Domestic chickens recognize a tiger by smell

Like the leopard’s spots that have never changed, today’s domestic chickens react to the scents of predators – an inheritance from the jungle fowl they originated from, as shown in a study by researchers from both Linköping University and Stockholm University published in the periodical: Animal Behaviour.

The study was conducted by Josefina Zidar, currently a doctoral student at Linköping University (LiU), and Hanne Løvlie, research associate at the Department of Physics, Chemistry and Biology (LiU).

This is the first time researchers were able to show that today’s domestic chickens can detect predators using solely their sense of smell. The chickens reacted to scents, like tiger droppings, with more watchful behaviour. However droppings from other prey animals like elephants or antelopes left them unaffected.

“Up until a couple of decades ago, it was believed that birds depended on sight and hearing in their everyday lives, and there is still the general idea that birds don’t make use of their sense of smell. But today we know that a number of bird species use smell for things like navigation, searching for food, and recognising fellow members of their species,” says Løvlie.

Whether domestic birds like chickens use their sense of smell – which is relatively weak – has until now been poorly researched. However the study, now being published in the British periodical Animal Behaviour, shows they do.

Domestic chickens originate from Asiatic jungle fowl. They live in the rainforests, where visibility is often obstructed, and it’s of course an advantage if they can smell a predator before they themselves are detected. Even old Swedish dwarf chickens seem to know that the scent of a tiger means staying alert. Some 80 hens and roosters at the Tovetorp research station were observed for the study.

“That old Swedish dwarf chickens have inherited recognition of predators they’ve never been exposed to is a fascinating discovery. Not a dramatic reaction, yet when tiger droppings were put into the chicken’ yard, they stopped eating and became clearly alert,” Løvlie says.

The Kolmården Zoo supplied droppings from tigers, Asiatic wild dogs, antelopes, and elephants, which were presented to the Tovetorp flock in various proportions.

“We wanted to make sure that the chicken’ reaction didn’t depend on the fact that the predator droppings simply smelled stronger, so they were also tested with small amounts of predator droppings and large amounts from the elephants.”

The reaction was obvious. The chickens reacted to tigers and wild dogs, but not to droppings from other prey animals like elephants and antelopes.

“The few previous studies conducted on predator recognition in birds through smell yielded inconsistent results, where some birds displayed a response while others had no response at all. This means that there is very likely an explanation for why certain birds have this ability and others don’t, which for example could be connected to the birds’ ecology,” says Zidar, currently a doctoral student at LiU.

It may be that wild chickens use their sense of smell in several ways. Such as avoiding inbreeding:

“They don’t mate with close relatives, even those they didn’t grow up with. It might be that, for example, they can sniff out hens that are their siblings,” says Løvlie.

Article

• Scent of the enemy: behavioural responses to predator faecal odour in the fowl by J. Zidara & H. Løvlie. Animal Behaviour, 12 July 2012

Related Links

• Department of Physics, Chemistry and Biology at LiU
• Kolmården Zoo  
  
  Photo: Josefina Zidar

Gunilla Pravitz 2012-08-01