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Using olfactory cues to protect vulnerable species

What the nose doesn't know helps wildlife: using olfactory cues to protect vulnerable species

Ground-nesting shorebirds such as the double-banded plover are vulnerable to invasive New Zealand terrestrial predators, including cats, hedgehogs and ferrets. Olfactory cues can help wildlife managers reduce nest predation by these predators to protect populations. Credit: Grant Norbury

Animals – both herbivores and predators – follow their noses for a wide variety of food sources. The principle applies to hunters trying to track down easy prey or grazers looking for the richest plants.

Now behavioral ecologists have discovered a way to harness animals’ sense of smell to protect vulnerable plants and endangered animals. In a new study published in the journal of the Ecological Society of America: Limits in ecology and environmentUniversity of Sydney ecologist Catherine Price has developed a practical and theoretical framework that sheds light on how animals use their sense of smell to find food, and how conservationists can use scents to deter unwanted predation.

People have been using similar tactics for thousands of years. Gardeners plant marigolds and chrysanthemums to deter insects and rabbits, and people burn citronella or spray garlic oil around their yards to deter mosquitoes. However, why this works is still a mystery.

“It’s only now that we’re beginning to discover the mechanism by which these methods work and identify the important volatiles in the odors,” Price said. “We’re starting to take apart the ecological basis of smell and understand how animals use smell and why they behave the way they do — and how we can use that knowledge to save species and protect ecosystems.”

What the nose doesn't know helps wildlife: using olfactory cues to protect vulnerable species

Bush curlew was one of the first species that Dr. Price studied. They are visually well camouflaged. Olfactory camouflage can help protect them from foxes and other predators in Australia. Credit: Andrew Lothian

The role of smell in the animal world has sometimes been overlooked, perhaps because humans don’t hunt for scent much anymore. Scientists have studied scent marking and territorial defense, as well as the effects of scent on mating behavior, but not much research has been done on how animals use scent to find food.

Price’s paper, more than a decade in the making, examines the ways animals use olfaction to find food, and how to circumvent that process to reduce predation. Methods include masking the scent of a food source (such as seeds, eggs, or an animal you are trying to protect), hiding the scent, or spreading a similar scent across the landscape to a hunter or grazer. train to ignore a particular scent when it is hunting for food.

“It’s about the food we don’t want them to eat — an endangered bird or plant — that we don’t want them to eat, is hard for them to find. They have other, easier food options, so they don’t struggling to find what we’re trying to protect.”

Price and her team literally tested her theory on the ground by soaking a chicken scent in petroleum jelly and spreading it over a thousand acres where endangered shorebirds nested. Because the scent appeared before the birds, and because it was everywhere and therefore not a useful clue for finding dinner, ferrets and stoats left the shorebirds’ nests alone. Nest predation decreased by more than 50 percent, an effect that lasted for a month.

“You can compare it to camouflage — we just hide things in plain sight,” Price said. “Foragers use scent to find things, and if they can’t find it in all the scents in the background, they look for something else.”

In the trials done to date, using olfactory cues for protection costs about the same as other methods, including fences, lethal predator control methods and other deterrents, but is more effective, more durable and does not involve animal welfare problems.

  • What the nose doesn't know helps wildlife: using olfactory cues to protect vulnerable species

    Invasive predators, including urchins and ferrets, threaten New Zealand shorebirds like this South Island oystercatcher, which evolved without the threat of mammal egg thieves. Olfactory misinformation helps protect nesting colonies from predators and ensure more nestlings survive. Credit: Grant Norbury

  • What the nose doesn't know helps wildlife: using olfactory cues to protect vulnerable species

    Invasive hedgehogs like an easy snack of eggs from a colony of nesting shorebirds. Olfactory misinformation can contribute to making the eggs harder to find, encouraging hedgehogs to more easily seek out food sources. Credit: Grant Norbury

  • What the nose doesn't know helps wildlife: using olfactory cues to protect vulnerable species

    New Zealand shorebirds evolved without having to worry about mammalian predators like this invasive ferret. Olfactory cues help hide eggs and protect them from predation. Credit: Grant Norbury

“It’s important to work with the motivations of the foraging animal,” says Price. “That’s why it’s different from other strategies like fences and other deterrents. That’s why they don’t often work.”

When conservationists remove predators from a population, they cannot guarantee that they have protected anything. One fox can wreak havoc on a colony of shorebirds in one night. Olfactory control also allows managers to focus only on problematic or invasive predators, leaving the native predators in an ecosystem unaffected.

More practical on-site studies are needed to test the scope, methods and particulars of olfactory cues in ecosystems, but early results are encouraging.

“There’s still a lot to understand,” Price said. “But this is a new, powerful tool to add to wildlife managers’ kit.”

Invasive hedgehogs and ferrets get used to and categorize scents

More information:
Catherine Price et al, Olfactory misinformation : creating “fake news” to reduce wildlife foraging, Limits in ecology and environment (2022). DOI: 10.1002/fee.2534

Provided by Ecological Society of America

Quote: What the nose doesn’t know helps wildlife: Using olfactory cues to protect vulnerable species (2022, June 21) Retrieved June 21, 2022 from https://phys.org/news/2022-06-nose-doesnt -wildlife-olfactory -cues.html

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