Parasites, depredators, and limited resources as potential drivers of winter mortality of feral honeybee colonies in German forests.

Wild honeybees (Apis mellifera) are considered extinct in most parts of Europe. The likely causes of their decline include increased parasite burden, lack of high-quality nesting sites and associated depredation pressure, and food scarcity. In Germany, feral honeybees still colonize managed forests, but their survival rate is too low to maintain viable populations. Based on colony observations collected during a monitoring study, data on parasite prevalence, experiments on nest depredation, and analyses of land cover maps, we explored whether parasite pressure, depredation or expected landscape-level food availability explain feral colony winter mortality. Considering the colony-level occurrence of 18 microparasites in the previous summer, colonies that died did not have a higher parasite burden than colonies that survived. Camera traps installed at cavity trees revealed that four woodpecker species, great tits, and pine martens act as nest depredators. In a depredator exclusion experiment, the winter survival rate of colonies in cavities with protected entrances was 50% higher than that of colonies with unmanipulated entrances. Landscapes surrounding surviving colonies contained on average 6.4 percentage points more cropland than landscapes surrounding dying colonies, with cropland being known to disproportionately provide forage for bees in our study system. We conclude that the lack of spacious but well-protected nesting cavities and the shortage of food are currently more important than parasites in limiting populations of wild-living honeybees in German forests. Increasing the density and diversity of large tree cavities and promoting bee forage plants in forests will probably promote wild-living honeybees despite parasite pressure.

Robin Who? Bird Species Knowledge of German Adults.

Knowledge of species is the basis for involvement in biodiversity awareness and protection. For the first time, we investigated how bird species knowledge is spread among adults in Germany in a representative study. It was shown that of the 15 species presented, only 6 were recognized on average, and 4.5% of the tested persons did not recognize any species at all. Only 0.5% knew all presented species. Younger participants in particular knew significantly fewer species than the group over 60 years. We also tested if species knowledge has an impact on the motivation to act for nature conservation. In this study, knowledge of species correlated directly with the willingness to take action for species protection, e.g., through donating money for proactive nature conservation. Simply being in nature was meaningless for the test result. However, if one was actively involved with birds, e.g., via bird counts or bird feeding, species knowledge was significantly better.