Threskiornithidae family (Ibises and Spoonbills) belongs to the
Ciconiiformes order and is taxonomically divided in two subfamilies, Threskiornithinae
(Ibises) and Plataleinae (Spoonbills). These birds are relatively large
(48 to 107 cm) with a distinctive general shape. In flight their necks are held straight out,
not curved back in a lying down 'S' as in Herons and Storks. Their long legs and necks are combined
with long beak or bill to make them adapt at hunting small prey in wetland habitats. Their bills are
downward curving in the Ibises and flattened at the tips into a spoon-like
shape in the aptly named Spoonbills. They both have 11
primaries, though the 11th may be greatly reduced, and 12 retrices (tail feathers).
Ibises and Spoonbills have a world-wide distribution in temperate and tropical climes. They are believed to have evolved
more than 25 million years ago in South America where fossils of species relating to the
Glossy Ibis and
White-faced Ibis have been found. They are primarily wetland birds, and a number of them are in danger of extinction because so
much wetland habitat has been destroyed. The IUCN lists Black-faced
Spoonbill, Great Ibis, Waldrapp Ibis and Oriental Crested Ibis as endangered
and Madagascan Crested Ibis as vulnerable.
Ibises bills are designed for probing into the soft mud in shallow waters
whereas Spoonbills are designed to feed by moving their partially open bills
from side to side, their bills snap shut very quickly whenever anything solid
passes between the two mandibles. Ibises and Spoonbills are carnivorous,
primarily tactile hunters, and can feed as well by night as they can by day.
The birds use a number of foraging techniques from standing still at the edge
of, or in some water waiting to spear a fish, through acts like stirring the
water or grass with a foot or flicking the wings, to disturbing or startling
prey, to walking rapidly through the environment.
Most birds of this family are monogamous and nest in colonies, exception
being the Oriental Crested Ibis (Niponnia nippon) which nests in
isolated pairs. Many species have crests of erectile feathers on the head
which are raised as part of the courtship display.
Nests are built of vegetable matter, sticks, reeds or vines brought by the
male. The female does most of the building. Eggs are incubated by both sexes.
The young are fed regurgitated food which they obtain by sticking their heads
down into the parent's gullet. Both parents feed the young and one adult
remains at the nest at all times while the young are small. The young cannot
stand when first hatched and have short simple bills.
Eurasian Spoonbill (Platalea leucorodia) - widespread winter visitor & resident
Glossy Ibis (Plegadis falcinellus) - widespread winter visitor & resident
Red-naped Ibis (Pseudibis papillosa) - widespread resident
Black-headed Ibis (Threskiornis melanocephalus) - widespread resident
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