Conservation taxonomy of the Cuban Parrot (<em>Amazona leucocephala</em>): variation in morphology and plumage

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M. Bryant J. Reynolds
William K. Hayes

Abstract: Conservation taxonomy, the study of organismal classification to clarify conservation priorities, seeks to define species and subspecies limits. Allopatric populations, such as those present on islands, pose special challenges to identifying taxonomic boundaries which can be practically addressed using diagnostic criteria. Because some of the island populations of Cuban Parrot (Amazona leucocephala) are highly endangered, the five recognized subspecies need careful re-evaluation. We measured 18 morphological and plumage characters from 188 museum specimens representing the six extant and one extirpated island populations. We relied largely on discriminant function analyses (DFA) to assess diagnosability and to examine patterns of similarity among the populations. Most morphological characters indicated sexual dimorphism, with males 1-4% larger than females. The plumage characters, in contrast, demonstrated complete absence of sexual dichromatism. Stepwise discriminant analyses including all specimens and 14 characters revealed substantial differentiation among island groups, with 81.4% of individuals classified correctly to island. Pairwise comparisons among islands showed reciprocal discrimination > 80%, with the exception of Cuba / Cayman Brac (67%). None of the populations possessed a single diagnostic character. Although currently lumped into a single subspecies (A. l. bahamensis), each of the three Bahamas populations, including an extirpated population on Acklins Island, was equally distinct as the four other currently-recognized subspecies. Collectively, the evidence supports the view that all seven island populations, including the extirpated population, warrant subspecies status. We apply the name A. l. bahamensis to the extirpated Acklins population and propose the new names A. l. abacoensis for the Abaco Parrot and A. l. inaguaensis for the Inagua Parrot. The small and vulnerable populations on Abaco, Inagua, Isla de la Juventud, Cayman Brac, and Grand Cayman deserve special conservation status and should be treated as independent conservation units. Exemplary programs using these threatened populations as “flagship” taxa illustrate why recognizing the subspecies rank can greatly benefit conservation efforts by island nations.


Keywords: conservation taxonomy, systematics, Cuban Parrot, Amazona leucocephala, morphology, plumage, new subspecies


Resumen: Taxonomía conservacionista de la Cotorra Cubana (Amazona leucocephala): variación en la morfología y el plumaje- La taxonomía para la conservación, que es el estudio de la clasificación de los organismos para esclarecer las prioridades de conservación, busca definir los límites de las especies y subespecies. Las poblaciones alopátricas, como las presentes en las islas, plantean desafíos especiales para la identificación de los límites taxonómicos que pueden abordarse de forma práctica utilizando criterios de diagnóstico. Debido a que algunas de las poblaciones de Cotorra Cubana (Amazona leucocephala) están en grave peligro de extinción, las cinco subespecies reconocidas necesitan de una cuidadosa reevaluación. Se midieron 18 caracteres morfológicos y del plumaje de 188 especímenes de museo, que representan a las seis poblaciones existentes y a una población extirpada. Se basó en gran medida en análisis de función discriminante (DFA) para evaluar la capacidad de diagnóstico y examinar los patrones de similitud entre las poblaciones. La mayoría de los caracteres morfológicos indican dimorfismo sexual, siendo los machos 1-4% mayores que las hembras. Los caracteres del plumaje, en cambio, demostraron la ausencia completa de dicromatismo sexual. El análisis discriminante paso a paso, incluyendo todas las muestras y 14 caracteres, reveló diferencias sustanciales entre los grupos de las islas, con 81,4% de los individuos clasificados correctamente en relación con la isla. Las comparaciones por pares entre las islas mostraron la discriminación recíproca > 80%, con la excepción de Cuba / Cayman Brac (67%). Ninguna de las poblaciones tuvo un carácter de diagnóstico único. Aunque las tres poblaciones de Bahamas y la población extirpada de Acklins están incluidas en una sola subespecie (A. l. bahamensis), todas fueron igualmente diferentes, como ocurre con las restantes cuatro subespecies actualmente reconocidas. Colectivamente, las evidencias apoyan el punto de vista de que las siete poblaciones de diferentes islas, incluyendo la población extirpada, merecen el estado de subespecie. Le asignamos el nombre de A. l. bahamensis a la población extirpada de Acklins y proponemos los nuevos nombres de A. l. abacoensis para la cotorra de Abaco y A. l. inaguaensis para la cotorra de Inagua. Las poblaciones pequeñas y vulnerables de Abaco, Inagua, Isla de la Juventud, Caimán Brac y Gran Caimán, merecen un estatus especial de conservación y deben ser tratadas como unidades de conservación independientes. El uso de estos programas puede ser un ejemplo en el estudio de poblaciones amenazadas de especies banderas, ya que ilustra por qué el reconocimiento del rango de subespecies, puede beneficiar enormemente los esfuerzos conservacionistas en las naciones insulares.


Palabras clave: Amazona leucocephala, Cotorra Cubana, morfología, nuevas subespecies, plumaje, sistemática, taxonomía para la conservación


Résumé: Taxonomie et conservation de l’Amazone de Cuba (Amazona leucocephala): variation de la morphologie et du plumage- Taxonomie et conservation s’associent pour que l’étude de la classification des organismes permette de clarifier les priorités de conservation, en redéfinissant les limites séparant les espèces et les sous-espèces. Les populations allopatriques, telles que les populations insulaires, offrent des défis particuliers quant à l’identification de limites taxonomiques grâce à des critères de diagnostic. Certaines populations insulaires d’Amazone de Cuba (Amazona leucocephala) étant fortement menacées d’extinction, le statut des cinq sous-espèces actuellement reconnues doit être soigneusement ré-évalué. Nous avons mesuré 18 caractères morphologiques et de plumage, sur 188 spécimens de muséums, issus de 7 populations insulaires dont une éteinte localement. Nous nous sommes appuyés essentiellement sur des analyses discriminantes pour évaluer les possibilités de diagnostic et examiner des patrons de similitude entre populations. La plupart des caractères morphologiques présentaient un dimorphisme sexuel, les mâles étant de 1 à 4% plus grands que les femelles. Le plumage, en revanche, n’a montré aucun dichromatisme sexuel. Les analyses discriminantes pas à pas, concernant tous les spécimens et 14 caractères ont révélé des différences importantes entre les groupes d’îles, avec 81,4% des individus classés correctement par île. Les comparaisons par paires entre les îles ont montré une discrimination réciproque supérieure à 80%, à l’exception de Cuba / Cayman Brac (67%). Aucune des populations ne présentait un caractère de diagnostic unique. Bien qu’elles soient actuellement considérées comme appartenant à une seule sous-espèce (A. l. bahamensis), chacune des trois populations des Bahamas, y compris une population éteinte sur l’île Acklins, étaient toutes aussi distinctes que les quatre sous-espèces actuellement reconnues. Ainsi, ces résultats viennent soutenir l’hypothèse que les sept populations insulaires, y compris la population localement éteinte, justifient le statut de sous-espèce. Nous appliquons le nom de A. l. bahamensis à la population localement éteinte et nous proposons les nouveaux noms A. l. abacoensis pour l’Amazone Abaco et A. l. inaguaensis pour l’Amazone Inagua. Les populations d’Abaco, d’Inagua, de Isla de la Juventud, de Cayman Brac et de Grand Cayman sont petites et vulnérables. Elles méritent de ce fait un statut de conservation particulier et devraient être traitées comme des unités de conservation indépendantes. Des programmes exemplaires traitant ces populations menacées comme taxons «phares» démontrent en quoi la reconnaissance du rang de sous-espèce peut grandement bénéficier aux efforts de conservation des pays insulaires. 


Mots clés: Amazona leucocephala, Amazone de Cuba, morphologie, nouvelle sous-espèce, plumage, systématique, taxonomie de la conservation

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