African elephants use smell to communicate

African elephants use their acute sense of smell as a form of communication, researchers report.

Professor Louw Hoffman from the University of Queensland’s Queensland Alliance of Agriculture and Food Innovation co-led a study of elephants in wildlife parks in Malawi, which found that smell was used to distinguish characteristics including age, health, reproductive status, and family relationships between elephants.

“We tested the DNA, glands, urine, and manure of 113 African elephants to identify family groupings,” Hoffman says.

“We found a number of chemicals were common to group members, but others that were unique to each individual.

“Elephants never mate with a sibling, even if they’ve been separated for years and can tell a strange elephant is close by from the smell of their manure or other excretions.”

Hoffman says social behavior also suggests elephants use odor to monitor other pachyderms, both within and outside their herd.

“We observed elephants greeting each other by squealing and flapping their ears,” he says.

“We believe they’re pushing their pheromones towards the other elephant as a sign of recognition.

“When elephants charge each other flapping their ears, rather than making themselves look bigger, we believe they’re blowing their pheromones as a warning not to mess with them.”

Hoffman says elephants not only identify different smells quickly, but also retain them in their memory.

“Some of the animals in the study were bred in captivity, and one of the tricks they’d been taught was to take a tourist’s hat and smell it,” he says.

“When the tourist came back hours later the elephant would be able to immediately identify who the hat belonged to.”

Hoffman says elephants could be trained to sense many things, including blood and explosives.

“These findings show elephants are complex creatures, and sound is not their only form of communication,” he says.

“We see humans as the apex, but we now know elephants are one of many animals that have senses more finely attuned than ours.

“There is a lot we can learn from the elephant.”

The study was co-led by Katharina von Dürckheim and Alison Leslie from the University of Stellenbosch.

The research appears in Scientific Reports.

Source: University of Queensland

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To woo a mate, male whales choose fighting over singing

Male whales along Australia’s eastern seaboard are giving up singing to attract a mate, switching instead to fighting their male competition.

Researchers analyzed almost two decades of data on humpback whale behavior and found singing may no longer be in vogue when it comes to seduction.

“…humans aren’t the only ones subject to big social changes when it comes to mating rituals.”

“In 1997, a singing male whale was almost twice as likely to be seen trying to breed with a female when compared to a non-singing male,” says Rebecca Dunlop, associate professor at the University of Queensland’s School of Biological Sciences.

“But by 2015 it had flipped, with non-singing males almost five times more likely to be recorded trying to breed than singing males. It’s quite a big change in behavior so humans aren’t the only ones subject to big social changes when it comes to mating rituals.”

The researchers believe the change has happened progressively as populations recovered after the widespread cessation of whaling in the 1960s.

“If competition is fierce, the last thing the male wants to do is advertise that there is a female in the area, because it might attract other males which could out-compete the singer for the female,” Dunlop says.

“By switching to non-singing behavior, males may be less likely to attract competition and more likely to keep the female. If other males do find them, then they either compete, or leave.

“With humpbacks, physical aggression tends to express itself as ramming, charging, and trying to head slap each other. This runs the risk of physical injury, so males must weigh up the costs and benefits of each tactic.”

“Male whales were less likely to sing when in the presence of other males. Singing was the dominant mating tactic in 1997, but within the space of seven years this has turned around,” she says.

“It will be fascinating to see how whale mating behavior continues to be shaped in the future.”

Celine Frere, an associate professor and study coauthor, says previous work from Professor Michael Noad found the whale population grew from approximately 3,700 whales to 27,000 between 1997 and 2015.

“We used this rich dataset, collected off Queensland’s Peregian Beach, to explore how this big change in whale social dynamics could lead to changes in their mating behavior,” Frere says.

“We tested the hypothesis that whales may be less likely to use singing as a mating tactic when the population size is larger, to avoid attracting other males to their potential mate.”

The research appears in Communications Biology.

Source: University of Queensland

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Even without ears on the outside, snakes can hear sound

Contrary to popular belief, snakes can hear and react to airborne sound, according to a new study.

The researchers played three different sound frequencies to captive-bred snakes one at a time in a soundproof room and observed their reactions.

“Because snakes don’t have external ears, people typically think they’re deaf and can only feel vibrations through the ground and into their bodies,” says Christina Zdenek from University of Queensland’s School of Biological Sciences.

“But our research—the first of its kind using non-anesthetized, freely moving snakes—found they do react to soundwaves traveling through the air, and possibly human voices.”

The study involved 19 snakes, representing five genetic families of reptile.

“We played one sound which produced ground vibrations, while the other two were airborne only,” Zdenek says. “It meant we were able to test both types of ‘hearing’—tactile hearing through the snakes’ belly scales and airborne through their internal ear.”

The reactions strongly depended on the genus of the snakes.

“Only the woma python tended to move toward sound, while taipans, brown snakes, and especially death adders were all more likely to move away from it,” Zdenek says.

“The types of behavioral reactions also differed, with taipans in particular more likely to exhibit defensive and cautious responses to sound.

“For example, woma pythons are large nocturnal snakes with fewer predators than smaller species and probably don’t need to be as cautious, so they tended to approach sound,” Zdenek says.

“But taipans may have to worry about raptor predators and they also actively pursue their prey, so their senses seem to be much more sensitive.”

The findings challenge the assumption that snakes can’t hear sound, such as humans talking or yelling, and could reshape the view on how they react to sound.

“We know very little about how most snake species navigate situations and landscapes around the world. But our study shows that sound may be an important part of their sensory repertoire.

“Snakes are very vulnerable, timid creatures that hide most of the time, and we still have so much to learn about them.”

The research appears in PLOS ONE. Damian Candusso, a professor at Queensland University of Technology is a coauthor.

Source: University of Queensland

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