Sex determination in glosssy Ibis chicks based on morphological characters
[ENG ] Sex determination in glossy ibis chicks based on morphological characters. Aims: We derived two discriminant equations to sex glossy ibis Plegadis falcinellus chicks (2 - 5 we- eks old) based on morphological characters. Location: Doñana, South-West Spain. Methods: Wing length and tarsus leng...
| Autores: | , , , , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2006 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/40881 |
| Acceso en línea: | http://hdl.handle.net/10261/40881 |
| Access Level: | acceso abierto |
| Palabra clave: | discriminant function Genetic analyses glossy ibis leg morphology Sex determination sexual size dimorphism Plegadis falcinellus |
| Sumario: | [ENG ] Sex determination in glossy ibis chicks based on morphological characters. Aims: We derived two discriminant equations to sex glossy ibis Plegadis falcinellus chicks (2 - 5 we- eks old) based on morphological characters. Location: Doñana, South-West Spain. Methods: Wing length and tarsus length and width of 198 individuals were measured in the 2002 and 2003 breeding seasons. Results: Tarsus width was the most discriminant character and in combination with wing length allo- wed us to sex 86.9 % of individuals correctly. A formula based on wing and tarsus length also sexed 84.9 % of individuals correctly. The reliability of this second equation was also tested with an independent sam- ple of 209 individuals measured in 2004, with error rates similar to those of the original data. Intervals for discriminant scores reducing errors in sexing to 10 % or 5 % were derived, at the cost of reducing the proportion of individuals that can be sexed. These equations should not be applied in other localities wi- thout validation, but our analyses suggest they can be used on different cohorts. We also describe a vi- sual sexing technique found to have 95 % accuracy for an experienced observer. Conclusions: Sex can be reliably determined for many glossy ibis chicks. Given the considerable se- xual size dimorphism found in many species of the family Threskionidae, tarsus width is likely to be a good variable to include in future analyses of sexual dimorphism in spoonbills and ibises. Key words: discriminant function, genetic analyses, glossy ibis, leg morphology, sex determination, sexual size dimorphism, Plegadis falcinellus |
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