These Giant Birds Might Self-Medicate Their STIs

During the breeding season, great bustards consume two plants that may combat common pathogens

a large bird eats a plant
Male great bustard (Otis tarda) Carlos Palacín

If you’re feeling under the weather, you might drink some tea or take drugs to feel better. Humans have been treating our diseases using plant and animal products for thousands of years. 

But we aren’t the only creatures to self-medicate. Lemurs have been spotted smearing millipedes on themselves to prevent gastrointestinal diseases. Likewise, chimpanzees catch and apply winged insects to their wounds. 

Now, researchers suggest the world’s heaviest birds capable of flight, great bustards, also engage in this behavior. In a new study published in Frontiers in Ecology and Evolution, scientists have identified two plants these birds consume that may combat sexually transmitted infections. 

“Great bustards select corn poppies and purple viper’s bugloss mainly in the mating season, in April, when their energy expenditure is greatest,” says first author Luis M. Bautista-Sopelana, a scientist at the National Museum of Natural Sciences in Spain, in a statement. “And males, who during these months spend much of their time and energy budgets on sexual display, prefer them more than females.”

Great bustards are “lek breeders,” meaning males gather together at a chosen site and put on a show to entice females to mate with them. This ritual includes elaborate feather displays, body contortion and inflation of a throat sac. Sometimes, males will present their cloaca—the single opening for the bird’s digestive, urinary and reproductive tracts—which females inspect, perhaps looking for signs of infection, writes New Scientist’s Christa Lesté-Lasserre. Male great bustards can weigh up to 45 pounds, though females are much smaller, at around 11 to 15 pounds. 

Bautista-Sopelana and his colleagues examined 623 droppings from female and male great bustards under a microscope and counted the abundance of remains from 90 plant species grown locally. They found that the birds ate unexpectedly high amounts of corn poppies and purple viper’s bugloss—two plants that are also used by humans in traditional medicine, per the statement. 

The researchers collected flowering plants of these two species growing at one of the largest great bustard breeding grounds in central Spain, near Valdetorres del Jarama. They obtained a total of 17 extracts from the plants and tested their activity against a sample of common pathogens. “Both [corn poppies and purple viper's bugloss] contain antiprotozoal and nematicidal (i.e., worm-killing) compounds, while the second also contains antifungal agents,” co-author Azucena Gonzalez-Coloma, a researcher at the Institute of Agricultural Sciences in Spain, says in the statement. 

Great bustards, which are found in parts of Asia, Europe and northern Morocco, are listed as vulnerable on the International Union for Conservation of Nature Red List. Nests of field-dwelling bustards are threatened by agricultural machinery, and pesticides kill the insects that chicks would eat.

“We normally associate self-medication in species like primates, so to see researchers studying endangered birds is brilliant,” Paul Rose, a zoologist and behavioral ecologist at the University of Exeter in England who was not involved in the study, tells CNN’s Hafsa Khalil. The results show that great bustards can adjust their foraging and diets based on their needs at certain times, he adds.

Still, the authors caution that further research is needed to prove that the birds are really self-medicating and to understand how well their remedies work. 

“Although the efficacy of self-medication in bustards is far from proven, the behavior of bustards in selecting these plants requires an explanation,” Bautista-Sopelana tells New Scientist. “And it seems unlikely to be purely nutritional.”