Wednesday, July 11, 2012

Don’t Challenge a Fruit-Eating Bat to a Drinking Contest

Did you think humans invented inebriation? Guess again!

Frugivores (animals that eat fruit) and nectarivores (animals that eat nectar) are limited to food sources that last a relatively short time before they ripen, then ferment, then completely rot. So you would think that a fruit-eating animal would be much more successful at feeding itself if it could eat foods in various stages of fermentation, right? Not only would the ability to eat fermented fruits increase food abundance, but alcohol also has high caloric content (ehem: beer bellies), and makes the food easier to find by that distinctive alchy-smell. So rock on, little frugivores! It’s all good!

Watch this drunk squirrel try to escape the
"predator"-people with the camera. You're welcome.

Or is it? Imagine you’re drunk: kinda happy, stumbling occasionally, saying things you’ll likely regret in the morning, and getting lost on the way to the bathroom. Now imagine you’re being chased by a mountain lion. Crikey! You were so busy getting blitzed on fermented fruit, you forgot that you are a prey animal… and it’s a dangerous world out there!

If frugivores, such as fruit-eating bats, consumed a lot of fermented fruit, you would think they would be drunk all the time and would fly wonky and get lost and generally be less likely to survive… unless they had developed an ability to tolerate alcohol. Dara Orbach, Nina Veselka, Louis Lazure and Brock Fenton at the University of Western Ontario and Yvonne Dzal at the University of Regina decided to test the ability of several fruit-eating bats to hold their liquor. The researchers went to Belize and caught bats from six different fruit-eating species. They fed them either sugar-water or sugar-water with 1.5% alcohol in it (that’s less than a Molson Light) and later measured their blood alcohol level (BAC) in their saliva.

A little yellow-shouldered bat being fed it's alcoholic cocktail.
Photo provided by Nina Veselka.

Then the researchers put the bats in an obstacle course. That’s right, an obstacle course! They timed how long it took each bat to traverse the obstacle course (if they completed it) and counted how many times they ran into something or went in a circle. Afterwards, they gave them time to sober up before they released them back into the wild… presumably to go tell their friends about the crazy night they had. Ooohhh, was this gonna be funny!

Scientists building the drunk-bat obstacle course in Lamanai, Belize.
Photo provided by Nina Veselka.

To the researchers’ surprise, despite the fact that several bats had a BAC over 0.3% (the equivalent to a 150 pound person after 10 drinks), the bats on alcohol did not seem to be impaired in any way! They traversed the obstacle course just as fast and completed the course just as often as their kiddie-cocktail sugar-water drinking counterparts. They never even ran into anything.

So, I guess we’re not going to be entertained by drunken bat antics. But this is good news for the fruit-eating bats – Somehow, they are able to metabolize fermented fruit to get the caloric benefit without the risks of impairment. Now, if we could just figure out how they do that…

The moral of this story: Don’t drink alcohol when there are predators around unless you are a fruit-eating bat. And don’t challenge a fruit-eating bat to a drinking contest. He will drink you under the table!

Want to know more? Check this out:

Orbach DN, Veselka N, Dzal Y, Lazure L, & Fenton MB (2010). Drinking and flying: does alcohol consumption affect the flight and echolocation performance of phyllostomid bats? PloS one, 5 (2) PMID: 20126552

1 comment:

  1. aka the Drunken Monkey Hypothesis