Geronticus eremita

Geronticus eremita

The northern bald ibis or hermit ibis (Geronticus eremita Linnaeus, 1758) is a bird belonging to the Threskiornithidae family.

Systematics –
From a systematic point of view it belongs to:
Eukaryota Domain,
Kingdom Animalia,
Phylum Chordata,
Aves class,
Order Pelecaniformes,
Threskiornithidae family,
Subfamily Threskiornithinae,
Genus Geronticus,
Species G. eremita.

Geographic Distribution and Habitat –
The hermit ibis is a bird classified as endangered.Once upon a time its range was very extensive: it included practically all of North Africa and the Middle East, as well as in the mountainous areas and in the cliffs of southern Europe, but also in Switzerland , Austria and Germany; numerous colonies were located along the Danube and the Rhone.
Unfortunately, around 300 years ago, the species started towards a slow and inexorable decline which caused its disappearance first from central Europe, then from southern Europe.
In North Africa, the population of these birds remained rather stable until the mid-twentieth century, when here too there was a constant decrease in the number of hermit ibises: the last Algerian colony of these birds disappeared in the late 1980s. , while in Morocco it went from 38 breeding colonies surveyed in 1940 to 15 in 1975. The last colony present in the Atlas Mountains never returned from migration in 1989.
At present, a large part of this bird species is concentrated in Morocco, where three breeding colonies in the Souss-Massa National Park and a large colony at the mouth of the Oued Tamri, near Agadir, have been recorded, for a total of about 700 specimens in 2019: between the two sites there is a constant natural exchange of individuals.
Another colony is located in Turkey, near the town of Bireçik in the south-east of the country, where it has been preserved for centuries thanks to the protection of the local religious authorities, as the annual migration of ibises traditionally drives hajj pilgrims to La Mecca: still today there is a festival that celebrates the return of these animals from the southward migration. The Turkish colony of hermit ibis counted about 3000 specimens until the seventies: subsequently the number of specimens returning from migration was drastically reduced and an attempt to reintroduce breeding pairs in 1977 was worthless.
Fortunately, the Turkish population of Geronticus eremita, which is kept in semi-captivity at the behest of the government, is in good health and is growing in numbers.
The goal is to allow migration as soon as the number of adults in the colony exceeds 100 breeding pairs. Periodically some specimens are marked and left free to migrate south.
On the other hand, the wild Turkish hermit ibis population has decreased steadily, to the point of no longer breeding pairs in 1992.
It should be reported instead that in the spring of 2002 scholars discovered in the Syrian Desert, near the archaeological site of Palmyra, still isolated populations of hermit ibis, despite this bird having been declared extinct in Syria about 70 years earlier: in particular, they were found fifteen abandoned nesting sites and one still occupied by a nesting colony. The Syrian population would have a fertility rate, but also a mortality rate, higher than that found in the Turkish and Moroccan ones: however, despite the spontaneous arrival in the colony of some individuals of Turkish origin, in 2010 at the Palmyra site there was nothing left but a breeding pair with three adults.
In addition to these findings, specimens of birds that can be identified as exponents of this species are sporadically reported in Saudi Arabia, Yemen, Israel, Mauritania and Eritrea: other reports, especially in Europe, may also derive from the erroneous interpretation of sightings of glossies, the which, although smaller and slender than the hermit ibis, especially in flight can easily be confused with it.
Its habitat, unlike most of the members of its family, who live in humid areas and nest on trees, is that of rocky areas and cliffs, where it nests, near steppe or semi-arid areas where to look for food. In any case, a source of water must always be found near the nesting areas.
The decrease in the populations of this bird is linked to various factors such as: hunting activities, the destruction of steppe habitat, intensive agriculture and the use of pesticides.

Description –
The hermit ibis is a large bird with a length of about 70-80 cm, a wingspan of 125-135 cm, for a weight that rarely exceeds 500 grams. It has a slight sexual dimorphism with males tending to be slightly larger at the same age than females; they also have a slightly longer beak.
It has a completely jet black plumage in both sexes: on the chest and in particular on the wings there are metallic reflections of green, violet and bronze color, while the wing coverts have a characteristic red-copper shade. On the cervix and on the back of the neck the feathers are ruffled to form a sort of saddlecloth, while on the nape they appear lanceolate and are partially erectile to form a tuft. The naked parts of the body are of a fleshy-reddish color.
The conformation of the legs is robust and these are quite long and have on the four fingers strong slightly hooked nails, of which three are turned forward and one back.
The eyes of this bird are large and placed sideways; they have a round pupil and are yellow-ocher in color.
The beak, of red color, is very long and slightly curved, wide at the base and tending to gradual narrowing as one proceeds towards the tip.
The young specimens already have the typical black plumage, however the beak is gray-black and the areas of bare skin, much less extensive than in the adult, are of the same color. In fact, the young have rather sparse lanceolate feathers of a whitish-gray color on the whole head, except for a circle of naked skin around the eyes and beak. These feathers tend to fall off with age, and areas of bare skin tend to acquire the adult reddish color as the animal grows and reaches maturity.

Biology –
The hermit ibis reaches sexual maturity no earlier than three years old although it is quite rare that a specimen begins to reproduce before it is 4-5 years old.
The reproductive period is the summer one. Once a nesting site has been identified, the male carefully cleans it of any plants and shows it insistently to the chosen female: everything is accompanied by the ruffling of the feathers of the nape and by the emission of low gurglings by the suitor. . If the female likes the location where the cavity is located, then she gives in to the advances of the male and the two form a fixed couple.
The nesting place corresponds to a cavity in the rock in a rocky cliff or in a cliff, or in any case in a steep and difficult place to reach for any terrestrial predators: in the past, when these birds were also widespread in Europe, many of them chose as a place for nesting the battlements and windows of castles or other abandoned buildings.
The nest is built with a cluster of twigs placed in a circular shape and lined with grass or straw. In this nest the female lays from 2 to 4 eggs with a rough surface, weighing about fifty grams and initially of a blue color with brown spots: during the incubation, however, the whole egg would tend to acquire a yellowish-brown hue. .
The hatching is carried out by both parents, who take turns for the 24-25 days necessary for the incubation: while one is brooding, the other looks for food for itself, or watches the surroundings for possible sources of disturbance for the eggs.
Even the young are fed by both parents at least until they are able to fly, which happens around the second month of life.
Although they are usually silent animals, in colonies, hermit ibises can emit sounds similar to grunts or nasal meows, the significance of which for intraspecific communication remains obscure.
The life expectancy of this bird, in captivity, is about 25 years: the longevity record is 37 years for a male and 30 for a female. In nature, however, it is believed that the life expectancy of these birds does not exceed 15 years.

Ecological Role –
The hermit ibis is a gregarious bird, which tends to spend most of its time in groups.
During the night the colonies remain safe along the cliffs or cliffs that these animals choose as their home: at the first light of dawn, groups of even 100 specimens detach from the colonies, which in a “V” formation move in search of food, moving up to 10-15 km compared to night shelters.
This species feeds mainly on small reptiles which they capture by probing the sandy soil with their long beak. The diet is also based on small mammals and birds, snails, spiders and scorpions.
Sometimes the males wait for the females to capture something, and then steal it from them by virtue of their greater size.
The Geronticus eremita, in search of food, prefers steppe areas, however they can also be found in cultivated or bushy areas. Here these birds move on the ground walking with their beak held perpendicular to it and continuously inserted like a probe, ready to grab any small prey that comes within range.
It is a species in danger of extinction and was one of the first animals ever to become a protected species: it was in fact the Archbishop of Salzburg Leonhard von Keutschach, in 1504, who issued a decree that sanctioned the absolute prohibition for anyone, except for the nobles, to kill these birds, already in decline then. However, this decree was not very effective, as this bird species soon became extinct in Austria, as well as in the rest of Europe.
As a critically endangered species, it is one of the main species targeted by the AEWA conservation plan: the species is also listed in Appendix I of CITES, which means that the capture and trade of these animals is illegal and can take place only in exceptional cases, for example for research purposes and with the appropriate certifications.
The hermit ibis was once quite common along the rocky areas and cliffs of southern Europe, the Middle East and North Africa. The numerical decline began centuries ago and at least until the early 1900s its causes are unknown: since the beginning of the twentieth century, however, the ibis population has suffered a drastic decline, equal to about 98%, due to the combination of various factors. , first of all poaching, but also the destruction of the habitat to make way for intensive breeding and plantations, the use of pesticides, the disturbance of migratory routes and reproductive colonies due to excessive anthropization.
Currently the hermit ibis has disappeared from most of the original habitat and in the wild only a few isolated colonies remain in Morocco and Syria (where it was rediscovered only in 2002), for a world total of about 550 wild individuals. In addition to the wild colonies, however, especially in Europe, semi-wild or captive colonies of these birds are present for a total of about a thousand specimens: starting from these, various programs for the reintroduction of the hermit ibis are being studied or implemented. in its original environment.

Guido Bissanti

Sources
– Wikipedia, the free encyclopedia.
– C. Battisti, D. Taffon, F. Giucca, 2008. Atlas of nesting birds, Gangemi Editore, Rome.
– L. Svensson, K. Mullarney, D. Zetterstrom, 1999. Guide to the birds of Europe, North Africa and the Near East, Harper Collins Publisher, UK.