Social skills give social squirrels an advantage
University
of California - Davis
A study from the University of California, Davis is the first to document personality in golden-mantled ground squirrels, which are common across the western U.S. and parts of Canada.
The study, published in the journal Animal
Behaviour, found the squirrels show personality for four main traits:
boldness, aggressiveness, activity level and sociability.
While
the golden-mantled ground squirrel is under no conservation threat, the
findings suggest that understanding how an animal's personality influences use
of space is important for wildlife conservation.
'Individuals matter'
To
see them chitter and skitter, stop and then scurry, the fact that ground
squirrels have personalities may not seem surprising. But the scientific field
of animal personality is relatively young, as is the recognition that there are
ecological consequences of animal personality. For instance, bolder, more
aggressive squirrels may find more food or defend a larger territory, but their
risky behavior may also make them vulnerable to predation or accidents.
"This
adds to the small but growing number of studies showing that individuals
matter," said lead author Jaclyn Aliperti, who conducted the study while
earning her Ph.D. in ecology at UC Davis. "Accounting for personality in
wildlife management may be especially important when predicting wildlife
responses to new conditions, such as changes or destruction of habitat due to
human activity."
Personality
tests
Scientists
have been studying golden-mantled ground squirrels at the Rocky Mountain
Biological Laboratory in Gothic, Colorado for decades. It was established as a
long-term study site more than 30 years ago by Aliperti's advisor, Dirk Van
Vuren, a professor in the UC Davis Department of Wildlife, Fish and
Conservation Biology.
Aliperti
drew from this powerful data set for her study, while also initiating a series
of experiments there over the course of three summers to observe and quantify
the squirrels' personalities.
She
notes that while there are no Meyers-Briggs tests for animals, there are
standardized approaches to quantifying animal personalities. She observed and
recorded squirrel responses to four tests:
- Novel environment: Squirrels were placed in an enclosed box with gridded lines and holes.
- Mirror: Squirrels are presented with their mirror image, which they do not recognize as their own.
- Flight initiative: Squirrels were approached slowly in the wild to see how long they wait before running away.
- Behavior-in-trap: Squirrels were caught, unharmed, in a simple trap and their behavior briefly observed.
The
social squirrel's advantage
Overall,
the study found that bolder squirrels had larger core areas where they
concentrated their activity. Bold, active squirrels moved faster. Also,
squirrels that were bolder, more aggressive and more active had greater access
to perches, such as rocks. Perch access is important because it can provide a
better vantage point for seeing and evading predators. Interestingly, perch
access was also associated with sociability.
Golden-mantled
ground squirrels are considered an asocial species. They are relatively small,
giving them little opportunity to form the tighter social bonds common in
larger ground squirrels, which typically spend more time in family units while
reaching maturity. However, the study said that "within this asocial
species, individuals that tend to be relatively more social seem to have an
advantage."
In
such cases, being more social could save an individual's life. Such personality
differences can influence a squirrel's ability to survive and reproduce, which
could scale up to the population or community level.
Squirrels
of Davis
UC
Davis is home to many squirrels, which have become an honorary mascot of sorts
on campus.
"The
squirrels of UC Davis are something else," said Aliperti.
She
means it literally. They are tree squirrels and very different from the ground
squirrels Aliperti studied. Yet she says her work has changed how she views the
squirrels of Davis.
"I
view them more as individuals," Aliperti said. "I view them as, 'Who
are you? Where are you going? What are up to?' versus on a species level."
Noticing
such individuality brings a more personal angle to viewing wildlife.
"Animal
personality is a hard science, but if it makes you relate to animals more,
maybe people will be more interested in conserving them," said Aliperti.
In
addition to Aliperti and Van Vuren, the study's coauthors include Brittany
Davis, Nann Fangue, and Anne Todgham of UC Davis.
The
study was funded through the Rocky Mountain Biological Laboratory Graduate
Fellowship, Dr. Lee R. G. Snyder Memorial Fellowship, American Society of
Mammalogists Grant-in-Aid of Research and the UC Davis Walter and Elizabeth
Howard Award and Ecology Student Endowment Award.
