Grey Heron Ardea cinerea, on a Hippopotamus Hippopotamus amphibius Those birds feel more confidence on the hippopotamus in case a crocodile attack In this way, they find easier to fish their preys and move themselfes through the dam, Kruger National Par. Grey Heron Ardea cinerea, on a Hippopotamus Hippopotamus amphibius Those birds feel more confidence on the hippopotamus in case a crocodile attack In this way, they find easier to fish their preys and move themselfes through the dam, Kruger