The unique pattern of dots for each lemur's lice.
Hey lemur, sit down right here. I've got my bottle of nail polish---oh no no, don't need your hands, let's look at your ears instead. While we're at it, can you show me the lice on your eyelids and testes too? Just another day in the life of a lemur biologist. The brown mouse lemur
of Madagascar is a five-inch-long primate that sleeps in tree-holes all day and only comes out after dark. To study their social interactions
, scientists had to get crafty with toothpicks and a few bottles of nail polish. They trapped 23 male and 9 female lemurs, finding and tagging the lice on each of them with a unique pattern of nail polish dots. From August to October, they then mapped how lice spread from lemur to lemur, which seemed to mostly happen mostly between males fighting each other for mates. Breeding season began a few weeks into the tracking period, and lice transfers between males shot up dramatically. (Only one louse was ever found on any of the female lemurs. Hmm...) Fourteen of the 23 males donated or received at least one louse, and some of them seemed to be superdonors, spreading their lice far and often. The lice pattern revealed male lemurs to move around over greater distances than previously thought. Lice originally on the ears of one host were most often transferred to the testes of another. Lemur testes are "dramatically distended" during breeding period, rich in blood vessels but sparse in fur. In other words, an ideal place for lice to grab on and feed. Nail polish and lice may be low tech compared to radio tracking, but it's smart, taking advantage of the lice's natural behavior. It doesn't require expensive or breakable equipment out in the field, either. So watch out, other nocturnal mammals: nail polish-painted lice may be coming for you next.
Image courtesy of S. Zohdy / BMC Ecology