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Hieraaetus pennatusbooted eagle

By Kevin Pennala

Geographic Range

Booted eagles (Hieraaetus pennatus) are found in southern Europe (France, Portugal, Italy, Spain, Russia, Turkey and Ukraine), North and South Africa, the Middle East to central Asia and the Indian Subcontinent. It is a trans-Saharan migratory bird, spending its summers in its northern region in Europe to Asia and wintering in the Sahel region and tropical Africa. (Baghino, et al., 2007; López-López, et al., 2016)

Habitat

Booted eagles will nest in a variety of habitats across their range. Their main habitats include: marshes, scrublands, scattered cork oaks, stone pines, and sand dunes along coastlines. The dominate part of their habitat consists of the eucalyptus species, stone pine and cork oak. The booted eagle is a common species of the forests and woodland areas of the Iberian Peninsula. They also inhabit mixtures of woodlands, such as pine forests, open lands, and mountain slopes. The booted eagle is described as a trans-Saharan migrant, moving from Europe in March to Africa in September. (Martínez, et al., 2006; Suarez, et al., 2000)

  • Range elevation
    0 to 3000 m
    0.00 to 9842.52 ft

Physical Description

Booted eagles are medium-sized birds, weighing 0.6-1.2 kg, ranging in length from 50-54cm long and a wingspan of 110-135 cm. They are described as “stocky” with round heads, feathered legs, long wings and a square-ended tail. They are dimorphic with a pale and dark morph form. The melanin-based color variation within and between bird species normally has a strong genetic component and is also related to sex, age, season and geographical range. Most are brown with patches of cream, gold, and/or white throughout. The one distinct factor between booted eagles are the color of their underbodies, either cream or dark brown. Eye color is either red, yellow or orange, with brown and their feet are yellow with feathered legs. (Jiménez-Franco, et al., 2011; Martínez, et al., 2016)

  • Sexual Dimorphism
  • sexes colored or patterned differently
  • Range mass
    0.6 to 1.2 kg
    1.32 to 2.64 lb
  • Range length
    50 to 54 cm
    19.69 to 21.26 in
  • Range wingspan
    110 to 135 cm
    43.31 to 53.15 in

Reproduction

Booted eagles use elaborated aerial displays to establish a pair bond. Courtship displays include very fast and marvelous stoops. From the beginning of the breeding season, through to the end of the season, birds perform spectacular nuptial displays. The main feature is a series of dives followed by upward swoops, performed at great speed and accompanied by active calling. The male may dive at the female repeatedly, and she may turn on her back and present her claws upwards to his. Booted eagles are otherwise generally silent, except during the breeding season. (Bosch, et al., 2016; Orta, et al., 2018)

Booted eagles select breeding areas with a mixture of woodlands and open lands, often times near marshland and stone pine trees. Trees used for nesting are often larger (wide and tall) and usually are in small groups or large isolated trees, cliff edges have also been used for nest. Nests are built out of sticks and lined with leaves or conifer needles. They are built on a large branch of a tree or cliff ledge, 6-35 meters up. Eggs are laid from March to June, with most in mid to late April, depending on the area and weather. Normally two eggs are laid, however, sometimes 1 egg and rarely 3 eggs can be laid and are incubated mostly by the female for 37-40 days before hatching. If more than one egg hatches, both chicks often survive. Fledging takes 50-55 days and the chick is independent around 2 weeks after that. (Suarez, et al., 2000)

  • Breeding interval
    yearly
  • Breeding season
    March-June
  • Range eggs per season
    1 to 3
  • Range time to hatching
    37 to 40 days
  • Range fledging age
    50-55 (low) days
  • Average time to independence
    2 weeks days

After fledging, the young are dependent on the parents, however this will only last for a few weeks. Females will lay larger clutches when they do not know what the food outlook will be like. (Casado, et al., 2008)

Lifespan/Longevity

There is no information on lifespan reported in the literature.

Behavior

The booted eagle is considered a “rare” bird in Europe, breeding in both in Western Europe in the countries of France, Portugal and Spain and in Eastern Europe in the countries of Russia, Turkey and Ukraine. However, in Italy, the booted eagle is a regular migrant, but irregular when it comes to wintering. During wintering, the birds are seen in wetlands and marshes. Mainly they will overwinter in southern Asia, southern Europe and Africa. They leave the breeding grounds in August/September and return in March/April. They are typically found in pairs or singly and are not usually found in groups more than five, even when migrating.

Booted eagles mainly soar high above clearings and forest. They will soar in circles and glide in straight lines, relying on rising thermals, updrafts or wind to gain altitude. Gliding in a straight line gives better progression of direction in their flight. When migrating, booted eagles rely on thermal updrafts for gliding. Switching from flapping to this soaring-gliding style of flight saves the booted eagle energy. (Baghino, et al., 2007; Spaar, 2008)

Communication and Perception

Booted Eagles use elaborated aerial displays to establish a pair bond. During the breeding season and often before and after, they perform very spectacular nuptial displays. The main feature is a series of dives followed by upward swoops, performed at great speed and accompanied by calling (mainly shrills). The male will sometimes dive at the female repeatedly, and she may flip over on her back and present her claws upwards to his. The birds are generally silent, except during the breeding season. The call of both sexes is described as a rapid “kli kli kli”. During courtship displays, the male will repeatedly make a “pi-pi-piiii” call. (Bosch, et al., 2016; Orta, et al., 2018)

Food Habits

The diet of booted eagles consists of a wide range of animals including birds, small mammals, reptiles, rodents, amphibians, and insects. Booted eagles hunt their prey by perching from a lookout or on the ground, or by circling open country at 10-250 meters. They occasionally chase birds throughout the tree canopy; however, the majority of their prey is caught on the ground. They have also been known to hunt near villages and cities. Their main prey is the European rabbit. Prey birds consist of larks, pipits, pigeons, starling and thrushes. (Rouco and Vinuela, 2009)

  • Animal Foods
  • birds
  • mammals
  • reptiles
  • eggs
  • insects

Predation

The main predator of the booted eagle is the Eurasian eagle owl, which preys on nestlings. Predation by this owl is well documented in Europe and is especially intense in areas where owls and diurnal raptors compete for breeding habitats and prey resources. (Martínez, et al., 2006)

  • Known Predators
    • Eurasian eagle owl Bubo bubo

Ecosystem Roles

The booted eagle is a bioindicator of human dominated agro-forestry landscapes in which low-intensity traditional agricultural practices still persist. It is an ecological top predator preying on small birds, mammals, reptiles and insects. It represents an example of high biodiversity values, justifying conservation practices based on their role as major ecological indicators. (López-López, et al., 2016)

Economic Importance for Humans: Positive

Booted eagles play a role as an ecological bioindicator of landscapes, inhabiting areas of forest edges with natural openings or traditional organic agriculture practices. Large-scale agriculture operations that use pesticides and other biocides have less biodiversity and prey availability for booted eagles, which has led the European Union to approve a strategy to halt the loss of biodiversity and ecosystem services (López-López, et al., 2016)

Economic Importance for Humans: Negative

Booted eagles have been found to hunt in or near cities and villages and may prey on penned or free ranging domestic fowl and small pets. (Carlon, 1996)

Conservation Status

The main threats for booted eagles includes habitat loss and degradation, power line electrocution, occasional forest fires, poor forest management, deforestation, direct persecution and disturbance at breeding sites due to construction of roads and forest trails, all of which have caused some decline in populations in certain parts of their range. Hunting and other human activities have also been found to play roles in disturbing booted eagle habitat and hunting grounds. Pesticides accumulating in wintering areas may affect their reproductive success. The European Union approved a strategy to halt the loss of biodiversity and ecosystem services by 2020. This species is also highly vulnerable to the impacts of potential wind energy developments, where millions of birds are killed per year when flying into wind turbines. The booted eagle has an extremely large range and does not approach the threshold for vulnerable under its range size or population size criterion. It is listed as least concern by IUCN.

Recommended conservation measures include better maintenance and protection of large areas with a mixture of open habitats and mature forests. Prohibiting deforestation or any habitat fragmentation or human activity during the breeding season as well as education and measures to halt destruction of nest habitat. There should be better conservation and enforcement of illegal hunting of booted eagles and their prey species. Modifying the design of power lines could reduce electrocution mortality. Further research should be done on the bird in order to better understand the negative impacts on it. (Carlon, 1996; López-López, et al., 2016; Orta, et al., 2018)

Contributors

Kevin Pennala (author), Northern Michigan University, Alec Lindsay (editor), Northern Michigan University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

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

agricultural

living in landscapes dominated by human agriculture.

arboreal

Referring to an animal that lives in trees; tree-climbing.

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

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.

female parental care

parental care is carried out by females

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).

keystone species

a species whose presence or absence strongly affects populations of other species in that area such that the extirpation of the keystone species in an area will result in the ultimate extirpation of many more species in that area (Example: sea otter).

male parental care

parental care is carried out by males

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.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

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

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

oviparous

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

scrub forest

scrub forests develop in areas that experience dry seasons.

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

suburban

living in residential areas on the outskirts of large cities or towns.

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.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

visual

uses sight to communicate

References

"Booted Eagle - Aquila pennata" (On-line). The Eagle Directory. Accessed April 25, 2018 at http://www.eagledirectory.org/species/booted_eagle.html.

Baghino, L., G. Premuda, M. Gustin, A. Corso, U. Mellone, C. Cardelli. 2007. Exceptional wintering and spring migration of the Booted Eagle Hieraaetus pennatus in Italy in 2004 and 2005. Avocetta, 31: 47-52.

Bosch, J., J. Calvo, A. Bermejo, J. Puente. 2016. Factors influencing the movements during the breeding season of a female booted eagle (Aquila pennata) tagged by satellite in central Catalonia (Spain). Slovak Raptor Journal, 10/1: 81-94.

Carlon, J. 1996. Response of booted eagles to human disturbance. British Birds, 89: 267-274.

Casado, E., S. Suárez-Seoane, J. Lamelin, M. Ferrer. 2008. The regulation of brood reduction in Booted Eagles Hieraaetus pennatus through habitat heterogeneity. International journal of avian science, 150/4: 788-798.

Chevallier, D., F. Jiguet, T. Nore, F. Baillon, P. Cavallin. 2010. Satellite tracking of a Booted Eagle (Aquila pennata) during migration. Ringing and Migration, 25/1: 62-64.

Jiménez-Franco, M., J. Martínez, J. Calvo. 2011. Territorial occupancy dynamics in a forest raptor community. Oecologia, 166/2: 507/516.

Jiménez-Franco, M., J. Martínez, I. Pagán, J. Calvo. 2013. Factors determining territory fidelity in a migratory forest raptor, the Booted Eagle Hieraaetus pennatus. Journal of Ornithology, 154/1: 311-318.

López-López, P., J. Puente, U. Mellone, A. Bermejo, V. Urios. 2016. Spatial ecology and habitat use of adult Booted Eagles (Aquila pennata) during the breeding season: implications for conservation. Journal of Ornithology, 157/4: 981-993.

Martínez, J., J. Calvo, M. Jiménez-Franco, I. Zuberogoitia, P. López-López. 2016. Colour morph does not predict brood size in the Booted Eagle. Ornis Fennica; Helsinki, 93/2: 130-136.

Martínez, J., I. Pagán, J. Calvo. 2006. Interannual variations of reproductive parameters in a booted eagle (Hieraaetus pennatus) population: The influence of density and laying date. Journal of Ornithology, 147/4: 612-617.

Martínez, J., I. Pagán, J. Palazón, J. Calvo. 2006. Habitat use of booted eagles (Hieraaetus pennatus) in a Special Protection Area: Implications for conservation. Biodiversity and Conservation in Europe, 16/12: 3481-3488.

Mellone, U., J. Puente, P. López-López, R. Limiñana, A. Bermejo, V. Urios. 2013. Migration routes and wintering areas of Booted Eagles Aquila pennata breeding in Spain. Bird Study, 60/3: 409-413.

Orta, J., P. Boesman, J. Marks. 2018. "Booted Eagle" (On-line). Handbook of the Birds of the World Alive. Accessed February 20, 2018 at https://www.hbw.com/species/booted-eagle-hieraaetus-pennatus.

Rouco, C., J. Vinuela. 2009. Booted Eagle (Hieraaetus pennatus) Wetting More than its Boots While Catching a Eurasian Coot (Fulica atra). Journal of Raptor Research, 43/3: 257-258. Accessed March 21, 2018 at http://www.bioone.org/doi/full/10.3356/JRR-08-109.1.

Spaar, R. 2008. Flight strategies of migrating raptors; a comparative study of interspecific variation in flight characteristics. International Journal of Avian Science, 39/3: 523-535. Accessed March 21, 2018 at https://onlinelibrary-wiley-com.nmu.idm.oclc.org/doi/epdf/10.1111/j.1474-919X.1997.tb04669.x.

Suarez, S., J. Balbontin, M. Ferrer. 2000. Nesting habitat selection by booted eagles Hieraaetus pennatus and implications for management. Journal of Applied Ecology, 37/2: 215-223.

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