DO MIGRATION COUNTS REFLECT POPULATION TRENDS? A CASE STUDY OF THE HONEY BUZZARD PERNIS APIVORUS ¿REFLEJAN LOS RECUENTOS MIGRATORIOS LAS TENDENCIAS POBLACIONALES? UN ESTUDIO CON EL ABEJERO EUROPEO PERNIS APIVORUS Nicolantonio AGOSTINI* 1 , Michele PANUCCIO*, Ugo MELLONE*, Giuseppe LUCIA*, Stephen WILSON* and Jack ASHTON-BOOTH* * MEDRAPTORS (Mediterranean Raptor Migration Network) Via Mario Fioretti, 18 00152 Rome, Italy. 1 Corresponding author: nicolantonioa@tiscalinet.it The honey buzzard Pernis apivorus is a sum- mer resident in Europe that winters in west- central Equatorial Africa (Cramp and Simmons, 1980). During post-reproductive movements, adults migrate earlier than juveniles crossing the Mediterranean Sea en route to Africa be- tween the last week of August and the first ten days of September (Agostini and Logozzo, 1995a; 1997; Schmid, 2000; Agostini, 2004). In the central Mediterranean region, adults fol- low the Italian Peninsula and after crossing the Straits of Messina deviate westwards crossing the sea at its narrowest point between western Sicily and the Cap Bon Peninsula with at least part of them concentrating over the is- lands of Marettimo and Pantelleria (Agostini and Logozzo, 1997; Agostini et al., 2000; 2004; Panuccio et al., 2005). During spring migra- tion thousands of birds cross the Adriatic Sea en route to the former Yugoslavia (Gustin and Sorace, 2004; Premuda et al., 2004) while, dur- ing autumn migration sporadic observations made over the Island of Lastovo (Croatia) be- tween 24 August-3 September 2001, Schnei- der-Jacoby (2001) reported the passage of 221 honey buzzards en route to southern Italy (Fig.1). Recent data concerning populations of this species breeding in Europe reported no- table increases just in the Balkans (BirdLife International, 2004), from which adult birds using this route are supposed to come (Agos- tini et al., 2004). In particular, according to BirdLife International (2004) an average of 5810 pairs breed in Croatia, Slovenia, Serbia and Macedonia. Indeed, recent autumn surveys made in the Central Mediterranean showed an apparent increase in numbers of adults using this route: 4045 birds were counted at the two islands of the Sicilian Channel (Marettimo and Pantelleria; Agostini et al., 2004) between 24 August and 12 September 2003, while at the Straits of Messina on average 5680 ± 521.4 (SD) migrants were recorded between 24 Au- gust and 10 September 2002-2004 (Panuccio et al., 2005; Morabito and Repaci, pers. obs.). These counts differ from those made between 1993 and 1996 in a bottle-neck along the Cal- abrian Apennines about 100 km NE of the Straits of Messina (Fig. 1). There, Agostini and Logozzo (1995a; 1997; pers. obs.) reported 1015 ± 341.2 (SD) birds per season during the same period (24 August-12 September). As Ardeola 54(2), 2007, 339-344