Shirley Buzzard, 67, arrived early for her volunteer shift at the National Zoo’s reptile house. She likes to grab a coffee and check out the Great Ape House, or maybe the pandas, before her three-hour stint with snakes. The snakes are her favorite—-the retired anthropologist has loved them since she was 10.

She also likes feeding the iguanas chameleons, but the Natonal Zoo recently put the brakes on that privilege. “The keepers thought [the volunteers] were overfeeding them, giving them too many crickets, so we don’t feed them anymore.”