Monkeys roam free at zoo
For about 20 years, the National Zoo has allowed a pair of golden lion tamarins, a species of endangered monkeys, to roam freely during the summer so volunteers can study their behaviors and the animals may eventually be returned to the wild. The tamarins' trouble comes from a lack of space in their natural habitat, which leads to a limited gene pool and interferes with their breeding, according to National Zoo spokeswoman Pepper Long.