La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	The significance of timing of laying for production and survival of young in the Sparrowhawk Accipiter nisus in Vendsyssel, Northen Denmark
Auteurs :	Jan Tottrup Nielsen, Auteur
Type de document :	Article
Dans :	Dansk Ornitologisk Forenings Tidsskrift (99(2) 2005)
Article en page(s) :	107-114
Langues:	Anglais
Résumé :	Data were collected during 1977-1997 in a 2417 km(2) study area in Vendsyssel (see Nielsen 2004a for details on methods and study area). Time of laying was estimated from nestling age at ringing, based on wing measurements, and on incubation periods (laying of first egg to mean hatching of brood) of 38 days for 4-egg clutches, 40 days for 5-egg clutches, 41 days for 6-egg clutches, and 42 days for 7-egg clutches. Clutch size was determined as total number of live and dead young, and (remnants of) unhatched eggs. Parents were aged (I year old ('ly') or older ('adult')) from shed feathers. As a measure of mortality was used recoveries to and including 2002 of dead birds ringed during the study; those recovered before I May of their 2nd calendar year were considered never to have bred, while those recovered after I April of their 3rd calendar year were assumed to have been breeders.

Lundi , mardi et jeudi de 9h à 12h et de 13h à 17h00 : ouverture au public ...