Dodo, giant tortoises and other ancient beasts of Madagascar were wiped out by the deadly combination of human activity and a MEGADROUGHT 1,000 years ago
- The researchers studied 8,000 years of climate data from rock and soil samples
- They found evidence of repeated mega droughts on the islands around that time
- The megafauna appeared to have survived previous episodes of prolonged drought
- What ultimately killed them coincided with the appearance of humans
The giant creatures of Madagascar and the Mascarene Islands were killed by a deadly combination of human activity and a major drought, according to a study of mineral samples.
The creatures, including dodos and giant tortoises, survived millennia of repeated droughts until humans arrived and eventually wiped them out.
Both islands suffered a “megafauna crash” between 1500 and 500 years ago which saw the extinction of significant species of large animals and birds over the same period.
Researchers from the University of Innsbruck studied climate data and mineral deposits in Madagascar and the Mascarene Islands dating back 8,000 years.
Experts found that it was likely a “double whammy” of intensified human activity combined with a particularly severe “mega drought” that doomed the creatures.
The creatures, including dodos and giant tortoises, survived through millennia of repeated droughts until humans arrived and eventually wiped them out, the authors say.
Nearly all of Madagascar’s megafauna, including the famous Dodo bird, gorilla-sized lemurs, giant tortoises, and the elephant bird that was 9 feet tall, vanished.
Theories suggested that this could have been due to a changing climate, large droughts for long periods of time, or excessive hunting by humans upon their arrival.
The Mascarene Islands, just east of Madagascar, are of particular interest because they are among the last islands on earth to be colonized by humans.
“Curiously, the islands’ megafauna crashed in just a couple of centuries after human settlement,” according to the research team.
The large and charismatic animals native to the islands managed to survive repeated mega droughts for thousands of years before humans arrived.
The team says a combination of hunting, deforestation and other human-caused stressors could have contributed significantly to the extinctions.
Although both Madagascar and the Mascarene Islands are considered “hotspots” of biodiversity, these islands have lost most of their endemic animals.
Lead researcher Hanying Li and colleagues reconstructed millennial-scale climate trends in calcite deposits from La Vierge cave in Rodrigues in the Mascarene Islands.
They determined that these deposits represent the climate record for the region in a broader sense, rather than just for that island.
Using these proxy data, the researchers defined periods of drier and wetter conditions, observing numerous longer and more severe drying trends during the late Holocene than when the megafauna went extinct.
This suggests that the climate and severity of the drought had been much worse at various times in the past than when the creatures went extinct.
The researchers rule out climate change as the sole cause and instead suggest that the impact of human colonization was a crucial contributor.
Almost all of Madagascar’s megafauna, including the famous Dodo bird, lemurs the size of a gorilla, giant tortoises, and the elephant bird which was 9 feet tall, vanished between 1500 and 500 years ago
The most recent of the drying trends in the region began about 1500 years ago, at a time when archaeological and proxy records began to show definitive signs of increased human presence on the island.
Ashish Sinha, a professor of earth sciences at California State University, said they can’t say that certain human activities were “the last straw that broke the camel’s back,” but records suggest it did.
This is because the megafauna had shown resistance to past climatic swings, suggesting that an additional stressor contributed to their extinction.
“There are still many pieces missing to fully solve the puzzle of the collapse of the megafauna. This study now provides an important multi-millennial climate context for megafaunal extinction, ”says Ny Rivao Voarintsoa of KU Leuven in Belgium.
The results were published in the journal Science Advances.
WHY DID THE DODO EXTINCT?
Little is known about the life of the dodo, despite the notoriety deriving from being one of the most famous extinct species in the world in history.
The bird got its name from the Portuguese word for fool after colonialists mocked its apparent lack of fear of human hunters.
The 3-foot (one meter) tall bird was wiped out by visiting sailors and the dogs, cats, pigs, and monkeys they brought to the island in the 17th century.
As the species lived in isolation in Mauritius for millions of years, the bird was fearless and its inability to fly made it easy prey.
Its last confirmed sighting dates back to 1662, after Dutch sailors first sighted the species only 64 years earlier in 1598.
Because it had evolved without predators, it has survived in bliss for centuries.
The arrival of human settlers on the islands meant that its numbers dwindled rapidly as it was eaten by the new species that invaded its habitat: humans.
Sailors and settlers ravaged the docile bird and went from a successful animal occupying an environmental niche with no predators to extinct in a single lifetime.
Other birds, such as the kakapo in New Zealand, have also evolved to be equally fearless, plump, and lazy.
As humans spread around the world, they also decimated the population numbers of these birds.
The kakapo is now an endangered species.
The dodo (left) is now extinct after a 17th-century onslaught by starving sailors destroyed the docile and fearless bird population. The kakapo (right) is an equally fearless and flightless bird that is now struggling to survive and is currently in danger