Prairie Dogs Become Serial Killers of Ground Squirrels Due to Competition
Cute does not really mean innocent, and this was proven in a discovery of serial killers that have been masking its blood-stained lifestyle with its furry cuteness.
John Hoogland of the University of Maryland and Charles Brown of the University of Tulsa discovered a series of ground squirrel murders done by a species that eats the same grass and prickly pears--the white-tailed prairie dogs.
According to the research published in the journal Proceedings of the Royal Society B: Biological Sciences, Hoogland and his team found that interspecific killings of ground squirrels by prairie dogs are common.
White-tailed prairie dogs are rodents within the squirrel family that can grow 13 to 15 inches long and weigh around one to three pounds.
During the course of the six-year study, researchers recorded 47 different killers. Out of the 47 killer prairie dogs, 19 of them include a female who murdered nine squirrels over four years.
The study showed that 30 percent of female prairie dogs have killed at least one ground squirrel in their lifetime.
Based on evidence gathered during the study, prairie dogs which have several kills went on to have more offspring than the non-killers, according to a New Scientist report, since competition has been eliminated.
The "fitness" levels of killer prairies dogs were also discovered to be three times higher than the non-killer throughout their lifetime.
"Fitness" level is a measure of evolutionary advantage based on the animal's and their offspring's survival.
"The condition of the female, her longevity--the factors that normally influence [success]--none of them applies to this case," said Brown.
National Geographic reported that it is the first time that an herbivorous mammal has been seen killing its competitors without eating it, which suggests that plant-based diet does not prevent mammals from killing others for game and survival.
Hoogland noted that prairie dogs just leave their kill behind. They gnaw the chest and brain of the ground squirrel just to be sure that it is dead. After which, they leave the carcass for nearby birds to scavenge.