Is this why grey squirrels are so common? Hidden hazelnut puzzle reveals intelligence and adaptability of crafty rodents

  • Five squirrels surprised University of Exeter researchers with the speed at which they solved a puzzle involving hidden hazelnuts
  • Test comprised 4 hidden compartments diagonally across from each other
  • Clever squirrels worked out that if one well contained a reward, another nut would be located in the well diagonally opposite it - and got faster at it
  • Animal learning study could help explain why some species are more adaptable than others and could be used to control invasive species

If you have ever hung a bird feeder in your garden only to find it emptied by a squirrel minutes later, you’ll already believe the pesky rodents are smart.

Now scientists have shown the creatures really are fast learners, capable of adapting tactics to improve efficiency and reap the best rewards, which perhaps explains their ability to nibble even the most well-protected foods ... and to spread like wildfire.

A group of five grey squirrels surprised researchers with the speed at which they solved a puzzle involving hidden hazelnuts.

A nutty challenge? Using an intelligence test (pictured) scientists have shown grey squirrels really are fast learners, capable of adapting tactics to improve efficiency and reap the best rewards

A nutty challenge? Using an intelligence test (pictured) scientists have shown grey squirrels really are fast learners, capable of adapting tactics to improve efficiency and reap the best rewards

The intelligence test, devised by researchers at the University of Exeter, test took form of a box with 12 sunken wells, four of which were hollow.

Nuts were placed in the four hollow wells diagonally across from each other, so that the least efficient way to look for them was by going from well to well in a clockwise or anti-clockwise sequence.

Over a number of successive attempts, the squirrels - named Simon, Arnold, Sarah, Leonard and Suzy - worked out that if one well contained a reward, another nut would be located in the well diagonally opposite it.

They were given training before the task so they were proficient at using their paws or teeth to peel back the layer of paper hiding a nut inside the wells, but their reasoning was their own. 

The intelligence test (pictured) took the form of a box with 12 sunken wells, four of which were hollow. Nuts were placed in the four hollow wells diagonally across from each other, so that the least efficient way to look for them was by going from well to well in a clockwise or anti-clockwise sequence

The intelligence test (pictured) took the form of a box with 12 sunken wells, four of which were hollow. Nuts were placed in the four hollow wells diagonally across from each other, so that the least efficient way to look for them was by going from well to well in a clockwise or anti-clockwise sequence

THE SMARTNESS OF SQUIRRELS 

Animal intelligence is generally judged by how well a creature can adapt to its environment and make use of resources around them.

Squirrels have shown they can live almost anywhere, by spreading from North America to other regions, including the UK where they have all but replaced the native red squirrel.

A previous study by the University of Exeter showed that quarrels learn by observation.

In an experiment, squirrels watched another find a nut under an up-turned pot. They learned that the pot would be empty and that the untouched pot was a better bet.

But without observation, the animals showed no preference.

The animals are best known for burying nuts so they can find them in the freezing winter months when food is scarce, demonstrating they have great memories.

A study by Princeton University showed grey squirrels are capable of using spatial memory to retrieve buried nut caches and they remember fruitful hiding places year-on-year.

They can also memorise the easiest route up a free to get to their nest most easily.

If a squirrel stumbles across a nut it has not buried itself, it will think nothing of eating it.

So to deter robbers, squirrels rebury nuts to make them harder for rivals to find and even fake the burying process if they think they're being watched.

This act of tactical deception was previously only thought to have been used by primates. 

In the study, published in the Journal of Experimental Psychology: Animal Learning and Cognition, all the squirrels became more efficient at finding the nuts in the box.

‘This was only a small study, but the results are quite remarkable - the squirrels learned to pick the diagonally opposite well if the first one they picked contained a nut,’ said researcher Pizza Ka Yee Chow.

‘They made a decreased number of errors as they learned and progressively changed their tactic to increase efficiency and obtain the hidden rewards.’

Co-author Dr Lisa Leaver, said: ‘We predicted that squirrels would be quick to learn this task because learning spatial arrays is crucial for them in order to recover their food caches in the winter months.

‘These results are interesting because they don’t just show that the squirrels were quick to learn about changes in food location, they also give some indication about how they learned to complete the task.’

The experts hope to better understand how animals, and squirrels in particular, learn about changes in the environment.

Squirrels have shown they can live almost anywhere, by spreading from North America to other regions, including the UK where they have all but replaced the native red squirrel. 

‘Flexibility in learning might allow particular species like squirrels to be successful invaders and understanding more about their learning processes may be the first step in helping to control invasive species,’ Dr Leaver added.

Ms Chow told MailOnline it’s very difficult to compare a squirrel’s learning speed with another animal’s.

‘We are really only in the early stages of investigating intelligence in squirrels,’ she said.

‘Whilst it would be fascinating to compare them with, say, crows or even primates, it would be difficult to carry out that kind of comparative study given that squirrels and crows see and manipulate things differently, and therefore it takes time to develop a task that is effective to test both species.’ 

Over a number of successive attempts, the squirrels - named Simon, Arnold, Sarah, Leonard and Suzy - worked out that if one well contained a reward, another nut would be located in the well diagonally opposite it. Here, Simon enjoys the fruits of his labours

Over a number of successive attempts, the squirrels - named Simon, Arnold, Sarah, Leonard and Suzy - worked out that if one well contained a reward, another nut would be located in the well diagonally opposite it. Here, Simon enjoys the fruits of his labours

Scientists at the University of Auckland, last year claimed that crows have a reasoning ability rivalling that of a human seven-year-old.

They came to the conclusion after subjecting six wild New Caledonian crows to a battery of tests designed to challenge their understanding of cause and effect.

They included a 'water displacement task', where crows worked out how to catch floating food rewards by dropping heavy objects into water-filled tubes.

They demonstrated an ability to drop sinking rather than floating objects, solid rather than hollow objects, to choose a high water level tube over one with low water level, and a water-filled tube over one filled with sand.

Ms Chow told MailOnline it’s very difficult to compare a squirrel’s learning speed with another animal’s like a crow's. Scientists at the University of Auckland, last year claimed that crows have a reasoning ability rivalling that of a human seven-year old. Here, a crow carries out an intelligence test

Ms Chow told MailOnline it’s very difficult to compare a squirrel’s learning speed with another animal’s like a crow's. Scientists at the University of Auckland, last year claimed that crows have a reasoning ability rivalling that of a human seven-year old. Here, a crow carries out an intelligence test

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