A starling. (Daniel Baleckaitis/University of California at San Diego/AP) 
 
 It’s been well-documented that a decreased sex drive can be one of the side effects of antidepressants like Prozac. But the amount of these drugs that end up in sewage plants may also have an impact on the mating habits of wild birds, a new study from the University of York shows. 
 
 Researchers found that female starlings that had been exposed to small doses of fluoxetine, the generic name for Prozac, became less attractive to male starlings, which sung to them less often and treated them more aggressively. Kathryn Arnold, one of the study’s authors and a senior lecturer in ecology at the University of York, described it as “the first evidence that low concentrations of an antidepressant can disrupt the courtship of songbirds.” 
 
 That’s problematic because birds that are slow to find a mate may not get the chance to breed, she wrote. 
 
 “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,” Arnold told The Washington Post. 
 
 Birds like to graze at sewage treatment plants, which are teeming with worms, flies and maggots, she explained. But because antidepressants often make their way through the human body and into sewage plants without fully breaking down, those insects are frequently laced with prescription drugs. 
 
 To figure out the effect that these pharmaceuticals have on birds, the researchers first had to figure out how much fluoxetine is typically found in worms and bugs at sewage treatment plants. They then replicated that, dosing worms with a low concentration of Prozac — less than 10 percent of what a human would be given for therapeutic purposes, Arnold said. 
 
 The Prozac-treated worms were fed to starlings living in outdoor aviaries that mimicked the natural environment as much as possible while keeping the birds in captivity. The following spring, during breeding season, male starlings were “set up on essentially blind dates,” Arnold said. 
 
 The results were striking. When paired with female starlings that had been eating the Prozac-laced worms, males only sang half as often and for half as long as they did when they were paired with a female that hadn’t been exposed to the drug. 
 
 That’s significant, Arnold said, because singing is an important part of birds’ courtship rituals, and is used to judge potential mates. “The equivalent of reduced libido, in a wild animal, is how they behave during courtship,” she said. 
 
 Male starlings were also much more aggressive toward female starlings that had been exposed to low doses of Prozac, the researchers found. 
 
 “They chased them, they pecked them, they tugged on their feathers,” Arnold said. 
 
 Interestingly, female starlings didn’t seem to be turned off by male starlings that had consumed small amounts of Prozac. Arnold credits that to the fact that the male starlings’ behavior didn’t change drastically, while female starlings seemed less interested in the opposite sex and were often inconsistent in their behavior. 
 
 “They were blowing hot and cold,” she said. “They could be aggressive, and they could be passive.” 
 
 Could this result in fewer baby birds being born and, ultimately, a decline in the number of starlings? Arnold said it’s possible, but further research is needed to determine if the same behavior that her team witnessed is also happening in the wild. Complicating the question is the fact that birds aren’t just being exposed to Prozac — they’re also potentially ingesting a whole slew of other drugs that have ended up in the sewage system. 
 
 “There is growing evidence around the world that shows that we need to be taking a look at what it is we’re pumping out,” she said. “These cocktails of pharmaceuticals are drugs that your medical provider would never prescribe in combination with one another.” ||||| Pharmaceuticals in the environment are a recently identified global threat to wildlife, including birds. Like other human pharmaceuticals, the antidepressant fluoxetine (Prozac) enters the environment via sewage and has been detected at wastewater treatment plants. Birds foraging on invertebrates at these sites can be exposed to pharmaceuticals, although the implications of exposure are poorly understood. We conducted experiments to test whether chronic exposure to a maximally environmentally relevant concentration of fluoxetine (2.7 μg day−1) altered courtship behaviour and female reproductive physiology in wild-caught starlings (Sturnus vulgaris), a species commonly found foraging on invertebrates at wastewater treatment plants. When paired with a female over two days, males sang less and were more aggressive towards fluoxetine-treated females than controls. Fluoxetine-treated females were initially aggressive towards males, becoming significantly less aggressive by the second day. In contrast, control females expressed intermediate levels of aggression throughout. We found no effect of female treatment on female courtship behaviour. Female body condition, circulating testosterone and circulating oestradiol were unaffected by treatment and did not account for male preference. 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. ||||| Potent pharmaceuticals flushed into the environment via human and animal sewage could be a hidden cause of the global wildlife crisis, according to new research. The scientists warn that worldwide use of the drugs, which are designed to be biologically active at low concentrations, is rising rapidly but that too little is currently known about their effect on the natural world. 
 
 Studies of the effect of pharmaceutical contamination on wildlife are rare but new work published on Monday reveals that an anti-depressant reduces feeding in starlings and that a contraceptive drug slashes fish populations in lakes. 
 
 “With thousands of pharmaceuticals in use globally, they have the potential to have potent effects on wildlife and ecosystems,” said Kathryn Arnold, at the University of York, who edited a special issue of the journal Philosophical Transactions of the Royal Society B. ”Given the many benefits of pharmaceuticals, there is a need for science to deliver better estimates of the environmental risks they pose.” 
 
 She said: “Given that populations of many species living in human-altered landscapes are declining for reasons that cannot be fully explained, we believe that it is time to explore emerging challenges,” such as pharmaceutical pollution. 
 
 Research published in September revealed half of the planet’s wild animals had been wiped out in the last 40 years. In freshwater habitats, where drug residues are most commonly found, the research found 75% of fish and amphibians had been lost. 
 
 A few dramatic examples of wildlife harmed by drug contamination have been discovered previously, including male fish being feminised by the synthetic hormones used in birth-control pills and vultures in India being virtually wiped out by an anti-inflammatory drug given to the cattle on whose carcasses they feed. Inter-sex frogs have also recently been found in urban ponds contaminated with wastewater. 
 
 Vultures in India were virtually wiped out by an anti-inflammatory drug given to the cattle on whose carcasses they feed. Photograph: Adrian Page/Alamy 
 
 But because the pharmaceuticals are not designed to kill – unlike pesticides – the damage caused to wildlife can be more subtle. 
 
 In one of the new studies, Tom Bean at the University of York and colleagues, showed that the common antidepressant fluoxetine, at the low levels expected in the environment, led starlings to feed less often during the key foraging times of sunrise and sunset. “Importantly, fluoxetine is not the only pharmaceutical, or indeed the only antidepressant, to be detected in the environment,” he said. “Mixtures of pharmaceuticals could potentially be more potent.” 
 
 Another new study, led by Karen Kidd at the University of New Brunswick, showed synthetic oestrogen used in the birth control pill not only wiped out fathead minnows in lakes used for experiments in Ontario, but also seriously disrupted the whole ecosystem. The lakes’ top predator – trout – declined by 23-42%, due to the loss of the minnow and other prey, while insects increased as they were no longer being eaten by the minnows. 
 
 Amphibians are suffering the hardest in the global biodiversity decline and Cecilia Berg, at Uppsala University, and colleagues reported that a number of hormonally active pharmaceuticals harm reproduction in amphibians at concentrations that occur in natural waters. 
 
 The most environmentally dangerous drugs are identified in a paper by Anette Küster and Nicole Adler, both at Germany’s Federal Environment Agency. “For human medicinal products, hormones, antibiotics, [painkillers], antidepressants and [anti-cancer drugs] indicated an environmental risk,” they said. For veterinary drugs, hormones, antibiotics and parasiticides were highlighted. 
 
 Pharmaceuticals can contaminate the environment through discharges from drug factories, as well as through sewage. Professor Joakim Larsson, at the University of Gothenburg, found that drug levels in effluents can even exceed those found in the blood of people taking medication. 
 
 Larsson cited antibiotic pollution coming from factories in China, India, Pakistan, Korea, Denmark, Norway and Croatia. “Although pollution from manufacturing is less widespread, discharges that promote the development of drug-resistant microorganisms can still have global consequences.” He also documented antidepressant pollution from factories in Switzerland, Israel and Spain and “narcotic opioid” pollution in the US. 
 
 The use of pharmaceuticals is rising with increases in the human population and the livestock it keeps. Environmental exposure is also rising as sewage is increasingly used to irrigate or fertilise farmland. In the US, for example, about 4m tonnes of dry sewage biosolids are applied to land each year. 
 
 Sally Gaw, at the University of Canterbury, and colleagues warned that even less is known about the effect of pharmaceutical pollution in the oceans. “This is a critical knowledge gap given the significant increase in coastal human populations around the globe and the growth of coastal megacities, together with the increasing importance of coastal [fisheries] around the world.”
– 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.)