Chicks are born with the ability to recognise and react to different dangers, new research suggests.
Scientists say the baby birds are born with the knowledge to flee from predators rather than learning from experience.
The newborns also know when to slow down or freeze in order to avoid detection when a predator is far away, according to a study by University of Trento and Queen Mary University of London.
The study, published in the journal Proceedings of the National Academy of Sciences, indicates these responses do not require learning but are known by the chick before it is born.
Dr Elisabetta Versace, co-author of the study from Queen Mary University of London, said: “Our results show that at the beginning of life animals are well equipped to cope with threats present in their environment, they possess some predispositions that help them to survive.”
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Researchers say appropriate reactions to predators are fundamental for survival, and that learning the best strategy by trial and error is very dangerous and might result in death.
For this reason, it has been assumed that these responses of fleeing and freezing do not require learning but the evidence was sparse and contradictory.
Professor Giorgio Vallortigara, leading the University of Trento team, said: “Together with our previous studies about the social predispositions that help young chicks and humans to interact with their social partners these findings clarify we are not born as blank slates, but with sophisticated mechanisms that enable us to use specific strategies in front of particular stimuli.”
Scientists ran an experiment where the chicks did not have a chance to interact with any moving objects once they hatched.
They found that on their first encounter with approaching threats – a looming stimulus overhead, like an approaching raptor, or distant moving threats – a small object sweeping overhead, like a raptor exploring territory for prey – the chicks responded appropriately.
The chicks ran away from the approaching threats and slowed down in response to far sweeping stimuli.
Reader Q&A: Which came first, the chicken or the egg?
Asked by: Alan Healy, France
Eggs are much older than chickens. Dinosaurs laid eggs, the fish that first crawled out of the sea laid eggs, and the weird articulated monsters that swam in the warm shallow seas of the Cambrian Period 500 million years ago also laid eggs. They weren’t chicken’s eggs, but they were still eggs.
So the egg definitely came first. Unless you restate the question as ‘which came first, the chicken or the chicken’s egg?’ Then it very much depends on how you define a chicken’s egg. Is it an egg laid by a chicken? Or is it an egg that a chicken hatches from? Chickens are the same species as the red jungle fowl of Southeast Asia, although they were probably hybridised with the grey jungle fowl when they were domesticated 10,000 years ago.
But it doesn’t matter; at some point in evolutionary history when there were no chickens, two birds that were almost-but-not-quite chickens mated and laid an egg that hatched into the first chicken. If you are prepared to call that egg a chicken’s egg, then the egg came first. Otherwise, the chicken came first and the first chicken’s egg had to wait until the first chicken laid it.
This experiment can be conducted with chicks because they are able to move around and feed by themselves from birth, unlike other animals that require parental care.
Not much is known about predisposed behaviour at the beginning of life and the neural mechanisms underlying responses to a visual threat.
Responses to looming stimuli can be observed in human infants while freezing responses can also be observed in humans, in situations of extreme danger such as a fire or a sexual assault.
Dr Marie Hebert, first author of the study from University of Trento, is now investigating which parts of the chick’s brain are activated by the visual threats.