One of the world's largest tiger populations could be wiped out this century as rising seas threaten to engulf their dwindling habitat in the coastal mangrove forests of Bangladesh, researchers said Wednesday.
A projected sea-level rise of 11 inches above 2000 levels along coastal Bangladesh by 2070 may cause the remaining tiger habitat in the Sundarbans to decline by 96 percent, pushing the total population to as few as five tigers, according to the new World Wildlife Fund-led study published this month in the peer-reviewed journal, Climatic Change.
Studies in the past have shown that tiger populations below 25 have difficulty surviving.
Colby Loucks, WWF's deputy director of conservation science, said in a statement that tigers were capable of thriving in a wide range of habitats from the snowy forests of Russia to the tropical forests of Indonesia, but the projected sea-level rise in Bangladesh would likely outpace the tiger's ability to adapt.
"If we don't take steps to address the impacts of climate change on the Sundarbans, the only way its tigers will survive this century is with scuba gear," said Loucks, the lead author of the study.
Tigers are among the world's most threatened species, with just 3,200 estimated left in the wild following widespread poaching and deforestation. There are believed to be close to 250 tigers on the Indian side of the Sundarbans, and another 250 on the Bangladesh side.
The study is the first to assess the impact of a sea-level rise on the tigers, and its conclusions were made possible by advances in the data collected on the Sundarbans, although it does not assess the impact on the Indian side of the forest.
The Bangladesh government said it was working with several international groups to address the threats to the tigers highlighted in the study.
Aminul Islam, a Bangladeshi tiger expert, said studies suggested a sea-level rise was likely, but remained hopeful the tigers still could be saved as the deposit of silt in the delta region of the Sundarbans could compensate for the rising water.
"Different water modeling studies suggest that the issue of sea-level rise is a reality, and may affect the ecosystem of the Sundarbans," Islam said. "But I am also optimistic. ... If the rate of siltration is higher than the pace of sea-level rise, things would be different."
The Sundarbans lies at the mouth of the Ganges River. It is a 3,700-square-mile region of mangrove forest and islands. The tiger habitat is already declining due to farming, expanding villages and fisheries in what is one of the world's most densely populated countries. Millions live in the Sundarbans, and about two dozen people are killed by tigers every year.
Rising sea levels and worsening floods have already forced villagers who can no longer grow enough crops to venture into the tigers' domain in search of fish, crabs and honey to sell. And tigers are creeping ever closer to villagers in search of fresh water and food, according to scientists who track their movement.
The study calls for local authorities to take immediate steps to conserve and expand mangroves while preventing poaching. Neighboring countries should increase freshwater flows to the coastal region to support agriculture and replenishment of the land, it said.