Sickle Beak

Tuesday, January 14, 2025

Sickle Beak

Today’s special animal friend is the Glossy Ibis, Plegadis falcinellus. This tall wading bird is found in the Americas, Europe, Asia, and Africa. As you would expect from this wide distribution, it is a species of Least Concern to IUCN. They are about two feet high with a wingspan up to 41 inches. Their curved beaks (bill, rostrum) can be 5.7 inches long. Beaks have additional vocabulary! The culmen is the straight-line length of the upper mandible, while the ridged underside of the lower mandible is called the gonys. This will be on the test.

From a distance, the glossy ibis is an unremarkable sooty black or dark brown shade, but when you get close and the sun is shining, you see that their feathers are shiny in an array of colors: blue, green, yellow, bronze, red. Breeding adults are usually darker and have more dramatic highlights, while juveniles and non-breeding adults are less conspicuous.

Glossy ibises live in shallow wetland habitats. They can live in fresh, brackish, or saltwater marshes, manmade wetlands such as rice fields, and seasonally or episodically flooded agricultural areas. They forage in groups, probing with their beaks and stirring up the substrate to feed on seeds, insects, amphibians, reptiles, worms, and small fish. They are often joined by other wading bird species such as snowy egrets. They will also eat grain from dry fields.

Wouldn’t you like to go to a nice island like Grenada and see the glossy ibis? I know I would! It is assumed that glossy ibis are monogamous for the season, but ornithologists haven’t studied them enough to know whether they form longer-term partnerships. Courtship behavior includes bowing, preening, and billing. They nest in large groups, with their platform nests close together. In spite of this, territorial disputes seem to be rare.

They usually have three or four eggs, which are incubated by both parents for 20 to 23 days. Fledging takes about a month, but the chicks can leave the nest on foot in about a week. The parents feed them for six weeks or more. Some populations are migratory. Birds that breed in Central Asia spend the off-season in India, while European breeders often winter in Africa. Others are year-round residents in their regions.

Glossy ibis are known to live 20 years. In North America, the population has been increasing steadily since the 1960s. Predation of adults is rare; eggs and young are vulnerable to birds of prey, snakes, and mammals, but the habit of nesting in large groups limits losses. Threats include habitat loss and disruption, but they are adaptable to new habitats, including cities, as long as food can be found.