November 17, 2009
By HENRY FOUNTAIN
Predators do not always play fair. Sometimes they choose their victims based on physical condition, preferring young, old, sick or injured prey.
That is the idea, although surprisingly it has not been tested much. But now researchers have found that one predator does, in fact, show a preference for less-than-fully-capable victims. The findings may have implications for the spread of chronic wasting disease among deer populations.
Working in the northern Front Range of Colorado, Caroline E. Krumm and Michael W. Miller of the state’s Division of Wildlife, and colleagues, sampled adult mule deer carcasses known to have been killed by mountain lions, testing them for chronic wasting disease, a degenerative neurological illness that is similar to mad cow disease.
They also sampled tissue from deer killed by hunters in the same area, to get an idea of the infection rate in the general population. Since the deer generally do not have obvious symptoms, hunter-killed deer would have close to a random chance of being infected.
As reported in Biology Letters, they found that the prevalence of infected deer among the mountain-lion-killed group was higher than among the hunter-killed group, suggesting that the big cats actively seek out infected prey.
Dr. Miller said the mountain lions might notice signs of illness that were too subtle for humans to see — slightly slower reaction times, for example.
He said there was no evidence so far that mountain lions were susceptible to the disease. But by consuming infected carcasses, the animals may be keeping infectious agents out of the environment, reducing transmission to healthy deer.
Learn more about big cats and Big Cat Rescue at http://www.bigcatrescue.org