This species is universally distributed over Van Diemen’s Land and New South Wales. It is represented in western and north-western Australia by a nearly allied species, to which I have given the name of _occidentalis_. In its disposition it is neither so bold nor so daring as the typical Falcons, and while it partakes much of the habits and actions of the true Kestrils, particularly in the mode in which it hovers in the air, it also often soars and skulks about after the manner of the Harriers. Although it sometimes captures and preys upon birds and small quadrupeds, its principal food consists of carrion, reptiles and insects; the crops of several that I dissected were literally crammed with the latter kind of food. It is generally to be met with in pairs, but at those seasons when hordes of caterpillars infest the newly-sprung herbage it congregates in flocks of many hundreds; a fact I myself witnessed during the spring of 1840, when the downs near Yarrundi, on the Upper Hunter, were infested with this noxious insect, which spread destruction throughout the entire district. By the settlers this bird is considered one of the pests of the country, but it was clear to me that whatever injury it may inflict by now and then pilfering the newly-hatched chickens from the poultry-yard is amply compensated for by the havoc it commits among the countless myriads of the destructive caterpillar. After the morning meal it perches on the dead branches of the neighbouring _Eucalypti_ until hunger again impels it to exert itself for a further supply. To give an idea of the numbers of this bird to be met with at one time, I may state that I have frequently seen from ten to forty on a single tree, so sluggish and indisposed to fly that any number of specimens might have been secured. So much difference occurs in the plumage of this species, that unless the changes it undergoes are known to him, the ornithologist would be apt to consider that there were more than one species; a close attention to the subject has, however, convinced me that the contrary is the case, and that in the countries which I have stated to constitute the true habitat of this bird there is but one species. During the first autumn the dark markings are of a much deeper hue, and the lighter parts more tinged with yellow than in the adult state, when the upper surface becomes of a uniform brown, and the white of the under surface tinged with yellow. The sexes are nearly alike in colour, but the female is the largest in size. I discovered the _Ieracidea Berigora_ breeding in the months of October and November both in Van Diemen’s Land and New South Wales, the nests in both countries being placed on the highest branches of the lofty _Eucalypti_.