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JOURNAL OF AVIAN BIOLOGY 35: 469 Á/470, 2004

Additional observations of age-dependent migration behaviour in
western honey buzzards Pernis apivorus

Nicolantonio Agostini

Agostini, N. 2004. Additional observations of age Á/dependent migration behaviour in
western honey buzzards Pernis apivorus. Á/ J. Avian Biol. 35: 469 Á/470.

N. Agostini, Via Carlo Alberto n84, 89046 Marina di Gioiosa Jonica (RC), Italy. E-mail:
nicolantonioa@tiscalinet.it

The western honey buzzard Pernis apivorus is a summer Thus Agostini and colleagues concluded that adult
resident in Europe that winters in west-central Equator- honey buzzards apply true navigational abilities, thus
ial Africa (Cramp and Simmons 1980). Individuals of avoiding a longer flight across the central Mediterra-
different ages migrate in different periods. Adults move nean, probably to minimize risks and energetic costs
about two to three weeks earlier than juveniles (Kjelle´n (Agostini and Logozzo 1997, Agostini et al. 2000). Only
1992, Agostini and Logozzo 1995). In a recent paper, a few juveniles migrate together with adults on this
Hake et al. (2003) reported data on the autumn migration route (Agostini et al. 1999, 2000). Most of
migration of nine honey buzzards (six adults and three them arrive at least two weeks later at the coasts of the
juveniles) from Sweden that were tracked by satellite. Mediterranean, typically in all juvenile flocks or alone.
The results showed that whereas adults crossed the Unlike adults, juveniles passing through southern con-
Mediterranean Sea at the Straits of Gibraltar, juveniles tinental Italy after the second week of September take off
migrated on a broader front and undertook long in southern Sicily and then concentrate over Malta to
powered flights ‘‘somewhere’’ over the open sea. Visual reach probably Libya, moving along a NE-SW innate
observations in the central Mediterranean region clearly axis (Fig. 1, Agostini and Logozzo 1995, Agostini et al.
showed the existence of different spatial migration 1999). During their first migration, inexperienced juve-
patterns between adult and juvenile honey buzzards nile honey buzzards are not familiar with the shortest
during post-reproductive movements (Agostini and route to cross the central Mediterranean and presumably
Logozzo 1997, Agostini et al. 1999, 2000, 2002). are moving along innate migratory directions. It is
Unfortunately, Hake et al. did not quote these sources interesting to note that observations at the Circeo
causing a gap in their work. Here I review these papers in promontory (central Italy, Fig. 1) and over Malta
an effort to fill this gap. suggest that at least part of the juveniles crossing the
Tyrrhenian Sea change their innate direction of migra-
In the central Mediterranean, adult honey buzzards tion in response to the open water (Agostini et al. 2002,
migrate mainly from late August through early Septem- see also Agostini et al. 2004). In the case of juvenile
ber (Agostini and Logozzo 1995). Here they tend to honey buzzards Agostini and colleagues (2000, 2002)
follow the Italian peninsula and, upon reaching the concluded that these spatial migration patterns may
Straits of Messina between the ‘‘toe’’ of southern Italy explain why they show a broader front in migration, and
and Sicily turn west. Many of them will fly across Sicily, why concentrations of juveniles but only a few adults are
and then southwest across the Sicilian Channel heading reported at many islands of the Mediterranean, such as
towards the Cap Bon peninsula (Agostini and Logozzo Cabrera, Corsica, Capri, Pianosa, Malta and
1997, Agostini et al. 2000, Fig. 1). The experienced adult Cyprus (Frost 1994, Rebassa 1995, Agostini et al.
birds probably use the reverse of the spring route
(Agostini et al. 1994, Agostini and Logozzo 1998).

# JOURNAL OF AVIAN BIOLOGY 469
JOURNAL OF AVIAN BIOLOGY 35:6 (2004)