Threskiornithidae – Ibises & Spoonbills

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. 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.

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 are notable in that these wetland plains support seven species of ibis in the one region.

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.

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. 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.

According to the IOC there are 35 species of Ibises and Spoonbills in the family Threskiornithidae, which are:

African Sacred Ibis Threskiornis aethiopicus
Malagasy Sacred Ibis Threskiornis bernieri
Black-headed Ibis Threskiornis melanocephalus
Australian White Ibis Threskiornis molucca
Straw-necked Ibis Threskiornis spinicollis

Red-naped Ibis Pseudibis papillosa
White-shouldered Ibis Pseudibis davisoni
Giant Ibis Pseudibis gigantea

Northern Bald Ibis Geronticus eremita
Southern Bald Ibis Geronticus calvus

Crested Ibis Nipponia nippon

Olive Ibis Bostrychia olivacea
Sao Tome Ibis Bostrychia bocagei
Spot-breasted Ibis Bostrychia rara
Hadada Ibis Bostrychia hagedash
Wattled Ibis Bostrychia carunculata

Plumbeous Ibis Theristicus caerulescens
Buff-necked Ibis Theristicus caudatus
Black-faced Ibis Theristicus melanopis
Andean Ibis Theristicus branickii

Sharp-tailed Ibis Cercibis oxycerca

Green Ibis Mesembrinibis cayennensis

Bare-faced Ibis Phimosus infuscatus

American White Ibis Eudocimus albus
Scarlet Ibis Eudocimus ruber

Glossy Ibis Plegadis falcinellus
White-faced Ibis Plegadis chihi
Puna Ibis Plegadis ridgwayi

Madagascan Ibis Lophotibis cristata

Eurasian Spoonbill Platalea leucorodia
Black-faced Spoonbill Platalea minor
African Spoonbill Platalea alba
Royal Spoonbill Platalea regia
Yellow-billed Spoonbill Platalea flavipes
Roseate Spoonbill Platalea ajaja