Biometría, fenología y razón de sexos del Ruiseñor Bastardo Cettia cetti en carrizales del Valle del Tajo (España Central)

• Autores: Alfonso Villarán
• Localización: Butlletí del Grup Català d'Anellament, ISSN 1130-2070, Vol. 17, Nº. 1, 2000, págs. 1-9
• Idioma: español
• Enlaces
  • Texto completo
• Resumen

  • Data were analysed from 228 ringing records and 66 recoveries of Cetti? s Warbler Cettia cetti obtained in an area of reedbeds in central Spain. Biometrical measurements show clear sexual dimorphism, males being larger and heavier than females. Both wing-length and body weight show bimodal distributions. These data suggest that in central Spain, birds with wing-length greater than 59 mm or body mass heavier than 14 g can be reliably sexed as males. Similarly, birds with wing-length shorter than 57 mm or body mass lighter that 12 g can be sexed as females. The percentage of females increased in autumn and winter, suggesting that females carried out dispersal movements to this reedbed area after breeding. This is reflected in a decrease in mean population wing-length and body mass in autumn and winter. No significant differences were found in mean wing-length within either sex during the annual cycle. However, mean body mass in females varied through the year. Females were heavier in spring (during the breeding season) and lighter in autumn (during dispersal movements)