Threskiornithidae – Ibises & Spoonbills

Threskiornithidae (Ibises & Spoonbills) are part of Pelecaniformes along with, Scopidae (Hamerkop), Balaenicipitidae (Shoebill) and Pelecanidae (Pelicans). The Threskiornithidae family includes 35 species of large wading birds. The family has been traditionally classified into two subfamilies, the ibises and the spoonbills; however recent genetic studies are casting doubt on the arrangement, and revealing the spoonbills to be nested within the old-world ibises, and the new-world ibises as an early offshoot.

Members of the family have long, broad wings with 11 primary feathers and about 20 secondaries. They are strong fliers and, rather surprisingly, given their size and weight, very capable soarers. The body tends to be elongated, the neck more so, with rather long legs. The bill is also long, decurved in the case of the ibises, straight and distinctively flattened in the spoonbills.

Northern Bald Ibis Geronticus eremita – ©Dubi Shapiro

They are large birds, but mid-sized by the standards of their order, ranging from the dwarf Olive Ibis Bostrychia bocagei, at 45cm and 450g, to the Giant Ibis Thaumatibis gigantea, at 100cm and 4.2kg.

Crested Ibis Nipponia nippon – ©Dubi Shapiro

They are distributed almost worldwide, being found near almost any area of standing or slow-flowing fresh or brackish water. Ibises are also found in drier areas, including landfills. The Llanos wetland plains are notable in that they support seven species of ibis in the one region.

African Spoonbill Platalea alba – ©Dubi Shapiro

All ibises are diurnal; spending the day feeding on a wide range of invertebrates and small vertebrates: ibises by probing in soft earth or mud, spoonbills by swinging the bill from side to side in shallow water. At night, they roost in trees near water. They are gregarious, feeding, roosting, and flying together, often in formation.

Black-faced Ibis Theristicus melanopis – ©Dubi Shapiro

Nesting is colonial in ibises, more often in small groups or singly in spoonbills, nearly always in trees overhanging water, but sometimes on islands or small islands in swamps. Generally, the female builds a large structure out of reeds and sticks brought by the male. Typical clutch size is two to five; hatching is asynchronic.

Bare-faced Ibis Phimosus infuscatus – ©Dubi Shapiro

Both sexes incubate in shifts, and after hatching feed the young by partial regurgitation. Two or three weeks after hatching, the young no longer need to be brooded continuously and may leave the nest, often forming creches but returning to be fed by the parents.