Page 1 - Panuccio_et_al_002
P. 1

41.4 l
             2002                          Kurze Mineilungen                     27 1






































                  Crossing the Tyrrhenian Sea: spring migration of Marsh Harriers
                  (Circus aeruginosus), sex classes and relation to wind conditions
             The Marsh Harrier (Circus aemginosus), unlike other raptors using mostly soaring flight over land
             during migration, tends to migrate on a broad front carrying out long powered flight over water (KER-
             LJNOER  1989). This species has high aspect ratio (long) wings decreasing energetic costs during pow-
             ered flight (KERLINOER  1989).  For this reason, concentrations of thousands of Marsh Harriers rarely
             occur  (KERLINOER  1989,  CLARKE  1995,  ZALLES  &  BILDSTEIN  2000,  CoRSO  2001)  although
             51,000-74,000 pairs breed in Europe (mostly in Russia, Poland and Ukraine;  FEROUSON-LEES et al.
             200 l) and winter in  the Mediterranean basin and tropical Africa. As  to  Marsh  Harriers migrating
             across the Channel ofSicily, birds ringed in Tunisia during spring were recovered NE in the Ukraine,
             Poland, Belarus and the Czech Republic (CRAMP & SIMMONS  1980). T o date, during spring migration,
             t.he greatest concentration of Marsh Harriers was recorded a t the Straits of Messina, between southern
             continental ltaly and Sicily (Fig.  l; AOOSTINI  &  Looozzo 2000, ZALLES &  BILDSTEIN 2000, CORSO
             2001). There, between 1989 and 2000, on average 2215 birds were counted each year in the months
             Aprii  and  May (ZALLES  &  BrLDSTEIN  2000, CoRSO  2001). Apparently, at that site,  Marsh  Harriers
             crossing the centrai Mediterranean between Tunisia and western Sicily (150-165 km over sea, Aoos-
             TINI  &  Looozzo 1998,  AOOSTINJ  200 l) converge with those passing Libya and southern Sicily (via
             Malta; approx. 400 km, BEAMAN & GALEA 1974, Fig. l). However, during auturnn migrati o n, hundreds
             of Marsh Harriers undertake the crossing of the Tyrrhenian Sea flying about 500 km over water from
             central ltaly to Africa, part ofthem via western Sicily (AGOSTI N l et al. 200 l). In this peri od notable con-
             centrations ofbirds have been reported at the Circeo promontory (centralltaly) and over the islands of
   1   2   3   4   5