There are less than 8,000 tigers in the world, down from an estimated 100,000 a century ago. The fate of the last remaining tigers of Sri Lanka is particularly delicate: The populations of people around and near their habitat, however scarce, have become increasingly dense and cut off from available land. Last year, Wildlife Conservation Society experts succeeded in convincing local villagers to abandon two tiger reserves. But that wasn’t enough for the lion’s share of the reserve. The reserve’s tigers were the survivors of the original phase of the Big Cats Initiative designed to protect them in the northern part of the country. Now WCS needs $4 million to protect 50 tigers and to expand three others. Late last month, the conservation group announced it had launched a campaign to fund an extra 50 tigers, as well as to protect the leopards left in the remaining reserve. So far it has raised only about $1 million. The most common way to finance efforts to save tigers is through buying government land, since there is no money from the government to buy tiger land. Last month, the Central Bank of Sri Lanka announced that because of increased land prices, it would issue bonds to the government of private firms that own large portions of Sri Lanka. That will allow the bank to take a portion of those bonds and use it to buy property that could be used for the Big Cats Initiative. Advocates say that will raise enough money to protect the surviving tigers.