By Jim Drury
University of Exeter researchers have found that grey squirrels foraging for food are happy to take their time if it means getting a more nourishing meal.
The study showed that the medium-sized rodents demonstrate persistence and flexibility in order to find nourishment, while higher behavioural selectivity - the proportion of effective behaviours used - is directly related to more efficient problem solving among the creatures. Study authors suggest that the squirrels demonstrate distinct personality traits in their food finding behaviour.
Co-author Dr Lisa Leaver told Reuters the successful invasion of the grey squirrel across Europe make it a fascinating creature for animal behaviourists to observe.
"They're interesting to us because they have particular specialisations for catching food," she said. "They're a really successful invader in the UK and in Europe, and that might be related to their abilities to solve problems and perhaps dealing with learning in a different way or it maybe a more efficient way than other species do and we know that invasive species tend to be quite clever in a lot of different ways that you measure them. They tend to have slightly bigger brains relative to their body sizes."
The researchers, led by Leaver and Pizza Ka Yee Chow, from the university's Centre for Research in Animal Behaviour, and Emeritus Professor Stephen Lea, set up specially designed boxes containing visible, but out-of-reach hazelnuts in a controlled, indoor environment. The squirrels were observed to see how successful they were at understanding how to reach the food, figuring out which lever to pull or push to make the nuts fall to the floor.
The squirrels learnt to solve the puzzle quickly, and over time increased their efficiency. Leaver said the study gives the clearest indication yet as to the roles of flexibility and persistence in the grey squirrel's problem solving process.
She told Reuters: "We were surprised to find that flexibility was stable across trials learning how to use this apparatus, and that indicates that it might be more like what you would call a personality trait than something that they can change across learning, for instance that they can change over time depending on the situation. It's an indication that it is a much more stable trait in individual animals."
While persistence and behavioural selectivity appeared to be associated with problem-solving efficiency, the squirrels' flexibility - the rate that a squirrel switched between behavioural tactics - did not help them learn which lever to push or pull, and in fact increased the time it took for them to get their food.
According to Leaver, "it's important because flexibility is something that you automatically think of as changing over time and to know that it's not necessarily involved in helping animals learn, and in fact it might actually be costly is really interesting because it might change the way that we look at how animals solve problems in the wild, and also how an invasive species might or might not be successful when it faces and enters a new environment."
By identifying the mechanisms involved in solving problems, the team hopes to better understand the wide variation in behaviour between individuals and similar species. The team now plans to compare the cognitive abilities of the grey squirrel with its cousin, the red squirrel.
"That is particularly interesting to look at, perhaps also across species, looking at differences between red and grey squirrels, for instance, and how grey squirrels solve problems as opposed to how red squirrels solve problems. It may give us some insight into how they might differ in their cognitive abilities and their behaviours which might help them or hinder them from solving problems and help them enter new environments," said Leaver.
The study was published in leading scientific journal Animal Behaviour.