Glossy ibis (Plegadis falcinellus)

French: Ibis falcinelle
KingdomAnimalia
PhylumChordata
ClassAves
OrderCiconiiformes
FamilyThreskiornithidae
GenusPlegadis (1)
SizeLength: 48 - 66 cm (2)
Wingspan: 80 - 95 cm (2)
Weight485 - 580 g (2)

The glossy ibis is classified as Least Concern (LC) on the IUCN Red List (1).

With its long, slender, down-curved bill and magnificent plumage, the glossy ibis is a striking wading bird. Its Latin name, Plegadis falcinellus, refers to its distinctive bill and means ‘scythe’ or ‘sickle’ (3), while its dark colouration has earned it the alternative (but inaccurate) common name of ‘black curlew’ (4). In breeding plumage, the glossy ibis is rich chestnut on the head, neck, upper back and underparts, while the feathers of the lower back, wings and tail have a green, purple and bronze metallic sheen (3) (4). The legs are generally dark brown to olive-grey, and the bill is usually grey or brownish (2). During the breeding season, the facial skin between the base of the bill and the eye appears blue-black in adult birds, with a distinctive edging of pale-blue skin above and below (2) (4). The non-breeding plumage is similar, although much duller (4), appearing darker brown in colour, with dense white streaks on the head and neck (2) (3).

The male and female glossy ibis are similar in appearance, although the female is generally smaller (4). Immature glossy ibis appear similar to the non-breeding adults, with an oily-green sheen to the feathers, a grey-brown head and neck and variable flecks of white on the forehead, throat and neck (2) (3) (4).   

The most widespread of all ibis species, the glossy ibis is found in North, South and Central America, the Greater Antilles, southern Europe, Africa, Asia, India, and Australia (2) (4).

The glossy ibis inhabits a wide variety of inland wetland habitats such as shallow lakes, swamps and marshes, ponds, rivers, floodplains, wet meadows and irrigated agricultural fields, as well as occasionally using coastal lagoons, mudflats and estuaries (2) (4). It feeds in very shallow water, and nests in freshwater or brackish wetlands with tall, dense stands of emergent vegetation, low trees and bushes (5).

The glossy ibis is a ‘tactile forager’, locating prey items by touch as it probes the substrate with its long, curved bill (4) (6). Touch sensors on the bill allow the bird to rapidly snap it closed when it encounters prey, while ridges along the bill ensure that prey is grasped firmly in place. After catching its prey, the glossy ibis lunges the head forward to send the prey item closer to the mouth, sometimes biting it several times before it is swallowed, or else allowing it to pass straight down the gullet whole (6). The glossy ibis has a broad diet, which varies seasonally (5) (6). It generally feeds on the adults and larvae of various insects, as well as molluscs and crustaceans, but small vertebrates, such as fish, frogs, lizards and small snakes, are sometimes also taken when encountered (2). Plant material, such as cultivated rice and sorghum, may also supplement the diet in some areas (4) (6). The glossy ibis typically forages in small flocks (2), and will roost communally, often in trees located far from its wetland feeding sites (5).

Throughout most of its range the glossy ibis breeds colonially, in large, mixed-species aggregations which often number thousands of birds. The breeding season runs between March and May (October to February in Australia), or coincides with the rainy season, depending on the location (2) (5). Both the male and female help to construct the nest, which is typically a compact platform of twigs or reeds, lined with leaves and other soft vegetation. It is often built over or close to water, usually less than one metreoff the ground, although occasionally up to seven metres (2) (4) (5). The female lays 3 to 4 eggs, which are incubated by both the male and female glossy ibis for a period of 20 to 23 days, with the female carrying out the greater share (2) (4). The chicks are able to leave the nest after 8 days, although they do not fledge (take their first flight) until around 25 to 28 days after hatching (2) (4). Both the male and female actively feed the chicks in and around the nest site for around six to seven weeks before they become fully independent (4).

The glossy ibis is a migratory and nomadic wading bird, with adults and young birds dispersing in all directions following breeding, often in separate flocks (2) (4) (5) (6). In northern populations, the glossy ibis wanders widely, before migrating southwards to its wintering grounds (2) (4).

Although the glossy ibis is not currently considered threatened, it is likely to be affected by habitat destruction and degradation, human disturbance, hunting, pesticide use and diseases such as avian influenza (1) (2) (4). However, despite dramatic reductions in population size in some areas, the glossy ibis has shown a marked increase in numbers in others, and continues to expand its range, especially in the Americas (2).

There are no known specific conservation measures in place for the glossy ibis. However, it is likely that this species will benefit from an increased focus on wetland protection which aims to ensure the conservation and management of the huge biodiversity using these habitats (4).

To find out more about the glossy ibis and other birds, see:

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  1. IUCN Red List (December, 2010)
    http://www.iucnredlist.org/
  2. del Hoyo, J., Elliott, A. and Sargatal, J. (1992) Handbook of the Birds of the World. Volume 1: Ostrich to Ducks. Lynx Edicions, Barcelona.
  3. Lippson, A.J. and Lippson, R.L. (2006) Life in the Chesapeake Bay, Third Edition. An Illustrated Guide to the Fishes, Invertebrates, Plants, Birds and Other Inhabitants of the Bays and Inlets from Cape Cod to Cape Hatteras. The John Hopkins University Press, Baltimore, Maryland.
  4. Davis Jr, W.E., and Kricher, J. (2000) Glossy ibis (Plegadis falcinellus). In: Poole, A. (Ed.) The Birds of North America Online. Cornell Lab of Ornithology, Ithaca. Available at:
    http://bna.birds.cornell.edu/bna/species/545
  5. BirdLife International (December, 2010)
    http://www.birdlife.org/datazone/speciesfactsheet.php?id=3777
  6. Perrins, C. (2009) Encyclopedia of Birds. Oxford University Press, Oxford.