[order] ACCIPITRIFORMES | [family] Accipitridae | [latin] Haliastur sphenurus | [authority] Vieillot, 1818 | [UK] Whistling Kite | [FR] Milan siffleur | [DE] Keilschwanz-Weih | [ES] Milano silbador | [NL] Wigstaartwouw
Members of the genus Haliastur are large kites, having moderately long and slightly pointed wings; a longish, rounded tail, and short, heavy legs. The hook of the beak is more pronounced than in any other kite genus.
The genus, which is related to but less specialised than Milvus (Black Kites and Red Kites), contains, like that species, two members, the Whistling Kite, and the Brahminy Kite. Its range is restricted to Australia and neighbouring islands.
The Whistling Kite is a medium-sized raptor (bird of prey) with a shaggy appearance. It has a light brown head and underparts, with pale streaks, and dark sandy-brown wings with paler undersides. The underwings have a characteristic pale ‘M’ shape when open. The head and body are relatively narrow and the tail is rounded. The wings are long and well-rounded, with a wingspan of 123 cm to 146 cm. The sexes are similar, but the females are larger. Yong birds are slightly darker above, with paler streaking on head and underbody. A long-winged, long-tailed bird, the tail rounded at the tip and not forked. The outer primaries are black, the first few secondaries pale, and the remainder dark brown. The flight feathers are separated from the lesser under-wing coverts by a pale band, creating a distinctive underwing pattern. The body is light brown with darker streaks. In flight the wings are held out level with the body with no noticeable dihedral.
Listen to the sound of Whistling Kite
Copyright remark: Most sounds derived from xeno-canto
Australasia : widespread. The Whistling Kite, also known as the Whistling Hawk and the Whistling Eagle can be found throughout Australia, but not Tasmania. It is somewhat rarer in the south-west, but well represented in most of the continent. It is also to be found in Eastern New Guinea and New Caledonia.
Both in Australia and in islands to the north it prefers the vicinity of water, whether sea coasts and harbours, inland waterways or flood plains and swamps, but it is not con.fined to wet areas and ranges also over dry open country. Its flight is easy and buoyant, a little like a harrier, though it is larger, and in general similar to the Black Kite Milvus migrans. It calls often in flight. It is usually seen in pairs or small groups, and hunts over the countryside flying at 100-200 feet above the ground or over water. It is less likely to hunt from perches than some other birds of its size. In New Caledonia each pair has a fixed territory which is hunted systematically. In Australia, however, it tends to perform local movements at which times it is likely to be quite gregarious, as it is before the breeding season, when up to 100 may be seen together.
The birds move into breeding areas from their wintering areas in large flocks. In these flocks they soar and call continually, and the flocks later break up into smaller groups and into pairs, when the birds become even more voal. Nuptial display is initiated in the migrant flock, and after separating into pairs becomes more intense. It consists mostly of soaring over the breeding ground with much calling, but without spectacular aerial manoeuvres. Very often several birds soar together in the breeding season and the display then tends to be communal. Nests are built in trees larger than the neighbouring trees, often growing along a river. A new nest takes about a month to build, and will be small and slight, but is often used year after year and in the course of time grows to 26-30 inches across by twelve inches deep, with a cup six inches across and three inches deep in the centre. It is built of sticks, by the birds themselves, though sometimes based on the abandoned nest of another species. Several pairs may nest in the same tree. The birds roost in an old nest for about four months before finally laying. Two eggs are normally laid, sometimes three. They are laid in almost any month of the year, with a peak laying period between July and October. Both the season and the number of pairs breeding may be affected by variations in food supply. Replacement clutches may be laid if the first is lost. The young develop feathers by 35 days and spend at least 40 in the nest.
Rabbits, small mammals, lizards, fish, sea-snakes, insects, caterpillars and occasionally unguarded poultry are taken. Rabbits are probably the most prominent prey, on which grounds the species is sometimes regarded as beneficial to man. It feeds on carrion freely and as a result is liable to poisoning. All food, apart from some insects, is taken on the ground or from the water surface, and it will wade to obtain dead fish. It is not agile enough to take birds in the air, though it will snatch small birds from the ground. It is occasionally piratical, robbing other birds of prey.
copyright: Josep del Hoyo
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Partly migratory and dispersive within Australia. Migratory in South and Southeast, wintering in milder coastal and Northern areas; some birds resident in both temperate and tropical areas. In its movements it tends to be nomadic rather than truly migratory. The movements are in part a result of variations in food supply, e.g., plagues of caterpillars or abundant carrion.