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There are eight species of pelican worldwide that form the genus Pelecanus and family Pelecanidae. Pelicans can be found worldwide except for Antarctica.

There are eight pelican species worldwide, and four are classed as critically endangered. The most significant threats are habitat loss, egg collecting, and hunting.

Photo of white-bellied heron
White-bellied Heron Ferran Pestana Flickr CC by SA2.0

White-bellied Heron

IUCN Status: Critically Endangered.

The white-bellied heron, also referred to as the great white-bellied heron or imperial heron, is a large heron species. The White-bellied Heron is the world’s second-largest heron, with adults towering over a meter tall.

The white-bellied heron has a white belly, long silvery plumes on the rear crown, and uniform dark grey feathers throughout the body.  Juveniles have a paler bill and paler legs, and their upper bodies are browner.

How many are alive?

50-249 mature individuals.

It is believed that this species’ population is rapidly declining. It is estimated that only 50-249 mature individuals are present in the wild. However, further research is required for proper estimation.

Where do they live?

It is most commonly found in small or large rivers having sand or gravel banks, generally inside or next to subtropical/tropical broadleaved forests, from the lowlands to at least 1,500 meters. They are also present in lakes and marshes near wet grasslands. 

The white-bellied heron is found in the eastern Himalayan foothills of Bhutan and northeast India, as well as the hills of Bangladesh, north Myanmar, and, historically, in central and west Myanmar. According to the IUCN, it is possibly extinct in Bangladesh. 


The extensive loss, deterioration, and disturbance of forests and wetlands are thought to be the main threats.

Pollution, the quick proliferation of aquatic vegetation, and resource overuse have all contributed to the degradation of wetlands.

In important protected areas, agricultural transformation, increasing habitat degradation from resource extraction from wetlands, and poaching pose serious threats.

In Bhutan, natural forest fires have burned nests of white-bellied herons.

São Tomé Ibis

IUCN Status: Critically Endangered.

The  São Tomé Ibis is also known as the “Dwarf Ibis” or “The Dwarf Olive Ibis.” It was once believed to be a subspecies of the larger olive ibis, but it is now recognized as a distinct species. The eyes and the bill’s base are framed by black on the dull olive head.

The mantle and wing coverts have a pale copper colour.  It is mostly silent, but when disturbed, it makes a variety of noisy grunts and a loud honking while going to roost.

How many are alive?

130-1700 mature individuals.

Considering this species occurs in the smallest range of 55 km2, the projected population would be between 190 and 2,500 individuals, which equates to 130-1,700 mature individuals. The population of dwarf ibises is believed to be declining.

Where do they live?

The species is restricted to forests below 1000 m, while most reports are of birds in native forests at elevations of up to 500 m. It can be found in secondary forests and clean palm plantations. It tends to favor flatter regions with higher tree density and thicker canopies. It forages for food in marshy places along watercourses and on the bare forest floor with little vegetation.

The Dwarf Olive Ibis is a resident of São Tomé and Príncipe, an island republic in the Gulf of Guinea. It is sparsely dispersed throughout the southern part of the island, usually seen in a few spots but never in great numbers. It is believed to occupy a region of between 55 km2 to 130 km2.


Hunting is the biggest threat to this species since it is a large, friendly bird that inhabits native lowland trees, which are easier for hunters to reach.

A large-scale palm oil plantation is encroaching on its habitat and has already devastated the secondary forest belt in which ibises were once found. This belt served as a protective barrier for the majority of the population within the primary forest.

The forest is under attack from timber exploitation and agricultural development, which puts the Ibis in danger. 

Another risk is the infrastructure growth brought on by offshore oil extraction and the population and economic explosion.

Mona Monkey, African Civet, House Rats, and feral cats are all introduced species in the habitat of the Dwarf Ibis. All of them are potential predators of Ibis.

White-shouldered Ibis

IUCN Status: Critically Endangered.

The White-shouldered Ibis is a large wading bird. This Ibis is 60-85 cm tall as an adult, with males being significantly larger and having relatively longer bills than females. The appearance is brownish-black, with glossy blue-black wings and tail and a bare dark head characterized as blue or white.

A prominent neck collar made of a bluish-white strip of exposed skin that is wider in the rear and thinner in the front stretches from the chin to the nape at the skull base.

The distinct white patch on the top portion of the neck and chin in some individuals gives the White-shouldered Ibis its name. In flight, these white patches may seem like “white shoulders.”

How many are alive?

670 mature individuals

The species declined considerably over the 20th century after being widespread earlier in the century. The total population is predicted to be at least 1,000 individuals, with 670 of them being mature.

Where do they live?

Formerly, the species depended on wetlands and grasslands like pools, marshes, open grasslands, or watercourses with large rivers and sand and gravel bars. However, especially in Indochina, deciduous dipterocarp forest now seems to be of utmost importance.

In a research study of the local population along the Mekong River in Cambodia, it was discovered that the ibises used a combination of habitats for nesting, including dry inland dipterocarp forests and flooded riverine forests. This blend of habitats was not seen in any other population.

White-shouldered Ibis was previously far more common than it is now. The historical range spanned from Myanmar to Thailand, Cambodia, Malaysia, Laos, Vietnam, and north into China’s Yuman. The present population is tiny, with distribution limited to northern and eastern Cambodia, extreme southern Laos, southern Vietnam, and East Kalimantan.


The most severe threats to this species’ populations include habitat degradation, such as wetland draining for agricultural sectors like plantations, unsustainable rural development, altering land management through land acquisitions, and infrastructural facilities.

Due to the disturbance and killing of adult birds, eggs, and chicks for food, habitat degradation has also occurred, resulting in the loss of safe feeding, roosting, and nesting habitats.

Mammalian predators, including civets and the yellow-throated marten, might potentially pose a threat to ibis populations.

Giant Ibis

IUCN Status: Critically Endangered.

The Giant Ibis is a large, impressive bird that stands out since it is the only member of its genus and the largest bird in its family. The Giant Ibis is the national bird of Cambodia. 

The adult birds’ general plumage is a deep grayish-brown, and their heads and upper necks are bare and greyish. With a bare, greyish head and upper neck, the adults have dark grayish-brown overall plumage. The delicate silvery-grey wing tips also bear black crossbars, and the rear of the head and shoulder region are marked with dark bands. They have red eyes, orange legs, and a yellowish-brown beak. 

How many are alive?

194 mature individuals

The population was predicted to include at least 194 mature individuals or around 290 individuals overall. Over the past three generations, there is believed to have been a swift population reduction; this quick decline is thought to be continuing, and further rapid decreases are expected to happen over the next three generations.

Where do they live?

Although it appears to rely on soft mud near seasonal pools, it can be found in marshes, pools, large rivers, and seasonal water meadows in open, deciduous, lowland forest.

The species is primarily found in northern and eastern Cambodia but is very rare. A few birds from the same group have also been spotted in the far southern Lao PDR. It was historically present in Vietnam, but it may be extinct now.


According to the latest studies, the biggest threat to the species is habitat alteration brought on by extensive economic land transfers.

Due to hunting, egg collection, wetland drainage for cultivation, and deforestation, the population of this species have decreased.

Being sensitive to human presence, giant Ibis frequently live and forage in marsh regions many kilometers distant from villages. These waterbirds’ habitat choices are decreasing as rural areas, and private property projects are expanding.