It sounds implausible that the white-tailed deer, North America’s most popular big game animal and one of the most widely distributed species on the continent, could one day be no more. Add to such an outlandish idea the fact that chronic wasting disease could be the cause and you have the makings of an unbelievable scenario. But new findings on CWD have scientists wondering if in 50 years—or less—whitetails could be extirpated in many regions of the U.S., with the species as a whole hurrying along the way of the dodo.
Scientists with the University of Wyoming published their findings this week after eight years of research on just that issue. The team studied deer in southeastern Wyoming from 2003 to 2010, asking the question: Could CWD alone account for the decline of an entire free-ranging population?
After years of capturing fawns of both sexes, testing them for CWD, and outfitting them with radio-transmitting collars, the research group was able to establish the population’s growth rate and mortality per year. The researchers found that CWD, where present, led to a ten percent decrease in a herd’s size per year, which could cause extirpations—extinctions in certain areas—within 50 years.
“The decline was caused directly by CWD lowering annual survival of female deer, which have the biggest impact on population growth rates,” said David Edmunds, a PhD graduate from UW and the head of the research team. “This was because CWD-positive deer died both directly from the disease and were more likely to be killed by hunters than CWD-negative deer.”
CWD is a form of transmissible spongiform encephalopathy that can be found in all the species of deer, similar in its effects to mad cow disease in bovines and Creutzfeldt-Jacob disease in humans. It is 100 percent fatal if contracted, makes a deer roughly four and a half times more likely to die in a given year than one that is unaffected, and is more prevalent in does than bucks (possibly due to the higher number of females to males in a given population).
To read the full research paper (and you should), click here.