Golden Eagle (Aquila chrysaetos) Fact Sheet: Behavior & Ecology

General (Kochert et al. 2002)

• Well-studied in some protected areas of Idaho
  • Less well-studied are Alaskan and western Canada's golden eagles
• Populations are made up of juveniles, subadults, floaters, and breeders
  • Floaters have no territory but are important as replacements for birds without mates
  • Floaters not easily counted by biologists
• Although largely solitary except for breeders, degree of social behavior varies:
  • May bathe in groups
  • In very cold weather, may roost communally
  • Immatures often associate with each other in winter
  • Fledgling pairs may preen each other
• Play behavior observed on occasion: (Palmer 1988)
  • Carrying, dropping and re-catching sticks
  • Playing with stones
  • Chasing colts and calves
  • Young may play dive each other

Activity Cycle (Kochert et al. 2002)

• Diurnal
• Males perched 78% of day, females 85 %
• In nesting pairs, male and female activities differed (Collopy & Edwards 1989)
  • Males incubated eggs 14% of day, provisioned the female and nestlings and brought nest materials
  • Females incubated eggs 83 % of day, arranged nest materials, incubated, brooded, fed young
  • Females spent less time on nest and more time hunting as chicks grew older

Territory/Range Size

• Densities of breeding pairs in 9 separate studies: 41-251 sq km per pair (16-97 sq mi per pair). (Phillips et al. 1984)
• Breeding pairs in highest densities in North America: Snake River canyon, Idaho: one pair per 5-8 km (3-5 mi) (Beecham & Kochert 1975)
  • Territory size 1,161 ha (2,869 acre) to 4,898 ha (12,103 acre) (Collopy & Edwards 1989)
  • Territory size reported from California studies - 9,324 ha (23,040 acres); in Utah 2,300 ha (5,683 acres) (Collopy & Edwards 1989)

Aggression

• Physical contact between territorial birds uncommon. (Kochert et al. 2002)
• Most aggressive interactions are prior to egg laying (Watson 1997)
• Young may make mock attack on parents; parents may make mock attacks on recently fledged young
• Territorial adults dive steeply towards intruders, then chase (Bergo 1987)
• Two birds only rarely lock talons in aggressive encounters (Ellis 1979)
• Golden eagles are much more aggressive than bald eagles (Garcelon & Bogue 1977)

Territorial Behavior

•  Aerial activities: (Bergo 1987)
  • Undulating flight displays seems to occur at edge of territory, or when encountering other territorial eagles (Collopy & Edwards 1989)
  • Soaring and "hanging on the wind"

• Golden eagles raised at latitudes greater than 60° N are usually migratory (MyIntyre et al. 2008)
  • Golden eagles from lower latitudes in North America do not make long-distance migration; tend to move more locally (MyIntyre 2008)
• Migrate south in winter from northernmost part of North America and Asia
  • From subarctic North America go to southwestern U.S. desert regions (Watson 1997)
  • Birds hatched in Denali National Park Alaska traveled 818-4,815 km (508-2,992 mi) to winter across western North America (McIntyre et al. 2008)
  • Birds hatched in Hudson Bay area of Canada travel long distances to eastern U.S.
  • Often use soaring-gliding flight during migration, rather than powered flight (McIntyre et al. 2008)
• In dry southwestern U.S., move to high elevations once they have bred. (Palmer 1988)

Displays

• Undulating flight or "sky dancing" seen in winter and early spring (Watson 1997)
  • Interpreted as a territorial display  

Vocalizations (Kochert et al. 2002)

• Used for communication, not as song or to mark territory
• Vocalizations limited
• Food begging calls are ones most commonly heard
  • Nestlings begin chirping 2 days before hatching
  • Other reasons for young to call: temperature stress, aggression, parent comes into view
• A series of repeated "yelping" notes uttered when carrying prey near the nest (Johnsgard 1990) 
• Ellis (1979) noted 9 distinct calls in western Montana Golden Eagles
  • Chirp
  • Seeir
  • Pssa
  • Skonk
  • Rattle-chirp or cluck
  • Wonk
  • Wip
  • Honk
  • Hiss
• Typical voice: See Cornell Lab's All About Birds: http://www.allaboutbirds.org/guide/Golden_Eagle/sounds

Terrestrial locomotion

• Walk awkwardly
  • Walks to carrion
  • Walks uphill to gain elevation when too heavy with a full crop
  • Newly hatched eaglets crawl using wings and legs (Ellis 1979)
  • Walk backwards before defecating
  • May wait on ground for rodent to emerge from burrow, then fly if necessary (Palmer 1988)
• Hop- jump by crouching with legs bent, body nearly horizontal:
  • Eaglet pouncing to foot-stab a practice prey
  • Eaglet bounding across nest
  • Eaglet jumping into flight
• May flap and run on ground in attempts to catch prey missed in air
• Can swim, if necessary (Ellis 1979)
  
  • Nestlings observed paddling with wings when frightened into water
  • Also observed swimming using wings and feet
  
  
  

Flight

• Wing and tail held in one plane when soaring
• Primary tips may be spread
• Slow gliding and parachuting (with wings and tail up, legs dangling)
• Fast gliding - up to 190 km/hr (118 mph)
• Flapping flight less common than gliding
• Dives with wings tightly closed, legs up against tail - 240-320 km/h (149-199 mph)
• Flap/hold: eaglet flaps wings while grasping nest with feet
  • Strengthens wings
  • Develops coordination
  • Allows bird to feel wind forces

• Out-compete Peregrine Falcons for suitable nest sites on cliffs in Britain (Newton 1979) 
• Avoid trespassing in Bald Eagle territories but may be seen together roosting in winter at communal roosts (Palmer 1988).
  • Occasionally feed together with Bald Eagles at carrion
• In Spain, Golden Eagles and Bonelli's Eagles (Hieraaetus fasciatus) are able to co-exist when certain conditions met: (Moreno-Rueda et al. 2009)
  • Human population densities are low
  • Temperatures are not severe
  • Prey is abundant
• Wolverines (with their good climbing skills) prey on eagle nestlings (Petersen et al. 1991)
• By eating rabbits and rodents, eagles enhance forage for livestock (Matchett et al. 1991)
• Crows, jays and other raptors harass golden eagles (Palmer 1988)
  • If contact occurs, attacking birds may be injured or killed. (Walker 1983)
  • Grizzly bears (Ursos arctos) ate nestlings in Denali National Park (Kochert et al. 2002)
• Usually dominant to California Condors
• Golden eagles inhabited the Channel Islands of California beginning in 1990's: (Roemer et al. 2001, 2002, 2003) (Coonan et al. 2005)
  • Responsible (along with possible introduced canine diseases) for significant declines in critically endangered island foxes (Urocyon littoralis)
  • Possible reasons eagles colonized islands:
    • Decline of bald eagles
    • Presence of feral pigs
    • Presence of foxes
    • Carrion of feral goats, deer, sheep
  • Attempts by managers to save foxes from extinction involve relocating eagles and eradicating feral pigs
  • 37 Golden Eagles removed by August 2004; a few remained

A golden eagle balances on one foot, atop a boulder in San Diego, California.

Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.

(Beecham & Kochert 1975)
(Bergo 1987)
(Collopy & Edwards 1989)
(Ellis 1979)
(Johnsgard 1990) 
(Kochert et al. 2002)
(MyIntyre et al. 2008)
(Palmer 1988)
(Phillips et al. 1984)
(Watson 1997)