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JORTAY, A. - Suivi et signification de la nidification d'un couple d'Echasses blanches (Himantopus himantopus) en Hesbaye liégeoise. - pp. 1 - 25 Résumé : Un couple d'Echasses blanches a élevé 3 jeunes avec succès à Lens-sur-Geer en 1999. Il s'agit de la quatrième nidification ou tentative de nidification en Wallonie, et la plus éloignée de la côte. Après la description du site et du déroulement de la nidification et la mise à jour du statut de l'espèce en Wallonie, la discussion du contexte de cette nidification aborde la comparaison avec les décennies précédentes et l'évolution dans les pays voisins. Follow-up and signification of the breeding by a pair of black-winged stilts (Himantopus himantopus) in Hesbaye region near Liège. Summary : In 1999, a pair of Black-winged Stilts successfully raised 3 fledglings in Lens-sur-Geer (Hesbaye region near Liège), in a sewage pond. This is the fourth breeding or attempt of breeding by the species in Wallonia. The two stilts arrived around may 23; the first egg was laid at the most 4 days later. Hatching occurred on june 20 or 21. The pair used three feeding areas covering 30, 180 and 220 m of shore, limiting itself to the smallest one, a shallow pool, around hatching (5 days). The time when the pulli left the nest was also when the parents started to use loud mobbing as alarm display. After leaving the site, around july 31st, the family group stayed for three weeks in the Hollogne-sur-Geer basins, 11.25 km to the south-west. The birds remained there until august 20th. The analysis of observations data for Black-winged Stilts in southern Belgium since 1960 shows a doubling per decade of the number of both observations and birds. Development of sewage basins may be the cause in Wallonia of the increasing presence of the Black-winged Stilts and its northward extension, a general phenomenon seen in western Europe. This is accompanied by the development and stabilisation of small breeding populations to the north of the main range, a phenomenon which has increased since the mid-eighties and seems to be related to climate warming. As in neighbouring regions, Wallonia seems to be favoured by its position in the migration axis of the species from its European population reservoir (Spain). The year 1999 was furthermore noticed for an important presence of stilts across north-western Europe, as were the years 1949, 1950 and 1958, when moderate invasions occurred. LOISON, M. & GODIN, J. - La nidification de la Mouette rieuse (Larus Ridibundus) dansle complexe marécageux de Harchies-Hensies-Pommeroeul de 1972 à 1999. - pp. 27 - 44 Résumé : La Mouette rieuse a niché régulièrement dans le complexe marécageux de Harchies-Hensies-Pommeroeul de 1972 à 1986. Après une absence de 13 ans, elle a réoccupé le site en 1999. Les données d'observation (historique de l'installation, effectifs nicheurs, localisation des colonies, chronologie de la reproduction, facteurs de perturbation de la reproduction : dérangements, prédation, compétiteurs et espèces commensales) ainsi que les données de baguage (modalités de baguage et effectifs bagués, reprises, distribution géographique des reprises, distance parcourue, direction, durée du port de la bague) sont présentées et commentées. Breeding of Black-headed Gull (Larus ridibundus) in the marsh complex of Harchies-Hensies-Pommeroeul from 1972 to 1999. Summary : Black-headed Gull was a regular breeder in the marsh complex of Harchies-Hensies-Pommeroeul from 1972 to 1986. After a gap of 12 years, the site was occupied again in 1999. |