Background The main distribution of the green club-tailed dragonfly (Ophiogomphus cecilia) is from the eastern parts of Europe to central Asia. A series of Natura 2000 sites in Bavaria act as important ‘stepping stones’ for the green club-tailed dragonfly, connecting populations in France and the Pfälzer Wald (German area close to France), at the western edge of the species’ range, with populations in the east of Germany. The species remains threatened in the whole of Europe, with the main threats being management measures implemented along rivers, the increased density of shading by trees along watercourses, the influx of nutrients and agrochemical pollutants, and the loss of structural diversity in rivers. Objectives The main objective of the Keiljungfer project was to improve the conservation status of green club-tailed dragonfly (Ophiogomphus cecilia) in Bavaria, via a coordinated set of habitat improvements in local watercourses. The project built on a previous study in Bavaria (Bayern) in the 1990s, where renaturing the river Schwarzach led to a tenfold increase in green club-tailed dragonfly numbers. The project aimed to increase structural diversity in the project watercourses and remove vegetation to let sunlight reach areas suitable as larval habitats. Results The Keiljungfer project increased structural diversity of rivers to create new habitat for green club-tailed dragonfly (Ophiogomphus cecilia), with both hydrodynamic and morphodynamic processes increasing at several places along about 8 km of seven small rivers. Additionally, more sunlight can now reach these rivers due to the removal of vegetation, with improvements in the warming of the air along the rivers. All of these changes should be beneficial for the target dragonfly species. At one project site, at least, near Kirschendorf, the dragonfly's population has responded positively to the project actions, with a recorded increase in numbers. On numerous sections along the seven rivers, poplar, willow and alder were removed. At these sections, these trees had grown so high and dense that the whole watercourse was entirely shaded. The green club-tailed dragonfly requires watercourses that are shaded up to 50-60% at most. Therefore, the project improved habitat at 11 places in total, by clearing narrow bands of alluvial wood next to the riverbank, but only where this did not lead to conflicts with other conservation goals (e.g. not in areas with the habitat type 6430 ‘hydrophilous tall herb fringe’). The project team widened the watercourses at several locations. This led to sedimentation and the creation of sandbanks. Trees were also placed at 10 suitable locations in the watercourses, to simulate dead wood falling into the river, around which sediment was deposited. Similar results were obtained by building three near-natural ground sills, though this action was later changed (at 14 places) to the introduction of gravel instead. The new approach will be subject to continued monitoring to evaluate its effectiveness. At around eight locations, bypasses totalling 1 600 m in length were dug off the main rivers, to create slowly flowing river areas favourable for dragonfly. At other locations, steep banks were flattened and banks cut back in a curved fashion so rivers lost their straight character, which enabled water to flush over the banks and helped to create sandbanks with different flow velocities. These actions led to a more dynamic river structure. Due to intensive contacts with the water authorities within the project area, the authorities of the region are now aware of the needs of the target dragonfly species and most of them are ready to maintain the improved areas and to implement similar actions at additional sites. Therefore, although the natural succession is working against the project actions, it is very likely that the open habitat conditions favourable for the target species can be maintained and kept at least within the near future. At one river, the Fränkische Rezat, project actions implemented from 2012 onwards were monitored, showing that good habitat conditions had been created. At the site near Kirschendorf, monitoring showed that the number of green club-tailed dragonflies had increased, with females seen using new habitat sites for oviposition. These effects were detectable despite inconvenient weather conditions for the target species in 2013 and 2014. As many of the concrete conservation actions were implemented in the last months of the project’s duration, due to adverse weather conditions making floodplain areas inaccessible to heavy machinery in the first two winters, it was too early to assess the overall effects of actions on the dragonfly’s population level. At the end of the project, however, it can be stated that seven rivers are prepared to provide suitable habitats for the target species. An After-LIFE Conservation Plan was provided to help the relevant authorities maintain these suitable habitats. Dissemination actions implemented by the project included a touring exhibition, the distribution of fliers and information brochures, a website and a CD-ROM containing all the information produced by the project. During the course of the project, several authorities and planning offices from other regions became interested and were informed about the activities. Thus it is likely that similar actions will be implemented at other sites in the future. Further information on the project can be found in the project's layman report and After-LIFE Conservation Plan (see "Read more" section).