A team of researchers based in Italy have found "compelling evidence" that African penguins use the same speech patterns as we do -- the first time this has been found in an animal other than a primate.
The team recorded 590 breeding calls known as "ecstatic display songs." They were sung by single birds during the mating season, from 28 adult African penguins in three different colonies in Italian zoos.
The songs' sounds are similar to the bray of a donkey, according to the paper which published Tuesday, and are responsible for the flightless birds' less-than-flattering nickname: the jackass penguin.
The study found that the vocal sequences contained three distinct syllables of different length, with the "words" used most often the shortest, while the longest sequences were made up of shorter syllables.
The researchers said this showed the flightless birds shared two traits of human speech -- that the most frequently used words are shorter, but also the longer the sentence (or for penguins: the call), the shorter the sounds within it.
The paper, which published in the journal Biology Letters, said these two linguistic laws known as Zipf's Law of Brevity and the Menzerath-Altmann Law respectively, are shared by most human languages.
Penguins use the syllables available to them to speak in the most economical fashion they can, the paper suggested, by reserving the shorter ones for the most common calls.
African penguins are native to the coasts of South Africa and Namibia.