European otters were nearly driven to extinction in the Netherlands, due to water pollution and habitat loss. In 2002, around 30 of them were introduced into the wild, in an effort to regrow their population. If this video is any indication, they've definitely made progress.
As the blog, The Dodo, reports:
After several worrisome months without a sighting of an otter in the town of Nieuwkoop, biologists there recently made a heartening discovery — one which suggests that the rare otters are not only still present, but that they seem to be having a good time, too. A wildlife cam captured footage of an otter appearing to be healthy and happy, spending several moments horsing around with a feather.
Park ranger John Pietersen calls it "the most endearing sideshow."