Hippo talk: study sheds light on purpose of call and response

Researchers say wheeze honks' are identity signals, with reactions ranging from calls to spraying dung linked to level of familiarity

A call from a stranger may elicit myriad responses - panic, confusion, maybe even excitement - but it turns out that hippos have a rather more corporeal reaction: they spray dung.

Researchers studying hippopotamuses in Mozambique have revealed that the creatures not only react to the vocalisations of other hippos, but that the calls act as an identity signal. In other words, they allow hippos to tell the difference between a familiar individual and a stranger.