For babies who are born until the time when it grows large number of their competitors or are experiencing other problems, puts the mother during pregnancy, the highest gear parenting efforts. At a time when young squirrels leave the nest, they are substantially larger than cubs that were born in a much quieter time.
Squirrels strongly listen to social signals during pregnancy and while caring for children. And it literally.
Females listen to the sounds of other squirrels. As increasing concentration of population in one place, the sound of "rattling", which feature a squirrel's territory is heard more often and louder. Because squirrels secrete more stress hormone that makes offspring grow faster. "When they see as the population grows, it must do everything so that their descendants were strong enough," explains Andrew McAdam of Guelphské University in Ontario.
Territorial behavior of the American red squirrels čikarí it helps to survive the winter. But when it is in place nesting large number of other squirrels, it is much harder to find a suitable place for nesting.
"When one places a lot of squirrels survive only those that are growing rapidly," said McAdam. Conversely, if the density is low, clearly benefit all squirrels, so it does not matter how fast growing.
During the six-year study, researchers squirrel mothers played from the record-recorded voices squirrels to nesting females had the feeling that there are high competition.
Scientists also tried to feed the squirrels peanut butter with stress hormones. Also, these mothers had children who were growing faster than in the control group.
"Despite the widespread notion that stress is bad, our study showed that high levels of stress hormones on the contrary helped babies," says lead study author Ben Dantzer.
According to the researchers stress induced by fear of high competition has led to an increase in growth of the offspring so high, if their mothers had higher food intake. This supposedly proves that not only open source, but the whole complex of environmental and physiological influences affecting reproduction and motherhood. However, investments in offspring with squirrels increased only in the case where the risk of overgrowth own species.
According to the study authors, probably similar principles work for other animals. "In the changing world of parenthood must be flexible and adapt to current conditions," said McAdam.
Source: Ekolist.cz
