Bird Buddy Blog

Back from extinction – recovered bird species

Courtesy of Wikimedia Commons

Worldwide, species of birds are in peril – some may even be extinct by the time you finish reading this. But all is not lost; some have flown back from the edge of extinction and continue to survive against all the odds, with a little help.

But first – some history. You may recall the ghoulish stories of the ill-fated passenger pigeon, said to have existed in such huge numbers in 19th century America that “the sky turned black”. Indeed, one flock passing overhead in 1866 took 14 hours to do so, allegedly 500 km long and 1.5 km wide. Many thought the entire population was there, which it could well have been. At that point it was estimated there were around 3 – 5 billion birds in existence.

Passing on

Passenger pigeons were a food source for Native Americans who avoided killing breeding adults, instead dining on the occasional juvenile. A balance was maintained: studies carried out suggest that known forestry techniques and food cohabitation had no impact on the number of pigeons. The diet of the passenger pigeon was beech nuts, acorns and other grains and seeds, also on the menu of the indigenous population.

Even though a species has been identified as at risk of extinction, it doesn’t have to mean that is what will happen.

With the arrival of settlers came two things – the wholesale murder of the pigeon’s main food competitor, and the introduction of intensive farming via deforestation. Pigeon numbers, now rising unchecked and more visible now many forests were gone, led to them being declared a pest and a threat to agriculture. Open season, cried the county mayors, and hunters began their purge. Methods ranged from attaching explosives to the base of trees and incinerating the lot, to poisoning corn, as well as the run-of-the-mill shooting them from the sky, which was easy to do given their numbers. As time passed, flocks became more concentrated as they migrated to fewer nesting sites, such as that dark day-long cloud in 1866.

Courtesy of Wikimedia Commons

The last large known nesting site was spotted in Michigan State in 1878, and hunting parties journeyed there on the new railroad network. Over 5 months, 50,000 birds were shot a day and surviving adults attempted nesting elsewhere, managing to limp on for fifteen or so years. One individual was sighted among a group of mourning doves and was shot in 1901, in Illinois, and there were no more verified sightings in the wild ever again. The last captive passenger pigeon, Martha, was found dead on the floor of her cage in Cincinnati Zoo on September 1st 1914, aged 29 and having never once laid an egg. In less than 70 years, a species of bird thought to be the world’s most numerous was wiped out.

Redress

The consequences of this animal genocide led to the creation of one of the world’s most respected and well-known environmental laws. Conservation became a concern for legislators and public alike when it was visibly obvious other species like bison and the whooping crane were headed the same way. In 1900, years before Martha passed but alas way too late for her, Congress enacted the Lacey Act, which over the decades sprawled into the Endangered Species Act (ESA), signed into law in 1973 by Richard Nixon. This act was created with the express intention of cancelling itself out, to become unnecessary. Alongside the International Union for Conservation of Nature (IUCN) Red List for the rest of the world, by categorising all of the known species in terms of their sustainability, it was hoped that steps could be taken in time to eventually delist all threatened species.

The irony is that some species classed as vulnerable could actually benefit from being downgraded to critical.

The ESA and the IUCN are still very much in existence, of course, as the concern for species is still very much necessary, but there have been triumphs along the way. Even though a species has been identified as at risk of extinction, it doesn’t have to mean that is what will happen. Since the inception of the ESA, a report in 2016 showed that 78% of the bird species listed have either been “upgraded” from threatened or endangered to stable with some, such as the bald eagle and peregrine falcon, achieving the perfect ratio of growth so as to be delisted completely, which is never a step taken lightly.

The saved and the saviours

Courtesy of Flickr

Pink pigeons are native to Mauritius, which also happens to be where our long-departed friend the dodo once lived, and in 1990 the conservation group Birdlife.org found that there were only 10 individuals left.

The Durrell Wildlife Conservation Trust and the Mauritian Wildlife Foundation combined to do what they could, and after two decades of captive breeding this serene and far too trusting bird went from critically endangered (i.e. in immediate threat of extinction) in 2000 to endangered in 2018, and is now classed as vulnerable, with numbers up into the 400s. This is of course still not many, but with genetic research being carried out to identify those pigeons with the “better” genes such as faster in flight or resistance to disease, the eventual hope is that the back-up captive breeding will help set them on their way.

The Chatham Islands is an archipelago of 10 islands that lies off the east coast of New Zealand’s South Island. In 1871 the first documented mention of a bird that lived throughout these islands was the black robin; they are indeed all black, legs and eyes too, except for the soles of their feet, which are bright yellow. The documentor was the professional collector and taxidermist Henry Travers, and in so doing, quite probably unleashed the forces that led to the robin’s subsequent decline. Rats on board his boats found a new home on the islands, and cats brought to keep control of the rats who kept running away down holes found it easier to prey on bird eggs.

A hundred years later, a thorough count of the black robin in 1976 found that they now only existed on one island called Little Mangere, and only seven were left; even worse, only two were female. Because of the coloured band on her leg, one of the females was named Old Blue by her rescuer, Don Merton, a wonderful conservationist who sadly died in 2011, but not before achieving one of the world’s most cherished conservation success stories.

Rehoming the birds on larger Mangere Island, a few years passed during which males disappeared and some chicks fledged, but numbers stayed the same, at 7, at one point dropping to a terrifying 5. A turning point came during one stormy night in 1979: one of the breeding pair’s newly hatched chicks was killed and the other egg was found cold. Merton removed the egg from the remnants of the nest, then noticed that the female, Green, immediately started to rebuild, making ready for another brood. This led Merton to think that these birds would try again if something happened to the nests and eggs “disappeared”. An experiment that sounded insane on paper – take the eggs and destroy the nests of the world’s rarest bird species – was started in haste. By placing the removed eggs in tomtit nests, a technique known as cross-fostering, Don Merton and his team managed to increase the population to a whopping 12 in 1982. Green’s chicks kept failing overall, but Old Blue and her partner Old Yellow raised 6 chicks, breeding among themselves thereafter, and every black robin in the world today is descended from those chicks. Black robins usually live to around 5 years of age, but almost as if she sensed what was at stake, Old Blue kept laying those eggs, finally growing too old to breed, and retired on South East Island, where she died at the age of 14. There are now around 250 wild individuals breeding successfully each year on Mangere and South East island.

Courtesy of Wikimedia Commons

Don Merton was also responsible for the survival of our last success story. He was actually working on saving this bird when he got the call about the black robins, and sped off to help them, of course leaving his work in equally capable hands.

The consensus seemed to be to grab one and stuff it while you can.

The kakapo is the world’s only alpine parrot, and can live to 95 years old. Endemic to New Zealand, the kakapo now inhabits mountainous terrain on islands off the coast of South Island, although Maori folklore has them documented as once living widespread across both islands in various habitats and at different altitudes. A combination of odd traits makes the kakapo exceedingly vulnerable: the world’s heaviest parrot, the only nocturnal parrot, and the only flightless parrot. Like most birds that live to be very old, they reach sexual maturity later, at around 5 years old, and they also only breed when the fruit of the rimu tree is ripe, which happens every 2 to 4 years.

European settlement and the rats and cats that came with them in the 1840s greatly reduced their numbers and by the late 19th century they were regarded as a collectible curiosity. Even though awareness of their decline was widespread, the consensus seemed to be to grab one and stuff it while you can. In the 1880s, stoats and weasels were introduced to the vast farmlands to keep rabbit numbers down, and that sealed their fate: the last time kakapos were seen on the North Island was in 1895.

Declared extinct on the North Island and in rapid decline on the South, numerous expeditions throughout the early and mid-1900s found only males in very small numbers. It was assumed that they would soon become extinct. In 1974, an expedition led by our tenacious friend Don Merton discovered that the males were engaged in some kind of booming performance, pumping themselves up with sharp intakes of breath and then emitting that air in short bursts as baritone notes, all sat at the end of tracks from their burrows around the edges of a scraped-out arena-like dustbowl. Merton speculated, again correctly, that this had to be some kind of courtship routine known as a lek, and hoped there must be females nearby. Sadly, none were found that time, but three years later the very first kakapo expedition to Stewart Island found the same bowl and track marks on day one. Shortly after, around 100 kakapos were discovered, females among them. The feral cat population was rife, so many of the birds were captured and relocated to other islands.

At the time none of New Zealand’s islands were predator-free, and recovery plans failed to take hold. Finally, in 1998 when David Attenborough lamented there were only 12 females left, two islands were also declared predator-free and gradually the birds began to breed in safety once more. Advances in GPS radio transmitters and a greater understanding of supplementary feeding to encourage more frequent breeding meant that in February 2020, 80 new chicks joined the world, and the kakapo is now considered to have almost reached the adult survival rates and productivity necessary for a sustained existence, but continued monitoring and assistance is needed. There are still only 208 birds alive today, and if you want to learn more you can read about the Kakapo Recovery Programme here.

The times they are a-changing

It leaves a sour taste in the mouth when you think that all of the above species and more had to get so perilously low before efforts were made to save them, and the irony is that some species classed as vulnerable could actually benefit from being downgraded to critical if that meant having more funds thrown at their conservation. The ESA’s efficacy has been eroded by “adjustments” made since 2016, but awareness of this situation is now taking hold and recent changes are expected to help any ground quite literally lost be recovered once more, one way or another. Against all odds, the men and women in conservation groups throughout the world will continue to work tirelessly where they can.