Teaching the Life-Saving Art of Eavesdropping: Implications for Conserving Endangered Species

By Lisa Horn

Eavesdropping. We’ve all done it.For wild animals, eavesdropping is a survival skill that can save their lives. But can teaching captive-reared animals to listen in on their neighbours help them stay safe in the wild?

Let’s be honest, who wouldn’t strain their ears if they overheard their name in a hushed private discussion? Although it may be considered a bit rude, eavesdropping can be an excellent way to gain intel. And not only can we get information by listening in on other people, but also other species. What assumption might we come to when we suddenly hear the neighbour’s dog barking wildly in the middle of the night?

Humans aren’t necessarily the only experts when it comes to eavesdropping. Many animals are able to gain critical information about their surroundings, such as the approach of a potential predator, by listening in on other species. Take for example birds such as warblers, nuthatches, and vireos. These birds benefit from foraging in safety near chickadees, listening for the chickadee’s scolding ‘chick-a-dee-dee-dee’ alarm calls, which they give when they notice owls, hawks and cats lurking nearby. Hanging around and understanding chickadee sentinels allows these eavesdropping birds to stay up-to-date on the potential threats that surround them.

Loggerhead shrikes use small branches or barbed-wire to impale insects in order to eat them. This hunting behaviour is learned in part from social interactions with other shrikes.

A bird can learn about the dangers in the world around them in several ways. They can learn through their own experience of what has worked for them and what hasn’t, such as a nuthatch who has had a direct encounter with a predator and lived to tell the tale. This is known as asocial learning. On the other hand, they can also learn by observing or interacting with others of their own species or different species, which is known as social learning. Birds can take advantage of others hard-won experience without having to go through all the trial and error themselves. Although a naïve young nuthatch may not have had direct experience with an owl or cat himself, by watching and listening in on a more experienced nuthatch (or chickadee) who may have, he can recognize the threat and figure out the correct action to take.

Animals who have been raised in captivity have generally grown up in the absence of real danger such as predators, unlike their wild counterparts. As a result, conservation-bred animals are often especially vulnerable to predators, and a major concern in conservation is that these endangered animals we are working so hard to protect will simply become easy prey once released. This concern is why Wildlife Preservation Canada utilizes a ‘soft-release’ method with the endangered Eastern loggerhead shrike. Conservation-bred shrikes are placed in release cages in their native habitat to help them adapt to the sights and sounds (and dangers) in their new home, while keeping them in relative safety. When it’s time for ‘release’, the cage doors are opened, and the shrikes can either choose to leave right away, or to stay a little while longer. A ‘soft-release’ method is less stressful for the birds and allows them to familiarise themselves with their habitat. But now there’s been an exciting new breakthrough  that may help further prepare conservation-bred animals to survive in their new wild home: tapping into their innate eavesdropping ability.

Conservation-bred shrikes learn about their natural environment in these “soft releases” cages. Photo: Vincent Luk/Evermaven

The experiment was designed to determine if the birds could understand social cues from other species.

Researchers in Australia were interested in shedding some light on how birds learn to eavesdrop on other species. In a recently published paper in Current Biology, they set out to discover if wild superb fairy-wrens, a small Australian songbird, could be trained to recognize and react to novel alarm calls of other species. The training regime was relatively simple. A situation was portrayed where there was an unseen aerial predator which had prompted concern from the bird neighbourhood in the form of a chorus of alarm calls. Amid the ruckus, the birds could hear alarm calls from their fellow fairy-wrens, as well as some of their other neighbours, but also a new alarm call that they were unfamiliar with. Since the birds recognized that something was up from the alarm calls that they did understand, they ducked for cover. Following the training, the researchers tested how the birds would now respond to the previously unfamiliar alarm call. Sure enough, the birds had learned to treat the novel sound as an alarm call for an aerial predator and respond appropriately by ducking for cover. The birds had learned to associate the previously unknown alarm call with the alarms they did know andwere able to effectively react to a perceived threat. All this without ever having to see the predator or even the informant themselves!

The take-home message: By training conservation-bred birds to learn alarm calls from some of their local neighbours, these animals may be better equipped for survival in the wild with a warning system for potential danger that doesn’t rely on their very limited personal experience. Eavesdropping isn’t as bad as it’s cracked up to be. In fact, understanding the mechanisms behind it may help facilitate conservation of endangered species.

Potvin DA, Ratnayake CP, Radford AN, Magrath RD. 2018. Birds learn socially to recognize heterospecific alarm calls by acoustic association. Current Biology Volume 28, Issue 16, 20 August 2018, Pages 2632-2637.e4

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Lisa Horn

Lisa Horn

Guest Blogger – MSc Candidate at York University in the Stutchbury Lab

Lisa is a guest ecologist and science blogger with a passion for wildlife and conservation. Lisa has wide-ranging experience in conservation, with a special interest in ornithology, species-at-risk, and environmental legislation. Lisa is currently investigating the effects of climate change in wintering habitats of migratory songbirds on their arrival condition in Ontario.