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Nestling sex ratio in the southwestern willow flycatcher

Paxton, Eben H. and Sogge, Mark K. and McCarthey, Tracy D. and Keim, Paul (2002) Nestling sex ratio in the southwestern willow flycatcher. Condor, 104 (4). pp. 877-881. ISSN 1938-5129


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Using molecular-genetic techniques, we determined the gender of 202 Southwestern Willow Flycatcher (Empidonax traillii extimus)nestlings from 95 nests sampled over a five-year period. Overall nestling sex ratio did not vary significantly from 50:50 among years, by clutch order, or by mating strategy (monogamous vs.polygamous pairings). However, we did observe significant differences among the four sites sampled, with sex ratios biased either toward males or females at the different sites. Given the small population sizes and geographic isolation of many of the endangered subspecies' breeding populations, sex-ratio differences may have localized negative impacts. Cociente de Sexos en Polluelos de Empidonax traillii extimus Original Abstract: Utilizando tecnicas moleculares determinamos el sexo de 202polluelos de Empidonax traillii extimus pertenecientes a 95 nidosque fueron muestreados durante un periodo de cinco anos. Engeneral, el cociente de sexos no vario significativamente de 50:50 entre anos, ya sea por orden de la nidada o por estrategia deapareamiento (monogamia vs. poligamia). Sin embargo, observamos diferencias significativas entre los cuatro sitios muestreados, enlos cuales la razon de sexos estuvo sesgada hacia los machos o las hembras dependiendo del sitio. Dados los pequenos tamanos poblacionales y el aislamiento geografico de muchas de las poblaciones reproductivas de esta subespecie en peligro, las diferencias en el cociente de sexos pueden tener un impacto negativo a nivel local.

Item Type: Article
Publisher’s Statement: © 2002 The Cooper Ornithological Society.
ID number or DOI: 10.1650/0010-5422(2002)104[0877:NSRITS]2.0.CO;2
Keywords: Birds; Breeding; Empidonax traillii; Endangered species; nestling sex ratio; Nests; sequence; sex ratio; Willow Flycatcher
Subjects: Q Science > QL Zoology
NAU Depositing Author Academic Status: Faculty/Staff
Department/Unit: College of Engineering, Forestry, and Natural Science > Biological Sciences
Date Deposited: 30 Sep 2015 22:16
URI: http://openknowledge.nau.edu/id/eprint/510

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