Washington, Jan 18 : A new research has shown that monkeys living on the Mentawai islands in Indonesia, do not recognize the calls of tigers and leopards, among other animals.
Conducted by Jessica Yorzinski, a graduate student in animal behavior at the UC (University of California) Davis, the research was conducted on the pig-tailed langurs, which are medium-sized monkeys that spend most of their day sitting in trees in small groups eating leaves. s part of the study, Yorzinski played recordings of tiger and leopard calls and growls, as well as the sounds of elephants, pigs, birds and people talking in the local language. n hearing the noises of the tigers and leopards, the monkeys would look around and at each other and did not immediately leave the area.
In fact, they did not show any greater alarm at hearing the big cat noises than at hearing an elephant, which would make them flee in about four to five seconds.
The main reason for the monkeys not recognizing the calls from tigers and leopards is that they have been isolated from these big cats for about half a million years on the Mentawai islands.
"This contributes to a growing literature on how animal behavior changes under relaxed selection pressures," said Yorzinski.
As for their reaction towards other noises, the monkeys would flee within a second on hearing recorded human voices. On the other hand, they did not flee from bird or pig noises.