Areas in which rare breeds of butterfly can thrive in eastern Denmark have shrunk by almost three-quarters in the last 26 years, according to a University of Copenhagen study. 

The decline of their habitats means that several species are endangered, the study found.

Meanwhile, researchers concluded that sate efforts to protect wildlife areas had failed and that the conditions are worse in Denmark than in comparable neighbouring countries.

Research led by biologist Emil Blicher Bjerregård tracked six endangered butterfly species over six years, the university said in a press statement.

“For the 22 butterfly species which we have been keeping an eye on, their distribution on Zealand, Lolland, Falster and Møn has shrunk by 72 percent overall since 1993,” Bjerregård said in the statement.

Only one of the species increased its numbers in that time and several are now only present in small local areas, he said.

The 22 species could be found in 565 localities in Denmark in 1993, compared to 158 localities in 2019 – a decline of 72 percent.

“This is solid data showing some dramatic figures which actually seem to be worse than in our neighbouring countries. Many of the species that were previously common and widespread in Denmark have become very rare,” associate professor Hans Henrik Bruun, a senior researcher on the study, said in the statement.

“And once they’re gone, they don’t come back,” he said.

Forest, marsh and grass butterfly habitats are all affected by the trend.

“Butterflies are a good indicator of nature quality,” Bjerregård noted.

Efforts by nature agencies in Denmark and the EU to protect the species maybe ineffective, the two researchers said.

“Most of the areas with butterflies have now been formally protected for decades. But we can see no signs that nature conservation – neither national nor EU-regulated – has made any positive difference to the rare species of butterflies in the last 30 years,” Bruun said.

“Butterfly habitats are too poorly protected from human activities. For example, you can find [nature] areas and national parks where there are supermarkets with hundreds of parking spaces,” Bjerregård noted.

Less human leisure activity – such as mountain biking, riding or trail running – in wild habitats would also increase their protection, he said in the statement.

“Protected natural areas in Denmark are small isolated patches, when what the species need are larger, continuous natural areas, so that the populations are not as vulnerable to fluctuations in weather and climate as they are now,” he explained.

There are currently 66 different species of butterflies in Denmark. Of these, some 37 are “red-listed”, meaning they are endangered or vulnerable. 12 species of butterfly have disappeared from Denmark since the 1960s.