Probably one of the most unusual introduced species is this one. When this private zoo was abandoned by its drug lord in the early 90's most animals died out, but the hippos escaped to the nearby Magdalena river and neighboring lakes/floodplains. The population is of about 50-60 right now and only 1 is actually contained, all others roam freely and are fed in order to maintain them within a specific area + some fencing is used. This, however, is not enough and animals often are found far away from the original area where they were introduced, including nearby villages.
@MonkeyBat It's actually quite a debatable topic to decide what to do with the animals. On one hand some have argued for the culling of the animals given the negative environmental and social consequences of the introduction, but on the other some argue that the animals shouldn't be culled and have become a touristic attraction.
@toto98 There seems to be a bird on the hippo, perching on it and most likely cleaning it. If so thats quite fascinating as oxpeckers and other birds do that in Africa to hippos.
@Yoshistar888 I think the bird is on the bank behind the hippo. It appears to be a Bare-faced Ibis, and I believe there is a second one in the grass in about the center.
@Great Argus@Yoshistar888 I would actually believe the bird behind the hippo is a wattled jacana. You can see a bit of its characteristic red/yellow in the beak and its definitely not the long beak that characterizes ibises.
They are quite damaging to the ecosystem. Generally this is the case with introduced species unless they are filling a similar ecological niche to that of a now extremely rare or extinct animal that came before it in that area.