This species of Eagle has been observed in every portion of Australia yet visited by Europeans, but is more abundant in New South Wales than in any other part of the continent; I have never yet seen an example from Van Diemen’s Land, and I am consequently led to believe that it rarely if ever visits that island. As might be expected from its almost universal diffusion, the _Haliastur? sphenurus_ is not a migratory bird; at least in New South Wales it is equally as numerous in summer as it is in winter; not that it is to be observed in the same locality at all times, the greater or lesser abundance of its favourite food inducing it to wander from one district to another, wherever the greatest supply is to be procured. Displaying none of the courage or intrepidity of the true Eagles, it never attacks animals of a large size; but preys upon carrion, small and feeble quadrupeds, birds, lizards, insects and fish, and while on the one hand it is the pest of the poultry yard, on the other no species of the _Falconidæ_ effects more good during the fearful visitations of the caterpillar, a scourge of no infrequent occurrence in Australia. In 1839 it was my lot to witness the inroad of vast swarms of caterpillars in the region of the Upper Hunter River, and at the same time I observed many hundreds of the Whistling Eagle assembled on the Downs near Scone preying solely on them, thus tending in a great measure to check their progress, and certainly to lessen their numbers; so partial, in fact, is the Whistling Eagle to this kind of food that the appearance of one is the certain prelude to the appearance of the other. The _Haliastur? sphenurus_ is little alarmed by the presence of man, and when sitting on the branches of low trees, will often admit of a near approach even to within a few feet: as an evidence of its indifference, I may mention that, having winged a very rare Tern on the surface of a lagoon, a Whistling Eagle immediately descended and carried it off; and although this circumstance took place at a very short distance from me, neither the shouts of the natives nor of myself deterred the Eagle from bearing off the bird in triumph, to my extreme vexation. It is generally to be seen in pairs, inhabiting alike the brushes near the coast and the forests of the interior of the country. It is incessantly hovering over the harbours, and sides of rivers and lagoons, for any floating animal substance that may present itself on the surface of the water or be cast on the banks; and it is nowhere more common or more generally to be seen than over the harbour of Port Jackson. Its flight, when high in the air, is buoyant and easy, and it frequently soars to a great altitude, uttering at the same time a shrill whistling cry, from which circumstance it has obtained from the colonists the name of the Whistling Hawk, and by which it is at once distinguished from all the other members of the family inhabiting Australia.