Scientists reveal the world’s heaviest flying birds’ secret to healing in a rare discovery
The research based on the great bustard's (Otis tarda) diet discovered that the bird uses two specific species of plants to self-medicate against disease - a rare example, according to a new study published on Wednesday by Frontiers, a peer-reviewed scientific publication.
"Here we show that great bustards prefer to eat plants with chemical compounds with antiparasitic effects in vitro," said Dr. Luis M Bautista-Sopelana, the study's first author, a staff scientist at the National Museum of Natural Sciences in Madrid, Spain.
The Iberian Peninsula is home to almost 70 percent of the bustards' world population.
"Great bustards seek out two species of weeds that are also used by humans in traditional medicine," said study co-author Dr. Azucena Gonzalez-Coloma, a researcher at the Institute of Agricultural Sciences in Madrid.
"We show that both contain antiprotozoal and nematicidal (i.e., worm-killing) compounds, while the second also contains antifungal agents."
The bird that breeds on the grasslands of western Europe, northwest Africa, Central Asia, and Eastern Asia is listed on the International Union for Conservation of Nature's Red List of Threatened Species.
Bird droppings analysis
Great bustards have been investigated by several members of the current research team since the early 1980s, mostly in the Spanish areas of Madrid and Castille-Leon.
They gathered 623 droppings altogether, including 178 during the great bustards' April mating season.
The abundance of recognizable remains (tissue from stems, leaves, and flowers) from 90 plant species that grow nearby and are known to be on the bustards' menu was tallied under a microscope.
The findings revealed that two species—corn poppies, Papaver rhoeas, and purple viper's bugloss, Echium plantagineum—are consumed by great bustards more frequently.
"Great bustards select corn poppies and purple viper's bugloss mainly in the mating season, in April when their energy expenditure is greatest," said Bautista-Sopelana.
"And males, who during these months spend much of their time and energy budgets on sexual display, prefer them more than females."
Self-medication is a reality beyond humans
With varying degrees of certainty, self-medication in animals is hypothesized to occur in a wide range of species, including primates, bears, deer, elk, macaws, honeybees, and fruit flies.
However, it can be challenging to establish in wild animals without a shadow of a doubt.
"We can't compare between control and experimental treatments. And double-blind trials or dose-effect studies, obligatory steps in human or veterinary medicine, are obviously impossible in wild animals," cautioned Bautista-Sopelana.
The first of two species of plants consumed by bustards is avoided by cattle and is employed as a painkiller, sedative, and immunological stimulant in conventional medicine.
The second is poisonous to both people and livestock if consumed in large quantities. Additionally, they are nutritious: maize poppy seeds are a rich source of fatty acids, while purple viper's bugloss seeds are a great source of edible oils.
The activity of the isolated molecular fractions was evaluated by scientists against the protozoan Trichomonas gallinae, the nematode (parasitic worm) Meloidogyne javanica, and the fungus Aspergillus niger, which are all common parasites of birds.
The findings demonstrate that purple viper's bugloss is also somewhat active against fungus, whereas extracts from both plants are highly effective at inhibiting or killing protozoa and nematodes in vitro.
According to the authors, great bustards are excellent candidates for birds that look for particular plants to self-medicate. However, they suggest further research is necessary.
"The ultimate proof of self-medication requires experimental protocols developed in the biomedical, veterinary, and pharmacological sciences," concluded Bautista-Sopelana.
"Until then, we continue with our fieldwork. For example, quantifying the prevalence of remains of corn poppies and purple viper's bugloss and pathogens in fecal droppings across different populations of great bustards could falsify our hypothesis of self-medication in this species."
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