Cows abandoned on a deserted island in the middle of the ocean 150 years ago develop a unique evolutionary story with an unsettling ending

For well over a century, a remote island in the Southern Indian Ocean was home to a rare breed of feral cattle - until the animals were controversially culled.

Understood to have been genetically closest to the Jersey breed, the bovine population thrived on Amsterdam Island, a French territory around 900 miles from the nearest land, after a small number of founding cattle were abandoned there by failed settlers in the late 19th century.

What to know about Amsterdam Island

Home to “only sparse vegetation”, per a description by the specialist wildlife blog Les Biodiversitaires, Amsterdam Island is a windswept location which currently does not have any permanent residents.

It is one of a number of islands that make up the French Southern and Antarctic Lands (TAAF), in an area that experiences “changing weather, important rainfalls and temperatures that range from -5 °C to 20 °C,” explains the Overseas Countries and Territories Association.

How did the cattle come to be on Amsterdam Island?

According to several accounts, the Amsterdam Island cattle arrived as a group of five or six animals in around 1870, having been brought to the island by a farmer and his family.

Named Heurtin, the farmer had travelled from another French island, Réunion, located in the Indian Ocean around 1,700 miles to the west.

But just a matter of months after arriving, the farmer and his family abandoned their attempts to settle there, went back to Réunion - and left the cattle to their fate.

“They [the settlers] were forced to return to Réunion by the difficult climate conditions, adaptation problems and isolation, leaving the cattle behind,” reads a paper in Futura magazine, written by a team of experts led by Laurence Flori, a research director at the Umr Selmet livestock research center.

However, while Heurtin and his family were unable to settle on Amsterdam Island, it appears the cattle had less trouble adapting to their surroundings.

Cattle’s population grows and grows

According to Futura, it was the apparent genetic links with Jersey cattle, a British breed, that proved a major factor in the population’s unsupervised survival.

The paper’s authors contend that the conditions on Jersey, an island located in the English Channel between the U.K. and France, are “relatively similar to those of Amsterdam Island”.

What’s more, the cattle seem to have avoided the harmful genetic mutations typically associated with heavy inbreeding, the researchers note.

By the end of the 20th century, the Amsterdam Island cattle’s population numbered around 2,000, according to a study by D. Berteaux and T. Micol of the Centre d’Etudes Biologiques de Chizé.

Described by Berteaux and Micol as noticeably “small bodied”, with “horns of a medium length, and [coats bearing] many different patterns of colour”, the island’s cattle survived with “no supplementary feeding, mineral supplementation or routine emergency veterinary care”, the scientists say.

Berteaux and Micol add that the cattle may have benefited from “unusual adaptations, particularly with regard to water economy”.

But a problem emerged: the animals’ grazing led them to become a major threat to Amsterdam Island’s ecosystem.

Which species were threatened by the cattle?

Notably, the cattle began to encroach on the breeding territory of the Amsterdam albatross, a bird species only found on the island. (In 2019, the island’s population of birds contributed to its addition to UNESCO’s list of World Heritage sites.)

Overgrazing had also placed the shrub Phylica arborea in danger of being wiped out, so TAAF administrators initially opted to herd the cows into a fenced-off section of the island.

“Cattle were removed from the larger part, allowing the terrestrial ecosystem to become rehabilitated,” Berteaux and Micol say.

After the turn of the 21st century, however, the decision was made to cull the population completely.

Opponents criticize “hasty” cull

While the team of experts behind the Futura paper do not appear to dispute the need to “safeguard endemic wild species” on Amsterdam Island, they describe the eradication of the cattle as “hasty”, citing the “ecological and evolutionary importance of this unique bovine population”.

They note that the purge was carried out in the face of petitions sent to TAAF administrators and despite complaints being put forward in the French parliament.

Les Biodiversitaires, meanwhile, brands the cull a “scandal”.

Suggesting that it is ironic it took place in 2010 - the International Year of Biodiversity - the blog said in 2011: “Here is a cattle population, genetically isolated for 140 years, living in extreme climate conditions, with its own genetic heritage, that is slaughtered like common game.”

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