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Marsh Harrier and Honey Buzzard migration in Eastern Mediterranean
other wind directions such as headwinds and peak. We found no significant difference in the
tailwinds (U = 1625, P < 0.05). numbers of European Honey Buzzards observed
with lateral winds in comparison with other winds
Table 2 – Estimated numbers of adults (males, at the island of Antikythira (U = 863, P > 0.05).
females) and juveniles of Western Marsh Harriers at Despite the similar aspect ratio of the Western
the two sites. Marsh Harrier and the European Honey Buzzard
(7.28 vs. 7.16) the latter shows a stronger
Adults Juv. Tot. increase in energy consumption during powered
(♂,♀) flight. In fact, the results provided by the Flight
programme show that during gliding flight the
Mount 125 143 268 energy consumption is similar in both species
Olympus (50,75) while during powered flight it is much higher
for European Honey Buzzards than for Western
Antikythira 139 48 187 Marsh Harrier (Table 1). In particular the use
(80,59) of powered flight for European Honey Buzzards
requires 4.3 times the energy used for gliding flight
177 migrating European Honey Buzzards were while the difference is only 2.4 times for Western
counted at Mount Olympus and 120 at the island Marsh Harriers.
of Antikythira. A correlation exists between the Discussion
passage of this species at the two sites (r = 0.637, P < The results of our research suggest that Western
0.05). In particular, migration showed a movement Marsh Harriers and juvenile European Honey
peak on 10 September (Fig. 2B; N. 42; 23.7%) Buzzards use different flyways across the study
at Mount Olympus and on 12-13 September area. In particular, differences concerning both the
(N = 54; 45%) at the island of Antikythira. On timing of migration and water crossing behavior,
the basis of aged birds (N = 134), the estimated as well as differences in age and sex classes (in the
numbers of juvenile European Honey Buzzards case of Western Marsh Harriers), show that the
outnumbered adults both at Mount Olympus two species use different migration strategies when
(154 vs. 23; χ² = 74.3, d.f. = 1, P < 0.001) and crossing the Mediterranean sea.
at the island of Antikythira (97 vs. 23; χ² = 25.8, Western Marsh Harrier
d.f. = 1, P < 0.001). The variation of the circadian The results show indirect evidence that this species,
migratory flow showed a clear midday peak at during post-reproductive journeys, tends to travel
Mount Olympus (χ² = 35.5, d.f. = 2, P < 0.01) along parallel NE-SW flyways using parallel
while at the island of Antikythira the passage of
European Honey Buzzard did not show an evident
Figure 1 - Occurrence of Western Marsh Harriers (A) and European Honey Buzzards (B) at the two sites.
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