A nature reserve is flooded with rare cross gentians. Thanks to wild horses

2015 - 07 - 22
A nature reserve is flooded with rare cross gentians. Thanks to wild horses

Instead of dry grass, blooming meadows with large tufts of critically endangered cross gentians. This is how the steppe areas of the former military training area of Milovice near Prague – where a herd of wild horses has been grazing since January – have changed. The cross gentian is one of the rarest plants of the local steppes and its local population is one of the largest in the Czech Republic. Saving this disappearing species is one of the main objectives of the project of the return of wild horses.

“The gentians have mostly appeared in the acclimatization area where the horses spent the first weeks of their stay in the Czech Republic during the winter. The horses completely grazed the coarse stands of last year’s vegetation consisting of nettle and blackberry. This was exactly how space was opened for the rare gentians that have no chance in tall grass stands,” said Miloslav Jirku from the Biological Centre of the Academy of Sciences of the Czech Republic, who coordinates the scientific research at the site.

Thanks to the wild horses, the natural systems are recovering much faster than the project’s authors had planned. “We did not expect that the positive change as a result of wild horse grazing would occur as quickly as several months. The first project results heavily exceeded our expectations,” added Dalibor Dostal, director of the conservation organization European Wildlife.

What is surprising is not only how quickly wild horses were able to kick-start the positive change, but also at what type of site they allowed rare gentians to return. “The acclimatization area is situated in a marginal location, the least valuable part of the entire area. Just a few years ago, there were military buildings here, followed by illegal landfills, where only weeds grew. It is fascinating that wild horses could make a difference to such a place – a garden full of flowers from an overgrown rubble area within less than a half of year,” says Jirku.

Unlike domestic animals, wild horses mainly feed on grasses, including aggressive wood small reed, and consume neither the rare gentians nor most of the other flowering plants. As a result, not only gentians, but also other flowering herbs are on the increase in the local steppes, so the formerly uniform tall grasses turn into flowery meadows before your own eyes. The grazing activity is also reducing the rate at which the steppe becomes overgrown by shrubs and self-sown woody species.

In addition to flowers, the rarest local butterfly species has appeared – the mountain alcon blue. It has already laid eggs on many individual gentians. The cross gentian is its single host plant, without which it cannot reproduce.

Initially, the larvae of this butterfly feed on gentians before falling to the ground after a couple of weeks, where they wait to be found by ants and carried to their ant hill. Here, the caterpillars are ant parasites for one or two years; sometimes they even consume ant eggs and larvae, since butterfly caterpillars smell like ant larvae to the hosts, so the ants consider them to be their own and feed them. Still, only 10 to 20 percent of butterflies live to adult age.

But, unlike the time it was a larva, the butterfly that has left the pupa inside the ant hill is unable to fool the ants, so it has to race for its life as soon as it leaves the pupa. If it is not fast enough in finding its way out of the ant hill, it will be eaten by the ants. Due to its bond to the increasingly rare cross gentian and habitats that are not overgrown, the mountain alcon blue is a critically endangered butterfly disappearing from the Central European landscape.

Wild horses arrived in Milovice on January 28th this year. They come from Exmoor, England, where they have been ranging in the wild since the distant past. The first written mention of them dates back to 1086 and is one of the oldest records of wild horses in Europe. Genetic research in recent years has shown that it is the horses from Exmoor that correspond to the native wild horses of Europe in their appearance and colour.

Photo: Miloslav Jirku

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