Newswise — If you see a great bustard (too late) in nature, you are unlikely to forget it. Massive, colorful and unmistakable, they are the heaviest living birds capable of flight, with the greatest size difference between the sexes. They are also “lek herders”, where males congregate at selected sites to put on an audio-visual show for visiting females, who choose a mate based on their appearance and the quality of their showbirdship.
But now a study in Frontiers in Ecology and Evolution suggests that great bustards have another claim to our interest: they actively seek out two plants with compounds that can kill pathogens. They may therefore be a rare example of a bird that uses plants against disease, i.e. self-medication.
“Here we show that great bustards prefer to eat plants with chemical compounds with antiparasitic effects. in vitro,said Dr. Luis M Bautista-Sopelana, researcher at the National Museum of Natural Sciences in Madrid and first author of the study.
Co-author Dr Azucena Gonzalez-Coloma, a researcher at the Institute of Agricultural Sciences in Madrid, said: “Great bustards seek out two weed species that are also used by humans in traditional medicine. We show that both contain antiprotozoal and nematicidal (i.e. worm destroying) compounds, while the latter also contains antifungal agents.
Humans aren’t the only species to self-medicate
Self-medication in animals is suspected to occur, with varying degrees of confidence, in animals as diverse as primates, bears, deer, elk, macaws, bees and fruit flies. . But it is difficult to prove beyond any doubt in wild animals, warns Bautista-Sopelana: “We cannot compare control and experimental treatments. And double-blind trials or dose-effect studies, mandatory steps in human or veterinary medicine, are obviously impossible in wild animals.
Great bustards, listed as Vulnerable on the International Union for Conservation of Nature’s Red List of Threatened SpeciesMT, breed in grasslands of western Europe and northwest Africa to central and eastern Asia. About 70% of the world’s population lives in the Iberian Peninsula. Females generally remain loyal to the home range where they hatched for their entire lives – 10–15 years – while after dispersal, males revisit the same lek site year after year. By staying (and especially pooping) in the same area for long periods of time, they risk re-infecting each other. And males need exceptional stamina during the mating season, which should cause their immune defenses to plummet.
“Theoretically, both sexes of Great Bustards could benefit from foraging for medicinal plants during the mating season when sexually transmitted diseases are common – while males using plants containing disease-active compounds could appear healthier. , vigorous and attractive to females,” says Gonzalez-Coloma.
Some members of this research team have been studying Great Bustards since the early 1980s, primarily in the regions of Madrid and Castile-Leon, Spain. They collected a total of 623 female and male bustard droppings, including 178 during the mating season in April. Under the microscope, they counted the abundance of recognizable remains (stem tissue, leaves and flowers) of 90 plant species that grow locally and are known to feature on the diet of bustards.
Contains compounds that kill parasites
The results showed that two species are eaten by great bustards more often than expected given their abundance: poppies, papaver rhoeas and purple bugloss, Echium Plantain.
“The great bustard selects poppies and purple bugloss mainly in the mating season, in April, when their energy expenditure is highest. And men, who during these months devote a large part of their budget of time and energy to sexual display, prefer them more than women,” Bautista-Sopelana concluded.
Of these two species, the first is avoided by cattle and is used in traditional medicine as an analgesic, sedative and immune stimulant. The second is toxic to humans and livestock if consumed in large quantities. They also have nutritional value: fatty acids abound in corn poppy seeds, while bugloss seeds are rich in edible oils.
The authors isolated water-soluble and fat-soluble compounds from both species and determined their chemical identity by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (HPLC-MS). They focused on lipids, volatile essential oils and alkaloids, produced by many plants as a defense against herbivores. For example, they found that corn poppies are rich in bioactive alkaloids like rhoeadine, rhoeagenine, epiberberine and canadine.
The authors then tested the activity of the isolated molecular fractions against three common parasites of birds: the protozoan Trichomonas gallinaethe nematode (parasitic worm) Meloidogyne javanicaand the mushroom Aspergillus niger.
The results show that the extracts of both plants are very effective in inhibiting or killing protozoa and nematodes in vitrowhile purple bugloss is also moderately active against fungi.
The authors always urge caution
The authors conclude that great bustards are prime candidates for birds seeking specific plants to self-medicate. But more research is needed, they warn.
“Ultimate proof of self-medication requires experimental protocols developed in the biomedical, veterinary and pharmacological sciences,” Bautista-Sopelana said.
“In the meantime, we are continuing our field work. For example, quantifying the prevalence of corn poppy and bugloss remains and pathogens in fecal feces in different populations of great bustards could falsify our hypothesis of self-medication in this species.
For publishers/news media:
Please link to the original open access research article “Bioactivity of plants eaten by wild birds against laboratory models of parasites and pathogens” in Frontiers in Ecology and Evolution in your reports: https://www.frontiersin.org/
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