Seit mehreren Jahrzehnten nehmen die Bestandszahlen von Bodenbrütern europaweit ab, ein Prozess, der hauptsächlich auf die Intensivierung der Landwirtschaft zurückzuführen ist. In diesem Zusammenhang könnte aber auch die zunehmende Prädation von Raubsäugern (Carnivora, Mammalia) eine wichtige Rolle spielen. Ziel dieser Studie war die Bewertung und Einschätzung des Prädationspotentials ausgewählter Raubsäugerarten auf Bodenbrüter im brandenburgischen Vogelschutzgebiet "Mittlere Havelniederung". Von Mai 2015 bis Juni 2017 wurde die Raumnutzung verschiedener Raubsäugerarten mittels Kamerafallen und einer Telemetriestudie untersucht und anschließend mit den Ergebnissen einer Vogelkartierung verglichen. Ergänzt wurden die Untersuchungen mit einer Losungsanalyse der am häufigsten beobachteten Raubsäugerarten Waschbär (Procyon lotor) und Rotfuchs (Vulpes vulpes). Waschbären wiesen eine hohe Standorttreue sowie eine hohe Präferenz für Gewässer und Feuchtgebiete auf, während Rotfüchse eine hohe intraspezifische Variabilität in Bezug auf ihre Habitatnutzung sowie ein hohes Abwanderungsverhalten zeigten. Die Ergebnisse lassen außerdem ein hohes Prädationspotential des Waschbären auf Wasservögel vermuten, während der Einfluss auf Wiesenbrüter geringer zu sein scheint. Diese scheinen den höchsten Prädationsdruck durch den Rotfuchs zu erfahren. Die Nahrungsanalysen bestätigen diese Ergebnisse und spiegeln auch räumliche Bewegungsmuster beider Arten wieder. Diese Studie liefert als eine der europaweit ersten Studien empirische Belege für ein starkes indirektes und direktes Prädationspotential des Waschbären insbesondere auf Wasservögel. Zudem hebt diese Studie die Notwendigkeit einer differenzierten Betrachtung potenzieller Auswirkungen von Raubsäugern auf Bodenbrüter hervor und gibt einen Hinweis darauf, dass das Prädationspotential einer Raubsäugerart eng mit der Strukturvielfalt eines Lebensraums und somit mit der Intensität der landwirtschaftlichen Bewirtschaftung zusammenhängt. / Over recent decades, a general decline in ground-nesting bird species has been recorded all over Europe and this trend is mainly a result of agricultural intensification. However, increasing predation pressure by carnivores (Carnivora, Mammalia) might also play an important role in this context. The aim of this study was to assess and evaluate the predatory potential of selected carnivore species on ground-nesting birds in the Special Protection Area `Mittlere Havelniederung’ in Brandenburg, Germany. Between May 2015 and June 2017, camera- trapping and a telemetry study were carried out to investigate the spatial behavior of mesocarnivore species. Subsequently, spatial data were compared with results of a bird mapping and complemented by an analysis of scat contents of the most abundant carnivore species raccoon (Procyon lotor) and red fox (Vulpes vulpes). Camera trapping revealed a high diversity of carnivores. In addition, spatial distribution patterns showed high site fidelity and an exclusive preference for waters and swamplands in raccoons, while red foxes showed a high level of intraspecific variance in habitat use and a pronounced level of migratory activity. Predator-prey spatial overlap assumes a high potential impact of raccoons on water-associated bird species, while their impact on grassland birds appears not as important. Grassland birds seem to experience highest predatory pressure by red foxes. Dietary analysis support these results and confirm species-specific spatial patterns. As one of the first studies in Europe, this study provides empirical evidence of raccoons’ strong indirect and direct predatory potential in particular on water-associated bird species. Besides, this study highlights the need for a differentiated view on the potential impact of carnivore species on ground-nesting birds and suggests, that the predatory potential of a carnivore species is linked with landscape diversity and thus with intensity of agricultural land use practices.

Bank voles, grey-sided voles, and field voles had synchronous 3-4 year density cycles with variable amplitudes which averaged about 200-fold in each species. Cycles of vole predators (red fox and Tengmalm's owl), and their (foxes') alternative prey (mountain hare and forest grouse) lagged behind the vole cycles. The nomadic Tengmalm's owl responded with a very rapid and strong numerical increase to the initial cyclic summer increase of voles (the owl’s staple food). Owl breeding densities in the springs were highly correlated with vole supply in the previous autumns. This suggested that the number of breeding owls was largely determined in the autumn at the time of the owl's nomadic migrations, and that immigration was crucial for the rapid rise in owl numbers. The owl's numerical response was reinforced by the laying of earlier and larger clutches when food was plentiful. In addition, the owl has an early maturation at one year of age. The transition between subsequent vole cycles was characterized by a distinct shift in rate of change in numbers from low to high or markedly higher values in both summer and winter. Regulation increased progressively throughout the cycle since the rate of change decreased continuously in the summers. Moreover, there was a similar decrease of the rate of change in winter. Rate of change was delayed density-dependent. The delayed density-dependence had an 8 month time-lag in the summers and a 4 month time-lag in the winters relative to the density in previous autumns and springs, respectively. These findings suggest that vole cycles are likely to be generated by a time-lag mechanism. On theoretical grounds, it has been found that a delayed density- dependence of population growth rate with a 9 month time-lag caused stable limit cycles with a period between 3 and 4 years. Some mechanisms for the delayed density-dependence are suggested and discussed. The mechanisms are assumed to be related to remaining effects of vole populations past interactions with predators, food supplies, and/or diseases. Unlike the other voles, the bank vole had regular and distinct seasonal declines in density over winter. These declines are proposed to be due to predation, mainly by Tengmalm's owl. Supranivean foraging for epiphytic tree lichens and conifer seeds most likely explains why this species was frequently taken by the owl under snow-rich conditions. The alternative prey hypothesis predicts that a reduction of predator numbers should increase the number of alternative prey. Alternative prey should be less effectively synchronized to the vole cycle by predation at declining and low vole (main prey) densities; they may also lose their 3-4 year cyclicity. The appearance of sarcoptic mange among foxes in northern Sweden in the mid 1970s provided an opportunity to "test" these ideas, and these were found to be supported. In areas with highest mange infection rates, foxes declined markedly from the late 1970s to mid 1980s, whereas hare numbers rose rapidly and appeared non-cyclic. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1991, härtill 7 uppsatser</p> / digitalisering@umu

The human use of landscape causes fragmentation and loss of original habitats. Different species vary in their sensitivity to habitat loss. Especially carnivores can be more sensitive to decrease of their habitat because of lower abundance of their prey. On the other hand several opportunistic carnivores can profit in human modified habitats. This study was carried out in the České Budějovice basin, Czech Republic during the years 2008 and 2009 and the aim of this study was to determine carnivore{\crq}s habitat preferences in the fragmented landscape. During these two years were seven carnivore species monitored in forest patches by using scent stations. Records of this monitoring were compared with physiognomy of these patches and structure of surrounding landscape.