Male starlings sing less at female birds on Prozac

Starlings (maybe) on Prozac
Starlings (maybe) on Prozac
Image: Reuters/China Stringer Network
We may earn a commission from links on this page.

Scientists in the UK have learned that male starlings, known for their gregariousness, sing less at female counterparts doped up on the antidepressant fluoxetine, better known by its brand name Prozac.

Yes, scientists fed female starlings the antidepressant as part of their research. No, nobody is working on a plan to design these drugs for birds. The research was an attempt to better understand the ecological impact of pharmaceutical residues that end up in waterways that support wildlife populations.

“Our findings suggest that exposure to an antidepressant reduced female attractiveness, adding to growing evidence that environmental concentrations of pharmaceuticals can alter important traits related to individual fitness and population dynamics,” the scientists wrote in their study, which was published recently in the journal Chemosphere.

The work is just one piece of mounting evidence showing that how unused, discarded drugs can wind up impacting wildlife. In the UK, doctors prescribed close to 65 million antidepressants in 2016. And like many other medications, a lot of those were tossed into the garbage or flushed, eventually making their way into wastewater-treatment plants. Those plants, however, are designed to filter out bacteria and solids, not chemical compounds. So a lot of the drugs that end up in wastewater—as much as half—wind up slipping by filtration systems and into the waterways accessible to birds and other wildlife.

As part of their work, the scientists captured 24 wild starlings, and over 28 weeks fed half the birds regular waxworms. The other half were fed waxworms that had been dosed with fluoxetine, the active ingredient in Prozac. Then, after putting males and females together in courtship areas, noted that the males sang twice as often and twice as long at female birds that had not been drugged. The researchers also found that the males tended to be more aggressive toward the females that had eaten Prozac-filled worms.

The researchers acknowledge in the study that their sample sizes were small, but write that they still feel the results are important because a relatively low dose of fluoxetine—just 10% of a typical human dose—was enough to disrupt starling mating practices.

It’s important research during a time when scientists have been noting for some time that wildlife species are in a rapid state of decline. If mating practices are being disrupted because of how people discard drugs, it’s just one piece of the larger puzzle, and identifies an area in which humans can design fixes to help curb those animal losses.