bustard heaviest living bird that can fly. Although it has a wingspan reaching up to 260 centimeters, its weight, nearly 16 kilograms, places it at the upper edge of what flight can support. It remains the largest bird found on the Iberian Peninsula. An important note is that these birds are being studied for their unusual relationship with plants that carry compounds capable of killing pathogens, a link rooted in traditional medicine.
Researchers note that bustards may stand as a rare example of a bird using plants to combat disease, effectively healing itself. The study appears in Boundaries in Ecology and Evolution.
“We observe this,” says Luis M. Bautista-Sopelana, a scientist at the National Museum of Natural Sciences in Madrid and the study’s first author.
Co-author Azucena González-Coloma, a researcher at the Madrid Institute of Agricultural Sciences, adds: “Great bustards seek two kinds of weeds that people have long used in traditional medicine. Our work shows that both contain compounds active against protozoa and nematodes, while one also displays antifungal properties.”
Self-medication in animals is suspected across many species, including primates, bears, deer, elk, macaws, bees, and fruit flies. Bautista-Sopelana warns that proving true self-medication in wild animals is tricky: controlled comparisons and double-blind dose studies, standard in human or veterinary medicine, are not feasible in the wild.
Great bustards are listed as Vulnerable on the International Union for Conservation of Nature’s Red List. They breed across grasslands from western Europe and northwest Africa to central and east Asia, with about 70 percent of the global population concentrated on the Iberian Peninsula. Males can weigh as much as 16 kilograms.
Females tend to stay within their natal territories for most of their lives, about 10 to 15 years, while males repeatedly return to the same areas after dispersal. Prolonged presence in the same locale, especially with waste excretion, can raise the risk of re-infection. During the mating season, males display high energy demands that can temporarily lower immunity.
Plants containing active compounds against diseases
“In theory, both male and female bustards could benefit from gathering herbs during the mating season, a period when sexually transmitted diseases are more common. Males using herbs with disease-active compounds may appear healthier, stronger, and more attractive to females,” González-Coloma explains.
Researchers who have followed bustards since the early 1980s, mainly in Madrid and Castilla y León, collected 623 scat samples from both sexes, with 178 gathered during the peak mating month of April. Under a microscope, scientists counted the identifiable remains of 90 plant species on the birds’ menu, including stems, leaves, and flowers.
Results showed two plant species were consumed more often than would be expected based on their abundance: the corn poppy (Papaver rhoeas) and purple viper’s bugloss (Echium plantagineum).
“Bustards gravitate toward purple viper poppies, especially during the mating season in April when energy use is high. Males, who devote significant effort to sexual display in these months, favor them even more than females,” Bautista-Sopelana notes.
Analyses showed that extracts from both plants strongly inhibited or killed protozoa and nematodes in vitro, with purple viper’s bugloss also showing moderate antifungal activity.
The authors conclude that great bustards are prime candidates for birds that actively seek certain plants for self-medication. They caution that more research is needed before drawing firm conclusions.
“Conclusive evidence of self-medication requires experimental protocols developed in biomedicine, veterinary medicine, and pharmacology,” Bautista-Sopelana stresses.
Reference work: Frontiers in Ecology and Evolution, 2022, article detailing these findings
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