Elephant seals recognize each other by the rhythm of their calls

Date: July 20, 2017

Source: Cell Press

Summary: Every day, humans pick up on idiosyncrasies such as slow drawls, high-pitched squeaks, or hints of accents to put names to voices from afar. This ability may not be as unique as once thought, researchers report. They find that unlike all other non-human mammals, northern elephant seal males consider the spacing and timing of vocal pulses in addition to vocal tones when identifying the calls of their rivals.

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Wild monkeys use loud calls to assess the relative strength of rivals

June 21, 2017 by Jared Wadley

Gelada males—a close relative to baboons—pay attention to the loud calls of a rival to gain information about his relative fighting ability compared to themselves, a new study indicated.

Researchers at the University of Michigan, Georgia State University and Princeton University found evidence that gelada males decide to escalate contests with their opponents based on their own condition relative to the condition of their opponent.

They appear to do this by using the acoustic quality of the loud calls of their rivals—long-distance vocalizations that carry honest information about the fighting ability of the caller.

There has been much debate on specifically how animals make competitive decisions during contests. Game theoretical models predict that animals should assess an opponent's condition relative to their own condition prior to engaging in combat to avoid costly fights they are unlikely to win, a strategy known as mutual assessment.

Despite the benefits of such mutual comparisons ("I am stronger than him"), remarkably few studies have been able to reject much simpler assessment strategies such as self-assessment ("I am strong and should fight") and opponent-only assessment ("he is strong and so I should not fight").

Researchers say one approach for distinguishing these strategies is to use animal displays (rather than aggressive contests) to examine how animals make informed decisions about rivals.

"Particularly for quality signals that contain honest information on the condition of its bearer, signals used in animal displays offer an ideal situation for examining mutual assessment because they are low cost and allow for experimental manipulation," said Marcela Benítez, a postdoctoral research associate at Georgia State University and the study's lead author.

In geladas, harem-holding "leader" males engage in loud call displays to deter challenges from "bachelor" males, who must compete with leaders to gain reproductive access to females. Supporting a mutual assessment strategy, gelada males responded to loud calls of different quality (in both playback experiments as well as in natural observations) according to attributes of themselves and their opponent.

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Linguists team up with primatologists to crack the meaning of monkey calls

July 6, 2016

It has long been known that monkeys convey information through alarm calls, but now a combined team of linguists and primatologists has laid the groundwork for a systematic 'primate linguistics.'

In a series of five articles published in multiple linguistics journals, the authors have brought the general methods of contemporary linguistics to bear on monkey morphology (pertaining to the structure of calls), syntax (how the calls are put together into sequences), and semantics (what calls and call sequences mean), building on several earlier studies conducted within primatology.

"We can now study the form and meaning of monkey calls using methods from theoretical titi monkeys linguistics," explains Philippe Schlenker, a senior researcher at Institut Jean-Nicod within France's National Center for Scientific Research (CNRS) and a Global Distinguished Professor at New York University. "Using this approach, we can compare one monkey species to another and see, for instance, that some of their calls have been preserved over three million years."

The research, which Schlenker co-authored with Emmanuel Chemla, a research scientist at France's National Center for Scientific Research (CNRS), and Klaus Zuberbühler, a professor at Switzerland's University of Neuchâtel, appears in the journals Natural Language & Linguistic Theory, Lingua and Theoretical Linguistics and follows an earlier study in Linguistics & Philosophy. The team of authors includes several other primatologists and linguists, as well as a statistician.

The authors emphasize that monkey languages in no way have the complexity of human language, but that they still display exciting and sometimes challenging formal properties.

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Some like it loud: Warning coloration paved the way for louder, more complex calls in poisonous frogs

Date:

October 25, 2014

Source:

National Evolutionary Synthesis Center (NESCent)

Summary:

Species of poison frogs that utilize bright warning coloration as protection from predators are more likely to develop louder, more complex calls than relatives that rely on camouflage. New research indicates that because these visual cues establish certain species as unsavory prey, they are free to make noisy calls in plain sight and better attract possible mates.

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Foraging bats can warn each other away from their dinners

Date:

March 27, 2014

Source:

University of Maryland

Summary:

A new call that some bats use to tell other foraging bats to 'back off' from bugs they've claimed for themselves has been identified by scientists. This sound, called a 'frequency-modulated bout,' warns other bats away from prey. The researchers are first to report this ultrasonic social call produced exclusively by flying, foraging male big brown bats, in a new article.

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Dolphins 'call each other by name'

By Rebecca Morelle

Scientists have found further evidence that dolphins call each other by "name".

Research has revealed that the marine mammals use a unique whistle to identify each other.

A team from the University of St Andrews in Scotland found that when the animals hear their own call played back to them, they respond.

The study is published in the Proceedings of the National Academy of Sciences.

Dr Vincent Janik, from the university's Sea Mammal Research Unit, said: "(Dolphins) live in this three-dimensional environment, offshore without any kind of landmarks and they need to stay together as a group.

"These animals live in an environment where they need a very efficient system to stay in touch."

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