Quarries May Be Last Chance For Many Rare European Butterflies

"Increasing evidence is revealing the counterproductivity of such practices," say Jiri Benes, Pavel Kepka and Martin Konvicka, all of the University of South Bohemia in Ceske Budejovice, Czech Republic, in the August issue of Conservation Biology.

Throughout Europe, butterflies that depend on warm, dry areas have declined because many of the steppe-like grasslands that provide this habitat have been lost to intensified agriculture, conifer plantations and urbanization. Two of the researchers (Benes and Konvicka) have been butterfly enthusiasts since childhood and noticed as high school students that many steppe grassland species were essentially found only in quarries in the Czech Republic's Moravian Gate, one of Europe's most important north-south migration corridors. Thus, the researchers were concerned that these butterflies would be further threatened by the Czech Republic's policy of reclaiming old quarries, which usually means covering them with topsoil and planting trees.

To see if quarries can help compensate for the loss of steppe habitat in Europe, Benes and his colleagues surveyed the diversity and abundance of butterflies in 21 limestone quarries in the Moravian lowlands. The researchers surveyed the butterflies in four habitat types: recently excavated rock, sparsely vegetated, herbaceous plants, and trees and shrubs.

The researchers found that quarries serve as refuges for two groups of butterflies that depend on steppe-like habitats. The first group comprises 20 species, nine of which are threatened in the Czech Republic, that thrive in active quarries because they prefer habitats such as rocks and stony terraces. While managing reserves to maintain such habitats would be an ongoing and costly task, "the service is provided for free in the quarries as a side-effect of the excavation," say Benes and his colleagues.

The second group comprises 19 species, 10 of which are threatened in the Czech Republic, that thrive in old quarries because they prefer habitats that grow on previously excavated surfaces, notably scrubby forest-steppes. These habitats are virtually gone elsewhere in Central Europe because managers of steppe reserves there typically remove scrub in favor of orchids and other charismatic plants.

More than half of the quarries studied are in areas that no longer have any natural steppe grasslands. "The quarries are thus the only chance for preserving steppe butterflies there," note Benes and his colleagues. They recommend operating active quarries and managing old ones to maintain the bare rock and scrubby habitats that the two groups of steppe butterflies require. "Conservationists should pragmatically exploit these opportunities by cooperating with quarry operators," they say.