The Scarce Large Blue (Maculinea teleius) is an endangered butterfly throughout Europe due to its special life-cycle and habitat loss. Our aims were to describe the microhabitats available to this butterfly, to test what factors influence the presence and density of M. teleius adults and to investigate the relationship between host ant species and M. teleius. The vicinities of eight fens were sampled, where there are four types of microhabitats available for this butterfly: Narrowleaf Cattail (Typha angustifolia), Purple Loosestrife (Lythrum salicaria), Marsh Woundwort (Stachys palustris) and Purple Moorgrass (Molinia coerulea) dominated vegetation. In five transects (50 × 5 m) around each fen (running from the edge of the fen into the meadows) the number of imagos was counted twice a day during the flight period. Along the transects, the following parameters were measured or assessed: number of flowerheads of foodplant (Sanguisorba officinalis), microhabitat type, grazing intensity, soil humidity, vegetation height and host ant presence. The four microhabitat types differed significantly in soil humidity, vegetation height, foodplant density and distance from a fen. Generally the Typha microhabitat, situated closest to fens, had the highest soil humidity and vegetation height, followed by the Lythrum, Stachys and finally the Molinia microhabitat along a gradient decreasing soil humidity and vegetation height. The foodplant was most abundant in the Lythrum and Stachys microhabitats. Using linear mixed models and forward stepwise manual selection we found that microhabitat type was the most important factor determining the presence of M. teleius. The local grazing intensity had no direct effect but flowerheads of the foodplant had a positive effect on the abundance of butterflies. The number of butterflies was significantly higher in quadrats where the host ant (Myrmica scabrinodis) was present compared to those where they were absent. Our results suggest that grazing should be continued in order to maintain the current distribution of microhabitats and survival of the butterflies.
Higher nest predation at habitat edges is a major problem for conservation biology. We studied nest predation using artificial nests resembling great reed warblers’ nests at edges and interiors of reedbeds in four large wetlands in Europe: Lake Hornborga (Sweden), Lake Neusiedl (Austria), Lake Velence (Central-Hungary) and Kis-Balaton marshland (West-Hungary). Nest losses showed great local and temporal variation, and in general there was larger nest predation at the edges than in the interior reedbeds. Predation rates of artificial nests along different reedbed edges showed great variation. In contrast, predation rates of interiors were more similar across all experiments, with less variation. This may indicate the existence of a habitat-specific predation rate with less variation in interiors of large habitats, while edges are more exposed to the influences of other factors, which resulted in higher variation of predation rates among study sites. Therefore, reedbed conservation should prefer large stands if considering only passerine nest predation, because (1) nest survival seems to be higher in interior than at edges, and (2) because interiors are less variable, i.e. more stable than edges. The designation of reedbeds cannot rely on reedbed edges, where predation can change due to factors not related to the reed habitat at all.