Little Eagle Hieraaetus morphnoides Scientific name definitions

The Little Eagle occurs throughout most of continental Australia, to which it is endemic now that the closely related Pygmy Eagle (Hieraaetus weiskei) (of New Guinea and the Moluccas) is classified as a separate species. It breeds throughout much of its mainland range, to an elevational limit of ~1,300 m. Individuals breeding at higher elevations (800 m) in temperate southeastern Australia migrate up to 3,000 km to winter in tropical northern Australia before returning to their breeding territories. During post-natal dispersal, first-year birds can also disperse or migrate across the continent, and some of these may return to their natal region. Others in climatically milder areas may be resident or move locally or regionally to winter in coastal or lowland areas. The Little Eagle inhabits most treed habitats and climatic zones and builds stick nests in mature woodland or forest trees. It avoids only the most rugged and densely or continuously forested areas, where the much larger and dominant Wedge-tailed Eagle (Aquila audax) can occur, and it is scarce or absent in the most arid treeless regions. It seems to be most abundant in areas of varied terrain and tree cover in southeastern Australia.

As its name implies, it is a small eagle (male ~600 g, female ~1 kg), which is generally inconspicuous apart from its loud calls; often given when the bird is so high above the ground as to be nearly invisible. Its main interactions with humans relate to displacement of breeding pairs by expanding urban sprawl, accidental mortality and injury from collisions with vehicles, and less frequently, barbed-wired fences or windfarm turbines, as well as accidental poisoning and trapping aimed at introduced carnivores. It lacks a prominent cultural history and is seldom persecuted.

The Little Eagle is a powerful predator of a range of vertebrates: mammals, birds, and reptiles in varying proportions according to locality and climatic zone. Prey size ranges up to rabbits and juvenile hares, birds up to duck and crow size, and reptiles including large skinks and small monitor lizards. Agile prey can be taken in a fast, falcon-like vertical or angled dive to the tree canopy, ground, or even in the air. Carrion is seldom taken, and when it is, it is typically fresh road-killed rabbits or hares. Insects, typically large volant species such as grasshoppers, are occasionally taken by dependent juveniles honing their hunting skills.

The age at which it establishes territory is unknown; partially because the redder hues of juvenile plumage quickly fade, and it starts to acquire adult-like plumage with its first post-juvenile molt towards the end of its first year. Home-range size is 40–80 km² for breeding males in the southeastern temperate zone, and 30 km² for a wintering adult male in the tropics. Breeding pairs maintain and repair one or sometimes two nests annually at the start of the breeding season before settling on one and may alternate between nests in different years.

In temperate and arid zones, the Little Eagle starts nestbuilding in late winter, and the breeding cycle from egg-laying in early spring to fledging in early summer occupies ca. 3 months, with the post-fledging dependence period extending the whole cycle to five or six months. Early mishaps and repeat laying can extend fledging to late summer. Successful pairs raise one or rarely two young per year; some rearing many more in their lifetimes if they are successful for several years running. Breeding productivity appears to depend on food supply and weather. Some pairs do not breed in all years, and forego laying or fail, especially in years of severe drought. In the tropics, the laying season occupies the dry season, extending from the austral autumn to early spring.

Most studies of the Little Eagle have been conducted in temperate southeastern Australia, with few in the arid zone and tropics. Gaps in knowledge include dispersal routes and destinations of juveniles, age at first breeding, population-level impact of agricultural chemicals (e.g., poison baits), biology of pre-breeding and nonbreeding individuals, and ecological studies in regions where the species is unstudied (e.g., southwestern Australia).