Migration of butterflies

Insects as indicators of climate change and biodiversity

The admiral (Vanessa atalanta) used to immigrate to Germany every year. For 10-20 years he is one of the overwinterers in Central Europe. © Manfred Hund, Ludwigshafen
Read out

In Europe, a migration of butterflies is currently taking place. Cause: climate change. This was pointed out by experts at a conference at the Helmholtz Center for Environmental Research (UFZ). Warmth-loving species then penetrate further and further north through the mild winters. Animals that prefer cold weather, however, are getting more and more in trouble and even threaten to die out in the future. The migratory movements of butterflies could therefore serve as an indicator of progressive climate change, the researchers said.

According to the observations of 500 volunteers, who have regularly counted butterflies as part of the butterfly monitoring program since 2005 and according to a standardized method, there are clear indications that species composition will change significantly in the coming years. The long-term observation program is an action coordinated by the UFZ that contributes to the implementation of the UN Convention on Biological Diversity.

Winner and Loser

The results of the monitoring show that the warm winters allow numerous, especially heat-loving species, to expand their area to the north. The Great Fox, ten years ago pushed back to some remaining locations, can be found again in many parts of southern Germany. Similar observations come from other European regions such as Scotland. There, the so-called Brown-Thick-headed Brown-throated Brown-eyed and Red-brown Ox-eye are now appearing, which were too cool in these latitudes.

What seems good to a number of species is bad for others, researchers say. Especially species that have cooler climatic requirements and occur, for example, in moors and mountains, get into trouble. In the UK the Graubindige Mohrenfalter is gradually displaced to the north. Outside of the Alps, a decline of previously rare species is to be expected in Germany. These include: the bog-bog, the marginal fritillary, the moor-blue, and the common nightspotted fritillary.

According to the scientists, the mourning mantle, for example, seems to be scarcely surviving in some parts of Europe like the last winter, whereas in northern Germany and the Netherlands last year a strong occurrence was probably recorded from animals migrating to the east could. display

Too early or too late?

Not only the distribution areas of the butterflies are in motion, also the time, when they appear in the year, changes, according to the results of the monitoring. In the case of the peacock butterfly, the changed climate has led to the emergence of a second generation in many regions of Germany, which was previously the case only in the hottest parts of southwestern Germany. The admiral is considered a classic migratory butterfly, which immigrates every year from the Mediterranean area with us. In the meantime, the winters are so mild that the moth has been wintering here for ten to 20 years, and wintering caterpillars and dolls have also appeared. Thus, in the spring, the offspring of the moths, who have propagated with us with the new additions from the south.

Butterflies as indicators

The trends observed confirm how much butterflies are useful as indicators of the impact of environmental change. They react quickly and sensitively, thus revealing developments that affect entire communities, but that can not be reproduced in their entirety and, in some cases, only react with great delay.

Not least because of this indicator function - but also because of its popularity in the public - butterflies are central elements of international research. Thus, they are also a central component of the EU project ALARM, which has set itself the goal of research into the manifold factors influencing biodiversity - in other words biodiversity. a project in which more than 200 scientists from 67 institutions from 35 countries work together In 2010, the European states must comply with the Biodiversity Convention on the state of biodiversity in Europe report to their countries. Due to the sensitive reaction of butterflies to environmental changes, the European Environment Agency in Copenhagen (EEA) has among other things for this purpose the butterflies besides the birds as key indicators at European level ausgewhlt.

How does it look in Germany? - The butterflies monitoring Germany TMD

In order to standardize the detection of butterflies, the so-called monitoring, Europe-wide, in 2004 the Foundation "Butterfly Conservation Europe" was founded in the Netherlands, which is supposed to accompany the various national initiatives as an umbrella organization.

In 2005, Butterfly Conservation Europe supported the start of butterflies monitoring in Germany, as part of a European network covering more and more countries. The long-term observation program is a joint action of currently around 500 volunteers, who regularly and according to a standardized method butterflies count. However, in order to be able to scientifically substantiate changes in biodiversity and species composition, such as those currently triggered by climate change, and to be able to interpret the data accordingly, it will take several more years of continuous observations. However, sound statements can already be expected for the 2010 reports at European level - and Germany could thus come a step closer to fulfilling its obligations,

In total, more than 50, 000 datasets have been collected in two years' time, and about 200 species of diurnal butterflies - including about 100 butterflies - have been registered. The most common encounters with the butterfly counters are the Little Cabbage, the Greenbreast, and the Big Oxglove.

Climate research for all - the new season starts!

This year, the counting season starts again in the first week of April. At various locations in Germany, numerous experts with the support of the UFZ are organizing informational events and excursions with the aim of attracting new volunteers for the project. In the long term, in addition to recording trends in monitoring, a solid basis for documenting the distribution of butterflies in Germany should be developed.

(idw - Helmholtz Center for Environmental Research - UFZ, 19.03.2007 - DLO)