Wolves are better hunters when monkeys are around

An unexpected co-existence in the Ethiopian highlands

Date:June 22, 2015

Source:Dartmouth College

Summary:Through a rare mixed-species association observed between a carnivorous predator and a potential prey, biologists have identified that solitary Ethiopian wolves will forage for rodents among grazing gelada monkey herds. Through consistent non-threatening behavior, the Ethiopian wolves have habituated gelada herds to their presence, foregoing opportunities to attack the juvenile geladas in order to better capture the rodents.

Gelada monkeys are a close relative of baboons. As grazing primates, they eat grass and some herbs. They live in large herds, between 200-1000 individuals. Ethiopian wolves are the rarest canids in the world, with only between 300-500 individuals remaining in the wild. These wolves are rodent specialists. Both geladas and Ethiopian wolves are endangered and endemic to the Ethiopian highlands.

Through extensive data collection from all-day follows on the Guassa Plateau in north central Ethiopia from 2006 to 2011, researchers studied a band of approximately 200 gelada monkeys, who regularly associate with the wolves living in the area.

According to the study's findings, gelada monkeys would not typically move upon encountering Ethiopian wolves, even when they were in the middle of the herd -- 68 percent of encounters resulted in no movement and only 11 percent resulted in a movement of greater than 10 meters. In stark contrast, the geladas always fled great distances to the cliffs for safety whenever they encountered aggressive domestic dogs.

Continued ...

Primate call gives clues to human speech origins

By Rebecca Morelle, Science reporter, BBC World Service

The gelada makes a bizarre sound that shares a rhythm with the patterns heard in human speech

A bizarre sound made by a primate could help to reveal more about the origins of human speech, a study suggests.

Scientists have found that the gelada, a species that is closely related to the baboon, makes a gurgling noise that shares features with human language.

They believe the monkey's call could be similar to the primitive noises that the evolutionary ancestors of humans once made.

The study is published in the journal Current Biology.

The lead author Dr Thore Bergman, from the University of Michigan in the US, said: "Geladas make vocalisations that have some speech-like properties - it's the first time that that has been shown in a non-human primates."

The 'wobble'

The call of the gelada, which is found in the highlands of Ethiopia, sounds like a cross between a yodel and a baby's gurgle.

Continued:  http://www.bbc.co.uk/news/science-environment-22067192

How Cooperation Can Trump Competition in Monkeys

ScienceDaily (July 4, 2012) — Being the top dog -- or, in this case, the top gelada monkey -- is even better if the alpha male is willing to concede at times to subordinates, according to a study by researchers from the University of Pennsylvania, the University of Michigan and Duke University.

Alpha male geladas who allowed subordinate competitors into their group had a longer tenure as leader, resulting in an average of three more offspring each during their lifetimes.

The findings, collected from data during a five-year period ending in January 2011 through the University of Michigan Gelada Research Project, were published in the Proceedings of The Royal Society.

The research was conducted by Noah Snyder-Mackler, then a graduate student in the Department of Psychology in Penn's School of Arts and Sciences. He collaborated with Thore Bergman, assistant professor of psychology at Michigan, and Susan Alberts, professor of biology at Duke.

Cooperation is surprisingly common among wild animals, the researchers said. While it makes evolutionary sense for animals to help their kin, it is harder to explain cases where competitors -- especially unrelated adult males -- join forces. This conundrum is particularly hard to explain because mating is generally a zero-sum game in which males can only reproduce by stealing mating opportunities from each other.

Continued:  http://www.sciencedaily.com/releases/2012/07/120704021831.htm

Pregnant Monkeys Miscarry to Avoid Infanticide

Joseph Castro, LiveScience Contributor

When a new male gelada monkey takes control of a reproductive group, he will typically kill off the babies of his predecessor. Now, new research shows that pregnant females have an adaptive strategy to minimize their losses: They spontaneously miscarry.

In 1959, biologist Hilda Bruce first demonstrated the so-called Bruce effect in mice, where recently pregnant females miscarry after being exposed to novel males. Since then, researchers have documented the phenomena in other rodent species. However, until now, the Bruce effect seemed to be something restricted to the laboratory, as nobody had conclusively shown that it exists in wild animal populations. Moreover, studies have not shown that there is any evolutionary advantage to miscarrying when confronted with new males.

To see if the Bruce effect exists in gelada monkeys (Theropithecus gelada), Jacinta Beehner, an anthropologist at the University of Michigan, and her colleagues tracked 110 females across 21 groups of wild geladas living in the Simien Mountains National Park in Ethiopia. [Gallery: Photos of Gelada Monkeys]

"We saw that as soon as a new male came into a group, there were no births for the next six months," Beehner told LiveScience. In fact, the researchers documented only two births in these replacement groups in the five years of the study. "We get this big gap, screaming out that something is going on — it's statistically almost impossible to get this by chance."

Read more:  http://www.livescience.com/18629-pregnant-monkeys-miscarry-avoid-infanticide.html