Abstract

ABSTRACT A small but significant northward movement of raptors occurs across the Strait of Gibraltar in June and July, following the main spring passage. Six key species ­ Honey-buzzard Pernis apivorus, Black Kite Milvus migrans, Egyptian Vulture Neophron percnopterus, Griffon Vulture Gyps fulvus, Short-toed Eagle Circaetus gallicus and Booted Eagle Aquila pennata ­ continue to arrive throughout June, while the passage of Short-toed Eagles and Honeybuzzards in particular persists into July.The possible reasons for this protracted passage are discussed.he northbound migration of raptors across the Strait of Gibraltar in spring has received less attention than the southbound, or `autumn', passage. In particular, co-ordinated counts along the entire width of the Strait have been attempted only in autumn, beginning with the studies by the Grupo EspaГ±ol de MigracГ­on de Rapaces (GEMRA) in 1972 (Bernis 1980) and continuing today under the auspices of Programa Migres (ConsejerГ­a de Medio Ambiente de AndalucГ­a , in collaboration with the Sociedad EspaГ±ola de OrnitologГ­a). Spring movements are much harder to monitor fully since the arrival front may extend from Cape Trafalgar, Spain, in the west to Gibraltar in the east, a span of some 60 km; some species, notably Honey-buzzards Pernis apivorus, can arrive on an even broader front. Nonetheless, many observations of the spring passage have been carried out, especially at Gibraltar itself, where monitoring has taken place, albeit variable in coverage, during most years from 1964 until the present day, with some records available from earlier periods. Gibraltar is particularly well suited