The "little dodo", a flightless parrot and the world's largest ibis are among the world's 100 most unusual and endangered birds, according to a new study.

Scientists from the Zoological Society of London (ZSL) and Yale University assessed the world's 9,993 bird species according to their evolutionary distinctiveness and global extinction risk to produce a list of the world's 100 most Evolutionarily Distinct and Globally Endangered (Edge) species.

Topping the list is the rare and striking giant ibis (Thaumatibis gigantea) – the world's largest ibis weighing in at 4.2kg and reaching more than one metre in height. With only 230 pairs estimated to remain in the wild, it is a critically endangered species. Habitat loss, human disturbance and hunting have reduced its range to an extremely small, declining population concentrated in Cambodia.

At number four on the list is the kakapo (Strigops habroptila), a nocturnal parrot that has evolved to be flightless due to the historic absence of mammalian predators in its New Zealand habitat. Hunting, the introduction of predators, forest clearance and habitat degradation have caused a catastrophic decline in numbers. It is now extinct in its natural range, and survives only on three small, intensively managed islands after being relocated. Dedicated conservation efforts have increased the population to 125 individuals.

The giant ibis, Thaumatibis gigantea, which lives in Cambodia, tops the list. Photograph: FLPA/Alamy

At number 34 on the list is the tooth-billed pigeon (Didunculus strigirostris), also known as the "little dodo" and found only on the island of Samoa. With less than 250 adults estimated to survive in the wold, conservationists say urgent action is needed to prevent the species from meeting the same fate as its closest relative, the dodo. Loss of its forest habitat to agriculture and cyclones, hunting and invasive species are the greatest threats to this bird.

Half of the 100 highest ranked Edge bird species are receiving little or no conservation attention, the study warned. Carly Waterman, Edge programme manager at ZSL, said: "We lament the extinction of the dodo, but without action we stand to lose one of its closest relatives, the tooth-billed pigeon or 'little dodo', and many other extraordinary birds.

"The release of the Edge birds list enables us to prioritise our conservation efforts in the face of a mounting list of endangered species. These one-of-a-kind birds illustrate the incredible diversity that exists in our natural world."

The Egyptian vulture ( Neophron percnopterus) is one of only three European species on the list. Photograph: Alamy

Only three of the 100 Edge species are found in Europe. The Egyptian vulture (Neophron percnopterus), ranked at number 30, is found from the Ukraine, south throughout the Balkans to Greece and Turkey, but is threatened by poisoning, poaching, electrocution and human disturbance. At number 49, the sociable lapwing (Vanellus gregarius) has been found in Armenia, Turkey and Ukraine – and once in Essex – while the slender-billed curlew (Numenius tenuirostris) breeds in Russia and spends the winter in several eastern European countries.

At number 11, the spoonbilled sandpiper (Eurynorhynchus pygmeus) has become a temporary resident of the UK, with a captive breeding population of 25 birds at the WWT Slimbridge reserve in Gloucestershire. Eggs from the birds will eventually be taken back to the Arctic in a bid to rebuild the rapidly declining wild population.

The top 100 Edge birds are found in more than 170 countries. The list includes species from 22 of the 29 living orders of birds, with 18% made up of Passeriformes, more commonly known as perching birds. Twelve of the top 100 species belong to the family Charadriiformes (sandpipers), 11 from the family Accipitridae, which includes eagles, hawks and kites, and eight from the family Columbiformes (doves and pigeons).

At number 11, the spoonbilled sandpiper ( Eurynorhynchus pygmeus), was a one-time resident of the UK after 13 young birds were flown over for captive breeding. iPhotograph: Chris Schenk/Corbis

Sixty-four per cent of the top 100 species are country endemic, meaning they are found nowhere else in the world. India has the highest number of Edge birds with 14 species, while the Philippines has the highest number of endemic Edge birds at nine species.

The study, "Distribution and conservation of global evolutionary distinctness in birds", published on Thursday in the journal Current Biology, found that species representing the most evolutionary history over the smallest area as well as some of the most threatened distinct species are often found far from places that are species-rich or already on the conservation radar.

Lead author Prof Walter Jetz from Yale University and Imperial College London, said: "By identifying these top 100 species, we can now focus our efforts on targeted conservation action and better monitoring to help ensure that they are still here for future generations to come. As we show, conservation priorities can be adjusted to better conserve the avian tree of life and the many important functions it provides."

The study was a collaboration between Yale University, Imperial College London, Sheffield University, University College London, Simon Fraser University and the University of Tasmania.

The world's 100 most unusual and endangered birds

Giant Ibis

New Caledonian Owlet-nightjar

California Condor

Kakapo

Kagu

Bengal Florican

Forest Owlet

Philippine Eagle

Christmas Island Frigatebird

Sumatran Ground-cuckoo

Spoon-billed Sandpiper

Northern Bald Ibis

Plains-wanderer

New Zealand Storm-petrel

Hooded Grebe

White-shouldered Ibis

Maleo

Black-hooded Coucal

Madagascar Serpent-eagle

Dwarf Olive Ibis

Rufous Scrub-bird

Noisy Scrub-bird

Junin Grebe

White-collared Kite

Congo Bay-owl

White-eyed River-martin

Red-headed Vulture

Secretarybird

Peruvian Diving-petrel

Egyptian Vulture

St Helena Plover

Australian Painted Snipe

Cuban Kite

Tooth-billed Pigeon

Nahan's Francolin

Sulu Hornbill

Shoebill

Purple-winged Ground-dove

Asian Crested Ibis

Sangihe Shrike-thrush

Jerdon's Courser

Lesser Florican

Kokako

Rufous-headed Hornbill

Masked Finfoot

Bahia Tapaculo

Waved Albatross

Stresemann's Bristlefront

Sociable Lapwing

Eskimo Curlew

Slender-billed Curlew

Bannerman's Turaco

Ashy Storm-petrel

Siberian Crane

White-throated Storm-petrel

Juan Fernandez Firecrown

Dark-winged Trumpeter

Uluguru Bush-shrike

Polynesian Ground-dove

Sichuan Jay

Mountain Serpent-eagle

Sulu Bleeding-heart

Zapata Rail

Mindoro Bleeding-heart

Kaka

Negros Bleeding-heart

Black Stilt

Makira Moorhen

Great Indian Bustard

Abbott's Booby

Kittlitz's Murrelet

Titicaca Grebe

Greater Adjutant

Western Bristlebird

Eastern Bristlebird

Shore Plover

Udzungwa Forest-partridge

Madagascar Fish-eagle

White-bellied Heron

Subdesert Mesite

Long-whiskered Owlet

Philippine Cockatoo

Spix's Macaw

South Island Wren

Crow Honeyeater

Northern Brown Kiwi

Banded Ground-cuckoo

Flores Hawk-eagle

Tachira Antpitta

Beck's Petrel

Cebu Flowerpecker

Blue-eyed Ground-dove

Javan Trogon

Pulitzer's Longbill

Alagoas Antwren

Pernambuco Pygmy-owl

Jamaica Petrel

Grenada Dove

Wood Snipe

Rio de Janeiro Antwren

• This article was corrected on 11 April 2014 because in several places it referred to the "most unique" birds. As our style guide points out, unique is "one of a kind, so cannot be qualified as 'absolutely unique', 'very unique', etc".