What is a hypothetical species?

The South American Classification Committee of the American Ornithological Society (SACC) keeps track of the bird species described and valid for South America. Each species included on the official list went through a process of review of proposals submitted to the committee.  peru_hypothetical_species
There are nearly 60 species still considered hypothetical on the official list of the birds of Peru. See the complete list at the end of this article.

This is to say, it is not enough that a species has been described as a new through a publication. It is still necessary that a committee (SACC) reviews such publication and votes on the validity of the proposed species.

Also, this page (http://www.museum.lsu.edu/~Remsen/SACCBaseline.htm), show a list of what the committee calls “hypothetical species”.

A hypothetical species is defined as a “species whose presence (in South America) is based only on direct observation or on evidence not published or not archived in a tangible manner”. In other words, if the occurrence of a species is not supported by a photo, video, a recording of the song properly cataloged or a museum specimen, the species is considered hypothetical.

Hypothetical birds in Peru

In Peru, we have a long list of hypothetical species. As of today, January 7, 2017, this list includes 60 hypothetical species. In 2012 there were 94. As we can see, that number has been decreasing, thanks to a combined effort of researchers and bird watchers.

The White-tailed Kite was considered a hypothetical species but was elevated to the official list of the Birds of Peru after an analysis of a documented record. 

Case study: White-tailed Elanio (Elanus leucurus) and Tero Lapwing (Vanellus chilensis)

One way to reduce the number of hypothetical species and increase the number of confirmed ones for Peru is through the publication of an article. For example, in 2012, the White-tailed Kite (Elanus leucurus) and the Southern Lapwing (Vanellus chilensis) were still considered hypothetical species for Peru, despite the fact that there were numerous sightings in the Madre de Dios region. Photos of these birds were kept in private hands. These two birds were even mentioned in the book Birds of Peru, in the second edition of 2010. But, if you look carefully, at least E. leucurus was marked inside square brackets […], indicating that the species was known in Peru only through visual records.

Learn about Peru’s Bird Records Committee

I saw and obtained photographs of both species on the Interoceanic Highway near Puerto Maldonado in 2012. Having this documentation, I collaborate with O. Diaz who also had documentation of both species. We put together a manuscript, which was published in 2015: Díaz, O. & F. Angulo. (2015). Documented records of White-cheeked Duck (Dendrocygna viduata), White-tailed Kite (Elanus leucurus) and Southern Lapwing (Vanellus chilensis) in Peru. Bulletin of the Peruvian Ornithological Union (UNOP), 10 (1): 66-68, available at the following link: http://boletinunop.weebly.com/uploads/6/2/2/6/62265985/boletin_unop_vol._10_n%C2%BA1_2015_-_diaz___angulo.pdf

Although there were many sightings of the Southern Lapwing, shown in this photo, at least one had to be analyzed by Peru’s Bird Records Committee in order to be elevated to the Official Bird List of Peru.

In this publication, we indicate: “the records presented here constitute the first documented and published records of E. leucurus and V. chilensis for Peru. Both species are listed as “Hypothetical” (H) in the bird list of Peru (Plenge 2015). These records confirm their presence in Peru”.

It is worth mentioning that in the year 2015 there were already several reports of these three species on eBird. However, in order to “confirm” its presence in Peru, the evidence needed to be published.

So, an important step has already been taken: the evidence of the presence of both the kite and the lapwing in Peru has been published and moved from the list of hypothetical birds to the official list of birds known to occur in Peru!

List of Species still considered Hypothetical in Peru.

Scientific Name Common Name (English) Common Name (Spanish)
Crypturellus brevirostris Rusty Tinamou Perdiz Ocrácea
Aptenodytes patagonicus King Penguin Pingüino Rey
Diomedea exulans Wandering Albatross Albatros Errante
Diomedea epomophora Royal Albatross Albatros Real
Phoebetria palpebrata Light-mantled Albatross Albatros de Manto Claro
Pterodroma ultima Murphy’s Petrel Petrel de Murphy
Pterodroma externa Juan Fernández Petrel Petrel de Juan Fernández
Pterodroma nigripennis Black-winged Petrel Petrel de Ala Negra
Pterodroma longirostris Stejneger’s Petrel Petrel de Más Afuera
Halobaena caerulea Blue Petrel Petrel Azulado
Puffinus subalaris Galapagos Shearwater Pardela de las Galápagos
Fregetta grallaria White-bellied Storm-Petrel Golondrina de Mar de Vientre Blanco
Ardea herodias Great Blue Heron Garza Azulada
Plegadis chihi White-faced Ibis Ibis de Cara Blanca
Theristicus carulescens Plumbeous Ibis Bandurria Mora
Anas sibilatrix Southern Wigeon Pato Overo
Anas platyrhynchos Mallard Pato de Cabeza Verde
Netta peposaca Rosy-billed Pochard Pato Picazo
Leucopternis plumbeus Plumbeous Hawk Gavilán Plomizo
Aramides wolfi Brown Wood-Rail Rascón-Montés Moreno
Fulica armillata Red gartered Coot Gallareta de Ligas Rojas
Charadrius falklandicus Two-banded Plover Chorlo de Doble Collar
Nycticryphes semicollaris South American Painted-Snipe Becasina Pintada
Gallinago delicata Wilson’s Snipe Becasina de Wilson
Gallinago undulata Giant Snipe Becasina Gigante
Larus philadelphia Bonaparte’s Gull Gaviota de Bonaparte
Cypseloides rothschildi Rothschild’s Swift Vencejo de Rothschild
Chlorostilbon poortmani Short-tailed Emerald Esmeralda de Cola Corta
Amazilia versicolor Versicolored Emerald Amazilia Versicolor
Sappho sparganura Red-tailed Comet Cometa de Cola Roja
Melanerpes cactorum White-fronted Woodpecker Carpintero de Frente Blanca
Empidonax traillii Willow Flycatcher Mosquerito de Sauces
Empidonax minimus Least Flycatcher Mosquerito Menor
Vireo altiloquus Black-whiskered Vireo Vireo Bigotudo
Hylophilus semibrunneus Rufous-naped Greenlet Verdillo de Nuca Rufa
Cyclarhis nigrirostris Black-billed Peppershrike Vireón de Pico Negro
Progne dominicensis Caribbean Martin Martín de Vientre Blanco
Tachycineta bicolor Tree Swallow Golondrina Bicolor
Euphonia plumbea Plumbeous Euphonia Eufonia Plumbea
Tiaris olivaceus Yellow-faced Grassquit Semillero de Cara Amarilla
Sicalis columbiana Orange-fronted Yellow-Finch Chirigüe de Frente Naranja



Buletin de la Union de Ornitologos del Peru. (UNOP). http://boletinunop.weebly.com

eBird. (2017). eBird: Una base de datos en línea para la abundancia y distribución
de las aves [aplicación de internet]. eBird, Ithaca, New York. Disponible:
http://www. ebird.org (Accedido el 09/12/2017).

Plenge, M. A.  Versión [January 2018]  Lista de las Aves de Perú.  Lima, Perú. Disponible en: https://sites.google.com/site/boletinunop/

Schulenberg, T. S., D. F. Stotz, D. F. Lane, J. P. O’Neill, & T. A. Parker III. (2010). Birds of Peru. Revised and updated edition. Princeton University Press. Princeton, New Jersey.

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