La colonia de ardéidos de las islas Medes (NE de España)

Resum

The heronry of the Medes Islands (NE Spain)
A mixed heronry placed in the Medes Islands (NE Spain) is described. Such mixed heronry is composed, in order of abundance, by Cattle Egrets (Bubulcus ibis), Night Herons (Nycticorax nycticorax) and Little Egrets (Egretta garzetta). Data on nest distribution among the different vegetal. substrata indicate that Cattle Egrets built their nests mainly on Olea europaea var. sylvestris, whereas those of Night Herons were mainly placed on Ficus carica and those of Little Egrets were cattered inside the Cattle Egret groups. Estimated phenology data indicates that Night Herons were the first species to breed in here, followed by Cattle and Little Egrets. Mean brood sizes range between 2.78 (Night herons) and 3.4 chicks per nest (Little Egrets) in the breeding season of 1992. Since this colony was detected ten years ago has continuously increased its numbers. The number of breeding pairs in this colony is compared with the main heronries in Catalonia.