ARTÍCULO

Hatching order and sex ratio in Southern Grey Shrike Lanius meridionalis in relation to clutch size

Autores: Moreno-Rueda , G.; Campos, F.; Gutiérrez-Corchero , F.; Hernández Minguillón, María de los Ángeles
Título de la revista: IBIS
ISSN: 0019-1019
Volumen: 159
Número: 1
Páginas: 230 - 234
Fecha de publicación: 2016
Resumen:
Despite major advances in sex ratio theory, how offspring sex should vary with hatching order remains unclear. We examine nestling sex ratio in the Southern Grey Shrike Lanius meridionalis according to hatching order and clutch size. Southern Grey Shrike nestlings present a different sex ratio with body-mass rank order depending on clutch size. When the clutch size was five eggs (with a very low risk of brood reduction; 13%) the less costly sex (male) was found at the end of the body mass hierarchy. However, when clutch size was six eggs (with a high risk of brood reduction; 42%) the larger sex (female) was found at intermediate positions in the hatching order, possibly to decrease competitive asymmetries.