In the light of the successful reintroduction of Guam Rail, we consider the prospects of the five remaining bird species categorised as Extinct in the Wild – all of which face unique barriers to re-entry.

Guam Kingfisher © Guam Department of Agriculture

By James Lowen

Extinction is forever. Or is it? Granted, there’s no way to reincarnate the Dodo Rapphus cucullatus. Yet five species that have vanished from forests or  skies still survive in captivity. They may live behind bars, but they at least exist. Classified as ‘Extinct in the Wild’, these ‘lucky few’ have at least a smidgeon of hope of joining Guam Rail Hypotaenidia owstoni and California Condor Gymnogyps californianus in coming back from beyond the brink. So what plans are there to reintroduce the quintet?

Conservation breeding programmes – ex-situ fostering of a species’ population, usually in zoos or aviaries – have become an increasingly valuable tool thanks to what BirdLife International’s Nigel Collar and Stuart Butchart described in a 2014 scientific paper as “the increasing rapprochement between aviculture and conservation organisations”. The duo identified 257 bird species where captive breeding should be contemplated, including 13 where they judged it ‘necessary’.

Reintroductions are complex, requiring long-term commitment from a network of organisations. The birds featured here – three from Pacific islands, two Brazilian – tell different stories. Two are benefiting from painstaking recent reintroductions, with another planned for 2021. But there’s no date set for the others.

It is right not to rush, because conditions for success are exacting. The captive supply must be sufficiently high: the number of Guam Rails already released is considerably more than that of the entire caged population of Guam Kingfisher Todriramphus cinnamominus. Reintroduced birds must be genetically robust, able to fend for themselves, ward off predators and succeed as parents. The release site must be ready to receive its precious new inhabitants: there’s no point releasing a species dependent on extensive intact forest into a small, scrappy woodlot. Restoration of habitat – whole landscapes, even – may be needed. Alien invasive predators must be removed and local communities engaged to mitigate birds being persecuted or purloined.

Reintroductions are also costly. But lofty price tags must be viewed in perspective: 205 films have wallowed in a budget bigger than the forecast cost ($145 million) of the 50-year plan envisaged for Guam Kingfisher. And when that reintroduction works, the return on investment is massive.

Hawaiian Crow Corvus Hawaiiensis

Hawaiian Crow ©Lynx Edicions

Where did it live?

Hawaiian Crow used to inhabit Hawaii. The last wild birds were confined to higher-elevation forest around Kona.

How many are left?

Following an unsuccessful reintroduction during the 1990s, the last two truly wild individuals of this species disappeared in 2002. The captive population has grown from 24 birds in 1999 to around 114 (including 20 breeding pairs) today. Following a second reintroduction that started in 2016, 28 captive-bred birds now live wild.

Why did it disappear?

The crow’s forest habitat was extensively degraded by logging and agriculture, with understorey food plants being browsed by cattle, sheep and goats. Forest fragmentation made it harder for birds to exploit patchy food resources. The crow’s confiding nature rendered it susceptible to human persecution, predation by the native Hawaiian Hawk Buteo solitarius (Near Threatened) and non-native mammals, and infection by other invasive alien species such as mosquitoes.

What reintroduction plans are in place?

The latest reintroduction initiative, a partnership between San Diego Zoo and Hawaiian/US government bodies, started in 2016. Birds have been gradually let free into Pu’u Maka’ala Natural Area Reserve on Mauna Loa. By spring 2019, three pairs had shown breeding behaviours, including nest-building: “A huge step forward for their recovery as a species,” says the zoo’s Alison Greggor.

What challenges lie ahead?

Predation remains an issue, and a community outreach programme is seeking to reduce human persecution (which is partly why the first reintroduction failed). To prevent habitat degradation at the reintroduction site, ungulates have been removed, the forest fenced and native vegetation restored. The same is needed at a second intended site. Finally, genetic in-breeding in the captive population may be an issue.

Alagoas Curassow Mitu mitu

Alagoas Curassow ©Lynx Edicions

Where did it live?

The Atlantic Forest of Alagoas and Pernambuco states in northeast Brazil.

How many are left?

In the wild, the last sightings were in the mid-1980s. From a starting point of just three individuals, the captive population now numbers over 100 individuals.

Why did it disappear?

As a large bird, it needed plenty of living space, but its lowland forest habitat was constantly being felled. Deforestation in northeast Brazil accelerated during the late 1970s, to make way for sugarcane crops. A meaty bird, it was also a target for poachers, which likely exacerbated its demise.

What reintroduction plans are in place?

In September 2019, exactly 40 years after Brazilian biologist Pedro Nardelli started breeding wild-caught Alagoas Curassows, three captive-raised pairs were flown from Belo Horizonte to Maceió for release nearby into the 1,000-hectare protected forest of Mata do Cedro. “We plan to release 15 pairs over the next two or three years, [but] it’s too early to judge success,” says Luis Fábio Silveira (Museum of Zoology, São Paulo University).

What challenges lie ahead?

Alagoas is extensively deforested with few remaining fragments large enough for viable curassow populations. “Habitat recovery and protection must be run in parallel with the reintroduction,” says Pedro Develey of SAVE Brasil (BirdLife Partner). “There’s already a ‘vegetation debt’. Landowners are already legally obliged to restore 90,000 hectares of forest.” Alexander Lees (Manchester Metropolitan University) hopes that reintroduction will “catalyse landscape-scale conservation connecting forest patches, hopefully through land purchase and protection or subsidies for restoration”. Even then, in this impoverished region, curassows risk ending up in a pot. One hunter could ruin the whole project in a matter of hours.

Spix’s Macaw Cyanopsitta Spixii

Spix’s Macaw ©Lynx Edicions

Where did it live?

For 150 years, its distribution was unknown. In 1985–86, three birds were finally tracked down to caatinga dry forest around the São Francisco River in Bahia, northeast Brazil.

How many are left?

The final wild Spix’s Macaw survived until late 2000. (An individual near Curaçá in 2016 is thought to have been of captive origin.) In the 2019 Red List update, the species was finally declared Extinct in the Wild. Meanwhile, the captive population has tripled in 20 years to around 160.

Why did it disappear?

Three centuries of development in north Bahia have destroyed the macaw’s gallery forest habitat. This was exacerbated by trapping for illegal trade in live birds – even the birds discovered in the mid-1980s were soon captured.

What reintroduction plans are in place?

Brazil’s Chico Mendes Institute for Biodiversity Conservation (ICMBio) is overseeing recovery. In August 2019, its updated action plan for the targeted release of Spix’s Macaws to a new 29,000-hectare reserve near Curaçá, created thanks to advocacy by SAVE Brasil. An agreement has been reached to transfer 50 Spix’s from Germany to a purpose-built aviary there during February 2020. The project team will learn lessons from a trial release of Blue-winged Macaws Primolius maracana (Near Threatened), before attempting to reintroduce Spix’s, hopefully in 2021.

What challenges lie ahead?

“The main challenge is to teach captive birds to be wild,” says Develey. In particular, captive pairs need to learn how to parent successfully if they are to breed in the wild without human intervention. Working with local people will be key, both to address overgrazing (which restricts regeneration of native vegetation) and the risk of released birds being captured and sold illegally. Additional land purchase may be necessary to ensure adequate protection of suitable habitat.

Guam Kingfisher Todiramphus cinnamominus

Guam Kingfisher ©Lynx Edicions

Where did it live?

Known locally as sihek, this kingfisher was endemic to Guam, a US territory that lies within the Mariana Archipelago in the western Pacific Ocean.

How many are left?

29 wild birds were taken into captivity in 1986; the last wild individual was seen in 1988. Today, a global captive population of 141 birds is spread between the USA and Guam.

Why did it disappear?

We explore the devastating impact of the Brown Tree Snake’s arrival on Guam in this recent article. Free of predators, the serpent’s population has ballooned to two million.

What reintroduction plans are in place?

The current captive population of 141 individuals found throughout various zoological facilities is at risk unless breeding and carrying capacity can be increased, and releases begin.  Various islands outside the native range have been identified, as well as a snake-controlled location on Guam. In 2019, the Guam Department of Agriculture, US Fish & Wildlife Service and the Association of Zoos and Aquarium Ko’ko’ Species Survival Plan teamed up with the IUCN Conservation Translocation Specialist Group to develop a strategy, with the first releases expected in early 2021.

What challenges lie ahead?

One of the many challenges is identifying the release site(s). Since locations outside its the native range are under consideration, permits and biological assessments as well as community approval (from both Guam and the host location) are needed prior to any release. As opposed to the Guam Rail, the kingfisher can fly, meaning there are concerns reintroduced birds may leave snake-supressed areas on Guam. Despite an $8 million eradication programme, snakes remain abundant. Proposed solutions include using snake-proof nest barriers to protect this cavity-nester.

Socorro Dove Zenaida graysoni

Socorro Dove ©Lynx Edicions

Where did it live?

Socorro, an island of just 132 km² in the Revillagigedo archipelago, 600 km west of mainland Mexico.

How many are left?

Judged common in 1958, Socorro Dove has not been recorded in the wild since 1972. About 150 captive birds survive in forty locations across 15 countries.

Why did it disappear?

Predation by feral cats was formerly thought to be the main cause, but clarity on the timing of the felines’ arrival suggests that they may simply have been the final straw. Key reasons for the ground-dwelling dove’s demise are now thought to consist of hunting for food by local people and overgrazing by sheep of the native forest understorey.

What reintroduction plans are in place?

In 1925, several Socorro Doves were taken into captivity, initiating nearly a century of ex-situ breeding that is now guided by an official European Endangered Species Programme. In 2013, breeders transferred six birds to a Mexican zoo, forming a national source ahead of eventual return to Socorro. “Sheep removal on the island was completed in 2012,”, says Juan Martínez-Gómez (Institute of Ecology, Mexico), following which vegetation has recovered rapidly. However, feral cats persist on the island. No date has yet been set for the dove’s return to Socorro.

What challenges lie ahead?

“Restoring forest cover is key to achieving a viable dove population in the long term,” says Martínez-Gómez. His team has already successfully cultivated and transplanted several hundred endemic trees and shrubs, with more to follow. Off-island, care is needed to ensure the genetic integrity and health of captive-bred doves, particularly as many have transpired to be hybrids with Mourning Doves Zenaida macroura. Martínez-Gómez urges patience: “Establishing a viable population will take decades,” he says.

Find out about BirdLife’s Preventing Extinctions Programme here.