World’s heaviest bird may be self-medicating on plants used in traditional medicine
Otis tarda. Credit: CC BY-SA 2.0, Wikimedia Commons

You are likely to forget a great bustard if you see it in the wild. They are the heaviest birds in the world and have the largest size difference between the sexes. Males gather at chosen sites to put on an audiovisual show for females, who choose a mate based on his appearance and the quality of his showbirdship.

A study shows that great bustards are interested in plants with compounds that can kill diseases. It is possible that they are a rare example of a bird that self-medicates.

The study's first author is a staff scientist at the National Museum of Natural Sciences in Madrid.

Azucena Gonzalez-Coloma is a researcher at the Institute of Agricultural Sciences in Madrid. We show that the two contain antiprotozoal and nematicidal compounds.

Humans aren't the only ones who self-medicate.

Animals as diverse as monkeys, bears, deer, and fruit flies are thought to have self-medication. It is difficult to prove beyond doubt in wild animals. It's impossible to conduct double-blind trials in wild animals.

Great bustards breed on grassland from western Europe to central and eastern Asia. The majority of the world's population live in the Iberian peninsula. After dispersal, males revisit the same lek site year after year, while females stay faithful to the home range where they were born. They risk re-infecting themselves if they stay in the same area for a long period of time. The immune defenses of males are expected to nose dive during the mating season.

According to Gonzalez-Coloma, both sexes of great bustards might benefit from seeking out Medicinal plants in the mating season when sexually transmitted diseases are common, while males that use plants with compounds active against diseases seem more healthy, vigorous, and attractive to females.

The research team studied great bustards in Madrid and Castille-Leon since the early 1980s. They collected a total of 623 droppings from females and males. They counted the remains of 90 plant species that grow in the area and are known to the bustards' menu.

Plants are capable of killing parasites.

The results show that two species are eaten by bustards more often than expected.

In April, when their energy expenditure is greatest, great bustards choose corn poppies and purple viper's bugloss. Bautista-Sopelana said that males prefer females more than they prefer them.

The first species is avoided by cattle and is used in traditional medicine as a pain relief and immune booster. If eaten in large quantities, the second is harmful to humans and animals. The seeds of purple viper's bugloss are rich in Omega 3's, while corn poppy seeds are rich in Omega 6's.

The authors isolated water and fat-soluble compounds from both species and used liquid and gas chromatography-mass spectrometry to determine their chemical identity. They focused on the defense of plants against herbivores. They found that corn poppies are rich in a number of alkaloids.

The activity of the isolated fractions against the three common parasites of birds was tested.

The results show that purple viper's bugloss is moderately active against fungi, and that extracts from both plants are very effective at killing parasites in petri dishes.

Authors still need to be cautious.

The authors think that great bustards are good candidates for self-medication. They caution that more research is necessary.

According to Bautista-Sopelana, the ultimate proof of self-medication requires experimental protocols.

We continue with our work until then. Our hypothesis of self-medication in this species could be changed if we could quantify the prevalence of remains of corn poppies and purple viper's bugloss and pathogens in fecal droppings.

Luis M. Bautista-Sopelana and his team studied the effects of plants eaten by birds against models of parasites and pathogens. There is a book titled "10389/fevo.

Journal information: Frontiers in Ecology and Evolution