Scientists say the consequences of human activity on the island of Madagascar will have a much longer impact on the island than previously realized.
According to a study published Tuesday in Nature Communications, it could take millions of years for the island's biodiversity to recover from human-induced extinctions.
Lowland stripes . A species of tenrec, a diverse and unique group of mammals, found only in Madagascar.
There are many unique animal species on the island, including the Madagascar sucker-footed bat, an ancient family of bats found only in Madagascar; Lowland striped tenrec, from a variety of mammals found only in Madagascar; the world's smallest chameleon; Nest; and ring-tailed lemurs.
Studies show that at least 17 species of lemurs on the island are extinct, and several others are threatened with extinction due to the effects of human activities such as deforestation, hunting, and climate change.
Researchers from the United States, Europe, and Madagascar, trying to quantify the extent to which humans have disrupted Madagascar's fauna and predict future outcomes, have brought together a comprehensive dataset of 249 living and recently extinct mammals, including species that disappeared shortly after humans first arrived on the island, such as giant lemurs and pygmy hippos.
The scientists then combined this data with statistical models of the species' evolutionary history and their geographic distribution over time.
Madagascar suck-cup-footed bat (Myzopoda aurita). The Madagascar sucker-footed bats belong to the ancient bat family found only in Madagascar.
Luis Valente, author and researcher at the Center for Natural Biological Diversity and the University of Groningen in the Netherlands, told ABC News that the impacts far exceeded scientists' expectations.
Researchers have found that if current threats are not mitigated, it could take Madagascar 3 million years to recover species that disappeared after human arrival.
In addition, the researchers say it could take more than 20 million years to recover if currently threatened species also disappear.
"We knew that there were a lot of species threatened in Madagascar, but we didn't expect it to take so long to recover them," Valente said.
See a brown rat lemur in Madagascar's Ranomafana National Park
According to the paper, even bat species that are easier to colonize islands than flightless mammals could take about 3 million years to recover. The number of endangered mammals in Madagascar has increased dramatically over the past decade, from 56 in 2010 to 128 in 2021.
Valente said this timescale, known as "evolutionary regression time," will take longer than other island nations because human impact is limited compared to places like New Zealand. He added that while humans first arrived in Madagascar about 2,500 years ago, much of the damage caused by human expansion has been done over the past 100 years, with much of the island's forests in pristine condition.
Essentially, Madagascar could lose more in the future because it is "catching up" with other island nations in terms of harmful human activities, Valente said.
"We have lost more history in Madagascar than any other system we have studied," Valeant said.
Varente said deforestation to grow crops was a major cause of human expansion in the last century, but communities have also begun to invade forests further to hunt bushmeat such as lemurs. Coupled with climate change, the lifespans of many species on the island are at risk.
The findings suggest that immediate conservation measures are needed to avoid long-term biodiversity loss, including plans to improve the socio-economic of local populations, reduce forest loss in the remaining natural habitats, and limit the exploitation of artisanal and commercial resources, such as hardwood, as well as animals used in the bushmeat trade, the scientists said.
Valente said the expansion of protected areas and enforcement will also be necessary.
Scientists say Madagascar's biodiversity could be affected for millions of years if timely conservation action is not taken.