We humans consume a lot of antidepressants, and that means birds inadvertently do the same while feeding at sewage plants. Now researchers in the UK suggest that it's taking a toll on the birds' libidos, making them—or at least the females—less attractive to prospective mates. In their study, researchers at the University of York focused on starlings in captivity. They fed the birds worms laced with Prozac, on par with what their counterparts in the wild might pick up while eating worms and insects at sewage plants, and then watched what happened. Dosed males didn't change much, but dosed females suddenly seemed less attractive to the boys. Male starlings sang less frequently to them and treated them more aggressively—pecking, tugging at feathers—than is typical in the wooing phase.
It's "the first evidence that low concentrations of an antidepressant can disrupt the courtship of songbirds," says study co-author Kathryn Arnold in a release. "We're definitely not saying that it's bad to take antidepressants, but certainly there is a greater need for new technologies to clean out sewage," she elaborates to the Washington Post. Presumably, the same type of behavior occurs in the wild, but researchers note that it's hard to replicate for a not-so-great reason: Wild birds are dining not just on Prozac but on a whole cocktail of pharmaceuticals, and the study adds to evidence that growing concentrations of them "can alter important traits related to individual fitness and population dynamics," per the study. (Drawings of a cockatoo revealed a medieval surprise.)