About Hieraaetus wahlbergi (Sundevall, 1850)
Wahlberg's eagle, scientifically named Hieraaetus wahlbergi (Sundevall, 1850), is a medium-sized raptor with similar appearance between males and females. It measures 53–61 cm (21–24 in) in body length and has a wingspan of 130–146 cm (51–57 in). On average, males have a body mass of 437–845 g (15.4–29.8 oz), while females average 670–1,400 g (24–49 oz). It has a small crest on its head and yellow legs. Its plumage varies in tone, but is most often dark brown, except for the undersides of the flight feathers, which are grey with dark streaks, and the undertail, which is grey with barring. Both light and dark plumage phases exist. A pale variant may be much lighter brown with whitish undertail and flight feather undersides instead of grey, and this pale variant is far less common than the darker morph.
Wahlberg's eagle ranges from central Chad to the northeast coast of South Africa. Its western range boundary is considered to be Cameroon, though it is most abundant in areas further east across the African continent. Across this broad range, it typically occurs at altitudes between sea level and 1,800 m (5,900 ft), but has also been recorded at 2,800 m (9,200 ft) in Ethiopia. This species can travel large distances over short time periods. In 1994, a female Wahlberg's eagle was tracked over nine months, during which it traveled more than 8,800 km (5,500 mi) on a round trip from northern Namibia to Chad. Its distance between southern breeding grounds and northern non-breeding areas was 3,520 km (2,190 mi), and it traveled more than 700 km (430 mi) directly north in just five days after leaving its breeding site.
Wahlberg's eagle mainly hunts birds, including other raptors such as the Gabar goshawk and barn owl. It also feeds on reptiles including various lizards and snakes, and a small number of small mammals including tree squirrels, mongooses, and hares. It has also been documented eating a variety of invertebrates such as termites, grasshoppers, and beetles.
Most Wahlberg's eagles breed in southern Africa between October and February. The species builds a stick nest placed in a tree fork or the crown of a palm tree. It is monogamous and forms long-term pair bonds. The eagles are well known for their complex, spectacular aerial courtship displays. They are highly territorial and nest solitarily. The same pair often reuses the same nest across multiple years. Their breeding season falls during the wet season in northern South Africa (October to February), when food is more easily accessible. The female feeds the chicks using prey caught and provided by the male. Reductions in reproductive output were observed in the 1990s, which were linked to increased population density of Wahlberg's eagle; breeding success is strongly density-dependent, and resource availability was not found to play a role in this trend.
