Changeable Hawk-Eagle

The Changeable Hawk-Eagle, scientifically known as Nisaetus cirrhatus, is a large bird of prey belonging to the family Accipitridae. This raptor is characterized by its slender build and a notable crest of feathers that can vary in presence and size among individuals. The species exhibits a wide range of plumage variation, from pale to dark, which changes with age and moult, hence the name "changeable."

Identification Tips

Adult Changeable Hawk-Eagles are typically dark brown above with bold streaking below. They possess a strong bill and a crest that can be prominent or nearly absent. Their wings are relatively short, and their tail is long and thinly barred. Juveniles are generally darker with more conspicuous white edges on the mantle and wings. The eyes of adults are yellow to orange-yellow, while juveniles have grey-brown to pale greenish eyes.

Habitat

This species is found in a variety of habitats, including savannah woodland, forest villages, and even suburban areas. They are also present in open or less dense parts of evergreen or deciduous forests, as well as second growth and wetlands.

Distribution

The Changeable Hawk-Eagle is widely distributed across the Indian subcontinent and Southeast Asia, including Sri Lanka, the Himalayan foothills, and various islands such as Sumatra, Java, Borneo, and the Philippines.

Behaviour

Changeable Hawk-Eagles are known for their agile flight, which includes powerful shallow beats interspersed with glides. They are primarily ambush predators, using concealing foliage to still-hunt from hidden branches, pouncing quickly to capture prey on the ground.

Song & Calls

During the breeding season, the Changeable Hawk-Eagle may call frequently, emitting a high-pitched scream that varies in pattern depending on the region. Calls can range from a shrill ringing "yeep-yip-yip-yip" to a penetrating "klee-leeuw."

Breeding

Breeding season varies by region, with nests built in large trees and lined with green leaves. The species typically lays a single egg, which is incubated by the female for an estimated 40 days. Nestlings are brooded intensively for about 25 days and fledge at around 60-68 days of age.

Similar Species

The Changeable Hawk-Eagle can be confused with other Nisaetus species, but it is distinguished by its more slender wings, straighter trailing edges, and unique tail patterns. Juveniles may be more difficult to distinguish but tend to show more white than other species.

Diet and Feeding

The diet of the Changeable Hawk-Eagle is varied and includes birds, mammals, reptiles, and other vertebrates. They are opportunistic hunters and may take prey ranging from small lizards to large mammals and birds.

Conservation Status

The Changeable Hawk-Eagle is classified as Least Concern by the IUCN. It has shown remarkable resilience in the face of habitat degradation and deforestation, maintaining stable or even increasing populations in many parts of its range. However, complete deforestation remains a significant threat to the species.