Falkland Islands wolves mystery solved

Old Falkland wolf family tree

From Wildlife Extra:

Mystery solved – Where did Falkland Islands wolves come from?

Ancient DNA solves 320-year-old mystery

March 2013. University of Adelaide researchers have found the answer to one of natural history’s most intriguing puzzles – the origins of the now extinct Falkland Islands wolf and how it came to be the only land-based mammal on the isolated islands – 460km from the nearest land, Argentina.
Previous theories have suggested the wolf somehow rafted on ice or vegetation, crossed via a now-submerged land bridge or was even semi-domesticated and transported by early South American humans.

Darwin questions

The 320-year-old mystery was first recorded by early British explorers in 1690 and raised again by Charles Darwin following his encounter with the famously tame species on his Beagle voyage in 1834.

New stuffed specimen found in New Zealand

Researchers from the University’s Australian Centre for Ancient DNA (ACAD) extracted tiny pieces of tissue from the skull of a specimen collected personally by Darwin. They also used samples from a previously unknown specimen, which was recently re-discovered as a stuffed exhibit in the attic of Otago Museum in New Zealand.

16,000 years ago

The findings concluded that, unlike earlier theories, the Falkland Islands wolf (Dusicyon australis) only became isolated about 16,000 years ago around the peak of the last glacial period.

“Previous studies used ancient DNA from museum specimens to suggest that the Falkland Islands wolf diverged genetically from its closest living relative, the South American maned wolf (Chrysocyon brachyurus) around seven million years ago. As a result, they estimated that the wolf colonised the islands about 330,000 years ago by unknown means,” says Associate Professor Jeremy Austin, Deputy Director of ACAD and co-lead author with Dr Julien Soubrier.

“Critically, however, these early studies hadn’t included an extinct relative from the mainland, the fox-like Dusicyon avus. We extracted ancient DNA from six specimens of D. avus collected across Argentina and Chile, and made comparisons with a wide group of extinct and living species in the same family.”

ACAD’s analyses showed that D. avus was the closest relative of the Falkland Islands wolf and they separated only 16,000 years ago – but the question of how the island colonisation came about remained. The absence of other mammals argued against any land bridge connection to the mainland.

Eureka moment

“The Eureka moment was finding evidence of submarine terraces off the coast of Argentina,” says study leader Professor Alan Cooper. “They recorded the dramatically lowered sea levels during the Last Glacial Maximum (around 25-18,000 years ago).”

“At that time, there was a shallow and narrow (around 20km) strait between the islands and the mainland, allowing the Falkland Islands wolf to cross when the sea was frozen over, probably while pursuing marine prey like seals or penguins. Other small mammals like rats weren’t able to cross the ice.”

The study was published in Nature Communications.

Good black-browed albatross news

This video, recorded on South Georgia, is called Black-browed albatross chicks.

From BirdLife:

Black-browed Albatross shows population increase

Tue, July 24, 2012

A new report indicates a healthy increase in the numbers of Black-browed Albatrosses breeding in the Falkland Islands (Las Malvinas). The report, submitted to the Environment Committee of the Falkland Islands Government, indicated that recent and historical survey results show an increase in this threatened species.

Black-browed Albatross is currently classified as Endangered by BirdLife on behalf of the IUCN Red List. Over two-thirds of the global population breed in the Falkland Islands, so the status of the Falklands population has significant bearing on the global conservation status of the species.

Within the Falkland Islands (Las Malvinas) different methods have been used independently to census the Black-browed Albatross population. Ian, and more recently, Georgina Strange have conducted aerial photographic surveys of colonies in the Falkland Islands since 1964, with archipelago-wide surveys in 1986, 2005 and 2010. Members of Falklands Conservation have carried out ground and boat-based surveys of the Falklands population in 2000, 2005 and 2010. Up until and including the 2005 census results, these initiatives reported contrasting population trends. The aerial based surveys indicated an increase in the population between the mid 1980s and 2005 and the ground based surveys a decline between 1995 and 2005.

However, the aerial and ground based surveys conducted in 2010 both reveal an increase in the population between 2005 and 2010 of at least 4% per annum. The positive trends from both of these surveys is further supported by favourable survival and breeding data from an ongoing study carried out by scientists at New Island (one of the twelve breeding sites in the Falkland Islands (Las Malvinas)), and an additional aerial photographic survey carried out later in the 2010 breeding season. The breeding population estimate obtained from the 2010 ground-based survey was larger than the estimate for 2000. Furthermore, the 2010 ground-based estimates for the two largest colonies in the Falklands (at Steeple Jason and Beauchêne islands) were similar to those derived from surveys carried out in the 1980s.
Dr Cleo Small from RSPB/BirdLife’s Global Seabird Programme said: “When 17 out of the world’s 22 species of albatross are listed as threatened with extinction, it is hugely encouraging that Black-browed Albatross colonies in the Falkland Islands are now known to be increasing. There is still some way to go – with the UK Overseas Territories other major population on South Georgia continuing to decline. But this result gives us great hope for turning around the fortunes of other albatrosses. Bycatch in fisheries is their main threat, and efforts are underway in many longline and trawl fleets worldwide to reduce the numbers killed. If we can keep this up, there is real hope that the black-browed albatross will set a trend for the future.”

Dr Anton Wolfaardt, ACAP (Agreement on the Conservation of Albatrosses and Petrels) officer for the UK South Atlantic Overseas Territories and author of the report said: “The exact reasons for the increase are not entirely clear, but efforts to reduce seabird bycatch, and beneficial feeding conditions, are likely to have contributed.” On the basis of the reported results, and the fact that the Falklands population comprises approximately 70% of the global total, the report recommends that consideration should be given to downlisting the species from Endangered. The report has been submitted to BirdLife International for use in the Red List assessment process. The report also recommends that efforts to further improve seabird bycatch mitigation should continue, both to buffer the local population against possible future changes, and to improve the conservation status of other populations and species.

Falkland skuas decline

This video is called Penguins of the Falkland Islands I: Mostly Gentoos.

This video is called Penguins of the Falkland Islands II: King Penguins.

From the BBC:

Wednesday, 6 April 2011

Bird colony survey reveals decline of Falkland skuas

By Matt Walker
Editor, Earth News

The number of Falkland skuas has declined by almost half in just five years, a survey of the bird’s largest breeding ground reveals.

It is unclear why the population has crashed on New Island, on the west of the Falkland Islands.

Something appears to be limiting the birds’ ability to reproduce, say scientists.

That raises questions over the health of the wider marine environment in the south-west Atlantic Ocean.

Skuas are gull-like birds that nest on the ground, with species living from the Arctic to Antarctica.

The Falkland skua is a subspecies of the brown skua.

“Although brown skuas have been the subject of many studies, virtually nothing has been done on the Falklands subspecies,” Dr Paulo Catry of the Museum of Natural History in Lisbon, Portugal, told BBC News.

So he and colleagues from Portugal and the UK conducted two surveys, five years apart, of the largest population of Falkland skuas, which nest on New Island.

The results have been published in the journal Polar Biology.

“Falkland skuas are really tame and do not hide their nests, which are placed in the open ground, which made the censuses quite easy, even if labour intensive for the amount of ground that needed to be covered.

“Birds are so tame that many individuals will remain sitting on the eggs even if you approach and touch them,” he said.

Overall, the number of Falkland skua territories on New Island suffered a reduction of 47.5% in the five years between the two surveys, conducted in 2004 and 2009, which equates to a decline of 12.1% per year.

The Falkland skua situation is “abnormal”

“In fact, long-lived seabirds like skuas usually change their numbers slowly and this situation cannot be considered as ‘normal’.”

The reason for the crash is not clear, and just a few thousand pairs of Falkland skuas now remain worldwide, living on the Islands and a few along the coast of Argentina.

“We were very surprised that the decline in numbers was so fast, particularly considering that other seabirds on New Island seem to have been doing quite well over the same past five to six years,” he told the BBC.

Brown skuas generally enjoy a high breeding success, with each pair raising a chick a year on average.

But Falkland skuas are today producing just 0.28 chicks on average per pair each year.

Large skuas, and Falkland skuas in particular, rarely start nesting before they are six years old.

Usually, immature skuas gather at specific sites, known as “clubs”, on the nesting islands in the years before they start breeding.

In large colonies, hundreds of birds gather in these clubs.

But Dr Catry’s team has never managed to locate any club site at New Island.

The odds are against successfully raising a chick

“This decline seems to be linked to an abnormally low reproductive output, the causes of which are still to be identified,” said Dr Catry.

“We are currently working on these questions. They are important not only for the sake of Falkland skuas, but more generally, for the marine environment of the Falkland Islands.”

One possibility is that the Falkland skua is suffering at the hands of a competitor.

Falkland skuas prey on a smaller bird, the thin-billed prion, and its eggs.

But so too does another prion predator, the striated caracara, a falcon-like bird of prey.

The caracara’s population has grown 15% a year in recent years, producing 2.5 chicks per nest per year, on average.

However, the Falkland skua’s demise may be linked to wider problems.

“Falkland skuas are top predators of marine ecosystems. They will take fish, squid, crustaceans, and they are also important predators of other seabirds,” said Dr Catry.

“If something is not well with them, it may mean that something is not well with the rich Patagonian shelf ecosystem.

“Many Falkland Island seabirds have known important declines over the past decades. We need to learn more about what is driving these changes, and skuas may help us with that.”

Antarctic penguins in trouble due to climate change: here.

Penguin-cam from the Antarctic: here.

Penguin declines may come down to krill: Lack of food appears to be hurting birds on the Antarctic Peninsula: here.

Falkland (Malvinas) islands: rare subantarctic birds

Striated caracaras

From BirdLife:

The Falkland Islands are a remote sub-Antarctic archipelago in the South Atlantic particularly significant for their bird life.

They are home to vast colonies of breeding seabirds, including albatross and penguins.

They contain two endemic birds, found nowhere else in the world—Cobb’s Wren Troglodytes cobbi (Vulnerable) and the Falkland Steamerduck Tachyeres brachypterus.

There are 13 Falkland races, or sub-species, and a number of other birds with their stronghold in the Islands—in particular the Striated Caracara Phalcoboenus australis (Near Threatened).

Patagonian toothfish fishery: here.

Spanish language guide for South American birds: here.

First nest of Red-throated Caracara in Central America for 50 years: here.