Habitats for Asian elephants have decreased by more than 64% across the continent, equating to about 3.3 million square kilometers -- more than 850 million acres -- since the year 1700, according to a new study published Thursday in Scientific Reports.
The timeframe coincides with colonial-era use of land in South Asia and the agricultural intensification that followed.
Biologically, elephants are important for their ecosystems and are nicknamed the "ecosystem engineers," author Shermin de Silva, an assistant professor of ecology at the University of California, San Diego, and founder of elephant conservation nonprofit Trunks & Leaves, told ABC News.
The findings are significant because Asian elephants are extremely adaptable and able to live in a range of habitats, including open grasslands that are relatively dry and lush, dense rainforests, De Silva said.
"That makes them a really good indicator species or a proxy for lots of different types of ecosystems," she said.
The study underscores how much the landscapes in Asia have changed over time, De Silva said.
In the late 1600s and early 1700s, a "massive change" began to take place for the elephants, researchers found. Land use practices that began in the colonial era gave way to the industrial revolution in Europe, leading to the exploitation of resources around the world, De Silva said.
"These landscapes that were previously appropriate for elephants ... we lost nearly two thirds of them over this past 300-year period," De Silva said. "And what we have today is highly fragmented."
Researchers also believe the rise of industrial agriculture in the mid-20th century also contributed to the severe habitat loss, De Silva said.
Mainland China, India, Bangladesh, Thailand, Vietnam and Sumatra have each lost more than half of their suitable elephant habitat range, the researchers said. The greatest declines occurred in China and India.
The only exception was in Borneo -- which has actually gained suitable habitat for elephants because they are restricted to one part of the island, De Silva said.
The findings are helping scientists to prevent populations from dropping further, especially since elephants do not breed quickly, which could lead to a slow population collapse, De Silva said.
Asian elephants are listed as endangered on the International Union for Conservation of Nature's Red List of Threatened Species.
In regions where Asian elephants exist today, only 50% of the land is suitable for them to live, De Silva said.
And an increase of elephant-human conflict has resulted from the loss of suitable habitat.
"As a result, elephants can be killed. People can also be injured or killed," De Silva said.