Falco eleonorae
Eleonora's falcon
(Also: Eleonora's falcon)

Eleonora’s falcons are distributed throughout the Mediterranean region, including the Canary Islands, Morocco, Algeria, Tunisia, the Balearic Islands, Sicily, Sardinia, Croatia, islands in the Aegean Sea, Crete, Cyprus, and Turkey. All breeding sites lie between longitude 14°W to 33°E, and latitude 43°N to 28°N. Approximately 10% of Eleonora falcon populations breed on the Tilos Island chain. All populations winter in Madagascar and the Mascarene Islands. (Cade and Clark, 1979; Ferguson-Lees and Christie, 2001; Mentzelopoulos, 2006; Thiollay and Meyburg, 1981; Walter, 1979)

Eleonora’s falcons commonly breed on the ground on small, rocky, undisturbed islands with little vegetation. On larger islands, such as Sicily and Sardinia, and on the mainland in Africa and Turkey, they seek inaccessible coastal cliffs to breed. They hunt over the open sea, as well as over wetlands, grasslands, and sometimes woodlands. Nest sites are found from sea-level to an elevation of 2,000 meters. (Ferguson-Lees and Christie, 2001; Walter, 1979)

Eleonora’s falcons are medium-sized falcons, of similar length to peregrine falcons (F. peregrinus), but much lighter in weight and build. Like all other falcons, Eleonora’s falcons show reversed sexual size dimorphism, with females on average slightly larger than males. Males vary in length from 37 to 43 cm, females from 38.5 to 45.5 cm, and in weight, males range from 350 to 390 g, females from 340 to 460 g. The shortest wingspan measurement for an Eleonora’s falcon was 84 cm, while large females may have a wingspan of up to 103 cm. Eleonora’s falcons have long, narrow wings that exceed the tip of the long tail when folded. There are two color morphs, a light and a dark morph. Dark morph birds are all brown, and may appear black from a distance. The male’s cere is yellow in color while the female’s is blue-gray. Light morph birds are also dark brown above and buff to rufous below with dark streaking. The light morph also shows the typical dark moustache stripe. (Ferguson-Lees and Christie, 2001; Rohwer and Paulson, 1987; Walter, 1979; Wink, Wink, and Ristow, 1982b)

There is no information available on lifespan in Falco eleonorae.

Eleonora’s falcons are gregarious. They nest in colonies of up to 300 pairs and may hunt migrating passerines and invertebrates singly or in small groups. Members of the colony aggressively chase off other birds, such as doves and gulls. When not occupying breeding colonies, these falcons are likely to be solitary. Migration starts late for Eleonora’s falcons, they usually leave the breeding grounds in late October to early November and migrate to Madagascar and the Mascarene Islands. Little is known about their migration route, although it is likely that they follow the east African coastline. (Ferguson-Lees and Christie, 2001; Walter, 1979)

Home Range

The breeding territories of Eleonora’s Falcons vary within each colony. Some territories are as small as 1 m² while others are up to 200 m². This space is defended by the local pair against any intruders, including other falcons. The air space up to 10 m in height above this area is also protected by the resident pair. The nesting cliff is defended by all members of the colony, and hunting falcons may fly up to 5 km from the colony to chase passerines. Individual birds have been observed to travel up to 30 km from the breeding cliff to hunt. (Cade and Clark, 1979; Walter, 1979)

Eleonora’s falcons are highly vocal and seem to have a wider range of vocalizations than other falcons. Vocal communication is especially common during the pre-mating season. Some common calls include recognition, territorial, display, copulation, greeting, prey transfer demand, prey arrival, alarm, and distress calls. Chuckles can also be heard by brooding falcons upon arrival of the mate. The young give a variety of calls to indicate discomfort, hunger, alarm, or excitement. (Walter, 1979)

Eleonora's falcons, like other falcons, have especially keen vision, used in capturing prey.

Eleonora’s falcons feed primarily on flying insects. During the breeding season, however, these falcons switch their hunting behavior and concentrate solely on migrating passerine birds. Over 100 species have been recorded as prey of Eleonora’s falcons. To hunt, falcons fly out to sea utilizing vertical winds for soaring, and may hunt close to sea level or up to a height of 1,000 m. Several falcons often hunt together spaced several hundred meters apart, creating a barrier which makes it harder for migrating birds to stay undetected. Eleonora’s falcons are also known to hunt until well after sunset. These falcons usually stoop down on their prey, but sometimes pursue it for longer distances. Insects are also caught and eaten in flight. During the breeding season excess prey is often cached and retrieved later. Male falcons do most of the bird-hunting during the breeding season, leaving females to incubate eggs and nestlings. (Ferguson-Lees and Christie, 2001; Hedenström and Rosen, 2001; Hedenström et al., 1999; Massa, 1978; Walter, 1979; Wink, Wink, and Ristow, 1980)

Eleonora’s falcons have few natural predators as adults. Black rats (Rattus rattus) inhabit many islands that harbor falcon colonies and may feed on unguarded falcon eggs or nestlings. Peregrine falcons (Falco peregrinus), Lanner falcons (Falco biarmicus), and Eurasian eagle owls (Bubo bubo) have been known to prey on adult falcons. Cory’s shearwaters (Calonectris diomedea) often breed within falcon colonies and occasionally take young falcons. (Walter, 1979)

Eleonora’s falcons play an important role in the migration of millions of small birds, mainly passerines from their Palearctic breeding grounds to African wintering areas. Falcons prey on migrating passerines, preferring small, juvenile birds. It is estimated that all Eleonora’s falcon colonies combined catch about two million migrating birds in a single breeding season. This, however, only represents 0.02 to 0.04% of the total number of migrating birds. Falco eleonorae is also important in regulating prey species populations throughout their range. (Ferguson-Lees and Christie, 2001; Walter, 1979)

There are no negative impacts of Eleonara's falcons on humans.

Eleonora’s falcons, like other raptors, are important bioindicators of healthy environments. They further help to reduce pest species, such as grasshoppers and rodents that cause damage to human crops. (Ferguson-Lees and Christie, 2001; Walter, 1979)

Due to the limited distribution and colonial breeding habits of Eleonora’s falcons, they are very vulnerable. The main threats are an increase in tourism, especially the use of motorboats near colonies, which often results in distressed parent birds and reproductive failure. In the Aegean Sea, colonies are often raided by fisherman who take the young and eggs for food. Persecution of adult birds has also been recorded. The total population is currently estimated at 4,500 breeding pairs. As long as breeding colonies are protected from poaching by humans and from heavy tourism, Eleonora’s falcon populations will likely remain stable. A decrease in migrating passerines due to habitat loss in mainland Europe has been observed over the past century and falcon populations have dropped accordingly, but seem to be currently stable. (Ferguson-Lees and Christie, 2001; Martinez et al., 2002; Palacios, 2004; Piasevoli and Scetaric, 2001; Walter, 1979)