To Protect An Endangered Snake, First Protect A Venomous One
If you go for a walk through the rocky hills of Finland’s Aland archipelago, you might come across a medium-size snake with gunmetal grey scales and darker diamonds running down its back. It looks a little bit like an adder, but it can’t be because its head is thin and tapered…
Wait, did that snake just change its head?
You can’t be sure, but now its head is definitely flat and triangular—the defining shape of adders and other vipers. That means it’s venomous. There are people living nearby, with kids and pets. You decide to kill the snake with a rock. That was a poor decision, especially since the dead snake wasn’t an adder. It was a smooth snake—completely harmless, rather endangered, and now very slightly more endangered.
The smooth snake is found throughout Europe but its populations are small and thinly scattered. It could be easily wiped out, so the European Union has listed it as a specially protected species. In Finland, it’s classified as “vulnerable”, and may be bumped up by one degree of concern to “endangered”.
For much of its existence, the smooth snake protected itself by mimicking the far more dangerous adder, and its charade (especially its shape-shifting head) is good enough to fool even trained biologists. But this disguise is now the snake’s undoing. The fear of venomous snakes might compel birds to flee, but it sometimes compels humans to kill the potential threat.
This is doubly problematic for the smooth snake because its brand of mimicry (known as Batesian mimicry) only works if the noxious creature it mimics is plentiful. If an island contains a lot of adders, birds soon learn that attacking a long thing with a triangular head and a diamond back is a very bad idea. That’s good for the smooth snake, whose predators avoid it too. But if an island contains no adders, birds could attack the smooth snakes with impunity. Why wouldn’t they? They’re never come to associate those markings with possible death. Batesian mimics should always be in the minority if their copycat acts are to work.
Johanna Mappes from the University of Jyvaskyla in Finland showed this in 1997, by creating an artificial example of mimicry. She injected mealworm larvae with a foul-tasting liquid, and stuck small sugarballs (the ones used to decorate cakes) onto their heads—these were the models. She stuck the same balls onto other mealworms without the nasty liquid—these were the mimics. She then presented both groups to great tits in varying ratios. Mappes found that if the number of mimics equalled or exceeded that of the models, the benefits of their disguises disappeared.
This is bad news for the smooth snake. On Aland archipelago, they already outnumber adders. If Mappes is right, their defence should already be worthless. “For the successful conservation of smooth snakes in Aland, it seems crucial to also protect adders,” writes Mappes, along with colleague Janne Valkonen. “Our results provide foresight to prevent a potential disaster in a situation where a mimic becomes endangered due to the decreased frequency of its model species.”
This might apply to other species too. Many harmless snakes mimic venomous ones, and many snake populations are crashing all over the world. The smooth snake example suggests that protecting an endangered mimic is when an endangered species mimics a dangerous one, we might need to protect both to save the former—a one-for-the-price-of-two deal.
Reference: Valkonen & Mappes 2014. Resembling a Viper: Implications of Mimicry for Conservation of the Endangered Smooth Snake. Conservation Biology http://dx.doi.org/10.1111/cobi.12368
Go Further
Animals
- What rising temperatures in the Gulf of Maine mean for wildlifeWhat rising temperatures in the Gulf of Maine mean for wildlife
- He’s called ‘omacha,’ a dolphin that transforms into a man. Why?He’s called ‘omacha,’ a dolphin that transforms into a man. Why?
- Behind the scenes at America’s biggest birding festivalBehind the scenes at America’s biggest birding festival
- How scientists are piecing together a sperm whale ‘alphabet’How scientists are piecing together a sperm whale ‘alphabet’
Environment
- What rising temperatures in the Gulf of Maine mean for wildlifeWhat rising temperatures in the Gulf of Maine mean for wildlife
- He’s called ‘omacha,’ a dolphin that transforms into a man. Why?He’s called ‘omacha,’ a dolphin that transforms into a man. Why?
- The northernmost flower living at the top of the worldThe northernmost flower living at the top of the world
- This beautiful floating flower is wreaking havoc on NigeriaThis beautiful floating flower is wreaking havoc on Nigeria
- What the Aral Sea might teach us about life after disasterWhat the Aral Sea might teach us about life after disaster
History & Culture
- This thriving society vanished into thin air. What happened?This thriving society vanished into thin air. What happened?
- These were the real rules of courtship in the ‘Bridgerton’ eraThese were the real rules of courtship in the ‘Bridgerton’ era
Science
- Why dopamine drives you to do hard things—even without a rewardWhy dopamine drives you to do hard things—even without a reward
- What will astronauts use to drive across the Moon?What will astronauts use to drive across the Moon?
- Oral contraceptives may help lower the risk of sports injuriesOral contraceptives may help lower the risk of sports injuries
- How stressed are you? Answer these 10 questions to find out.
- Science
How stressed are you? Answer these 10 questions to find out. - Does meditation actually work? Here’s what the science says.Does meditation actually work? Here’s what the science says.
Travel
- How to get front-row seats to an active volcano in GuatemalaHow to get front-row seats to an active volcano in Guatemala
- Urban wine is making a comeback in Paris. Here's how to try itUrban wine is making a comeback in Paris. Here's how to try it
- Discover the sordid history behind these English country homesDiscover the sordid history behind these English country homes
- The 'original' High Line is in Paris — here's how to walk itThe 'original' High Line is in Paris — here's how to walk it
- These rollerskaters take over Paris every Friday nightThese rollerskaters take over Paris every Friday night