Eleonora's Falcons Research Articles

Discovery of a novel Mediterranean Haemaphysalis (Ornithophysalis) doenitzi group tick species infesting Falco eleonorae on Antikythira Island, Greece.

Eleonora's falcon (Falco eleonorae Géné, 1839) is a well-known long-distance migrant of the Afro-Palaearctic flyway, a summer breeder of the Mediterranean region and North-west Africa and a winter resident of Madagascar and surrounding areas, thus characterized as a double endemic. Within the context of a long-term monitoring and conservation programme on Antikythira Island, Greece, which accommodates one of the largest concentrations of breeding pairs of Eleonora's falcons globally, birds were subjected to regular inspections for the presence of ticks from 2017 to 2023. In total, 104 adults and 149 nymphs (all belonging to Haemaphysalis genus) were collected. All ticks, apart from 2 nymphs, exhibited broadly salient palpi and did not possess the pronounced palpal segment 2 spurs or spur-like angles that are characteristic of adults, nymphs and most larvae of Rhipistoma, thus placed them in the Ornithophysalis subgenus. Following comprehensive morphological assessment and genetic analysis of the mitochondrial genome by means of next-generation sequencing of both adult and nymphal stages of the ticks, our empirical findings substantiate the delineation of a previously unclassified species. This taxonomic assignment situates the newly described species within the Ornithophysalis subgenus and the Haemaphysalis doenitzi group, marking its presence for the first time within the Western Palaearctic region.

A trans‐African migrant shows repeatable route choice in males and repeatable timing in females

Migrant bird populations often show substantial variation in route choice and timing. Determining whether this population‐level variation is driven by between‐individual differences and/or flexibility within individuals is key to identifying drivers of migration patterns. ‘Repeatability' (R, the proportion of population‐level variation attributable to between‐individual variation) has become a central metric for the relative consistency of individual behaviour. Individual repeatability in migratory route choice and timing is often reported to vary between seasonal and regional contexts and may also differ between demographic groups (e.g. sexes), but interpreting repeatability requires careful consideration of the underlying changes in between‐ and within‐individual variation. We GPS‐tracked repeat migrations for eight male and five female Eleonora's falcons Falco eleonorae and quantified the magnitude of within‐ and between‐individual variation and the individual repeatability of their seasonal routes and timing at 100 km intervals all across Africa. We did this across both sexes, and then separately for males and females. We found greater between‐individual variation in spring routes, albeit with substantial regional fluctuations in both seasons. The greatest between‐individual variation in routes occurred during the spring desert‐crossing, but this coincided with high within‐individual variation, and thus only low repeatability of route choice. Route repeatability instead peaked (R = 0.6–0.8) through the Horn of Africa in spring, and during the rainforest‐crossing in autumn. Variation and repeatability of timing was stable across regions, with generally higher between‐individual variation and repeatability in spring. Sex‐specific analyses suggest males exhibit higher route repeatability, while females exhibit stronger seasonal contrasts in timing repeatability. Such sex differences were unexpected, but overall, between‐individual variation and repeatability in routes and timings appear greater where environmental and annual cycle constraints are weaker. Route repeatability is especially high where falcons show fidelity to stop‐over sites, or individual barrier‐crossing preferences. Individual routines may be acquired through early‐life exploration‐refinement.

Cascading effects of climate variability on the breeding success of an edge population of an apex predator.

Large‐scale environmental forces can influence biodiversity at different levels of biological organization. Climate, in particular, is often associated with species distributions and diversity gradients. However, its mechanistic link to population dynamics is still poorly understood.Here, we unravelled the full mechanistic path by which a climatic driver, the Atlantic trade winds, determines the viability of a bird population.We monitored the breeding population of Eleonora's falcons in the Canary Islands for over a decade (2007–2017) and integrated different methods and data to reconstruct how the availability of their prey (migratory birds) is regulated by trade winds. We tracked foraging movements of breeding adults using GPS, monitored departure of migratory birds using weather radar and simulated their migration trajectories using an individual‐based, spatially explicit model.We demonstrate that regional easterly winds regulate the flux of migratory birds that is available to hunting falcons, determining food availability for their chicks and consequent breeding success. By reconstructing how migratory birds are pushed towards the Canary Islands by trade winds, we explain most of the variation (up to 86%) in annual productivity for over a decade.This study unequivocally illustrates how a climatic driver can influence local‐scale demographic processes while providing novel evidence of wind as a major determinant of population fitness in a top predator.

Louse flies of Eleonora's falcons that also feed on their prey are evolutionary dead-end hosts for blood parasites.

Host shifts are widespread among avian haemosporidians, although the success of transmission depends upon parasite‐host and parasite‐vector compatibility. Insular avifaunas are typically characterized by a low prevalence and diversity of haemosporidians, although the underlying ecological and evolutionary processes remain unclear. We investigated the parasite transmission network in an insular system formed by Eleonora's falcons (the avian host), louse flies that parasitize the falcons (the potential vector), and haemosporidians (the parasites). We found a great diversity of parasites in louse flies (16 Haemoproteus and 6 Plasmodium lineages) that did not match with lineages previously found infecting adult falcons (only one shared lineage). Because Eleonora's falcon feeds on migratory passerines hunted over the ocean, we sampled falcon kills in search of the origin of parasites found in louse flies. Surprisingly, louse flies shared 10 of the 18 different parasite lineages infecting falcon kills. Phylogenetic analyses revealed that all lineages found in louse flies (including five new lineages) corresponded to Haemoproteus and Plasmodium parasites infecting Passeriformes. We found molecular evidence of louse flies feeding on passerines hunted by falcons. The lack of infection in nestlings and the mismatch between the lineages isolated in adult falcons and louse flies suggest that despite louse flies’ contact with a diverse array of parasites, no successful transmission to Eleonora's falcon occurs. This could be due to the falcons’ resistance to infection, the inability of parasites to develop in these phylogenetically distant species, or the inability of haemosporidian lineages to complete their development in louse flies.

Hunting Altitude of Eleonora's Falcon (Falco eleonorae) Over a Breeding Colony

We investigated the flight altitude of hunting Eleonora's Falcons (Falco eleonorae) around their colony near the island of Crete (Greece). We used a broadband marine surveillance radar positioned on the coast of Crete and detected the falcons’ movements during the breeding period. The birds were monitored using a Java application that enabled us to manually track radar targets directly on the radar screen and transfer the data into a GIS environment. Thirty hours of radar monitoring between 14 September and 22 September 2017 produced 4774 records of the species (1218 over inland and 3556 over the sea). Hunting falcons flew on average at 1292 ± 11 masl (range = 17–3475, median flight altitude 1156 m), though 70% of them were tracked flying between 17 and 1750 m. The range of flight altitude recorded was greater than that previously published, and was consistent with the prey selection during the nestling-rearing period, i.e., migratory passerines. Eleonora's Falcons hunted more frequently over the sea than over the mainland and at a higher altitudes during the morning than at midday or in the afternoon. The daily flight pattern probably reflected the higher intensity of passerine migration in the early morning and late afternoon, as well as an opportunistic prey shift from birds to insects during midday when passerine migration is weak. Compared to other techniques previously used for tracking this species, namely visual observations (1970s), optical range finder (1990s), and satellite telemetry (2000s), broadband marine radar is not limited by small sample size, geolocation error, weather conditions, or poor visibility at high altitudes.

Satellite factors influencing the impact of recreational activities on wildlife

Satellite factors influencing the impact of recreational activities on wildlife

Nocturnal Hunting by Eleonora's FalconsFalco eleonoraeon Their Breeding and Non-Breeding Grounds

We report on nocturnal hunting by Eleonora's Falcons in their breeding range in the Mediterranean region and in their non-breeding range in Madagascar. Hunting activity of Eleonora's Falcons near floodlights during the breeding season in western Morocco peaked 30–60 min after sunset, but continued into the early morning. Hunting activity and prey capture rates near floodlights were highest during nights with little moonlight or overcast conditions. Fifty-one percent of 73 group capture attempts were successful. Of the migratory prey species identified at the Moroccan study site (26 species), 73% belonged to species mainly migrating at night, whereas 57% of all migratory bird prey species of Eleonora's Falcon reported to date (122 species) migrate predominantly at night; suggesting that hunting near artificial light may increase the proportion of nocturnal migrant species in the diet of falcons. Sylvia and Acrocephalus were the most commonly recorded genera among prey caught after dark. Our direct observations and analysis of satellite transmitter data indicated that Eleonora's Falcons also hunted away from artificial light in Morocco, Italy, and frequently so in Madagascar. Flight activity was detected in 18% of 342 night-time locations of seven satellitetagged Eleonora's Falcons in Madagascar, at an average moon illumination of 60%. We conclude that nocturnal hunting by Eleonora's Falcons is more common than previously assumed and occurs preferably, but not exclusively, at above-average moon illumination on wintering grounds or near artificial lights during the breeding period.

Plastic mistaken for prey by a colony-breeding Eleonora's falcon (Falco eleonorae) in the Mediterranean Sea, revealed by camera-trap

Discarded plastic is known to be harmful for marine animals through ingestion and entanglement. Here we report the first documentation of Eleonora's falcons providing plastic waste to dependent nestlings. Eleonora's falcons breed colonially on sea cliffs and islets in areas of the Mediterranean Sea and the Canary Islands in which they normally feed their nestlings exclusively with small migratory birds.

Ranging Behaviour of Eleonora's FalconsFalco eleonoraeDuring Chickrearing

The Eleonora's Falcon is a cliff-nesting raptor that breeds on isolated small islands adjusting its breeding season to coincide with the post-breeding autumn migration of its small passerine prey migrating over the sea, between late August and early October. Two adult female Eleonora's Falcons were equipped with Argos satellite transmitters during the chick-rearing period in Morocco giving the opportunity to study the ranging behaviour of the species during at least a part of the breeding season. Results showed that the falcons spent most of the time at sea during mornings, stayed mainly inland during afternoons, and rested in the colony during nights. Interestingly, although most distances were recorded shorter than 50 km away from the colony, movements took also place to areas located more than 100 km away. Locating and protecting these inland areas used for resting and foraging may be of interest for the conservation of the species in order to avoid perturbations such as poisoning and habitat destruction.

Wintering habitats of Eleonora's Falcons Falco eleonorae in Madagascar

Capsule Eleonora's Falcons wintering in Madagascar selected degraded humid forests and cultivated areas close to pristine humid forest. Aims To identify the habitat preferences of Eleonora's Falcon Falco eleonorae on their wintering grounds in Madagascar, and to use this information to gain insights into the conservation priorities of this species. Methods A total of 11 Eleonora's Falcons were captured in Spain in 2007 and 2008 and equipped with solar-powered satellite transmitters. We obtained information on five complete wintering events for three birds, two of them tracked for two consecutive years. Data were analyzed using geographic information system-based cartography. Results The analyses showed a preference for degraded humid forests and cultivated lands within areas where pristine humid forests were the most abundant habitat type. Conclusions Eleonora's Falcons could be taking advantage from a spill-over edge effect of their insect prey into cultivated and more open areas close to humid forests. However, the importance of humid forests for Eleonora's Falcons seems to be high. The current loss of this habitat in Madagascar is a cause for concern with respect to the conservation of this long-distance migratory falcon species.

Dead Embryos despite Low Contaminant Loads in Eggs of Eleonora's Falcon

As a long-distance migrant which crosses more than 20 African countries, Eleonora's Falcons might have experienced a substantial accumulation of contaminants when returning to their breeding grounds. In 2004 and 2005, we collected 21 failed eggs from two colonies on Sardinia, Italy. We found a high percentage of dead embryos and suspected this was due to a high contaminant load. Despite this, the overall values for the contaminants analysed were rather low and lay within the range found in other raptor species. We analysed the eggs for residues of DDT (p,p′-dichlorodiphenyltrichloroethane), PCB (polychlorinated biphenyl), and heavy metals. Although infertile eggs seem to be correlated with the highest values of∑DDT, we did not find substantial values of any of the contaminants investigated. Because of the low world population of the species and varying reproduction rates in the colonies ranging from Cyprus to the Canaries, we highly recommend further censuses of the reproductive success of Eleonora's Falcon, including the examination of failed eggs.

Prevalence of Neutralizing Antibodies to West Nile Virus in Eleonora's Falcons in the Canary Islands

Birds are the major amplifying host for West Nile virus (WNV), a flavivirus that may affect humans and transmitted by bloodsucking vectors. Eleonora's Falcons (Falco eleonorae) migrate to the Canary Islands annually from WNV-endemic regions. To investigate the possible role of Eleonora's Falcons in the circulation of WNV, we measured WNV-specific antibodies in 81 falcons captured in 2006. None of the nestlings but 14.8% of the adults had WNV-neutralizing antibodies. RT-PCR did not detect flaviviruses in nonculicine ectoparasites (n=231) of the falcons. These findings suggest that WNV infection did not occur locally, but rather on the wintering grounds or during migration.

Weather conditions promote route flexibility during open ocean crossing in a long-distance migratory raptor

Weather conditions are paramount in shaping birds' migratory routes, promoting the evolution of behavioural plasticity and allowing for adaptive decisions on when to depart or stop during migration. Here, we describe and analyze the influence of weather conditions in shaping the sea-crossing stage of the pre-breeding journey made by a long-distance migratory bird, the Eleonora's falcon (Falco eleonorae), tracked by satellite telemetry from the wintering grounds in the Southern Hemisphere to the breeding sites in the Northern Hemisphere. As far as we know, the data presented here are the first report of repeated oceanic journeys of the same individuals in consecutive years. Our results show inter-annual variability in the routes followed by Eleonora's falcons when crossing the Strait of Mozambique, between Madagascar and eastern continental Africa. Interestingly, our observations illustrate that individuals show high behavioural plasticity and are able to change their migration route from one year to another in response to weather conditions, thus minimising the risk of long ocean crossing by selecting winds blowing towards Africa for departure and changing the routes to avoid low pressure areas en route. Our results suggest that weather conditions can really act as obstacles during migration, and thus, besides ecological barriers, the migratory behaviour of birds could also be shaped by "meteorological barriers". We briefly discuss orientation mechanisms used for navigation. Since environmental conditions during migration could cause carry-over effects, we consider that forecasting how global changes of weather patterns will shape the behaviour of migratory birds is of the utmost importance.

All across Africa: highly individual migration routes of Eleonora's falcon

Eleonora's falcon (Falco eleonorae) is a rare raptor species that delays its breeding period until late summer to feed its young with passerines at the peak of autumn migration. Since the 1950s, this slender winged falcon has been believed to migrate along a historical route via the Red Sea to its main wintering area in Madagascar. In our study, we used satellite telemetry to investigate the real migration route of Eleonora's falcons and found that the species displayed a highly individual migration pattern. Furthermore, juvenile falcons migrated via West Africa to Madagascar and two juveniles could be tracked during spring migration and to their summering areas in East and West Africa. As juveniles migrated independently of adults, we discuss inherited navigation strategies forming part of a complex navigation system. We propose the idea of an orientation mechanism that naive falcons could apply during their long-distance migration towards their faraway wintering area located in the open ocean.

Long-term changes of species richness in a breeding bird community of a small Mediterranean archipelago

We analyzed the pattern of species richness changes in a bird–breeding bird community on a small western Mediterranean archipelago (Columbretes Islands) over a 40–year period (1964–2003). The aim of this study was to qualitatively account for the relative roles of local and regional factors in shaping the community. As expected, we found that regional factors (at the metapopulation spatial scale) increased diversity whereas local factors (i.e. ecological) probably prevented further increases in diversity. We found that the archipelago gained four new species (two seabirds and two falconids) during the study period, whereas no extinctions were recorded. The community seems partially or completely closed to some groups of species (e.g. small–sized birds such as passerines and storm–petrels), probably owing to predatory exclusion by Eleonora falcons (Falco eleonorae). As newly arrived species have breeding calendars that do not fully overlap with those of resident species, competition for space in a rather saturated area is prevented. Preservation of rare species which increase gamma (regional) diversity rather than alpha diversity with common species should be the main local conservation goal.

Hunting Flight Behaviour of the Eleonora's Falcon Falco eleonorae

The Eleonora's Falcon Falco eleonorae breeds on islands and islets in the Mediterranean region and feeds its young on migratory birds caught in the air. The breeding season is scheduled to coincide with the peak of bird migration. Between 12 and 20 September 1997 we measured flight tracks of falcons within a range of 4 km from their breeding cliffs on Isola di San Pietro 6 km off the south-west coast of Sardinia, by using an optical range finder. The male falcons left the colony in directions between W and NW to hunt far off-shore, probably intersecting migrants departing from mainland Europe in southern France. Flight tracks of falcons leaving for off-shore hunting and falcons searching for prey closer to the colony differed significantly, as revealed by a straightness index. Falcons leaving the colony for the far off-shore hunting area climbed to altitudes over 1000 m. The highest altitude recorded was 1649 m. The altitudes reported from radar studies on nocturnal migrants in the Mediterranean match the flight altitudes observed in the departing Eleonora's Falcons. Calculations based on the times taken for falcons to return with prey to the nest indicate a maximum distance to the hunting area of about 24 km. The falcons compensated partially for wind drift caused by cross winds when departing for off-shore hunting. Complete compensation might not be possible if the wave pattern of the sea is used for orientation, due to movements of the reference system relative the ground. The flight time of Eleonora's Falcons did not seem to be severely restricted by a metabolic ceiling, although such a ceiling does not allow extensive day and night hunting.

Relationships within the GenusFalco: A Comparison of the Electrophoretic Patterns of Feather Proteins

Variations in feather protein (SCMK) patterns from 36 members of the genus Falco were studied by electrophoresis to examine intrageneric relationships. Little or no polymorphisms were found within species but differences between species enabled identification of groupings of species with similar protein patterns. Eight to ten more-or-less distinct groupings were recognised. Typical kestrels and desert falcons, traditionally considered distinctive groups, were also grouped on the basis of their feather protein patterns The aberrant or grey-backed kestrels were allied to the hobbies and peregrines, rather than the typical kestrels. Hobbies from the Australasian region were not close to Empean and African hobbies. Eleonora's, Sooty and Bat Falcons shared similar patterns as did Brown and New Zealand Falcons and both groups were similar to each other (Gondwanaland falcons). They also resembled the Black and Grey Falcons which in turn resembled Australasian hobbies. The Aplomado Falcon was like the true hobbies while the Orange-breasted Falcon was most like the peregrines but showed similarities to other groups. Protein patterns of Barbary and Teita Falcons seemed closest to the Peregrine Falcon but not identical. Two main groupings were the typical kestrels, desert falcons and merlins, on the one hand, and the remaining Falco on the other. Two centres of origin of modern Falco are proposed for these main groupings: the kestrels, merlins and desert falcons from Africa; and the remaining falcons, earlier, from Gondwanaland.

FALCO ELEONORAE

SummaryThe approximate totals for each part of the range may now be tabulated(a) Northwest Africa 250 pairs(b) Western Mediterranean 130(c) Central Mediterranean 150(d) Eastern Mediterranean(i) Aegean Crete 850‐1,150 pairs(ii) Cyprus 150–300This gives a grand total of 1,550‐2,000 breeding pairs. Owing to the probable existence of undiscovered colonies not allowed for in the individual estimates, this total may be too small; on the other hand, many of the estimates for Aegean colonies were made fifty or more years ago, since when, on the analogy of the only two colonies in that area about whose history anything is known, there has probably been a decline in numbers. It should be remembered, too, that the size of many colonies has only been guessed. In spite of these uncertainties, however, I would suggest that the total world population of Eleonora's Falcons is under 4,000 birds, about half of which breed in the Aegean and Crete.The most important areas where large colonies perhaps remain to be discovered are the Dodecanese and Algeria. Birds have been recorded in summer from the Tuscan Archipelago (Arrigoni degli Oddi & Damiani 1911, Moltoni 1954), the Ligurian Sea (Giglioli 1889), Pantelleria (Moltoni 1957 a), the Adriatic (Moltoni 1957 b), the Ionian Islands (Reiser 1905) and elsewhere (e.g. Provence, Leveque & Vuilleumier 1958, and even Central Spain, Lilford 1866), and, though most of these records are from the early part of the summer, it is possible that some of them represent hitherto undiscovered breeding populations. There was once a colony at Gibraltar, but this has long since ceased to exist (Bate 1928, on palaeolithic cave remains). Irby (1895) points out that the Rev. John White's “Hobbies”, which he says bred on the Rock, must have been Eleonora's Falcons and in the seventeenth century Eleonora's Falcon bred on the lies ?Hyeres (?Arcussia 1644: 60).SummaryThe known facts about Eleonora's Falcon are brought together, and contributions to existing knowledge made, under the headings Characters, General Habits, Food, Breeding, Breeding Distribution and Numbers, Migration, and Predation. It is shown that the breeding season is from mid‐July to October, that Eleonora's Falcon is a largely crepuscular feeder, that it is a summer visitor to its breeding haunts, and that it is dimorphic. The total world population is estimated to be rather less than 4,000 birds.

Meteorology

Discarded plastic is known to be harmful for marine animals through ingestion and entanglement. Here we report the first documentation of Eleonora's falcons providing plastic waste to dependent nestlings. Eleonora's falcons breed colonially on sea cliffs and islets in areas of the Mediterranean Sea and the Canary Islands in which they normally feed their nestlings exclusively with small migratory birds.