Ibises and spoonbills

(Threskiornithidae)

Class Aves

Order Ciconiiformes

Suborder Ciconiae

Family Threskiornithidae

Thumbnail description
Medium-sized wading and terrestrial birds of temperate and tropic regions, with prominent bills (decurved in ibises, broad and flat in spoonbills), long neck and legs, anterior toes, and highly social habits

Size
19–43 in (48–110 cm): 1–5.5 lb (0.5–2.5 kg)

Number of genera, species
13 genera; 32 species

Habitat
Wetlands, forests, grassland, arid or semi-arid areas

Conservation status
Extinct: 1 species; Critical: 4 species: Endangered: 2 species; Vulnerable: 1 species; Near Threatened: 2 species

Distribution
Worldwide distribution in temperate and tropical zones. All continents except Antarctic have representatives of this family

Evolution and systematics

Two groups of Ciconiiformes, both with peculiarly-shaped beaks, make up the family of the ibises (Threskiornithidae). They are related to the storks, with the wood ibises (Mycteria also known as wood storks) forming a slight link with true ibises. With their slender curved beaks, the ibises differ strikingly from the flat-billed spoonbills but are nevertheless closely related. Spoonbill-ibis hybrids have been successfully raised in zoos. Hybridization raises some questions about the usual division of these birds into two subfamilies, but this division is retained here for practical purposes.

The two subfamilies are readily distinguishable by external characteristics: the ibises (Threskiornithinae), with their long, narrow, and markedly down-curved beak, probe for insects, mollusks, crustaceans, and worms in mud and soil; occasionally they also catch larger prey. Wing beats alternate with periods of gliding; when in flocks all birds alternate from one form of flight to the other at more or less the same time. There are 12 genera with 26 species.

The spoonbills (subfamily Plataleinae), with a beak that is flattened and widened at the tip, seize prey in side-to-side movements of the bill. They do not interrupt wing beats by gliding. This subfamily is comprised of one genus and six species.

Physical characteristics

All members of the family Threskiornithidae are medium to large in size. The face and throat are bare of feathers in most species; the medium-length legs are sturdy. The vocal apparatus is only feebly developed; they only utter low sounds or are almost mute, although a few species utter far-reaching calls. Spoonbills can also clatter with the beak. Both sexes are similar in color, the females generally being somewhat smaller than the males. Most plumage is white, brown, or black. Uniform coloration is the rule, sometimes with adornments such as display plumes. The standout exceptions in the family are the roseate spoonbill (Ajaia ajaja), whose shaded pink plumage is offset by a strange-looking head with bare greenish skin, and the scarlet ibis (Eudocimus ruber), with its striking uniform red plumage broken only by black wingtips. Most species have some areas of bare skin on the face. The sacred ibis (Threskiornis aethiopicus), has no feathers anywhere on the head or neck.

The fossil record of this family goes back 60 million years. It appears that, several times over the course of this long history, flightless species developed on islands. Of these, only the reunion flightless ibis (Threskiornis solitarius), survived into historical times.

Distribution

Ibises and spoonbills can be found almost everywhere in the world that moderate or warm temperatures prevail. They marginally inhabit the edges of deserts like the Sahara. With the exception of some regions of northern Africa and the Arabian Peninsula, most of the non-Antarctic world south of 45° North latitude is home to at least one species.

Habitat

Ibises and spoonbills can adapt to a surprising variety of habitats. Some species live on arid plateaus and mountains, while most inhabit savannas, forests, and wetlands of all types. Agricultural areas often attract these birds: in Asia, ibises often live near rice paddies, which provide excellent hunting grounds.

Behavior

Most species are very sociable, often breeding in large colonies and wandering about or migrating in flocks, often mingling with other Ciconiiformes such as storks and herons. Migration is common, especially in species living in areas such as sub-Saharan Africa, where food is highly dependent on seasonal rainfall patterns. Their social behavior extends to relationships between species: mixed flocks are common. As many as seven species have been counted in a roosting area.

In flight, the neck is extended forward, similar to that of storks. During the day, ibises and spoonbills will often leave foraging sites to drink and bathe in freshwater ponds. Preening is common and can take a considerable amount of time.

Feeding ecology and diet

Ibises and spoonbills generally obtain their food in shallow water and on the banks, catching small fish, crustaceans, insects, and miscellaneous other invertebrates. Occasionally, they will feed on the eggs of reptiles or other birds. Feeding in the water is done primarily by the sense of touch provided by the sensitive bill.

Reproductive biology

Trees and bushes are popular nest sites for the species in this family, although a few species build nests on the ground or on cliffs. Males often find a suitable nest site and advertise their presence to females, making a show of pointing their bills in the air, bowing, and other movements. They often snap their bills shut to make a popping sound, and will sometimes pick up a twig and shake it. When a female lands nearby, the male may initially reject her: if he accepts her, they join in a display of preening and bowing. Copulation normally takes place at the nesting site, and the male gathers the nesting materials. Both parents incubate the eggs, and share in the task of gathering and regurgitating food for the hatchlings. Clutch size is two to five eggs. White and blue

are the predominant egg colors, and in some species, the eggs have dark spots. The incubation period averages 20–31 days, with the chicks remaining in the nest for a fledgling period of 28–56 days.

Conservation status

The Reunion flightless ibis met a premature extinction, apparently at the hands of humans, around 1705. Several existing species are perilously close to following it. The four species classed as Critically Endangered by the IUCN are the dwarf olive ibis (Bostrychia bocagei), the hermit ibis or waldrapp (Geronticus eremita), the white-shouldered ibis (Pseudibis davisoni), and the giant ibis (Pseudibis gigantea). Considered Endangered are the black-faced spoonbill (Platalea minor) and the Japanese or crested ibis (Nipponia nippon), whose population in 2002 (wild and captive) was counted at 48 birds. The

black-faced, or Australian, spoonbill (Platalea minor) nests only on islands off the east cost of the Korean Peninsula. Destruction of the tidal zones that are the species' preferred feeding grounds is the suspected cause of the birds' decline, and as few as 700 individuals remain. The bald ibis (Geronticus calvus) is considered Vulnerable, while species subject to lesser threat are the Madagascar crested ibis (Lophotibis cristata) and the black-headed ibis (Threskiornis melanocephalus). Ibises and spoonbills are under pressure mainly due to wetland reduction by human activity and direct hunting. Pesticides, especially DDT (which is still used in many areas of the world and is blamed for thin, easily broken eggshells) are another source of concern.

Significance to humans

Large-scale trade of bird feathers has dwindled, and with it the hunting that drove many species into peril. However, in many parts of the world, local species are still hunted as a source of food. Ibises in particular have taken on religious significance in some areas. The sacred ibis (Threskiornis aethiopicus) has been a part of cultural history for 5,000 years; in ancient Egypt, it was revered as the embodiment of Thoth, the god of wisdom, as well as the scribe of the gods.

Species accounts

List of Species

Sacred ibis

Threskiornis aethiopicus

subfamily

Threskiornithinae

taxonomy

Tantalus aethiopicus Latham, 1790, Egypt. Three subspecies.

other common names

French: Ibis sacré; German: Heiliger ibis; Spanish: Ibis Sagrado.

physical characteristics

25.5–35 in (65–90 cm); 3.3 lbs (1,500 g). Plumage is mostly white; primary and secondary wing feathers tipped in black. Head and neck are bare, skin is black. Legs are black. Thickest bill of its genus.

distribution

Lives in most of the African continent south of 15° North latitude. There is an isolated colony at the southern tip of Iraq. Apparently the bird once was common in Egypt but it has not bred there since the first half of the nineteenth century.

habitat

Mainly coastal lagoons, marshes, damp lowlands, and agricultural areas (when flooded), but sometimes will travel far from water. Also garbage dumps and recently burned areas.

behavior

These birds commonly fly in staggered lines, with each bird slightly ahead and to one side of the bird behind. A relatively

quiet bird, the sacred ibis will make grunting and croaking noises during the breeding season, but these are the only vocalizations. Juveniles lack the long bill of the adults, and eat by reaching their bills into the parents' throats and removing food.

feeding ecology and diet

The sacred ibis is specialized by nature for aquatic prey like small fish and invertebrates, but is an opportunistic eater that will take anything available, such as carrion, bird eggs and nestlings, or small mammals.

reproductive biology

The nest is a platform made of sticks and twigs, lined with vegetation. Clutch size is usually three to four eggs, from which the young hatch after 21 days and are fledged in five to six weeks. Their downy plumage is dark.

conservation status

While its range has decreased, the species is not in imminent danger. Not threatened.

significance to humans

Thoth, the ibis-headed god of wisdom, is shown in many murals and sculptures, such as in the temple of Sethos, where it hands the hieroglyph of life to Osiris. It was used as a hieroglyphic symbol, and entire "cemeteries" of ibis mummies have been found at Sakkara near Cairo and at Hermopolis in middle Egypt.

White-faced glossy ibis

Plegadis chihi

subfamily

Threskiornithinae

taxonomy

Numenius chihi Viellot, 1817, Paraguay. Monotypic.

other common names

English: White-faced ibis; French: Ibis à face blanche; German: Brillensichler; Spanish: Morito Cariblanco.

physical characteristics

17–25.5 in (43–65 cm); 1.3 lb (610 g). Deep chestnut plumage with metallic green and purple gloss on back, wings, head, and neck. A border of white feather surrounds the pinkish to red facial skin. Legs are reddish.

distribution

The range forms a broad band across South America, reaching as far north as southern Peru and Brazil and south to include the northern thirds of Chile and Argentina. The range is markedly discontinuous, with the bird being absent north of this band until it reappears in central and western Mexico, northern California, and a large area of the midwestern and western United States, plus the western half of the United States Gulf coast.

habitat

Inhabits wetlands and all types of agricultural land. Congregates around streams, creek beds, lakes, and other water sources.

behavior

Some populations migrate, moving between breeding and wintering grounds, but others, especially those in the southern part of the range, stay in one place throughout the year.

feeding ecology and diet

Feeds in the shallows of lakes, ponds, streams, rivers, and wetlands. Also forages in rice and alfalfa fields when flooded. Takes fish and various other small aquatic vertebrates and invertebrates. In some areas, earthworms collected in irrigated fields are a dietary staple.

reproductive biology

Nests can be found in swamps, marshes, bushes, or trees, especially on vegetated islands. Nests built on the ground are usually woven from dry reeds, while those in trees are built of sticks and twigs. Clutch size is three or four eggs, with an incubation period of about three weeks.

conservation status

Some local populations are threatened, mainly by habitat destruction.

significance to humans

None known.

Hermit ibis

Geronticus eremita

subfamily

Threskiornithinae

taxonomy

Upupa eremita Linnaeus, 1758, Switzerland. Monotypic.

other common names

English: Waldrapp, northern bald ibis; French: Ibis chauve; German: Waldrapp; Spanish: Ibis Eremita.

physical characteristics

27.5–31.5 in (70–80 cm); 2.5 lb (1,280 g). Plumage is dark with metallic green and purple gloss. Front portion of head is bare (skin is reddish orange with black marks over the eyes), back portion features a crest of dark feathers.

distribution

The species breeds only in three colonies in Morocco, all in the Souss-Massa National Park. Formerly, the hermit ibis had widespread distribution in Africa and Europe, but populations dwindled due to loss of habitat and mass hunting in the seventeenth century.

habitat

Rocky plateaus, high-altitude meadows and streams, and arid or semi-arid plains within foraging range of riverbeds or ocean beaches.

behavior

Except for the habit of nesting on cliffs, the hermit ibis is a typical member of its family. It is colonial, not given to loud calls, and spends its non-breeding days wading in the shallows.

feeding ecology and diet

Primarily insects, larvae, spiders, worms, and small reptiles and amphibians.

reproductive biology

The species breeds colonially. Clutch size is usually two to three eggs. Adults feed not only their own young but also the young of other pairs from beak to beak. Incubation is 27 to 28 days, and the young are fledged after 46 to 51 days.

conservation status

Critically Endangered. A captive breeding experiment failed to save the Turkish population, leaving only the Moroccan colonies. The hermit ibis has undergone a long-term decline and now has an extremely small range and population. The major reasons for the shrinkage of the species' range include agriculture, development, and hunting. In 2001, the World Conservation Monitoring Centre estimated the entire population at 220 birds in the wild, plus 700 in captivity.

significance to humans

No economic significance. In ancient times, the bird's return to the Euphrates River was a harbinger of spring, and was celebrated with a festival.

Hadada ibis

Bostrychia hagedash

subfamily

Threskiornithinae

taxonomy

Tantalus hagedash Latham, 1790, Cape of Good Hope. Three subspecies.

other common names

English: Hadeda, Hadedah; French: Ibis hagedash; German: Hagedasch; Spanish: Ibis Hadada.

physical characteristics

25.5–30 in (65–76 cm); 2.4 lb (1,250 g). General tone of plumage is gray to olive-brown (depending on subspecies) with metallic green gloss. Culmen has a distinctive red base. No crest of feathers on the head.

distribution

Senegal and Gambia across the continent to Ethiopia and southern Somalia, and south to include most of South Africa.

habitat

Primarily in savanna, grassland, and along wooded rivers and streams. Also in gardens and cultivated land.

behavior

Hadadas are not as social as most ibises. They gather in flocks for breeding, but nest alone, not in colonies. Most populations are sedentary except for the normal radiation of young pushing out from the breeding area and local moves to adapt to environmental conditions. Hadadas do not hesitate to colonize areas of human habitation within their range, and are also known to display aggression toward domestic dogs and cats.

feeding ecology and diet

Insects and other small invertebrates, along with small fish and reptiles.

reproductive biology

Hadadas nest most often in trees, and occasionally in telephone poles. Pairs generally breed on their own in wooded ravines up to elevations of 6,600 feet (2,000 m), but the birds descend to agricultural areas for feeding. Both partners incubate and feed the young. Eggs hatch after 26 days, and the young stay in the nest for about 33 days.

conservation status

Not threatened. While other species have suffered from human activity, the hadada appears to have profited. The population is gradually rising.

significance to humans

None known.

Japanese ibis

Nipponia nippon

subfamily

Threskiornithinae

taxonomy

Ibis nippon Temminck, 1835, Japan. Monotypic.

other common names

English: Japanese crested ibis, crested ibis; French: Ibis nippon; German: Nipponibis; Spanish: Ibis Nipón.

physical characteristics

22–31 in (56–79 cm); 2.2 lbs (1,000 g). Mostly white, this ibis has orange-brown flight and tail feathers, a bare, orange-red face, and a crest of long, white feathers extending backward from the head. Legs are orange-red.

distribution

Before the twentieth century, this species bred in large areas of eastern China and Japan, and existed in Korea until the 1940s. Today, the remaining birds live in a reserve in southern Shaanxi, a province in east-central China.

habitat

Forested hills and adjoining wetlands, rice paddies, lakes, and ponds.

behavior

The Japanese ibis does not migrate. The known birds only travel from their breeding ground to foraging areas and back.

feeding ecology and diet

Frogs, newts, fish, crustaceans, and insects.

reproductive biology

Breeding takes place in a colonial setting. The nest is a simple platform of sticks built in a tree. Three eggs are normally laid.

conservation status

Endangered and on the edge of extinction, with a total of 48 individuals recorded in 2001. In recent years, the sole wild colony has never totaled higher than 22 birds, although an average of five fledglings per year was recorded over the last decade. One bird per year is taken from the wild to add to a captive breeding project in the Beijing Zoo, where several birds have been hatched and raised successfully. Hunting (once widespread, although now illegal), habitat destruction, and pesticides are blamed for the species' decline.

significance to humans

Revered as a Japanese national symbol. When only two were left in Japan, in 1994, a pair was brought from China for breeding, but the attempt was unsuccessful. The last Japanese ibis in Japan died in 1995 at the estimated age of 26.

Scarlet ibis

Eudocimus ruber

subfamily

Threskiornithinae

taxonomy

Scolopax ruber Linnaeus, 1758, Bahamas. Monotypic.

other common names

French: Ibis rouge; German: Scharlachsichler; Spanish: Corocoro Rojo.

physical characteristics

24 in (60 cm); 2 lb (900 g). Scarlet plumage and black recurved bill; non-breeding adults have pink or reddish bills.

distribution

Coastal Brazil to north Venezuela, Colombia, and eastern Ecuador.

habitat

Mangrove swamps, lagoons, estuaries, wetlands, and mudflats.

behavior

Often gather in large flocks, feeding during the day and roosting in trees at night in large numbers. Has a plaintive, high-pitched call.

feeding ecology and diet

Hunts fish, frogs, newts, insects, crabs, and other invertebrates. Forages in both saltwater and freshwater ecosystems.

reproductive biology

Pair formation takes place in the small nest territory which is defended by both partners. Nest material is brought mainly by the male, and is used for building by the female. Clutch size is usually two eggs. The young hatch after 21–23 days, are tended by both parents, and are fledged at 35–42 days.

conservation status

Not threatened.

significance to humans

None known.

Spoonbill

Platalea leucorodia

subfamily

Plataleinae

taxonomy

Platalea leucorodia Linnaeus, 1758, Sweden. Three subspecies.

other common names

English: Eurasian spoonbill, common spoonbill; French: Spatule blanche; German: Löffler; Spanish: Espátula Común.

physical characteristics

27.5–37.5 in (70–95 cm); 3.3 lb (1,500) g. Overall white plumage with varying amounts of yellow (from small patch to ring) at the base of the neck. Crest of white feathers on the back of the head. Black bill tipped in yellow and black legs. Males somewhat larger than females.

distribution

Has the largest modern range of any species in its family. Found across the Eurasian mainland, from the Atlantic coast of the Netherlands east across the Caspian and Black Seas, over

most of China, to Mongolia, southern Siberia, and the Korean Peninsula.

habitat

Marshes, lakes, ponds, rivers, lagoons, flooded areas, and mudflats.

behavior

Flies with the head and legs extended, using majestic, slow beats of its wings. Groups may fly in single file or in a loose V formation. Spoonbills rarely utter any cries. On the ground, it often rests standing on one leg. It will swim for short distances to reach suitable areas of shallow water.

feeding ecology and diet

Mainly insects, crustaceans, and fish. The spoonbill holds its straight, flattened bill slightly open while foraging, sweeping it through shallow water and picking up prey items disturbed by the motion. Experiments have determined that the bill's shape lets it act as a hydrofoil, setting up water currents which affect objects up to four inches (10 cm) away from the bill itself.

reproductive biology

The spoonbill breeds, like most birds of the ibis family, in colonies of varying size. Clutch size is about three to five eggs. The young hatch after 21 days and are cared for by both parents.

conservation status

Not threatened. Some local pressures due to hunting and habitat destruction.

significance to humans

None known.

Roseate spoonbill

Ajaia ajaja

subfamily

Plataleinae

taxonomy

Ajaia ajaja Linnaeus, 1758, Brazil. Monotypic.

other common names

English: Pink curlew, rosy spoonbill; French: Spatule rosée; German: Rosalöffler; Spanish: Espátula Rosada.

physical characteristics

31 in (80 cm); 3.3 lbs (1,500 g). The only pink spoonbill.

distribution

Range covers most of South America, excluding some western areas such as Chile, most of Argentina, and almost all of Peru. Also Central American nations up to northern Mexico and east along the Gulf Coast to Louisiana and Florida. Also occurs in Cuba, Haiti, and the Dominican Republic.

habitat

Mangrove stands, lagoons, swamps, rivers, lakes, and ponds.

behavior

Roseate spoonbills are colonial birds but are nonetheless territorial, with the male staking out and defending nesting areas. Unlike some members of its family, the roseate spoonbill sometimes feeds at night. The birds fly with neck and legs extended,

flapping the wings and then gliding. The flight is described as more leisurely than that of ibises.

feeding ecology and diet

Primarily small fish, although other types of small aquatic prey, such as crayfish and crustaceans, are also taken. Like the nominate species of spoonbill, the roseate spoonbill swings its flattened beak from side to side, disturbing prey species. When the sensitive nerve endings in the inner linings of the bill report contact, the bill claps shut. The birds toss their heads backward to swallow prey.

reproductive biology

Roseate spoonbills nest in colonies. Copulation takes place on the nest, which is loosely woven of sticks and twigs. Eggs are laid at the rate of one every two days. Clutch size averages three eggs, and incubation lasts an average of 22–23 days. Hatchlings have pink skin covered with short, sparse white down.

conservation status

Currently, the roseate spoonbill is not threatened. Before World War II, the species suffered a considerable decline in the areas of its range populated by humans, due to hunting for meat and feathers as well as habitat destruction. At one point, the population in the United States may have numbered as few as 20 to 25 nesting pairs. Before modern conservation efforts began on the species' behalf, safety was afforded only by the remote areas of South and Central America.

significance to humans

Once widely hunted for plumes and meat, the birds today have no economic significance.

Resources

Books

del Hoyo, J., A. Elliot, and J. Sargatal, eds. Handbook of the Birds of the World. Vol. 1, Ostrich to Ducks. Barcelona: Lynx Editions, 1992.

Elphick, Chris, John B. Dunning, Jr., and David Allen Sibley. The Sibley Guide to BirdLife and Behavior. New York: Alfred A. Knopf, 2001.

Hancock, J. A., J. A. Kushlan, and M. P. Kahl. Storks, Ibises and Spoonbills of the World. San Diego: Academic Press, 1992.

Sibley, C. G., and J. E. Ahlquist. Phylogeny and Classification of Birds: A Study in Molecular Evolution. New Haven and London: Yale University Press, 1990.

Periodicals

Martinez, Carlos, and Antonio Rodrigues. "Breeding Biology of the Scarlet Ibis on Cajual Island, Northern Brazil." Journal of Field Ornithology 70 (4)(1999): 558–566.

Other

United Nations Environment Programme World Conservation Monitoring Centre. Crested Ibis.<http://www.unep-wcmc.org/index.html><http://www.unep-wcmc.org/species/data/species_sheets/crestedi.htmmain> 30 October 2001.

United Nations Environment Programme World Conservation Monitoring Centre. Waldrapp (Northern Bald Ibis).<http://www.unep-wcmc.org/index.html><http://www.unep-wcmc.org/species/data/species_sheets/waldrapp.htmmain> 30 October 2001.

Matthew A. Bille MSc

Cherie McCollough, MS