Proposal (804) to South American Classification Committee

Reorganize the taxonomic ranks within Accipitridae

Effects on South American CL: This proposal would reorganize the taxonomic ranks within Accipitriformes based in a more appropriate interpretation of available data.

Background: Currently SACC classifies diurnal raptors in three separate orders: Cathartiformes, Accipitriformes and Falconiformes, based on the results of recent molecular studies. Thus, the families Cathartidae, Accipitridae and Falconidae, ascends to ordinal rank. Accipitridae is the most diverse clade of diurnal raptors, with more than 200 species of a great variety of sizes, morphology, diets and lifestyles. Many recent phylogenetic analyses confirm that Accipitridae contains several deeply divergent linages, which have been designated as subfamilies, tribes and subtribes, depending on the different interpretations. Up to date, SACC recognize that Accipitriformes include only two families in South America: Pandionidae and Accipitridae, which is divided into three subfamilies, following (with some modifications) Griffiths et al. (2007).

New information: According to some previous studies, Accipitridae contains from eight (Griffiths et al. 2007), to twelve separated linages (Lerner & Mindell 2005). Most recent data show ten recognizable linages (Barrowclough et al. 2014, Nagy & Tokolyi 2014). In addition, Jarvis et al. (2014) recognize the superorder Accipitrimorphae, which contains Cathartiformes and Accipitriformes.

Recommendation: Modern taxonomy should reflect phylogenetic relationships between taxa, and at the same time most be pragmatic. The current classification of major clades, such as orders, is more pragmatic, and do not reflect necessarily the time in which those groups radiate (all the orders differ of each other at different times). In my view, that pragmatic practice should be used also in lower classification levels such as families. Up to now, everything seems to indicate that the extraordinary diversity within Accipitridae is masked by the presence of Pandionidae and Sagitariidae as families, which forces to subdivide the other groups of more recent diversification. Since many general publications do not include the last branches of the cladograms (subfamilies, tribes, etc.), this diversity remains invisible to the eyes of most readers. As an example, for any of us an Elanus kite does not seem to be part from the same family of a Spizaetus eagle, or does it? Think in that way, this obviously is only a problem of focus rather than of phylogenetic relationships. Remembering that you modified the Griffiths´ nomenclature from Tribes to Subfamily, I suggest that a better classification is ascending all subfamilies to family rank, maintaining Pandionidae as a family or, alternatively, ascending it to ordinal rank, sister to Accipitriformes, forming the superorder Accipitrimorphae, which also include Cathartiformes (Jarvis et al. 2014), but I think the first proposition is better. I recommend recognizing at least six families (plus Pandionidae) within Accipitriformes following Nagy & Togolgyi (2014): Accipitridae (Accipiter and Circus), Aquilidae (Spizaetus), Buteonidae (Busarellus, Buteo, Buteogallus, Geranoaetus, Geranospiza, Ictinia, Leucopternis, Parabuteo, Rupornis and Rostrhamus), Elanidae (Elanus and Gampsonyx), Harpiinae (Harpia and Morphnus) and Perninae (Chondrohierax, Elanoides and Leptodon). These authors recognize other four groups that have not representatives in South America: Aegypiidae, Gypaetidae, Heliaeetinae and Circaetidae.

Literature Cited:

Barrowclough, G. F., J. G. Groth, J. E. Lai & S. M. Tsang. 2014. The phylogenetic relationships of the endemic genera of Austral-Papuan hawks. Journal of Raptor Research. 48(1): 36-43.

Griffiths, C. S., Barrowclough, G. F., Groth, J. G. & Mertz. L. A. 2007. Phylogeny, diversity, and classification of the Accipitridae based on DNA sequences of the RAG1 exon. – Journal of Avian Biology 38: 587–602. DOI: 10.1111/j.2007.09088857.03971.x

Jarvis, E. et al. 2014. Whole-genome analyses resolve early branches in the three of life of modern birds. Science. 346 (6215): 1230-1331.

Lerner, H.R.L. & D.P. Mindell. 2005. Phylogeny of eagles, Old World vultures, and other Accipitridae based on nuclear and mitochondrial DNA. Molecular Phylogenetics and Evolution 37:327–346.

Nagy, J. & J. Tokolyi. 2014. Phylogeny, historical biogeography and the evolution of migration in accipitrid birds of prey (Aves: Accipitriformes). Ornis Hungarica. 22(1): 15-35.

Tomás Rivas-Fuenzalida, August 2018

Comments from Remsen: “NO. All of these groups have formal names already, and no objective rationale is presented for why they should be changed.”

Comments from Areta: “NO. I don´t see anything wrong in the families of the Accipitriformes as currently defined and sub-familial and generic groupings seem good enough to sort out variation within Accipitridae.”

Comments from Stiles: “NO. The fact that there are several well-defined, speciose clades in Accipitridae does not in itself justify elevating then to family rank, much less elevating Accipitridae to ordinal rank. Rivas himself admits that there is considerable heterogeneity in the age of splits among these clades, and this is where (if anywhere) standardization of higher taxonomic ranks should be attempted. Moreover, phenotypic differences do not always correlate with phylogenetic age in rapidly radiating clades, and this could well be true among raptors, predatory specialists high on the food chains. The present division of Accipitridae into subfamilies adequately expresses diversity in this family.”

Comments from Claramunt: “NO. Although Accipitridae is very diverse, I don’t see compelling arguments supporting the proposed change, in particular, I don’t see substantial phenotypic gaps between the proposed families. Subfamily and tribe categories take care of subdividing the main subgroups.”

Comments from Pacheco: “NO. I consider the subdivision in sub-families and tribes as satisfactory for recognized groups.”

Comments from Zimmer: “ “NO. I would echo all of Gary’s comments on this, particularly regarding the considerable heterogeneity in the age of splits among the various clades, and the point that phenotypic differences do not always correlate with phylogenetic age in rapidly radiating clades. I would also have to say that I’m with Santiago in not being particularly impressed with the implied phenotypic gaps between most of the proposed families. Existing subfamily, tribe and generic groupings already adequately frame the diversity within Accipitridae as far as I’m concerned.”

Comments from Robbins: “NO. Comments by Gary and Santiago underscore why this is not necessary.”

Comments from Stotz: “NO I don’t see anything to be gained by raising the subfamilies within Accipitridae to family level.”