Selección de lugares de descanso por la Garza Real (Ardea cinerea) durante el periodo no reproductor en el río Ebro (Navarra, N de España)

• Autores: Jesús María Lekuona
• Localización: Butlletí del Grup Català d'Anellament, ISSN 1130-2070, Vol. 15, Nº. 1, 1998, págs. 15-23
• Idioma: español
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• Resumen

  • The age-structure of the wintering population, the effects of water level and some environmental variables on the distribution of birds, and the use and selection of resting habitats by Grey Herons Ardea cinerea were studied along the River Ebro (northern Spain) during the non-breeding season. Six different habitats were used by birds: river; gravel banks; marsh vegetation; riparian woodland; groynes; and sheer banks. The wintering population was mainly composed of young herons from September to October and from March to April, while adults predominated from November to February. Total number of Grey Herons peaked twice throughout the study period, apparently because of pre- and post-breeding migratory movements. Seasonal changes in the use and selection of habitats were found. The most frequently used sites were: between September and October, gravel banks and riparian woodland; from November to January, sheer banks and riparian woodland; and from February to April, sheer banks. Gravel banks were positively selected as resting sites by herons from September to October, as were sheer banks from November to April. Overall, the river itself was negatively selected. Wind speed seems to influence both the distribution of herons and the resting-habitat selection along the Ebro.