highland” birds; and Trinidad Motmot for bahamensis.

The important references for this study are given in Proposal 117 and the pdf of this study. I recommend a YES on this proposal (obviously!).

F. Gary Stiles, August 2009

Comments from Robbins: “YES. Gary has thoroughly documented species level differences among these taxa.”