Michele Panuccio

Ecological barriers promote risk minimisation and social learning in migrating short-toed snake eagles

The short-toed snake eagle (Circaetus gallicus) uses mostly soaring flight over land during migration to avoid long sea crossings. In particular, birds breeding in central Italy cross the Mediterranean Sea at the Strait of Gibraltar, using a route through northwestern Italy during both autumn and spring migration. Birds breeding in Greece, such as those breeding in Italy, are expected to use the same strategy passing through northeastern Greece and avoiding the longer sea crossing between southern Greece and Libya. In order to verify this hypothesis, contemporaneous observations were made at two watchsites, in northwestern Italy (Apuane Alps) and northeastern Greece (Mount Olympus), during autumn 2009 and spring 2010. During autumn migration 376 birds were seen migrating at Mount Olympus, nearly all heading NNE. Most birds were seen migrating in flocks, and at least 23 flocks contained both adults and juveniles. Over the Apuane Alps a total of 1042 short-toed snake eagles, all migrating NNW, was counted. At this watchsite the proportion of juveniles was lower than that reported at Mount Olympus. During spring migration, 606 birds were seen at Mount Olympus, 602 heading south. At the Apuane Alps 1307 birds were counted, all heading SSE. The orientation behaviour of short-toed snake eagles confirms that those breeding in Greece, like those breeding in central Italy, use a circuitous route during both spring and autumn. In particular those breeding in Greece are expected to cross the sea at the Dardanelles and/or at the Bosphorus. In addition, the higher proportion of juveniles reported at Mount Olympus during autumn migration would suggest that social learning could have been much favoured by natural selection in the case of birds breeding in Greece rather than in Italy, highlighting a relationship between the length of the barrier and the tendency of juveniles to follow the adults.

Crossing the sea en route to Africa: autumn migration of some Accipitriformes over two Central Mediterranean islands

Crossing the sea en route to Africa: autumn migration of some Accipitriformes over two Central Mediterranean islands Observations were made on the autumn migration of Accipitriformes over the islands of Marettimo and Pantelleria, located between western Sicily and Tunisia (Central Mediterranean). A total of 7451 raptors was counted between 24 August and 12 September 2003, mostly adult Honey Buzzards Pernis apivorus - 4045, and Black Kites Milvus migrans - 2489. Mixed-age flocks were regularly reported for the Black Kite (1956 adults and 533 juveniles estimated) confirming information transmission concerning orientation behaviour in this species. Although in the Honey Buzzard juveniles tend to migrate later than adults, crossing the Mediterranean on a broad front mostly after mid-September, we observed some mixed-age flocks, estimating the passage of 3830 adults and 215 juveniles. In particular, over Pantelleria we recorded in seven cases juveniles in flocks of adults heading towards WNW, presumably learning (similarly to juvenile Black Kites) the shortest route over water to reach Africa from this site. A total of 72 Egyptian Vultures Neophron percnopterus - 62 adults, 6 juveniles and 4 sub-adults - was counted over Marettimo confirming that their greatest concentration during autumn migration through Italy occurs at this island. In this species, all juveniles were seen migrating in flocks of adults. Finally, the passage of hundreds of Marsh Harriers Circus aeruginosus was reported, mostly over Pantelleria. Among adult harriers, it was possible to estimate the passage of birds belonging to different sex classes; unlike in the previous studies made in central, southern continental Italy and Malta during autumn migration, adult females outnumbered adult males (372 vs 298 individuals). Finally, considering the huge number of Accipitriformes observed, Pantelleria, so as Marettimo, should be enclosed among Important Bird Areas for the autumn migration of raptors in the Mediterranean basin.

Analysis of the Spatial Migration Patterns of Adult Honey Buzzards (Pernis apivorus) During Spring and Autumn in the Central Mediterranean

Analysis of the Spatial Migration Patterns of Adult Honey Buzzards (Pernis apivorus) During Spring and Autumn in the Central Mediterranean In this paper we analyse the spatial migration patterns and the water crossing tendency of adult Honey Buzzards during spring and autumn migration in the Central Mediterranean region. In this area, during spring, these long-distance migrants wintering in western-central Equatorial Africa, concentrate crossing the sea between Africa and Europe through the Channel of Sicily, about 150 km wide, at least part of them via the islands of Pantelleria and Marettimo. When they reach western Sicily most of them fly east, along the mountain chain of northern Sicily, towards the Strait of Messina. Nevertheless, thousands of birds use a more direct route to reach the continental mainland undertaking the crossing of the Tyrrhenian Sea via Ustica and the Lipari Islands. During autumn the migration of adult Honey Buzzards is less consistent. They tend to follow the Italian Peninsula and northern Sicily reaching Africa through the Channel of Sicily while very few cross the Tyrrhenian Sea. On the contrary, during their first migration, large numbers of juveniles, moving about two weeks later than adults, cross the Central Mediterranean region on a broader front presumably along NE-SW innate axis. It is supposed that larger numbers of adult Honey Buzzards choose the central Mediterranean route during spring migration to reach earlier their breeding areas in eastcentral Europe. During post-reproductive movements most of them would circumfly the Mediterranean Sea crossing at the Strait of Gibraltar and at the Bosporus. In this picture the discovery of more direct routes between breeding and wintering areas made by juvenile birds during their first migration may have the adaptive value.

Influence of wind and geography on orientation behavior of adult Honey Buzzards Pernis apivorus during migration over water

Abstract. During autumn migration across the Central Mediterranean, adult Honey Buzzards cross the sea at its narrowest point, between western Sicily (southern Italy) and the Cap Bon Peninsula (Tunisia). This study investigated the influence of prevailing winds and geography on the orientation behaviour of migrants during this sea crossing by observations over two islands, one on the northern side, the other on the southern side of the Channel of Sicily. The flock was taken as the sampling unit. Honey Buzzards reached the island of Marettimo, approx. 30 km off western Sicily and 130 km NE of the Cap Bon Peninsula, regardless of the direction of the prevailing winds (NW and S). By contrast, Honey Buzzards passed via Pantelleria, about 110 km SW of western Sicily and 70 km ESE of the Cap Bon peninsula, mostly during NW winds. Birds reached Pantelleria from the NE and left the island flying WNW They applied true navigational abilities in choosing the shorter crossing between Pantelleria and Tunisia and showing a curvilinear migration. Our results agree in part with the “optimal use of wind” hypothesis. In particular, wind, geography and navigational abilities seem to interact to shape the orientation behaviour of migrating Honey Buzzards, perhaps to minimize the risks of non-stop powered flight over the water.

Western Marsh Harrier (Circus aeruginosus) Migration Through the Mediterranean Sea: A Review

Abstract The Western Marsh Harrier (Circus aeruginosus) is a summer visitor in northern, eastern, and central Europe. Some birds, mostly juveniles and adult females, winter in the Mediterranean region, while others cross the Sahara to winter in tropical Africa. Unlike other Accipitridae, which use primarily soaring flight over land during migration, Western Marsh Harriers tend to move on a broad front, with long, powered flights over water. In the last two decades, several researchers have investigated the migration of this species through the Mediterranean basin using direct observations, radar, band recovery data, and satellite telemetry. We here present a short review of these investigations and results.

Differential wintering area selection in Eurasian Marsh Harrier (Circus aeruginosus): a ringing recoveries analysis

Capsule The Eurasian Marsh Harrier shows a leapfrog migration pattern with individuals breeding in Northern and Eastern Europe wintering further from their breeding grounds than individuals belonging to the populations of Western and Southern Europe. Aims We analyse wintering distribution of Marsh Harriers in relation to their breeding grounds to identify differential wintering area selection strategies. Methods We used ring recovery data of 320 individuals from the European population. Latitude and longitude of ringing sites as well as age-class were used to explain variation in the distances between breeding areas and wintering sites. Moreover, we analyse differences in migration distances performed by males and females and differences among individuals wintering in sub-Saharan Africa. Results Distance covered to reach the wintering ground increases with increasing latitude and longitude of the breeding sites. Marsh Harriers breeding in Northern and Eastern Europe migrate farther than individuals belonging to the populations within Western and Southern Europe, with no effect of age-classes in relation to the latitude of wintering. Males show a tendency to migrate longer distances than females. Finally, when taking into account only birds wintering south of the Sahara desert, juveniles winter further west than adults. Conclusions The results are consistent with the assumption that this species shows a leapfrog migration. We suggest that the difference in the longitudinal distribution of juveniles and adults wintering south of Sahara could be related to the different ability of experienced individuals to compensate for the wind drift of dominant easterly winds during migration over the desert in autumn.

Wind Effects on Visible Raptor Migration in Spring at the Strait of Messina, Southern Italy

EFECTOS DEL VIENTO SOBRE LA MIGRACION VISIBLE DE RAPACES EN LA PRIMAVERA EN EL ESTRECHO DE MESSINA, SUR DE ITALIA Resumen.—Se contaron las rapaces migratorias en el estrecho de Messina, el cruce sobre el agua mas angosto ubicado entre Sicilia e Italia continental, con el objetivo de investigar la influencia de la direccion y la velocidad del viento sobre el comportamiento de las rapaces que cruzan el estrecho. El estudio fue realizado en la primavera, del 27 de marzo al 31 de mayo de 2004. Los mayores numeros de rapaces se observaron migrando en el estrecho en dias con el viento en contra a la direccion de desplazamiento. La velocidad del viento no afecto el paso de la especie observada con mayor frecuencia, Pernis apivorus. Los resultados sugieren que las rapaces tipicamente cruzan el mar en el punto mas estrecho entre Sicilia y la peninsula italiana cuando las condiciones no son propicias para cruzar un tramo mas amplio sobre el agua. [Traduccion del equipo editorial]

Circannual variation in movement patterns of the Black Kite (Milvus migrans migrans): a review

The nominal subspecies of the Black Kite is a summer resident in Europe and Asia that winters mostly in western Africa, although numbers of birds wintering in the Mediterranean area are increasing. During migrations, tens of thousands are observed migrating through the Strait of Gibraltar between Spain and Morocco, along the eastern side of the Black Sea, and in the Middle East, while substantial numbers cross the central Mediterranean and the Bosphorus. This paper provides a review of research concerning migration and its relationship with foraging behaviour in a circannual perspective. In particular, research made both by satellite tracking and by visual observations suggests a more evident time-selected migration during autumn rather than spring. Moreover, differences in timing occurring among different flyways could be explained either by different rates of intra-specific competition in areas with different breeding density and/or by different distances between wintering and breeding grounds.

Autumn migration of Marsh Harriers [Circus aeruginosus] across the Central Mediterranean in 2002

Autumn migration of Marsh Harriers (Circus aeruginosus) across the Central Mediterranean in 2002 Observations on the autumn migration of the Marsh Harrier were made at two sites of the central Mediterranean: the Circeo promontory (central Italy) and the island of Malta. The aim was to investigate the passage of birds belonging to different sex and age classes. At the Circeo promontory a total of 787 individuals was counted, 37.5% of which were juveniles. Over the island of Malta the passage of 1535 Marsh Harriers was recorded with an evident peak comprising 906 birds on 13 September. At both sites males outnumbered females, mostly within the first half of September. Because, at least among adults, an imbalance towards females has been reported in the population wintering in central Europe, our results suggest that adult males could have a stronger tendency to migrate over a long distance, crossing the central Mediterranean area in large numbers. Whereas females, being larger than males, are able to tolerate colder temperatures and fast longer. Finally, our counts confirm the increase of the European population of the Marsh Harrier, which has occurred for the last three decades.

Factors affecting the visible southbound migration of raptors approaching a water surface

Abstract We investigated the visible migration of raptors when approaching a water surface in relation to local wind conditions, time of the day and topography. Observations were made during autumn migration in 2011 and 2012 at a watchsite located in the southernmost part of the Calabrian Apennines (southern continental Italy). In this area, the Apennines show differential topographical features with a plateau west of the mountain ridge. West–southwest of the plateau lies the Straits of Messina, the narrowest water surface between southern continental Italy and eastern Sicily. The passage of migrants was recorded along the ridge of the mountain chain and over the plateau. As expected for a soaring raptor, European Honey Buzzards were detected mostly during midday and early afternoon, while significant numbers were seen toward sunset probably when flying at lower altitude to roost. In addition, they were detected during strong winds when exploiting deflection updrafts, avoiding wind drift and limiting the negative effect of head winds. Western Marsh Harriers were detected mostly during crosswinds blowing from W–NW, perhaps because of a partial drift effect on birds passing along the Tyrrhenian coast. Black Kites were seen concentrating the passage over the plateau, confirming the hypothesis that these raptors tend to move along the western slope of the Italian peninsula perhaps because of foraging behaviour. Finally, European Kestrels/Lesser Kestrels were seen toward the sunset. This result seems to confirm that these small falcons migrate at considerable altitudes resulting in them being hardly detectable by direct visual observation but becoming more visible toward sunset, when they were probably moving to roost.