Flying jewels, vulnerable specialists

When he discovered the violet dropwing he was working on his Master’s thesis. In it, he was studying South Tyrol’s dragonflies at all altitudes, in natural and artificial waters. Over the course of almost four months, he completed a total of 200 visits to 41 bodies of water throughout the province, using trains, cable cars, and, as an avid cyclist (he is currently cycling around the world), his bicycle was his main means of moving. The violet dropwing was not the only surprise that resulted from the surveys: Puff also found two species of dragonflies that were considered lost and possibly extinct in South Tyrol. His study, conducted in collaboration with Biodiversity Monitoring South Tyrol, was recently published in the renowned Global Ecology and Conservation journal. It paints the first comprehensive picture of the local dragonfly fauna along the entire Alpine altitude gradient, providing a valuable basis for identifying future changes, for example, due to climate change or human intervention. “Dragonflies are perfect models for studying such dynamics,” explains Puff. “They are cold-blooded animals and therefore highly temperature dependent. The larvae live in water – some species for a few months, others for over a year, often highly specialized to specific microhabitats – between stones, in reeds, or in quiet peat holes. They are sensitive to change and show us how healthy a habitat is.”

There have been extensive dragonfly surveys in South Tyrol in the past, but they always covered limited areas: mainly various nature parks and the Adige/Etsch valley floor. These surveys document a great loss: since the 1950s, nine of 60 species have become extinct in South Tyrol: all species that lived in the valley floor, in riparian forests and shallow waters, lost their habitats with increasing urbanization and intensification of agriculture. Many species that were once common have become rare. In 1869, the early dragonfly researcher Carl Ausserer encountered the blue-winged beautiful demoiselle in such proliferation on South Tyrol’s lakes that the reeds looked like blue flowering plants. Today, the species is found in only two bodies of water in South Tyrol. The current Red List of dragonflies in South Tyrol classifies almost two-thirds of species as endangered in some way. A dramatic decline can occur in a short period of time: in 2010, the cold-adapted moorland hawker was still one of the most common dragonflies in the entire Alpine region but is now considered endangered throughout Europe. In just as short a time, however, South Tyrol has also seen a spectacular comeback: the return of the banded demoiselle. Once found throughout the Adige Valley, with irrigation ditches as its typical habitat, it began to disappear and was hardly seen at all in 2011. But suddenly it reappeared in more and more places every year. The secret? “Probably cleaner water, better sewage treatment plants, perhaps a change in pesticide use,” says Puff. The trend is evident throughout Europe: water protection measures have brought back species that live in flowing waters. “Political decisions are having an effect within ten years,” says Puff. He comes from Laives/Leifers, where the blue-shimmering damselflies are flying again – “for the first time in my lifetime.”

Puff included artificial water bodies in the study because he was interested in a specific question: can they be substitute habitats for species whose natural habitats are disappearing as a result of climate change or human intervention? This widespread hope, and the creation of ponds is also being promoted in the Alpine region – “although it is unclear to what extent such man-made water bodies can contribute to the protection of sensitive Alpine specialists,” says Puff. His study now shows that Alpine dragonflies do not benefit from such ponds. Only generalists were found in the high-altitude man-made water bodies – species that also occur at lower altitudes and tolerate a wide range of conditions; alpine species were absent. One reason could be the mostly undeveloped riparian vegetation zone of such water bodies, or the fact that their water level fluctuates independently of natural cycles – “One thing is certain: artificial ponds are not a refuge for alpine species,” says Puff. “That’s why we must be all the more determined to protect natural habitats.” Together with Giacomo Assandri from MUSE in Trento and Elia Guariento from Eurac Research, Puff has now completed another study based on the data collected, which is expected to be published soon. In the study, the researchers analyze how the isolation of habitats affects dragonfly communities. Compared to beetles or butterflies, science has paid relatively little attention to dragonflies, says Puff. So there is still a lot to discover. He already has ideas for what he will do after his trip around the world