an annual breeder. The length of incubation is unknown but is likely between 40 and 45 days. During the 'branching period', the nestling typically spends most of the day off the nest, periodically half-jumping and half-flying from one branch of the nest tree to another. Fledging age is reached between 70 and 100 days and the total time between nest initiation and independence of the juvenile is close to 260 days, which is similar to other booted eagles. When the stomach contents of collected specimens have been examined they have been found to contain the remains of birds and tree squirrels, although it is possible that other vertebrates are eaten too. Soaring above the forest canopy, Cassin's hawk-eagles are able to spot their prey from the air before commencing the attack. Mimicry Cassin's hawk-eagle is a proposed partner in a visual mimicry system where it is the model to the Congo serpent eagle (Circaetus spectabilis) mimic. This is one of two similar independent systems involving serpent eagles – the other being between the Madagascar serpent eagle (Eutriorchis astur) and Henst's goshawk (Accipiter henstii) on the island of Madagascar. These proposed mimicry systems are unusual in that they involve two predatory species that show remarkable similarity in plumage colour and pattern as well as in body size and proportions. A. africana and C. spectabilis differ greatly in diet though, with the former preying on forest birds and tree squirrels and the latter predominantly on reptiles like snakes. The visual mimicry, if true, is thought to have evolved due to a foraging advantage gained by the serpent eagle, since its prey do not flee from the bird-eating model, and/or lowered predation risk from the model or other predators towards the mimic, and/or reduced mobbing by small birds. However, random convergence due to the constrained evolution of plumage colours and patterns within a shared habitat, cannot be ruled out. Conservation status Cassin's hawk-eagle is currently categorised as Least Concern by BirdLife International and the IUCN. Despite a decreasing population, estimated at 1,000-10,000 individuals, Cassin's hawk-eagles has a large geographic range and its population decline is not severe enough for it to be given Vulnerable status as a species. Due to its reliance on primary tropical forest and the varying rates of destruction of this habitat across Africa, the Cassin's hawk-eagle is regionally threatened and in dire need of population studies to accurately establish