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Marsh Harrier and Honey Buzzard migration in Eastern Mediterranean
migration paths over water and over land, just as Agostini & Panuccio, 2010; Panuccio, et al.
they do in the Central Mediterranean region (Fig. 2002). The Western Marsh Harrier’s high degree
1A; Agostini et al., 2001, 2003; Panuccio et al., of spatial flexibility during migration is also shown
2005a; Agostini & Panuccio, 2010). In particular, by the modulation of their response to lateral
the timing of migration at the two sites allows us to winds at different places and times (Klaassen
exclude any correlation between the two migratory et al., 2010a; 2010b; Vardanis et al., 2011).
flows. This is suggested further by the different European Honey Buzzard
age and sex compositions of the individuals The notable correspondence between the
observed at the two sites. The higher percentage of migration of European Honey Buzzards at Mount
adult males observed at the island of Antikythira Olympus and at the island of Antikythira is not
appears to confirm that adult males, in autumn, consistent with the hypothesis that juveniles of this
tend to migrate earlier and over longer distances species migrate along parallel routes like Western
than adult females; in fact some authors have Marsh Harriers. On the contrary, an analysis of
hypothesized (Panuccio et al., 2005b) a latitudinal the migration at the two sites suggests that at
segregation of sexes over the populations of this least some of the individuals migrating through
species that are entirely migratory. According to continental Greece, once they have arrived in
this hypothesis adult females should overwinter southern Peloponnesus, follow the fingers of the
mostly in the Mediterranean area and adult males peninsulas and cross the sea between the islands of
mostly in Africa south of the Sahara, in accordance Kythira, Antikythira and Crete en route to Libya
with Bergmann’s rule which predicts that larger (Fig. 2B). Moreover, the analysis of migration in
individuals (i.e. females in this case) are better relation to wind direction suggests that juvenile
adapted to survival in colder climates (Cristol et European Honey Buzzards, unlike from Western
al., 1999). This is supported by observations in Marsh Harriers, compensate the drift effect of
Greece which show that during the winter adult lateral winds during the sea crossing between
males are extremely rare (Handrinos & Akriotis, Kythira and Antikythira. In this species the
1997). The higher number of juveniles observed ability to compensate wind drift is age-dependent
migrating in continental Greece rather than in (Thorup, et al. 2003). However, since the island of
Antikythira reflects the tendency of juvenile Antikythira is almost always visible from the island
Western Marsh Harriers to follow leading lines of Kythira, we suggest that juvenile European
of the mainland during their first migration, Honey Buzzards flying over the sea in this area can
as observed in Sweden and in Southern Italy compensate the drift caused by crosswinds as they
(Kjellén, 1992; Panuccio et al., 2005a). The higher are attracted by the sight of Antikythira, where
percentage of Western Marsh Harriers observed at thermal currents can be used.
the island of Antikythira in the afternoons (Fig.3a) Studies made in the Central Mediterranean
is consistent with the hypothesis that they use showed a similar behavior in migrating juvenile
the island as a stop-over site, as is also shown in European Honey Buzzards during the autumn. A
observed roosting birds (N.=27; 14.4%). broad migration front involves numerous islands
Finally, when testing the effect of lateral winds while hundreds of individuals migrating along the
during the water crossing, lower numbers of western coast of Central Italy deviate eastwards,
Western Marsh Harriers were observed in lateral following the mainland of the Italian Peninsula,
winds than in other wind directions at the island and thereby avoiding crossing the Tyrrhenian Sea.
of Antikythira. This result suggests that when they They than cross the Mediterranean Sea between
cross that body of water they do not compensate Southern Sicily and Libya, flying over the island of
the drift effect of lateral winds, perhaps because Malta (Agostini et al., 2002, 2004).
they are not attracted by this island since they are
capable of migrating over the Mediterranean Sea
using powered flight (Spaar & Bruderer, 1997b;
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