Il Nibbio Bianco

(Elanus caeruleus)

Abitudini - This is a bird of open country wherever it occurs, but it can be seen in all habitat types from moderately dense savannah to open semi-desert, or even deserts, at altitudes from 0-9,000 feet. It roosts in trees and is on the wing early in the morning. Having taken to the wing, it spends most of each day perched on a series of perches, which may be telegraph posts or wires, dead tree stumps, or sometimes rocks where trees are scarce. When not perched it flies at a height of 50-200 feet over the grasslands, hovering at intervals, and circling into the wind in the manner of a kestrel. Its mode of maintaining position during a hover is unlike that of a kestrel, however. When flying from place to place it flies directly, with measured beats of its rather pointed wings, much slower than those of small falcons. When perched it often raises and lowers the tail; this action is probably a form of display. It is very sedentary, and will usually be found in the same area (especially in the equatorial parts of its range), showing no tendency at all to migrate. Northern populations may wander more in winter, but perform no regular migrations. In India there is evidence of irruptions into particular areas of country for periods, and then disappearance for some years. It is said to be nomadic in the northern part of its range, but resident in the tropical parts. Occasionally groups of 15-120 will roost together outside the breeding season, using the same roost nightly, and converging on it from all round. Pairs remain together for most of the year, and are usually found not far apart. The range of a pair will depend on food supply, and can be anything from a square mile or less, to 35 square miles in open desert country. They may sometimes be seen soaring high up outside the breeding season, in a manner quite unlike the usual low hovering flight. When killing prey this species has a very recognisable method of dropping gently into the grass, wings high above the back and their angle altered frequently to control the speed of descent. A few feet above the ground the wings are held straight up and the bird drops onto its prey. The whole routine is very graceful, similar to, but more gracefully performed than, the killing methods of the Kestrel (Falco tinnunculus).

Alimentazione - The mainstay of the Black-shouldered Kite's diet is mammals up to the size of a small rat. There are taken in grasslands. A few small ground birds such as larks and pipits, and large insects, especially grasshoppers and locusts also feature on occasions. On the Arabian coast the staple diet is dead fish and offal, varied with lizards, no doubt because of shortage of other food. Most food is taken on the ground, but some insects are caught in the air.

Riproduzione - This kite is one of very few members of the order, that is occasionally double-brooded. What percentage of pairs do nest twice and whether such behaviour is correlated with unusual food supplies is not known. When the young of the first brood are well grown, if there is to be a second brood, mating activities resume and the male, as before, begins half-hearted nest-building. If a second brood is reared, the eggs are laid in a new nest as well constructed as the first. Just prior to egg-laying, and after some half-hearted nuptial chasing and mutual soaring, one or more birds may perch on the nest tree, calling a good deal. They also make short flights from tree to tree with gently fluttering wings. This is its pre-copulation display. The nest is built by the birds themselves, and a new one is built every year, though the same area, or even the same tree may be used. It is a small, light structure of thin twigs, flat and loosely made, not more than twelve inches across by three inches deep. It could be at any height from five to 60 feet above ground, and is usually in a large tree standing in open ground, often a thorny one. In South Africa they seem to prefer the tops of fir trees, and when there are no trees available, like in the desert islands of the Arabian Coast, they will breed on rock ledges. Both sexes build, breaking off twigs from trees and bringing them to the site in the beak. The male brings most of the material which is then worked into the nest by the female. Three to five eggs are laid at intervals of two to three days. In temperate regions the eggs are laid in spring, but in tropical regions the breeding season is elastic and may even extend into wet periods. The female carries out most, if not all of the incubation. She is fed on or near the nest by the male during the incubation period. Both birds are likely to be aggressive if the nest is disturbed during this period, and they vigorously attack other raptors and crows passing near by. The incubation period is about 26 days (25-28). The eggs hatch at two to three day intervals, so a brood of four will take a week or more to hatch;. Although this results in wide variation in the size of the chicks, the older chicks are not usually aggressive to the younger, and all are sometimes reared. The feathers appear through the down at about twelve to fourteen days, and the young are fully feathered by 21 days. They are ready to fly at 30 to 35 days. In exceptional conditions on the Arabian Coast the fledging period exceeds 40 days, probably due to lack of food. The young return to the nest at intervals after their first flight, and are fed by their parents away from the nest. ln the early fledging period the male brings all the prey and the female remains at or on the nest, tending the young. Later the female takes the major part in killing for the brood, but the male remains for long periods near the nest and takes some share. The female alone feeds the young, the male only bringing prey to the nest. She continues to feed them until they are feathered, at about twenty days, but thereafter drops prey on the nest and leaves them to tear it up. With a large brood, of three or four, she feeds all the young and does not favour the largest.

Habitat e Area di Distribuzione - Breeds and winters in areas of open country with scattered trees. Now relatively numerous in parts of Iberia and a pair has even set up territory near Le Harvre in northern France. The most reliable sites I know are near Elvas and Castro Verde (Portugal) and near Monroy (Spain). The Black-shouldered Kite is most likely to be found in north-west Africa, Southern Asia, the East Indies, Arabia and Africa south of the Sahara. There are occasional sightings in Southern Europe, although it is not a regular resident or visitor in that area. Its preferred terrain is open savannah, cultivated highlands, grassy plains and semi-desert grassland.

Status della Specie -