WITH TASMANIAN DEVILS GONE, POSSUMS COME DOWN FROM TREES

Since its discovery in the 1990s, a contagious cancer called devil facial tumor disease has wiped out 85 percent of the Tasmanian devils on the Australian island of Tasmania. The animals have yet to completely disappear from any one area of the island, but in some places, as many as 95 percent of the devils are now gone.For the creatures that the devils prey on — such as brushtail possums — the loss of a predator is good news. And the possums, scientists have found, are losing some of their wariness. In areas where the tumor disease has been present the longest — and the devils are at their lowest numbers — possums have become more comfortable venturing onto the ground from their arboreal homes, scientists report June 16 in the Proceedings of the Royal Society B. Brushtail possums spend most of their time up in the trees, where they are safe from ground-dwelling predators, such as devils and cats. But they venture down to the ground to feed. Tracey Hollings of the University of Tasmania and colleagues wanted to know whether the possums would change their ground behavior as the devil population disappeared. So they surveyed possum populations at 30 sites on the north side of Tasmania and six sites on Maria Island. That island, off the east coast of Tasmania, has not had devils for at least 10,000 years. (Devils were reintroduced last year , after this study.) Brushtail possums were introduced 50 years ago, so it is a good place to see how possums act without one of their major predators.