According to a new study, red squirrels born to mothers with high level of stress hormones are able to outcompete others for food and territories.
The red squirrel (Sciurus vulgaris) is a species of tree squirrel in the genus Sciurus common throughout Eurasia.
"When population density is high, only the fastest-growing offspring survive," explained Andrew McAdam, the study's researcher who is from Canada's Guelph University.
McAdam and his colleagues studied the red squirrels from the North American region in Yukon. They devised field experiments in which the experimenters exposed the squirrels to recordings of territorial squirrel vocalizations, also known as rattles. The experimenters was devised in a way that mother squirrels thinks that there were various contenders and fellow threats within the forest.
The researchers discovered that the rattles pushed the pregnant squirrels to have a stress hormone known as cortisol, which caused their offspring to grow much faster after they were born.
"Natural selection favors faster-growing offspring, and female red squirrels react accordingly to increase their pups' chances of survival," a postdoctoral researcher from the University of Cambridge, Ben Dantzer stated. "Surprisingly, squirrels could produce these faster growing offspring even though they didn't have access to additional food resources."
Dantzer said the results are surprising because researchers had previously thought baby animals always grow as fast as they can depending on the amount of food available. The data shows that baby animals generally aren't growing as fast as they possibly can, but only do when it necessary.
The result of the study can provide insight into the possible beneficial effects of stress for humans as well.
The study was published in the journal, Science.