Science & Environment

The rock hyrax surprises with syntax skills

The rock hyrax is a surprisingly sophisticated communicator, a study published in a Royal Society journal suggests.

The small mammal is extremely vocal: males sing complex songs that can last for several minutes.

But now scientists have discovered that the order of the notes is significant, suggesting that the songs have syntax.

They also found that hyraxes from different regions had a different dialect when they warbled.

This research places the hyrax in a small and eclectic group of skilled animal communicators, including primates, whales, birds and bats.

Arik Kershenbaum, the lead author of the study, from the University of Haifa in Israel, said: "This is something you find very, very rarely amongst mammals."

Love songs

The rock hyrax (Procavia capensis) is a social mammal, which lives in large groups, and is found in the Middle East and Africa.

Image caption The singing creatures are social and live in large groups

It is well known locally for its song, and scientists believe that males use these vocalisations to advertise their wares.

The team who carried out the study recorded singing hyraxes in nine regions around Israel.

Dr Kershenbaum said: "A typical hyrax song can last for several minutes, and their songs are broken down into small bouts, with each bout lasting for maybe 10 to 20 seconds.

"Each bout is composed of a number of notes, which we call the syllables. There are only a very small number of syllables that make up a hyrax song, and each sound is very distinct.

"And out of these, you can make up a whole language and combine them in an infinite number of ways."

Regional flavour

The researchers describe the syllables as wails, chucks, snorts, squeaks and tweets.

Using a mathematical analysis, they compared the songs of different hyraxes.

Dr Kershenbaum said: "We found that there is some significance to the order they composed their songs - the order of the notes within their song - and that is a syntax, the way the different elements are combined to make a whole."

The team were able to establish that these were not random differences by comparing singers from different regions.

They found that the rock hyraxes that lived less than 5km away from each other had a very similar structure, while creatures that lived further apart were significantly different in composition.

Dr Kershenbaum told BBC News that this was the equivalent of a regional dialect, comparable to the differences between UK English and US English.

He said: "It could be that [the neighbouring animals] are copying each other. It is an indication that the variation is not random."

Hidden meaning?

The findings suggest that the hyrax communication shares similarities with that of other mammals that use syntax.

Image caption The hyrax is one of only a few mammals which have syntax

These include whales, dolphins, marmots, bats, prairie dogs and some primates.

Dr Kershenbaum said that although the hyrax was not thought of as an intelligent animal, such as a chimp or dolphin, it could have developed complex language because it lives in large colonies, and communication is useful for animals living in groups.

Some studies have been able to elicit how combining different sounds can alter meaning.

For example, research on the Campbell's monkey revealed that if the primates made a sequence of "boom" sounds that signified a general alarm call, while a pair of "booms" followed by a noise described as a "krak-oo" seemed to indicate a falling tree or branch.

But Dr Kershenbaum said this kind of association would be unlikely to be deciphered from a singing hyrax.

He said: "We think they are not encoding any information in this syntax. We think the hyrax song is more similar to bird song.

"It is a form of advertising: the males want to sing more complex songs to show the females that they are fitter, more capable of a greater diversity of vocalisations.

"The young males are copying the dominant male, and trying to sing like he is singing, which is why you get the similarity existing in the same group."

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