Proposal (273) to South American Classification Committee

 

Recognize Leptodon forbesi (Swann, 1922)

 

Leptodon forbesi was described from a single specimen obtained at Pernambuco State, northeastern Brazil. It was considered for more than a half century an invalid taxon, almost without disagreement (beginning with Hellmayr 1929). The majority of authors believed that forbesi would be an anomalous/aberrant specimen of L. cayanensis, a well-known variable raptor (e.g. Foster 1971).

 

This statement was affected when Teixeira et al. (1987) communicated the obtaining of 3 specimens in Alagoas (near Pernambuco) all similar to the type of forbesi, including a couple in breeding condition.

 

Despite of the acceptance of L. forbesi for several recent authors (Sibley and Monroe 1990, Howard and Moore 1994, Bierregaard 1994, Sibley 1996, BirdLife International 2000, Clements 2000, Ferguson-Lees and Christie 2001), the validity of the taxon seems to continue under query, because regular L. cayanensis has also been found in the same area (Silveira et al. 2003, pers.obs.).

 

However, two new records from Pernambuco in 2006 (see pictures, Pereira et al. 2006) and 2007 (B. M. Whitney, pers. comm.) - each time at least 2 individuals sighted - suggest that a population in perfect match with forbesi exists in fact in the Atlantic forest of northeastern Brazil (Pernambuco Center). These repeated records in this same restricted area (see another record of E. O. Willis in BirdLife International 2000) in combination to the fact that any similar individual of forbesi is known in the wide distribution of cayanensis, I think that the best treatment by now is recognize Leptodon forbesi as a valid taxon.

 

References:

BirdLife International (2000) Threatened birds of the world. Barcelona & Cambridge: Lynx Edicions & BirdLife International.

Foster, M. S. (1971) Plumage and behavior of a juvenile Gray headed Kite. Auk 88:163-166.

Hellmayr, C. E. (1929) A contribution to the ornithology of north-eastern Brazil. Field Mus. Nat. Hist. Publ., Zool.12:235-501.

Pereira, G. A., S. M. Dantas & M. C. Periquito (2006) Possível registro de Leptodon forbesi no Estado de Pernambuco, Brasil. Revista Brasileira de Ornitologia 14(4):441-444.

Silveira, L. F., F. Olmos e A. J. Long (2003) Birds in Atlantic Forest fragments in north-east Brazil. Cotinga 20:32-46.

Teixeira, D. M., J. B. Nacinovic e F. B. Pontual (1987) Notes on some birds of northeastern Brazil (2). Bull. Brit. Orn. Club. 107:151-157.

 

Jose Fernando Pacheco, May 2007

 

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Comments from Remsen: "YES. The evidence presented above clearly places burden of proof on those who question the validity of L. forbesi."

 

Comments from Stiles: "YES. Clearly the burden of proof now lies with those who would lump them - they would have to show that forbesi-type birds occur elsewhere within the range of cayanensis and that they represent some immature plumage stage, for neither of which does evidence exist at present."

 

Comments from Robbins: "YES. Although I wish there were more solid data, I'm willing to support elevating forbesi to species level."

 

Comments from Zimmer: "YES. Glauco Pereira's field sketches and descriptions of the birds he has recently discovered in Pernambuco match perfectly with the few specimens of forbesi, and do not match any known immature plumage of cayanensis from anywhere in its extensive range. I'd say that the burden of proof lies on those who would contend that forbesi is not a valid taxon."

 

Comments from Nores: "YES, totalmente de acuerdo. En principio sería muy raro que un inmaturo de L. cayanensis o de cualquier otro Falconiforme tuviera diferencias como tienen estas dos especies, especialmente en la cola. Ahora que ya han sido coleccionados y observados varios ejemplares en un área restringida dentro del rango de L. cayanensis, disipa, para mí, toda duda sobre la validez de la especie."