Bateleur (Terathopius ecaudatus) Fact Sheet: Behavior & Ecology

Diurnal

• Active in daylight
• Spend as much as 80% of daylight hours in flight (Kemp et al. 2013)

Home range

• Resident pairs hold large ranges (from Ferguson-Lees and Christie 2001)
• Some adults and immatures are nomadic
• Home range size
• c. 40 km², Kruger National Park (KNP) (Ferguson-Lees and Christie 2001)
• Juveniles and Subadults range more widely (from Snelling 1969)
• One individual in KNP ranged > 525 mi² (>845 km²)

Often solitary (from Ferguson-Lees and Christie 2001)

• Most often alone
• Exceptions
• Mated pairs raise young together
• Young eaglets may remain with parents for some time after fledging
• Immatures may congregate in rich feeding areas

Aggression (from Watson 1989)

• Juveniles rarely aggressive
• Common during reproductive periods
• Adult aggression most intense during egg incubation
• Adult aggression toward juveniles higher during reproduction
• Agonism between adults is consistent throughout the year
• Male and female adults exhibit similar patterns of aggression
• Agonism between adults tends to occur between individuals of the same sex
• “Attack” display
• In flight, aggressor dives toward opponent with talons extended forward
• Attacker comes within contact distance of its adversary

Affiliative behaviors

• Allopreening (from Watson 1990b)
• Breeding partners preen one another
• Frequency of behavior peaks prior to egg laying
• Greeting ceremony (from Moreau 1945)
• A “formal bow”
• Body dips forward with wings raised
• Bill drops to the feet
• Vocal “haow” often accompanies this behavior
• Click here to see this behavior (begins at 00:48 of "Overview" ARKive video)

Territorial (from Watson 1989)

• Maintain territory throughout the year
• Possible reasons for territoriality
• To ensure sufficient food resources
• To secure exclusive mating access
• To ensure protection of the nest-site and offspring
• Aggressive when breeding
• Behavior targets adults and juveniles of the same species
• Typically induce the intruder to gain altitude and fly off
• Description of aggressive, “attack” display below

Vocalizations

• Generally silent (from Kemp et al. 2013)
• Adults vocalize when anxious or aggressive
• Call when perched or in flight
• Basic adult calls (from Brown 1955 unless otherwise noted)
• “kah-kah-kah” “kau… kroh” or “ka-ow… ka-ow” (Brown 1955; Moreau 1945)
• May be accompanied by jerking the body up and down with the wings half-spread
• Often with head thrown back (Ferguson-Lees and Christie 2001)
• Given by nesting birds when disturbed
• A deep and powerful barking sound (Moreau 1945)
• “shaaaaa-aw” (Kemp et al. 2013)
• Hatchling vocalizations (from Brown 1955)
• “twip”
• Unlike any adult call
• Described as a “melodious” sound
• Often uttered continually by young eaglets
• “kyup-kyup-kyaw-kee-aw-kee-aw…” and “whup-whip-whew-whew-whew-wheeep”
• A high-pitched, squalling greeting
• Given by older eaglets
• Typically in response to the presence of a parent near the nest
• Audio clips
• Click here for brief clips of Bateleur calls from the Cornell Lab of Ornithology Macaulay Library

Terrestrial prey (from Kemp et al. 2013 unless otherwise noted)

• Search for prey
• Low, gliding back and forth
• c. 50 m above the ground
• Descend in a tight spiral, most often
• May plummet at great speed to catch prey (Johnston 1902; Moreau 1945)

Predators

• Potential predators (from Watson 1990b unless otherwise noted)
• Terrestrial threats
• Baboons, genets, African wildcats, and Tree Monitor
• Avian threats
• Other eagles, Giant Eagle Owl, and Ground Hornbills

Raptor competitors (from Smeenk 1974 unless otherwise noted)

• Tawny Eagles consume similar prey (Smeenk 1974; Steyn 1980)
• Dietary overlap c. 66% of species taken; c. 78% by percentage weight
• Tawny Eagles appear to dominate most interactions (Steyn 1980)
• Immature Bateleurs often lose disputes over carrion
• Martial and African Hawk Eagles
• Dietary intake overlaps much less than that of the Tawny Eagle
• Diet more specialized than that of the Bateleur

Kleptoparasitism

• Bateleurs steal food from other predators

Nest sharing and take over

• Lanner Falcon (Falco biarmicus) (from Steyn 1980)
• Species makes use of abandoned Bateleur nests
• Lanner falcons are known to harass Bateleur fledglings and take over nests as soon as the young first take flight
• Verreaux’s (Giant) Eagle Owl (Bubo lacteus)
• Species makes use of abandoned Bateleur nests (Brown 1965)
• Wahlberg’s Eagle (Aquila wahlbergi)
• Bateleurs known to use abandoned nests of this species (Brown 1955)
• Often without completing much nest-repair

Symbiotic relationships

• Reports of association with humans (from Dean and MacDonald 1981)
• Observations of Bateleurs following safaris
• A single published report of this behavior; significance unclear, possibly to catch animals flushed out by human disturbance

Areal flight

• Strong and acrobatic in the air (from Brown 1955 unless otherwise noted)
• Soar
• Wings held straight in a deep V (Ferguson-Lees and Christie 2001)
• Glide with great speed
• Wings outstretched with wing tips pointed upward (Moreau 1945)
• Fly low in search of food (Watson and Watson 1985)
• Generally within 70 m (230 ft) (Watson and Watson 1985)
• Long, persistent flights, the wings barely moving (Smeenk 1974)
• The head points downward and is constantly moving (Smeenk 1974)
• Spin and tumble rapidly in the air
• Roll sideways with the wings near fully extended
• May complete several turns in less than 1 second
• Bodily movements (from Moreau 1945)
• Swivel body and wings, all in one piece, from side to side
• Adjustments unlike those of other eagles and hawks which use the tail to maneuver
• Heavily flap the wings with a strong down-beat
• Wing flapping infrequent (Steyn 1965)
• Take off from ground (from Ferguson-Lees and Christie 2001)
• Rapid wing beats

Terrestrial movements

• Walk

In addition to being acrobatic fliers, Bateleurs are often seen walking and performing a "greeting ceremony" on the ground.

Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved. (Note: This is a cropped image.)

Brown (1955)
Brown (1965)
Dean and MacDonald (1981)
Ferguson-Lees and Christie (2001)
Johnston (1902)
Kemp et al. (2013)
Moreau (1945)
Smeenk (1974)
Snelling (1969)
Steyn (1965)
Steyn (1980)
Watson (1989)
Watson (1990b)
Watson and Watson (1985)