Complementing the puzzle of Eleonora’s Falcon (Falco eleonorae) migration: new evidence from an eastern colony in the Aegean Sea

Abstract

Eleonora's Falcon (Falco eleonorae) is an endemic breeder of the Mediterranean Sea and the Canary Islands that overwinters in Madagascar and surrounding areas. Recent telemetry studies have revealed the migratory journey of falcons from the western and central Mediterranean breeding colonies. Our study complements the puzzle of the species' migration providing data from an eastern Mediterranean breeding colony. In this paper, we describe for the first time the migratory routes of four falcons originating from the Aegean Sea, the core of the species' breeding range. We tracked two adults and two immature siblings to their wintering grounds in Madagascar. According to our results, the timing of migration was consistent with previous studies. Our findings also suggest that the falcons adjust their flight speed according to the environmental conditions encountered en route, by accelerating during open-sea and desert crossings and by slowing down in potential foraging areas. Moreover, the selection of common staging areas, both among the two siblings and among the two adults, highlights the role of these areas in the migratory cycle of the species. Finally, according to the home-range analysis on the wintering grounds, space use was rather variable across the four tracked falcons. Still, the falcons were more frequently observed within the submontane forest, one of the last patches of primary rainforest in Madagascar. Thus, future studies aiming at unveiling the ecological requirements of the species in its wintering quarters are considered as top priority.

Ranging Behaviour of Eleonora's FalconsFalco eleonoraeDuring Chickrearing

“…Many aspects of its biology have been studied to date, but there are no satellite tracking data concerning its ranging behaviour during the breeding season. This technology has recently been used to reveal the species' migratory routes and main wintering habitats in Madagascar (Gschweng et al 2008, López-López et al 2009, 2010, Mellone et al 2011, Kassara et al 2012). However, transmission problems affecting the performance of the Argos system in the Mediterranean basin prevented the use of this method to study ranging behaviour of Eleonora's Falcons during the breeding season.…”

The trans‐equatorial loop migration system of Eleonora’s falcon: differences in migration patterns between age classes, regions and seasons

“…The Eleonora’s falcon Falco eleonorae is a long‐distance migratory raptor, which breeds colonially and almost exclusively on islands in the Mediterranean Sea, with almost the entire population wintering in Madagascar (Walter 1979). To travel between the breeding colonies and wintering areas, twice each year Eleonora’s falcons perform a trans‐equatorial journey of ca 10 000 km, encountering a huge variety of environments and climatic conditions, with juveniles migrating independently of adults (Gschweng et al 2008, López‐López et al 2009, 2010, Kassara et al 2012). Therefore, its migration system provides an excellent model to study the effects of both internal and external determinants on migration behaviour.…”

Ecological Specialization to Fluctuating Resources Prevents Long-Distance Migratory Raptors from Becoming Sedentary on Islands

“…However, long-term studies seem to contradict, at least in part, this assumption. Data from satellite-tracked Eleonora’s falcons from Spain, Italy and Greece demonstrate that 2 nd calendar-year birds (n = 6) do in fact leave the wintering grounds during spring, heading northwards [8], [18], [19]. Although many of them may not necessarily reach their natal colonies the first year [20], satellite telemetry data, banding recoveries and observations show that these young birds disperse widely throughout the Mediterranean basin [14], [17], [18], [20], thus becoming distributed across potential future breeding sites during their first summer.…”