Bateleur (Terathopius ecaudatus) Fact Sheet: Physical Characteristics

Body measurements

Measurements from Ferguson-Lees and Christie (2001); Smeenk (1974).

Body shape (from Ferguson-Lees and Christie 2001 unless otherwise noted)

• A medium-sized snake-eagle
• Tail
• Very short (Moreau 1945)
• Feathers completely concealed by the folded wings when perched (Johnston 1902)
• Legs and feet stick out beyond the tail when in flight; adults only (Brown and Cade 1972; Smeenk 1974)
• Wings
• General shape
• Long, bow-shaped
• Pinched at bases
• Broad across the secondaries
• Tips relatively narrow, pointed, and upturned
• Primary feathers
• Long and pointed (from Moreau 1945)
• Secondary feathers
• Numerous; c. 25 secondary feathers
• More than most other birds of prey
• Legs
• Bright red (Moreau 1945)

Facial characteristics (from Ferguson-Lees and Christie 2001 unless otherwise noted)

• Head
• Large cowl of feathers
• Bill
• Tricolored appearance, in adults
• Tip black with yellow center
• Bright red skin exposed at base of bill (Moreau 1945)
• Juvenile bill primarily pale gray-blue
• Eyes
• Brown in all ages

Adult plumage

• White, chestnut, gray, and black
• Body color
• Two color phases with varying colors on the back (from Moreau 1945 unless otherwise noted)
• Back chestnut or creamy white
• Chestnut coloration more common; c. 7% of adults with cream-colored backs (Kemp et al. 2013)
• Cream color morph possibly more common in drier regions (Kemp et a. 2013)
• Wings
• Ventral view (from Kemp et al. 2013)
• Mostly white from below
• Black trailing edge
• Dorsal view
• Appearance of males and female dissimilar
• Refer to descriptions of sexual dimorphism below

Juvenile plumage (from Brown and Cade 1972 unless otherwise noted)

• Body
• Light, straw brown
• Gray-brown on the back
• Feathers soft and dull in texture
• Wings
• More rounded than in adults
• Entire wing dark from below
• Tail
• Longer than in adults
• In flight, the tip projects beyond the feet
• Extending c. 55 mm (c. 2.2 in) beyond the feet
• Rounded
• Becoming more squared-off with age
• Facial skin and legs
• Blue-green (Kemp et al. 2013)
• Turning orange before assuming scarlet color of the adult (Kemp et al. 2013)
• Molt
• Timing of molts variable
• First molt occurring after 1 year of age
• Tail feathers becoming shorter with each consecutive molt

Dimorphic in appearance (from Kemp et al. 2013 unless otherwise noted)

• Wings of sexes dissimilar in adults
• Sexes separable when perched or in flight
• Sexes become easily apparent at c. 4-5 years of age (Brown and Cade 1972)
• Dorsal view
• Female with grayish-white secondary feathers
• Wing appears banded, black feathers separate the grayish-white secondaries from similarly colored feathers at the shoulder
• Primaries black
• Male with mostly black secondary feathers
• Grayish-white feathers confined to the shoulder area
• Ventral view
• Black band on the trailing edge of wing broader and more irregular in males when viewed from below (Brown 1955; Brown and Cade 1972)
• Female c. 6% larger than male (Ferguson-Lees and Christie 2001)

Chromosome number

• 33 pairs of chromosomes (2n=66) (Bed’Hom et al. 1998)

 Features of age and sex classes (from Brown and Cade 1972)

Plumages of a juvenile (left) and an adult (right) Bateleur.

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

Bed’Hom et al. (1998)
Brown (1955)
Brown and Cade (1972)
Ferguson-Lees and Christie (2001)
Johnston (1902)
Kemp et al. (2013)
Moreau (1945)
Smeenk (1974)