Published: 19:01 EDT, 5 May 2020 | Updated: 19:16 EDT, 5 May 2020
Otters are regularly seen using their little hands to juggle small rocks and this bizarre behaviour may be because they’re hungry, a new study claims.
Otter juggling has never been fully understood, with previous research saying it may be useful in improving their foraging skills.
But scientists have now discovered that when it is dinner time, otters often juggle as they wait for their food.
Researchers are still not convinced of rock juggling’s exact purpose but say there is definitely a link between hunger levels and the circus act.
Otters are regularly seen using their little hands to juggle small rocks and this bizarre behaviour may finally be understood, thanks to a new study. Pictured, two attentive Oriental small-clawed otters with one juggling a stone
The dextrous mammals are often seen lying on their backs and batting the stones into the air, catching them and rolling them around their chests and necks.
Scientists from the University of Exeter who conducted the study believe this behaviour might help juvenile otters develop their motor skills.
They found that young and elder otters juggled more than adults, but otter species and sex didn’t impact on juggling behaviour.
For the long-in-the-tooth otters, experts suggest juggling rocks could be a way to pass the time and keep their brains active, similar to humans doing puzzles to keep their minds engaged as they age.
However, the key driver for the behaviour is likely hunger, according to the study published today in the journal Royal Society Open Science .
Mari-Lisa Allison, of the University of Exeter and lead author of the study, says the ultimate function of the behaviour is still a mystery.
She said: ‘Our strongest finding is that otters juggled more frequently before being fed, indicating that the immediate driver of the behaviour is hunger.
Pictured, a young otter juggling with a pebble. Scientists found that young and elder otters juggled more than adults, but otter species and sex didn’t impact on juggling behaviour
A wet winter has seen Britain’s otter population flourish and they are raiding people’s gardens and eating their fish — some of which are worth hundreds of pounds each.
Otters almost disappeared from England in the 1970s after pesticides brought their numbers to near-extinction levels.
However, now that those chemicals have been banned and the mammals are protected, they have grown to thrive in almost every English county.
Experts says that this year’s wet weather has filled in ditches, making it easier for them to travel across the country — and plunder garden ponds of carp and goldfish.
The researchers studied 44 Asian small-clawed otters (Aonyx cinereus) and six smooth-coated otters (Lutrogale perspicillata) in captive environments.
While the species are closely related, Asian small-clawed otters forage on crabs and shellfish while smooth-coated otters hunt for fish.
The team used three different types of man-made food puzzles to analyse the animals’ foraging behaviour: tennis balls with holes to allow the otters to reach inside for food, plastic medicine bottles with the lid loosely screwed on, and two stacked Duplo bricks with the meat placed inside.
The team found the creatures juggled more when hungry, and that both juvenile and senior otters juggled more than adults with offspring.
Ms Allison said: ‘We hypothesised that juveniles may rock juggle to develop those food extracting skills.
‘When they reach maturity and begin reproducing, their time and energy is devoted to raising their offspring. As such, they may not have the time or energy to play.’
‘In senior otters, they no longer have those parental responsibilities so may have more time to rock juggle.
‘In a similar way to how humans stave off Alzheimer’s by reading and doing puzzles, we hypothesised that the senior otters may be performing the behaviour to engage their brains to prevent cognitive decline.’
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