Credit: Mark Boyce
If you come across an old elk in southwestern Canada, chances are it is female.
Though male elk, or bulls, rarely make it past 5 years old because they are targeted by hunters, female elk, or cows, can live as long as 20 years. Remarkably, cows over age 10 seem nearly invulnerable to hunters.
A team of scientists wanted to know: What makes senior cows so survival-savvy? Is it because these elk are more cautious by nature, which made them better at evading hunters all along? Or is it nurture, and cows can learn to dodge hunters over their lifetime, even if they start out more daring?
It seems both factors are at play, the researchers at the University of Alberta reported in PLOS One on Wednesday. Tracking dozens of female elk over several years, the authors found that, over all, careful cows were better at surviving. But they also found that individual cows were able to adjust their behavior and adopt more stealth strategies as they aged. In particular, as females got older, they moved shorter distances and sought safer ground if they faced a higher risk of encountering hunters.
During a postdoctoral stint in Alberta, Henrik Thurfjell, now a research specialist at the Swedish Species Information Center, led an effort to track 49 cows, monitoring each for two to five years with GPS collars that logged the animals’ locations every two hours.