European stag beetle

With a body length of up to 10cm, the european stag beetle is one of Europe’s largest beetle species

The imposing appearance of the males with their “antlers” make it one of the best-known beetles in Switzerland, but it is now rarely observed. Like almost all insect species, it suffers from the destruction of its natural habitats. Its disappearance was primarily caused by intensive forestry, which destroyed the beetle’s livelihood: hardly any deadwood, rapid rotation times and tree species unsuitable for stag beetles. Fortunately, the situation has changed today. Modern forest management concepts have led to a more sustainable approach to the forest. However, due to the few remaining populations north of the Alps and a very conservative dispersal strategy of the stag beetles, they are no longer finding their way back into our forests. With the help of the Project to promote deadwood-eating beetle species we are bringing the animals back into the Bernese forests as a first step. However, in order for a stable population to develop, numerous beetle sites are needed. In order to enable our reintroduced stag beetles to spread over a wide area, the next step will be to establish further deadwood areas on the Dählhölzli site as connectivity corridors with the aim of securing their continued existence.

Goals

• Long-term survival of a Bernese stag beetle population
• Create diverse small structures for various other animal species.
• Better understanding of the dispersal mechanisms of stag beetles for optimal promotion

Our bison facility in the Dählhölzli Forest, where a herd of red deer is also on the move, offers ideal conditions for this. The larvae develop in the mulm of old trees, with a preference for oaks but also other tree species. Therefore, the presence of an old tree stand with sufficient deadwood is a must in order to effectively help stag beetles. In other words, we must first ensure that there is enough deadwood. Because the process of wood decomposition (mulm is decomposed wood, i.e. it no longer has a cellulose content) takes several years, the construction of more generous deadwood gardens must begin today. So-called stag beetle piles are very suitable for this purpose and also provide habitats for many other animals (insects but also birds, amphibians, reptiles and small mammals).

A stag pile consists of sections of oak logs and starling boxes that are placed in a pyramid shape in a ground pit about one metre deep. The spaces between the log sections are filled with oak sawdust. With the help of fungi, with which the pile is inoculated, the wood begins to decompose and thus becomes attractive for the egg-laying of the stag beetle. The larvae develop over three to eight years in the mulm of the decomposing deadwood until the fully developed beetle can hatch. The location of the pile on a sunny but at the same time moist south-facing slope is important. Such an ideal location is within the bison red deer facility. Over the years, the stag beetle pile must be repeatedly “re-fed” with oak wood, sawdust and wood chips. Otherwise, only the very best humus will remain in the end and no stag beetle will be able to use the pile any more.

The factors that influence the dispersal of animals are very diverse and depend on various biotic and abiotic factors. In order to understand these mechanisms, the current situation offers the best conditions. By reintroducing stag beetles at a specific site, we know from where the animals recolonise potential habitats. The newly offered structures are built in such a way that they differ from each other in certain factors (age of the deadwood, different species of fungi, distance to the initial population, etc.). Monitoring is then used to investigate which structures are colonised most quickly and how the beetles develop there. This should help us to understand how and with what we can promote the beetles most effectively.

Animals

• European stag beetle
• Other beetle species inhabiting deadwood
• Insects
• Amphibians
• Small mammals
• Birds

What we use your nature conservation francs (Naturschutzfranken) for

• Establishment of a stag beetle pile and other deadwood areas
• Promotion, enhancement and protection of habitats for high biodiversity in forest areas, especially for stag beetles
• Building various other structures to create more diverse habitats
• Resettlement monitoring