![]() ![]() The size of a wolf hunting pack is related to the number of pups that survived the previous winter, adult survival, and the rate of dispersing wolves leaving the pack. This contrasts with the commonly held belief that larger packs benefit from cooperative hunting to bring down large game. Since we were unable to identify individual wolves in this study, we are unable to say with certainty whether particular animals crossed multiple times.Single wolves or mated pairs typically have higher success rates in hunting than do large packs single wolves have occasionally been observed to kill large prey such as moose, bison and muskoxen unaided. This may suggest dispersal but further monitoring of the green bridge would be necessary to confirm this. We did find that lone wolves tend to use the bridge to move northward, away from the established territories in the south. However, this may have just been a product of low sample size. Lone, dispersing wolves, showed little seasonal differences in crossing, so we were unable to explicitly demonstrate that young individuals used the bridge while searching for their own territory, as would be expected from known dispersal patterns. Packs tended to travel north during day and dusk and then southward again over night until dawn. We also did not find that prey avoided the bridge while wolves were active, suggesting no evidence of prey-trapping at crossing structures.įurther exploration of how wolves used the green bridge suggests that packs are using the bridge within their hunting territories. We saw no direct incidents of wolves hunting on the bridge itself. Daily activity patterns for all four species remained relatively consistent throughout the year – activity on the bridge was highest during dawn and dusk and lowest during the day. Wolves crossed the bridge most often in winter, whereas prey species crossed more often in spring and summer. While the bridge was used by prey species soon after it was constructed, it took almost 4 years before the first wolves were detected on the bridge, and another year before wolves used the bridge regularly. ![]() Wolves, red deer, roe deer, and wild boar all used the green bridge. We aimed to determine if the bridge functions successfully as a means for wolves to recolonize into their historical range, and if the bridge acts as a prey-trap limiting prey species from crossing. In this study, we used camera traps to investigate the seasonal and diurnal use of a green bridge by wolves, red deer, roe deer, and wild boar. As a result, prey may avoid the bridge when wolves are active, which in turn may push prey to attempt to across on the highway itself, or deter them from crossing at all. Some studies suggest that crossing structures can act as a “prey-trap” if predators wait at the site to ambush crossing prey. However, we hypothesized that high wolf presence may have a negative impact on prey species, such as red deer, roe deer, and wild boar. Green bridges were built in Germany with the purpose of facilitating all wildlife movement, and their use by wolves was particularly interesting due to the conservation implications. Wildlife overpasses, also known as “Green bridges,” are a commonly implemented mitigation strategy to try to offset the impacts of roads on wildlife, but prior to our research, the use of green bridges by wolves in the rewilding landscape of Eastern Germany has not been studied. Collisions were most numerous in February and November, possibly coinciding with wolves dispersing in winter. Wolf-vehicle collisions accounted for ~ 76% of total confirmed wolf mortality in Germany in 2020. In a landscape dominated by human-modification, crossing roads can be challenging for this re-establishing population. ![]() As the wolf population grows, packs expand into new areas, and young animals disperse to find new and unoccupied territory. Gray wolves have returned to Germany from Poland after their local extirpation in the 19th century. Swedish University of Agricultural Sciences (SLU), Department of Ecology ![]()
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