What does it take to survive in the fast-paced and dangerous world of squirrels? University of Alberta scientists have found that success has less to do with having a particular personality, and more to do with how changing environmental conditions favour different types of individuals.
"The most surprising finding of this study was that individuals were not more or less likely to die because of their behaviour," said April Martinig, lead author of the study and PhD student in the Department of Biological Sciences. "Instead, it appears that their survival depends on how different personalities fare in the face of different environmental conditions."
The research team in the Faculty of Science found that red squirrels do display consistent behavioural differences, called animal personality, and set out to determine whether these personality traits influenced the animals' odds of survival.
"Personality is behaviour that is consistent across contexts and over time," explained Martinig. "For example, relative to other squirrels, a squirrel that is active in trees will be similarly active while on the ground, or a squirrel that is aggressive today will be similarly aggressive in a year."
The scientists measured the personalities of many individuals and examined their success over two years to see whether a particular set of personality traits was most suited for long-term success—with surprising results.
"We found that personality didn't have an effect on survival in our study, and our research in the context of other studies coming out of the same population suggests changing environmental conditions lead to certain individuals winning under different circumstances," said Martinig.
For example, Martinig explained, varying numbers of predators in the environment over the years may have an impact on squirrels that are more active. When there are many predators, active squirrels may be less successful if they have more frequent run-ins with predators.
"It is important that we conduct research in this area because animal personality can have major ecological and evolutionary consequences," said Martinig, whose research was supervised by assistant professor and study co-author Kimberley Mathot.
Many studies in ecology examine how selection can change population composition. The researchers noted that changes in animal population can come about through many different mechanisms, and studying them is critical to gaining a better understanding of animals' resilience in the face of changing conditions.
"The basic ideas behind these mechanisms is that selection is acting on the survival and reproduction of individuals," said Martinig. "As a next step, we will need to get more measures of animal personality to try and untangle the underlying mechanisms behind the patterns we observed here."
The study, "Selective disappearance does not underlie age-related changes in repeatability in red squirrels," was published in Behavioral Ecology.
