La reproduction du vautour fauve Gyps fulvus dans les Pyrénées Occidentales : Historique d'une restauration d'effectifs et paramètres reproducteurs

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Titre du document / Document title

La reproduction du vautour fauve Gyps fulvus dans les Pyrénées Occidentales : Historique d'une restauration d'effectifs et paramètres reproducteurs = The Griffon Vulture Gyps fulvus breeding in the eastern Pyrenees : History of recovery of a population and breeding parameters

Auteur(s) / Author(s)

LECONTE M. ; SOM J. ;

Résumé / Abstract

The reestablishment of the breeding population of Gyps fulvus in a test area of 1300 km² on the north side of the western Pyrenees (32-34 clutches in 1976, 155-156 in 1992) implied an important colonization of new sites from 1987 onwards. The spatial dispersal towards the east and the west of the range occured at a rate of 1 km/year. The demographic evolution of the sites (arrival of new breeders) is different from one site to the other (6-7 increase, 4 decrease, 5 are abandoned). Breeding parameters have been calculated from 1976 to 1995, on the base of 777 clutches (2,7 % of second clutches, one third clutch) in two sites which received the status of Nature Reserve in 1975 (98 nests at a mean altitude of 850 m, 86 % facing west in cliffs colonized by Petrocoptis pyrenaica and invaded by Buxus sempervirens). 72% if the clutches are laid in isolated nests. The laying period extends from 27.12 to 27.03. 50 % on 25.01 but the laying season starts earlier every year. The incubation period is 47-57 days (M : 51-53 days, n = 113), the chick period in nest before fledging is 113-159 days (M = 135 d, n = 103). Consequently a nest is occupied on average between 188 and 365 days a year. The breeding success (S.R. in the French text) can vary from 0,40 fledgling/clutch/year to 0,95 (M = 0,76). 68 % of the abandoned nest are due to a failure during the incubating period (75 % of the cases). 80 % of the failures are due to persistent bad weather (heavy rainfalls, long period of snow melting). The S.R. is more important when the nest density is higher. The nests occupied more than 5 consecutive years have a breeding success higher than average. The annual productivity of juveniles is not directly correlated to the amount of food laid on the feeding site in Ossau (which was operated as soon as 1969). As this feeding site is intensively visited by the vultures from November to January (and not in March-April), it suggests that before breeding the birds search a source of regularly available carrion. The most probable hypothesis is that spatial expectation encourages the sedentariness of birds which don't have to go on uncertain foraging trips. During the ovogenesis (M = 24-27 days ; n = 16 ; min : 16d ; max : 38d) sedentariness is a positive factor for the synchrony of activity rhythm of the mates. Pairs can then spend time on the daily activities of the breeding cycle (mating, nest building and nest defense) in order to lay their eggs. The demographic consequences of the conservative management (artificial feeding place, creation of the Réserve Naturelle d'Ossau by the Parc National dels Pyrénées) on the recruitment of new breeders and the reproductive success are discussed in this paper.

Revue / Journal Title

Alauda ISSN 0002-4619 CODEN ALUDAI

Source / Source

Congrès
Colloque International d'Ornithologie Pyrénéenne, Ordino , ANDORRE (07/10/1995)
1996, vol. 64, n^o 2, pp. 120-270 (2 p.), pp. 135-148

Langue / Language

Français
Revue : Anglais

Revue : Français ; Anglais

Editeur / Publisher

Société d'Etudes Ornithologiques de France, Brunoy, FRANCE (1929) (Revue)

Localisation / Location

INIST-CNRS, Cote INIST : 5316, 35400006056577.0030

Nº notice refdoc (ud4) : 3172351