Animal Behavior | Nature | Education
Monkey Ransom Negotiators, Head Bobbing Frogs, and Wonder Woman Snakes
Recent research reports spotlight the quirky and the odd from across the animal kingdom.
From wild pandas that love to roll around in horse manure to moonwalking birds in the Amazon, the natural world never ceases to provide examples of fascinating and peculiar animal behavior. A few recently published scientific papers add to this list with reports about unique behaviors observed in Balinese monkeys, Guamanian brown tree snakes, and Ecuadorian glass frogs.
“Give Me the Fruit or the Camera Gets It!”
In a paper published January 11 in Philosophical Transactions of the Royal Society B: Biological Sciences, researchers described monkeys at the Uluwatu Temple in Bali, Indonesia, who have learned the finer points of negotiating for the best ransom payments.
Wild long-tailed macaques (Macaca fascicularis) at the temple have learned which high-value items to steal from humans in order to negotiate for the best offerings of food. They knew when they had taken something expensive, like an electronics item, and held out for more and/or better food rewards before giving it back. For lower-value items like empty camera bags or keyrings, the monkeys would accept a lesser reward.
The monkeys would stare at a visitor, approach them inconspicuously, snatch the object, then step aside waiting for an offering they deemed suitable to the value of the item. Lower value items included empty containers and accessories like hairpins. Higher value items included mobile phones, tablets, wallets, and prescription glasses.
The longest time before an item was returned was 25 minutes, including 17 minutes of negotiation.
The older monkeys were better at the robbing/ransom negotiation process, which was indicative of experiential learning.
The researchers noted that the behavior was an example of “unprecedented economic decision-making processes” among the monkeys. According to the researchers, this population-specific, cross-generational, learned, and socially influenced practice “may be the first example of a culturally maintained token economy in free-ranging animals.”
“Wonder Twin Powers, Activate! Form of a Lasso — I Mean, a Snake!”
From Bali, we hop over to Guam, where researchers have observed a unique type of locomotion in brown tree snakes.
In the January 11th issue of Current Biology, biologist Bruce Jayne from the University of Cincinnati and colleagues reported the discovery of snakes that climb poles and trees using a never before seen lasso-like gripping technique. The brown tree snakes (Boiga irregularis) hug their bodies around a cylindrical shape and cross over themselves to form a lasso, then use their vertebrae to wriggle their way upwards:
Before this discovery, snake locomotion had been classified into only four types: sidewinding, rectilinear locomotion, lateral undulation, and concertina locomotion. Variations of the concertina mode are what had been observed for tree climbing, involving wrapping around a cylindrical surface and hitching their way up like climbing rope in gym class.
It’s thought that the adaptation could help the snakes climb smooth-trunked trees in their native range throughout Indonesia and northern Australia.
Unfortunately, that’s bad news for native birds on the island of Guam, where the brown tree snake has decimated the native bird population since being accidentally introduced over 70 years ago. In fact, this new type of locomotion was discovered when researchers were attempting to save remaining birds and had placed bird nests on top of smooth poles that they were sure no snake would be able to climb.
“To say I was surprised would be an understatement,” said Jayne.
The movement is also surprisingly complex, according to Daniel Goldman, a biophysicist at the Georgia Institute of Technology who was not involved with the study. According to Goldman, “We have no human technology that can come close to what this snake is doing.”
A Night at the Roxbury — Ecuadorian Edition
When you’re a frog trying to attract a mate, what do you do if you’re in a place that’s too loud for any lady frogs to hear your romantic croaks of love? Rely on body language of course.
In the November issue of the journal Behaviour, researchers report that male Ecuadorian glass frogs (Sachatamia orejuela) that live almost exclusively in the loud spray zones of waterfalls use head bobs, hand waves, and foot flaps to supplement their love songs.
While this is not the first time that this type of full-body communication in loud environments has been observed in frogs, it is the first time it has been observed in this family of frogs.
According to Rebecca Brunner, a Ph.D. candidate at the University of California, Berkeley and the lead author of the paper, “A handful of other frog species around the world use visual signaling, in addition to high-pitched calls, to communicate in really loud environments.” Brunner added, “What’s interesting is that these species are not closely related to each other, which means that these behaviors likely evolved independently, but in response to similar environments — a concept called convergent evolution.”
Brunner hopes their findings will serve as a reminder of our planet’s incredible biodiversity, and that conservation is important not only for our well-being but also for our sense of wonder.
“One of the best things about fieldwork is that nature is always full of surprises — you never know what discoveries you may happen upon,” Brunner said.