For 20 years now, volunteers in Germany have been participating in the “Bagfalter Monitoring Germany” and counting face-to-face butterflies. The data is now sufficient for some types to show long -term trends. Accordingly, 18 domestic daily species increase, 28 species have held their level and decrease 36 species. Climate change, insecticides and destroyed habitats are responsible for the losses.
It has been 20 years ago that scientists from the Helmholtz Center for Environmental Research UFZ and members of the Society for Butterfly Protection (GFS) launched the “Bagfalter Monitoring Germany” in March 2005. Since then, hundreds of volunteers have been on the road every year in order to run out between April and September – so -called transplants – and to capture all day -active butterflies according to a uniform procedure that they meet on the go. Since the project started, almost 4.4 million dubble on a total of 1,620 transects have been counted. This corresponds to almost 55,000 kilometers expired.
Long -term trends are difficult to grasp
This abundance of data now allows long -term trends to be recognized by some of the monitored species. Before that, this was only possible to a limited extent, because butterfly populations change very quickly. Since the moths usually have special demands on the climate and the vegetation of their habitat, their stocks react promptly as soon as something changes – especially because a generation of butterflies usually only lives for a few months to a maximum of one year. If the occurrence of a kind of two or three years goes back, it does not have to be an alarm sign. If you want to track down real trends, you have to collect data for decades – and that in as many areas as possible.
Here the butterfly monitoring comes into play. But even twenty years of volunteering is not enough to assess the population development of all monitored butterflies. “We capture approximately 120 of the 178 daily species that are considered to be established in Germany. The rest is so rare or in such special habitats or regions (for example only in the Alps) that they have not yet been recorded in monitoring,” says Elisabeth Kühn from the UFZ. “For 82 types of folds, the data is good enough to calculate trends.”
Butterflies in danger
But how is this 82 fold species? In fact, the results are not particularly positive. Some heat -loving species such as the wall fox, the small mother -of -pearl butterfly or the Aurora age increase. However, if one looks at the development of all types, the transect data overall shows a downward trend, as Josef Settele, chairman of the GFS, reports: “18 species are increasing, 28 species have held their level and decrease 36 species.” However, it should be borne in mind that the butterflies, whose stocks have increased, are more widespread species. However, many specialists who are significantly worse have not yet been evaluated.
The fact that the stocks of many dubbed types go back can have various causes. This includes climate change and the use of insecticides in agriculture as well as the loss of habitat through development. In order to make their lives easier for the butterflies, it would therefore be important to renaturalize ecosystems, as the project coordinators emphasize.
Source: Helmholtz Center for Environmental Research-UFZ