In January, the height of summer in the Kalahari Desert, some meerkats poke their noses out of their burrows as early as 5 a.m. Other groups sleep up to an hour later. Over 11 years of observations, researchers found that each group stuck to its schedule, even when the original members of the population had all died. Meerkats move between groups, so the differences aren't genetic, the researchers will report  online tomorrow in the Proceedings of the Royal Society B. Instead, the immigrants adapt to the group's customs, and pups learn wake-up time from adults. Further evidence, the team says, that nonhumans can have traditions, too.