Tying animal personality to population-level trends
Given that humans display a wide range of personality types, it might not come as a great surprise to know that scientists are finding more and more evidence to support personality types in non-human species as well. In fact, individuals across a wide range of taxa have been found to consistently differ in boldness, aggressiveness, activity level, exploration tendency, sociability, and other behaviors. These differences in personality type, both within a species and among individuals within a population, can have large effects on important ecological dynamics, such as spatial distribution (e.g., more exploratory animals may disperse farther), disease dynamics (e.g., bolder animals may be at the leading edge of disease spread), or even predator-prey dynamics.
Jaclyn's research explored personality-dependent space-use in golden-mantled ground squirrels (Callospermophilus lateralis).
Jaclyn assayed individuals for personality three ways: 1. through repeated, standardized 'arena' trials, in which an ethogram of behaviors was quantified for a given individual during solitary (without mirror image) and 'social' (with mirror image) contexts, 2. through repeated Flight Initiation Distance trials, in which I approximated boldness by systematically approaching individuals in the field, and 3. though repeated 'behavior in trap' trials, in which she scored an animal's behavior for a given period of time after it was trapped. She then paired personality scores with known ecological parameters, such as home range size, movement speed, and resource use.
Results showed that:
Bolder individuals maintained larger core areas (had a larger area of concentrated space use) compared to shyer individuals
More active and bolder individuals moved faster under natural conditions
More proactive and sociable personality types had greater access to a preferred resource
Overall, results support a personality-dependent use of space and resources in nature.
Read the full paper here.
Research published in the journal Animal Behaviour received media coverage in over 130 outlets, including The Guardian, The Independent, People Magazine, Scientific American, The Daily Mail, and USA Today.
Individuals undergo standardized arena trials in a solitary and 'social' context. A clip from a Mirror Image Stimulation, or social, trial is shown above. A series of variables, such as number of jumps or time spent interacting with the mirror, were quantified for each trial.
In addition to manually coding behavior, I used a video software program called EthoVision to track individual movement inside of the arena and quantify more fine-grain continuous data, such as distance moved to the nearest cm, and both average and maximum velocity reached.