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Circannual variation movements of Black Kite

composed both by territory holders and non- during the southbound migration (Agostini et al.
territorial, non-breeding individuals, commonly 2000, 2004, Panuccio and Canale 2003).
known as floaters (Newton 2008). Compared to Movements
territory holders, floaters of both sexes are smaller, During southward movements Black Kites cross
younger and arrive late in the season from the the Mediterranean mainly at the Strait of Gibraltar
wintering grounds (Sergio et al 2009). It has been while substantial numbers migrate through the
shown that young floaters are physiologically central and eastern Mediterranean corridors (via
capable of reproduction (Blas and Hiraldo 2010) the Channel of Sicily and Bosphorus); the small
and therefore the cause for deferred breeding may breeding population of Greece (few tens of pairs)
have an ecological rather than a physiological basis cross the eastern Mediterranean between the
in which the limited access to breeding territories Peloponnesus, Crete and Libya (Fig.1; Finlayson
plays an important role. As a matter of fact, the 1992, Agostini et al. 2000, 2004, Migres 2009,
Doñana National Park population’s shows high Lucia et al. 2011). The huge populations of
density of breeding pairs and young birds have the Iberian peninsula, France, Germany and
poorer competitive abilities for resource and Switzerland reach Africa through the Strait of
territory defence (Blas and Hiraldo 2010). Gibraltar (Finalyson 1992, Meyburg and Meyburg
Autumn 2009). Maximum one-watchpoint count at the
Mortality rates are higher between the first Strait of Gibraltar during autumn 2008 reported
and second year of life, suggesting a very strong 88986 individuals migrating almost all in August
selection-episode during the first migration and while very few migrated in September (Migres
wintering (Sergio et al 2011). This powerful 2009).
selective force may have favoured juvenile Black In the Central Mediterranean area the migration
Kites to migrate together with adults during their peak of Black Kites occurs in a few days between
first migration, and this hypothesis could explain the end of August and the beginning of September
both the large overlap observed in the autumn with a large overlap in the migration period of
migration timing of adults and juveniles and the adults and juveniles (Agostini et al. 2000, 2004).
strong tendency of Black Kites to migrate in flocks During their travel to reach the Channel of Sicily,

Figure 1 - Flyways used by Black Kites during autumn migration. 1) Cap Bon Promontory, 2) Marettimo
island, 3) Pantelleria island, 4) Circeo Promontory, 5) Capri island, 6) Calabrian Appennines,
7) Antikythira island, 8) Kfar Qassem (Bijlsma 1983, Shirihai 2000, Agostini et al 2000,
2004, Zalles and Bildstein 2000, Panuccio et al 2005, Kirwan et al. 2008, Migres 2009, Lucia
et al. 2011, Verhelst et al. 2011).
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