Straw-necked Ibis

The Straw-necked Ibis, a member of the ibis and spoonbill family Threskiornithidae, is a large bird with a length ranging from 59 to 76 cm. It boasts a bare black head and a long, downcurved bill. The plumage is highly iridescent, appearing dark brown under certain lighting conditions, but revealing a multicoloured sheen in sunlight. The back is a glossy blue-black with a metallic luster of purple, green, and bronze, and the upper neck and underparts are white. The legs are red near the top, transitioning to dark grey towards the feet. Adults are adorned with straw-like feathers on their necks, which is the origin of their common name. Their wingspan measures approximately 100 to 120 cm, and they weigh between 1.1 and 1.5 kg.

Identification Tips

Both sexes of the Straw-necked Ibis are similar in appearance, with males typically having longer bills. Females can be identified by a dark band across their upper breast. Juveniles present with duller colors, shorter and less curved bills, and lack the straw-like neck plumes.

Habitat

These birds are found around shallow freshwater wetlands, cultivated pastures, edges of swamps and lagoons, and wet or dry grasslands. They avoid arid regions, saltwater areas, and coastal mudflats.

Distribution

The Straw-necked Ibis is commonly found throughout Australia and is also present in New Guinea and parts of Indonesia. They are vagrants to New Zealand, Norfolk Island, and Lord Howe Island, and are seen less frequently in Tasmania and other islands of the Bass Strait.

Behaviour

The Straw-necked Ibis exhibits partial migratory behavior, with some birds remaining sedentary while others undertake seasonal or erratic movements in response to changing water conditions. They are known to fly in line or V formations and can reach high altitudes during long-distance flights. Vocalizations are mainly heard around breeding colonies and consist of croaks, barks, and grunts. They feed in flocks, probing in various substrates for food.

Song & Calls

Calls of the Straw-necked Ibis are mainly produced around breeding colonies and include a series of croaks, barks, and grunts. A hoarse grunt may be heard from flying birds at intervals.

Diet and Feeding

The diet of the Straw-necked Ibis primarily consists of aquatic and terrestrial invertebrates. They feed on aquatic insects, molluscs, frogs, freshwater crayfish, and fish in shallow waters. On land, they consume grasshoppers, crickets, locusts, small lizards, reptiles, and rodents. They have been observed employing a "stress and wash" technique to safely consume poisonous cane toads.

Breeding

Breeding season varies, influenced by water conditions. They build large, rough nests of sticks and trampled plants in colonies, often alongside the Australian white ibis. Clutch sizes range from 2 to 5 eggs, with both parents involved in incubation and care for the young. The incubation period lasts about 24 to 25 days, and parental care continues for about 35 days post-hatching.

Conservation status

The Straw-necked Ibis is currently listed as Least Concern on the IUCN Red List.