From Z (oos) to A (rks) - NYTimes.com Beyond housing and breeding endangered species, zoos are doing a variety of things these days to respond to threats of extinction. Among the services provided by conservation-minded zoos are breeding programs to broaden the genetic diversity of isolated wild populations, relocations of species that are under stress, and research into reproduction dynamics. There is the example of the black and white ruffed lemurs, which I mentioned in my article on the conservation challenges facing zoos on Monday. One problem for these lemurs is that the rainforests of Madagascar have been so shrunken by the clearing of land for farming that the animals are often living in "islands" of forests on mountaintops and are therefore facing a risk of inbreeding. Zoos are maintaining an assurance population of ruffed lemurs. But scientists with the Madagascar Fauna Group, based at the St. Louis Zoo, have also introduced lemurs born in captivity to some of these "islands" as a way of restocking the gene pool. In the future, they say, they will be more likely to move individual wild lemurs from one forest island to another as needed. Moving animals in this way, known as translocation, is an emerging specialty for zoos. In its most common form, it involves taking some members away from their natural habitat when the species faces a particular threat and starting up a breeding colony in a safer comparable habitat elsewhere. One example is the golden white-eye, a tiny but brilliantly yellow bird found on the Northern Mariana Islands. The invasive brown tree snake, which devastated bird populations on Guam after it was introduced there during World War II, has been sighted in the golden white-eye's natural habitat. So, in April a group of zoo scientists moved a colony of the birds to a snake-free island 95 miles to the north. The move required capturing enough birds for a founding colony and extensive biological survey work to make sure the introduced species will not upset the ecology of its new home. While translocations can be exciting, perhaps the most powerful things zoos do these days is husbandry research on the exotic animals in their care. Animals in the wild often remain mysterious to the people who are trying to aid them. In zoos, scientists are able to gather all sorts of baseline data to aid in evaluating the health of the species in the wild - normal hormonal levels, typical age ranges for fertility, average numbers of eggs in a clutch, and so on. Recently researchers abroad asked the Central Park Zoo to help them study whether the scaly-sided merganser, an endangered bird native to East Asia - mainly the Russian Far East, China and North Korea - is successfully breeding. The problem was that the ducks are so rare - only about 2,500 remain in the wild - that little was known about their aging process and as a result, it was hard to determine whether new ducks were being born. The merganser faces extinction due to hunting and pollution and because it often gets caught in fishing nets. The Central Park Zoo has a large colony of mergansers that acts as an assurance population against extinction. Because scientists there have meticulously documented the growth and development of hatchlings, they were able to provide photographs and descriptions to scientists in the Far East. The photos helped "improve our understanding and description of certain behaviors that we are able to observe such as pair formation, display and territoriality," said Nial Moores, the director of Birds Korea, a group that works on conservation projects in South Korea.