This is a French video on the Eurasian roller.
From AFP news agency:
‘Vomit Bird’ Throws Up a Defense Against Predators
Babies of a bird species called the Eurasian Roller vomit a foul-smelling orange liquid as a defense mechanism.
Wed Mar 7, 2012 12:04 PM ET
The baby Eurasian Roller’s defense involves vomiting a noxious substance onto itself.
When a bird is covered in vomit, it becomes less attractive as a snack, plus the parents smell the liquid and rush back to their nestlings.
Offspring of the bright-blue jackdaw-sized bird — Latin name Coracias garrulus — throw up the repugnant fluid when they are frightened in their nests, according to a paper appearing on Wednesday in the journal Biology Letters.
Covered in vomit, the nestlings not surprisingly become less attractive as a snack, the team says.
But the smell also alerts parents, returning to the nest, that a threatening incident has happened in their absence, they believe.
The scientists tested the “olfactory cue” theory by visiting nests with 10-day-old nestlings inside.
They used a small paintbrush to daub a tiny amount of either lemon juice or vomit on the inside of the nest. Parents returning to a vomit-treated nest reacted with great caution, delaying the time when they would settle in the home.
Previous research has found that birds have a surprisingly wide range of defensive reactions.
However, the Eurasian roller is the first bird that has been found to use a scent, derived in response to a threat, as a means of communication, says the paper.
The study is led by Deseada Parejo of Spain’s Estacio Experimental de Zonas Aridas.