Defensive Vomiting

Defensive Vomiting

Posted: November 10, 2016

The other day I ate some suspicious tacos, and a few hours later I was face-first in the toilet bowl puking up my dinner. It was terribly unpleasant. But, wouldn’t it be great if I could have put that vomit to good use? Say, by scaring off a would be attacker? Some animals do just that. They use puke to avoid being eaten by predators.

I’m Anna Rothschild, and this is Gross Science.

A hungry predator might lose its appetite if its lunch suddenly came with a side of barf. At least, that’s the defensive strategy of certain birds, like the European roller. Chicks of this species spew stinky orange vomit if anything touches them. And when parents return to the nest and smell puke, they approach cautiously, in case a predator is still around.

The noxious chemicals in the birds’ vomit seem to come from grasshoppers they eat. The grasshoppers get these chemicals from eating plants—and interestingly these bugs also puke when they’re in danger! How weird and cool is that?!

As a side note, some of those tacos I ate were actually… grasshopper tacos! I’m not making this up. They were pretty delicious—though a little salty for my taste—and I don’t think they were what caused the vomiting that followed… But still—a funny coincidence.

Anyway, other birds use the vomit defense, as well. The fulmar is a kind of seabird that can shoot a stream of yellow stomach oil at targets up to 6 feet away. Even birds that haven’t finished hatching can reportedly squirt the liquid out of a hole in their eggshell.

Any other seabird that bothers a fulmar may find itself drenched in puke. The nasty-smelling goo clings to bird’s feathers just like a slick from an oil spill. And sadly, that means the puke-covered bird, unable to fly or float, will likely drown when it lands on the water.

Defensive vomiting isn’t just for birds and insects, though. Camels are famous for spitting at people and other animals. But that “spit” is really a combination of saliva and regurgitated stomach contents.

Clearly, this puke strategy is pretty effective. And as someone with a naturally sensitive stomach, it’s an attractive self-defense solution. It’s kinda like carrying around your own personal pepper except it comes out of your mouth…and is way more disgusting.

...Ew.

PRODUCTION CREDITS

Host, Producer, Editor

Anna Rothschild

Writer, Researcher

Elizabeth Preston

Quirky Idea

Music Provided by APM

FOOTAGE AND STILLS

Eurasian roller vomiting

Parejo et al. 2012
Courtesy Dr. Deseada Parejo

MS ZI ZO Baby northern Fulmar seabird vomits defending itself in rocky corner/Iceland

Getty/Discovery FootageSource

European Roller - coracias garrulus, Hungary

Shutterstock/David Havel

European roller (coracias garrulus) on the nest

Shutterstock/Porojnicu Stelian

Eurasian Roller-5357

Wikimedia Commons/Rudraksha Chodankar

Northern Fulmar (Fulmarus glacialis) flying, side-on

Wikimedia Commons/Avenue

Defensive Regurgitation

Wikimedia Commons/Siman Wagen

Oiled bird 3

Wikimedia Commons/Brocken Inaglory

Adventure World, Shirahama, Japan

Flickr/Pelican

Camel Spit

Flickr/Jason Borneman

SFX

Cockroaches

Freesound/StateAardvark­
(used with permission from author)

Squeak Pack/squeak_10

Freesound/Corsica_S

Produced by WGBH for PBS Digital Studios

POSTER IMAGE

Defensive Regurgitation

Wikimedia Commons/Siman Wagen

Want more info?

Paper on Eurasian (European) roller defensive vomiting:
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0068862

Bizarre paper from the 1970s showing the effects of fulmar vomit on different birds:
http://bit.ly/2eGLwUk