Large herbivores have greatly helped endangered butterflies. Their numbers increased by several hundred percent over a five-year period – YubaNet

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Prague – Over the past five years, the number of butterflies in the large herbivore reserve at the former Milovice military training area near Prague has increased significantly. During regular monitoring, scientists found that the number of butterflies increased from 4,592 in 2016 to 12,506 in 2021. This means an increase of 172%. The number of the rarest butterfly, Alcon Mountain Blue, has even increased by 1,700%.

Mountain Alcon blue in the former Milovice military training area. Photo: Michal Köpping

“Grazing large ungulates clearly has a positive effect on butterflies. The transformation of the location and the increase in the number of butterflies in recent years is so clear to see that even a layman must have noticed. The number of butterflies is visibly greater than it was when the pasture was opened, ”explains entomologist David Ricl.

It is important to note that populations of protected species are increasing. “This includes the blue of Alcon Mountain. They are not only growing in number, but also appearing in places where just a few years ago you would not have seen them, ”says Ricl. While in 2016, scientists had recorded just five individuals in four mapped locations and the species was on the verge of extinction, this year more than 90 have been seen in 14 locations. This means a remarkable increase of 1,700 percent. “Thanks to grazing and the removal of aggressive grass species, the endangered star gentian flower population has been revived and is starting to thrive in parts of the reserve that were once overgrown. This goes hand in hand with the expansion and strengthening of the blue population of the Alcon Mountains, ”Ricl adds. The star gentian is one of the plant species on which the females of the mountain Alcon blue can lay eggs.

Other species also thrive. The red skipper under the wings or the blue of the meleager are also experiencing a comeback in the region. More common butterfly species also thrive in large ungulate pastures. “An example is chalk blue, which is found by the thousands in the great ungulate reserve,” says David Ricl. In the monitored location, its number increased from 55 individuals in 2016 to 493 in 2021. The research lasted five years and its results were published in the scientific journal BMC Ecology and Evolution.

The significant growth in the number of butterflies confirms that grazing large ungulates is an ideal way to care for large areas of the countryside. “We started our project years ago precisely because butterfly species were disappearing. We are pleased that scientific research has confirmed that large ungulates can create an ideal environment for butterflies, and what is more, over hundreds of hectares ”, remarks Dalibor Dostal, director of the European organization for the conservation of wildlife .

According to scientists, butterflies are a good indicator of the general state of an ecosystem because they have complex life cycles. Their individual stages of development require diverse microhabitats. “Butterflies don’t just need species-rich grasslands, where adults can suck nectar from various grasses. Grasslands must also provide them with places without vegetation, where caterpillars can bask in the sun. Protected places in the shade of woody plants, where caterpillars can pupate, or many ant nests, where many species of butterflies undergo part of their development, ”explains Miloslav Jirku of the Academy’s Biology Center Czech science. In addition, these different environments must be brought together because the caterpillars cannot travel more than a few meters while looking for them. Butterflies therefore need grassland ecosystems that are diverse not only in plants but also in microhabitats.

The large ungulate reserve was established in the former military zone in 2015. It is maintained by grazing herds of wild horses, originating from Exmoor, England, European bison and purebred aurochs. . It currently covers an area of ​​350 hectares.

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