Wondering about the long-term effect of CWD on deer population
If you take the time to read a lot about chronic wasting disease, you will be struck, as I have been, by the lack of information about the long-term effect of the disease on deer herds.
I have wondered about what has happened to deer and elk numbers overall since CWD was discovered in deer in 1967 in northeast Colorado. Because the disease is always fatal for cervids, the accepted theory for decades was that if CWD came east and got into the higher density deer herds, it could spread rapidly and wipe out whitetails.
But then it reached Wisconsin, and that didn't happen. And it has continued to march toward the Atlantic Ocean, infecting wild whitetails in New York, West Virginia, Virginia, Maryland and now Pennsylvania.
Deer farmers, who have been frequently blamed for the spread, are quick to point out that CWD has not and will not decimate deer herds. Many, like Lancaster County's Steve Mohr, a former Pennsylvania game commissioner, contend the CWD threat has been sensationalized and way overblown.
A wildlife biologist from Wyoming with experience in the so-called CWD endemic area of Colorado, Wyoming and western Nebraska told us recently that deer and elk numbers are down as much as 25 percent there. I have located other credible sources and will be writing stories on this subject soon.
The Game Commission's wildlife veterinarian Walt Cottrell addressed this topic in a recent public meeting held in Roaring Spring, Pa., in Blair County, where two wild deer that tested positive for chronic wasting disease were killed by hunters last fall.
He said if the disease becomes endemic to Pennsylvania – as it’s done everywhere else – deer populations will suffer.
According to Cottrell, four decades after it was discovered in Wyoming, CWD is found in about 48 percent of all adult mule deer there. That has driven buck numbers down to two to three per square mile in places, he
In Wisconsin, which became the first state east of the Mississippi with CWD when it was discovered there in 2001, the disease has spread in the outbreak area to the point that 25 percent of all adult bucks are impacted.
Pennsylvania, with its similar population densities of whitetails, might expect similar effects, Cottrell said.
“The herd will decline over time,” he said, though he made no predictions about how severe the drop might be or how long it would take to occur.
Those kinds of questions will only be answered over the long term.