Road ecology blog. Fence on top of wildlife overpass Oud Reemst (about 35 m wide), to keep mouflon, horses and cattle from using the overpass, south of Otterlo, The Netherlands. This wildlife overpass connects "Planken Wambuis" (west side) to "National Park Hoge Veluwe" (east side). There is a fence (1.10 m high) and gates on the east side of the structure to keep mouflon (Ovis orientalis), a wild sheep species from south eastern Europe, minor Asia, Asia, and possibly parts of Arabia, inside the "Hoge Veluwe". It also keeps horses (New Forest pony's) and cattle (Sayaguesa (a Spanish cattle breed) and also Scottish Highland cattle) in "Planken Wambuis". Roe deer (Capreolus capreolus) and red deer (Cervus elaphus) can easily jump the fence. Presumably, wild boar (Sus scrofa) can push against the gates with hinges on the top side of the gate and pass through.
The images below are an illustration of how the interests of different landowners and perspectives on nature and nature management influence practical on the ground conservation efforts. The wildlife overpass connects two nature reserves and you would expect that the interests and goals of the organizations responsible for the management of the two areas would be the same. However, this is not necessarily the case. There are non-native species in both areas, neither organization wants the other's non-native species, and neither wants to get rid of its own non-native species. The horses and cattle in "Planken Wambuis" (managed by Natuurmonumenten) mimic the grazing of the now extinct European wild horse (tarpan) and wild cattle (aurochs) and now fill their ecological niche. The mouflon in "National Park Hoge Veluwe" (managed by a foundation) were introduced in 1921 and do not stand in for a now extinct wild species, but they are not doing well in their native range (status vulnerable, IUCN 2014). The mouflon are mimicking the grazing of domesticated sheep that used to roam the heathlands. While the heathlands are the result of historic overgrazing of forest by livestock, they are now considered an important nature management goal on their own (though they are clearly semi-natural at best). The grazing by sheep (domesticated or mouflon) helps keep the heathlands from growing into forest, though atmospheric deposition of nutrients (over the last 50 years or so) is making this a substantial challenge as it is. The mouflon are also considered important to attracting paying visitors to the park. The fence and gates on the overpass are the result of a compromise that should still allow red deer, roe deer and wild boar to use the overpass and move between the two areas. However, there also seem to be some concerns about potentially "losing" too many individual red deer (native species) to the neighboring area, potentially making wildlife viewing by tourists more challenging in the park. Of course it is also possible that more red deer will enter the park.
Ironically, when I was photographing the overpass I saw two pair of non-native invasive Egyptian geese (Alopochen aegyptiaca) in the ponds dug on each side of the overpass. ...Implementing a wildlife overpass and connecting two different nature reserves can be quite complicated.
For other images of wildlife overpasses (wildlife only) click here.
For images of multifunctional wildlife overpasses (wildlife, water, humans, non-motorized vehicles, motorized vehicles) click here.
For images of landscape bridges, road tunnels or very wide overpasses over longer road sections click here.
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