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Falco eleonoraeEleonora's falcon

By Dennis Lorenz

Geographic Range

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)

Habitat

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)

  • Range elevation
    0 to 2000 m
    0.00 to 6561.68 ft

Physical Description

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, et al., 1982a)

  • Sexual Dimorphism
  • female larger
  • Range mass
    340 to 460 g
    11.98 to 16.21 oz
  • Range length
    370 to 455 mm
    14.57 to 17.91 in
  • Range wingspan
    840 to 1030 mm
    33.07 to 40.55 in

Reproduction

Eleonora’s falcons are monogamous, colonial breeders. Aerial displays by male falcons begin as soon as the birds arrive on nesting sites. (Ferguson-Lees and Christie, 2001; Rosen and et al, 1999; Swatscheck and et al, 1993; Walter, 1979; Wink, et al., 1982b)

Breeding sites are occupied starting in late April, though breeding does not start until late July. The young hatch in late August to early September at the beginning of the migration period of most small, Palearctic birds. The nest is located on the ground or on a cliff, often in a small cavity or under a small bush, sheltered from wind. Clutch size ranges from 1 to 4 eggs, rarely 5. Incubation lasts between 28 and 30 days, and the young fledge after another 35 to 40 days. Average productivity differs among different colonies and can range from 1.26 fledglings per year to 2.6 young per year. Young males usually remain near their parents’ home range, while females disperse farther. (Ferguson-Lees and Christie, 2001; Walter, 1979)

  • Breeding interval
    Eleonora's falcons breed once yearly.
  • Breeding season
    Breeding occurs in late July.
  • Range eggs per season
    1 to 5
  • Range time to hatching
    28 to 30 days
  • Range fledging age
    35 to 40 days

As in most other falcon species, both males and females contribute to incubating, protecting, and nourishing their offspring. (Ferguson-Lees and Christie, 2001; Walter, 1979)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • male
      • female
  • pre-hatching/birth
    • provisioning
      • male
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • male
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female

Lifespan/Longevity

There is no information available on lifespan in Falco eleonorae.

Behavior

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)

  • Range territory size
    1 to 200 m^2

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)

Communication and Perception

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.

Food Habits

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, et al., 1980)

  • Animal Foods
  • birds
  • insects

Predation

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)

Ecosystem Roles

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)

Economic Importance for Humans: Positive

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)

  • Positive Impacts
  • research and education
  • controls pest population

Economic Importance for Humans: Negative

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

Conservation Status

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)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Dennis Lorenz (author), Michigan State University, Pamela Rasmussen (editor, instructor), Michigan State University.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

crepuscular

active at dawn and dusk

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

marsh

marshes are wetland areas often dominated by grasses and reeds.

migratory

makes seasonal movements between breeding and wintering grounds

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

polymorphic

"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

References

Cade, T., A. Clark. 1979. Birds of Prey. Science, 206/4415: 211-212.

Ferguson-Lees, J., D. Christie. 2001. Raptors of the World. Boston, New York: Houghton Mifflin Company.

Hedenström, A., M. Rosen. 2001. Predator versus prey: On aerial hunting and escape strategies in birds. Behavioral Ecology, 12/2: 150-156.

Hedenström, A., M. Rosen, S. Ǻkesson, F. Spina. 1999. Flight Performance During Hunting Excursions in Eleonora’s Falcon (Falco eleonorae). The Journal of Experimental Biology, 202: 2029-2039.

Martinez, A., D. Oro, V. Ferris, R. Belenguer. 2002. Is growing tourist activity affecting the distribution or number of breeding pairs in a small colony of the Eleonora’s Falcon?. Animal Biodiversity and Conservation, 25/2: 47-51.

Massa, B. 1978. Observations on Eleonora’s Falcon (Falco eleonorae) in Sicily, Italy and Surrounding Islets. Ibis, 120/4: 531-534.

Mentzelopoulos, K. 2006. "Tilos Park" (On-line). Accessed January 08, 2007 at http://www.tilos-park.org/about.htm.

Palacios, C. 2004. Current status and distribution of birds of prey in the Canary Islands. Bird Conservation International, 14/3: 203-213.

Piasevoli, G., V. Scetaric. 2001. Eleonora’s Falcon (Falco eleonorae) in Croatia: Range, threats and the proposal of action and management plan. Annales Series Historia Naturalis, 23: 81-86.

Rohwer, S., D. Paulson. 1987. The Avoidance-Image Hypothesis and Color Polymorphism in Buteo Hawks. Ornis Scandinavica, 18/4: 285-290.

Rosen, M., A. Hedenström. 2002. Soaring Flight in the Eleonora’s Falcon (Falco eleonorae). The Auk, 119/3: 835-840.

Rosen, M., et al. 1999. Hunting flight behavior of the Eleonora’s Falcon (Falco eleonorae). Journal of Avian Biology, 30/4: 342-350.

Swatscheck, I., et al. 1993. Population Genetics and Paternity Analysis of Eleonora’s Falcon (Falco eleonorae). Journal fuer Ornithologie, 134/2: 137-143.

Thiollay, J., B. Meyburg. 1981. Organization of an Island Population of Raptors in Madagascar. Alauda, 49/3: 216-226.

Walter, H. 1979. Eleonora's Falcon. Chicago: The University of Chicago Press.

Wink, M., C. Wink, D. Ristow. 1982. Biology of the Eleonora’s Falcon (Falco eleonorae): Biometrics of Sexual Dimorphism of Adult and Fledged Falcons. Vogelwelt, 103/6: 225-229.

Wink, M., C. Wink, D. Ristow. 1982. Biology of the Eleonora’s Falcon (Falco eleonorae): Breeding Success in Relation to Nest Site Exposition. Journal fuer Ornithologie, 123/4: 401-408.

Wink, M., C. Wink, D. Ristow. 1980. Biology of the Eleonora’s Falcon (Falco eleonorae): Clutch Size in Relation to Hunting Success and Weight of the Parent Falcons. Journal fuer Ornithologie, 121/4: 387-390.

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