Golden Eagle
Aquila chrysaetos
Summary 7
The Golden Eagle (Aquila chrysaetos) is one of the best-known birds of prey in the Northern Hemisphere. It is the most widely distributed species of eagle. Like all eagles, it belongs to the family Accipitridae. These birds are dark brown, with lighter golden-brown plumage on their napes. Immature eagles of this species typically have white on the tail and often have white markings on the wings. Golden Eagles use their agility and speed combined with extremely...
Description 8
Longueur 75-88 cm, envergure 2,05-2,20 m, poids moyen 2,8-4,6 kg pour le mâle, 3,8-6,7 kg pour la femelle.
Il vit dans les grands espaces ouverts, parfois les zones humides mais le plus souvent les zones montagneuses, loin des activités humaines. L’absence de spécialisation alimentaire (et de forte compétition interspécifique) et sa capacité à chasser sur de grandes distances lui permettent de survivre même avec une densité et une biomasse de proies relativement faibles.
L’Aigle royal se nourrit principalement de mammifères et d’oiseaux vivants ou morts, parfois aussi de reptiles et même de poissons et d’insectes. Il chasse habituellement d’un vol bas, parcourant méthodiquement le terrain et capturant ses proies par surprise. La plupart sont prises au sol mais un oiseau dérangé, un Lagopède par exemple, peut être poursuivi sur quelque distance. L’éventail de proies est très large : les mammifères vont du petit rongeur jusqu’aux Cervidés, tandis que les oiseaux vont de l’Alouette jusqu’à l’Oie ou la Grue. Ses préférences vont toutefois vers les animaux pesant entre 0,5 et 2 kg. Les proies les plus grosses ne sont consommées qu’à l’état de cadavre ou si elles sont affaiblies, et sont notamment attaquées par des individus spécialisés ou inexpérimentés. Il arrive que le couple chasse de concert, le premier oiseau pouvant ainsi disperser les groupes familiaux d’Ongulés et le second, suivant à une centaine de mètres, se concentrant alors sur un jeune isolé.
Les jeunes aigles se dispersent parfois sur de grandes distances, mais les adultes restent sur leur territoire. Même en hiver, ils gardent le contact avec leur site de nid, à moins que la famine ou les conditions météorologiques ne les forcent à s’éloigner. Les oiseaux solitaires, jeunes ou adultes, sont généralement erratiques mais certains s’établissent sur un territoire, parfois même inclus dans celui d’un couple nicheur. L’Aigle royal est monogame et les couples sont fidèles. Ils sont territoriaux et les aires des différents couples sont largement séparées (au moins 4 km et en général 10 à 20 km). Les parades aériennes sont peu fréquentes ; elles comprennent des plongées vertigineuses depuis de grandes hauteurs, suivies de remontées en chandelle.
La ponte de 1 à 3 œufs est déposée à partir de février-mars. L’aire est construite sur une paroi rocheuse ou un arbre. C’est un énorme assemblage de branchettes, couvert d’herbes, de laine et de feuillage. Les plus gros atteignent plusieurs mètres d’épaisseur. L’incubation dure 43-45 jours et les jeunes s’envolent à l’âge de 65-80 jours. En général, seul le 1er aiglon éclos survit, car il cause la mort des autres jeunes, plus petits. Il est chassé par ses parents entre septembre et novembre.
Distribution 9
Golden eagles (Aquila chrysaetos) have a Holarctic distribution. They occur throughout Eurasia, in northern Africa, and in North America. In North America, golden eagles are found in the western half of the continent, from Alaska to central Mexico, with small numbers in eastern Canada and scattered pairs in the eastern United States.
Biogeographic Regions: nearctic (Native ); palearctic (Native ); ethiopian (Native )
Other Geographic Terms: holarctic
Morphology 10
Golden eagles are North America's largest predatory bird. They are dark brown raptors with long, broad wings. Their length ranges from 70 to 84 cm, and their wingspan ranges from 185 to 220 cm. Males and females are similar in appearance, but females are much larger than males. Female weight ranges from 3940 to 6125 g whereas male weight ranges from 3000 to 4475 g. Adults are largely dark brown, except for a golden area near the crown, nape and sides of the neck and face. The tail is grayish brown. From below, the large flight feathers of the wings appear to be brownish gray, while the head, body and smaller feathers on the forepart of the open wings are blackish. The eyes of adults are dark brown. The bills and claws are black, while the cere and feet are yellow. The legs are feathered all the way down to the toes.
Juvenile golden eagles appear similar to adults, except for light patches on the tips of the wings, and a wide white band on the tail and a terminal band of black. This plumage is sometimes referred to as its "ringtail" plumage as a result of these bands. Juveniles attain adult plumage between ages 4 and 6 years.
There are 5 or 6 recognized subspecies of the golden eagle. These subspecies are differentiated by geographic distribution, size and coloration. Only one subspecies, Aquila chrysaetos canadensis is found in North America.
Range mass: 3000 to 6125 g.
Range length: 70 to 84 cm.
Range wingspan: 185 to 220 cm.
Other Physical Features: endothermic ; bilateral symmetry ; polymorphic
Sexual Dimorphism: female larger
Average basal metabolic rate: 4.9929 W.
Diagnostic description 11
This species differs from the bald eagle in lacking a white head in adults and in lacking white spotting on the underwing coverts in immatures.
Sierra madre occidental pine oak forests habitat 12
This taxon is found in the Sierra Madre Occidental pine-oak forests ecoregion, which boasts some of the richest biodiversity anywhere in North America, and contains about two thirds of the standing timber in Mexico. Twenty-three different species of pine and about 200 species of oak reside within the Sierra Madre Occidental pine-oak forests ecoregion.
Pine-oak forests here typically grow on elevations between approximately 1500 and 3300 meters, and occur as isolated habitat islands in northern areas within the Chihuahuan Desert. Soils are typically deep, where the incline allows soil build-up and derived from igneous material, although metamorphic rocks also form part of the soils in the west and northwest portions of the sierra. Steep-sloped mountains have shaped some portions of the Sierra, while others are dominated by their deep valleys, tall canyons and cliffs. These steep-sided cliffs have thinner soils limiting vegetation to chaparral types; characterized by dense clumps of Mexican Manzanita (Arctostaphylos pungens), Quercus potosina and Netleaf Oak (Q. rugosa). There are also zones of natural pasture, with grasses from the genera Arisitida, Panicum, Bromus and Stevis.
The pine-oak forests gradually transform into an oak-grassland vegetative association. Such communities represent an ecological transition between pine-oak forests and desert grasslands.. Here, species such as Chihuahuan Oak (Quercus chihuahuensis), Shin Oak (Q. grisea), Q. striatula and Emory Oak (Q. emoryi), mark a transition zone between temperate and arid environments, growing in a sparse fashion and with a well-developed herbaceous stratum resembling xeric scrub. Cacti are also part of these transition communities extending well into the woodlands. Some cacti species such as the Little Nipple Cactus (Mammillaria heyderi macdougalii), Greenflower Nipple Cactus (M. viridiflora), Mojave Mound Cactus (Echinocereus triglochidiatus), and Leding's Hedgehog Cactus (E. fendleri var. ledingii) are chiefly centered in these biotic communities. The dominant vegetation in the northernmost part of the ecoregion in the Madrean Sky Islands includes Chihuahua Pine (Pinus leiophylla), Mexican Pinyon (P. cembroides), Arizona Pine (P. arizonica), Silverleaf Oak (Quercus hypoleucoides), Arizona White Oak (Q. arizonica), Emory Oak (Q. emoryi), Netleaf Oak (Q. rugosa), Alligator Juniper (Juniperus deppeana), and Mexican Manzanita (Arctostaphylos pungens).
This ecoregion is an important area for bird richness and bird endemism. Likewise, virtually all of the ecoregion is included in the Sierra Madre Occidental and trans-mexican range Endemic Bird Area. Endemic bird species include the Thick-billed Parrot (Rhynchopsitta pachyrhyncha EN) which is in danger of extinction, with population estimates as low as 500 pairs; the Tufted Jay (Cyanocorax dickeyi NT), Eared Quetzal (Euptilptis neoxenus NT) and the Green-striped Brush Finch (Buarremon virenticeps). Temperate and tropical influences converge in this ecoregion, forming a unique and rich complex of flora and fauna. Many other birds are found in this ecoregion including the Green Parakeet (Aratinga holochlora), Eared Trogon (Euptilotis neoxenus NT), Coppery-tailed Trogon (Trogon elegans), Grey-breasted Jay (Aphelocoma ultramarina), Violet-crowned Hummingbird (Amazilia violiceps), Spotted Owl (Strix occidentalis NT), and Golden Eagle (Aguila chryaetos). Some species found only in higher montane areas are the Gould's Wild Turkey (Meleagris gallopavo mexicana), Band-tailed Pigeon (Patagioenas fasciata), Mexican Chickadee (Poecile sclateri) and Hepatic Tanager (Piranga flava).
The Sierra Madre Mantled Ground Squirrel (Spermophilus madrensis NT) is an endemic to the Sierra Madre Occidental pine-oak forests, restricted to southwestern Chihuahua, Mexico. The Mexican Gray Wolf (Canis lupus baileyi) and Mexican Grizzly Bear (Ursus horribilis), although considered by most to be extinct from this ecoregion, once roamed these mountains. Mammals also present include White-tailed Deer (Odocoileus virginianus), American Black Bear (Ursus americanus), Buller’s Chipmunk (Tamias bulleri), endemic Zacatecan Deer Mouse (Peromyscus difficilis), rock Squirrel (Spernophilis variegatus), Zacatecas Harvest Mouse (Reithrodontomys zacatecae) and Coati (Nasua nasua), to set forth a subset of mammals present.
Reptiles are also numerous in this ecoregion. Fox´s Mountain Meadow Snake (Adelophis foxi) is an endemic taxon to the ecoregion, only observed at the type locality at four kilometers east of Mil Diez, about 3.2 kilometers west of El Salto, in southwestern Durango, Mexico. There are at least six species of rattlesnakes including the Mexican Dusky Rattlesnake (Crotalis triseriatus), Mojave Rattlesnake (C. scutulatus), Rock Rattlesnake (C. lepidus), Western Diamondback Rattlesnake (C. atrox), Twin-spotted Rattlesnake (C. pricei), and Ridgenose Rattlesnakes (C. willardi). Clark's Spiny Lizard (Sceloporus clarkii) and Yarrow's Spiny Lizard (S. jarrovii), Bunchgrass Lizard (S. scalaris), and Striped Plateau Lizard (S. virgatus) are several of the lizards found in the Sierra Madre Occidental pine-oak forests.
Along springs and streams the Western Barking Frog (Craugastor augusti) and the Tarahumara Frog (Rana tamahumarae) are two anuran taxa occurring in the ecoregion. Other anuran taxa found here include: Bigfoot Leopard Frog (Lithobates megapoda), Northwest Mexico Leopard Frog (Lithobates magnaocularis) and the Blunt-toed Chirping Frog (Eleutherodactylus modestus VU). The Sacramento Mountains Salamander (Aneides hardii) is an endemic salamander found in the Sierra Madre Occidental pine-oak forests, restricted to the Sacramento Mountains, Capitan Mountains, and Sierra Blanca in Lincoln and Otero Counties within southern New Mexico, USA.
Migration 13
Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.
Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.
Migratory populations may exist in areas where the species is present throughout the year, so specific migration patterns may be obscure. Northernmost populations withdraw southward for winter (some individuals may remain in north); these migrants may migrate farther south than do birds from breeding populations to the south; migrants return to northern breeding areas mainly in March-April. Most vacate hot deserts during summer.
In predatory bird surveys over 12 months in the eastern Mohave Desert, San Bernardino County, California, Knight et al. (1999) observed golden eagles only during November and December, despite the species being a regular nesting bird in the Mohave Desert. The low number of observations may have reflected a naturally low density of eagles, lack of overlap of survey routes with eagle territories, or seasonal migrations of eagles between summer nesting areas in desert mountains and wintering areas in desert basins (Knight et al. 1999). See Palmer (1988) for discussion of seasonal movements.
A juvenile from Denali National Park, Alaska, migrated through Yukon Territory and interior British Columbia to a wintering site in east-central Idaho; another juvenile migrated through the Yukon, Alberta, and Saskatchewan to northeastern Montana (Britten et al. 1995).
Territory size in several areas of the western United States averaged 57-142 sq km (Palmer 1988). In desert regions, territories may be much larger (e.g., 258-310 sq km; see Wildlife Research Institute 2010).
Sources and Credits
- (c) Jerry Oldenettel, some rights reserved (CC BY-NC-SA), http://www.flickr.com/photos/7457894@N04/3086977792
- (c) d hutcheson, some rights reserved (CC BY-NC), http://farm1.static.flickr.com/148/335129594_c2149f6e32.jpg
- (c) Jerry Oldenettel, some rights reserved (CC BY-NC-SA), http://farm4.static.flickr.com/3211/3086977792_bf82ccbf8e.jpg
- (c) Juan Lacruz, some rights reserved (CC BY), https://upload.wikimedia.org/wikipedia/commons/c/c6/Chrysaetos_La_Ca%C3%B1ada_20120114_1.jpg
- (c) Maggie.Smith, some rights reserved (CC BY-NC), http://farm4.static.flickr.com/3384/3335733823_acd76fe475_o.jpg
- (c) Chuck Abbe, some rights reserved (CC BY), https://upload.wikimedia.org/wikipedia/commons/thumb/6/64/Golden_Eagle_%28Aquila_chrysaetos%29.jpg/460px-Golden_Eagle_%28Aquila_chrysaetos%29.jpg
- (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Aquila_chrysaetos
- (c) Muséum national d'Histoire naturelle. Service du Patrimoine naturel, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/29862151
- (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/31378410
- (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/31378412
- (c) NatureServe, some rights reserved (CC BY-NC), http://eol.org/data_objects/28740302
- (c) World Wildlife Fund & C. Michael Hogan, some rights reserved (CC BY-SA), http://eol.org/data_objects/27361823
- (c) NatureServe, some rights reserved (CC BY-NC), http://eol.org/data_objects/28740304
