The northern bald ibis, hermit ibis, or waldrapp (Geronticus eremita ) is a migratory bird found in barren, semi-desert or rocky habitats, often close to running water. This 70–80 cm (28–31 in) glossy black ibis, which, unlike many members of the ibis family, is non-wading, has an unfeathered red face and head, and a long, curved red bill. It breeds colonially on coastal or mountain cliff ledges, where it typically lays two to three eggs in a stick nest, and feeds on lizards, insects, and other small animals.
The northern bald ibis was once widespread across the Middle East, northern Africa, southern and central Europe, with a fossil record dating back at least 1.8 million years. It disappeared from Europe over 300 years ago, although reintroduction programs in the region are underway. In 2019 there were about 700 wild birds remaining in southern Morocco, and fewer than 10 in Syria, where it was rediscovered in 2002 but where their number declined in the following years, maybe to zero.
To combat these low numbers, reintroduction programs have been instituted internationally in recent times, with a semi-wild breeding colony in Turkey which counted almost 250 birds in 2018 as well as sites in Austria, Italy, Spain, and northern Morocco. These programs and the natural growth in Morocco from about 200 birds in the 1990s helped to downlist the northern bald ibis from Critically Endangered to Endangered on the IUCN Red List in 2018. There are about 2000 northern bald ibises living in captivity.
The reasons for the species' long-term decline are unclear, but hunting, loss of foraging habitat, and pesticide poisoning have been implicated in the rapid loss of colonies in recent decades.
The northern bald ibis is a large, glossy black bird, 70–80 cm (28–31 in) long with a 125–135 cm (49–53 in) wingspan and an average weight of 1.0–1.3 kg (35–46 oz). The plumage is black, with bronze-green and violet iridescence, and there is a wispy ruff on the bird's hind neck. The face and head are dull red and unfeathered, and the long, curved bill and the legs are red. In flight, this bird has powerful, shallow, and flexible wing beats. It gives guttural hrump and high, hoarse hyoh calls at its breeding colonies, but is otherwise silent.
The sexes are similar in plumage, although males are generally larger than females, and, as with other ibises that breed in colonies, have longer bills. The longer-billed males are more successful in attracting a mate. The downy chick has uniformly pale brown plumage, and the fledged juvenile resembles the adult except that it has a dark head, light grey legs, and a pale bill. The unfeathered areas of the young bird's head and neck gradually become red as it matures. Moroccan birds have a significantly longer bill than Turkish birds of the same sex.
If the eastern and western populations are considered to be separable subspecies, it is unclear which should be considered to be the nominate (first-named) form, since the first description of this species was based on a now-extinct population from Switzerland which is of unknown race.
The northern bald ibis is readily distinguished from its close relative, the southern bald ibis of Southern Africa, by the southern species' whitish face. The northern bald can also be confused with the similarly dark-plumaged glossy ibis, which overlaps its range, but it is larger and stockier than that species. In flight, when the bill and face colouration may not be visible, the bald ibis' less rounded wings and shorter neck give it a different profile from glossy ibis, and its relatively short legs mean that its feet do not project beyond the tail, unlike those of the glossy ibis.
