Defensive Vomiting

  • Posted 11.17.16
  • NOVA

If you're attacked you could run away, fight back... or you could barf. Learn more in this episode of Gross Science.

Running Time: 02:48


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.




Host, Producer, Editor
Anna Rothschild
Writer, Researcher
Elizabeth Preston
Quirky Idea
Music Provided by APM


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
Camel Spit
Flickr/Jason Borneman


(used with permission from author)
Squeak Pack/squeak_10
Produced by WGBH for PBS Digital Studios


Defensive Regurgitation
Wikimedia Commons/Siman Wagen


Want more info?

Paper on Eurasian (European) roller defensive vomiting:

Bizarre paper from the 1970s showing the effects of fulmar vomit on different birds:

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