 PART
3:
Is CWD Infectious? It may turn out that CWD is not infectious, but on the off chance that it is, scientists, game managers, game farmers and hunters must treat it as if it is. Assuming the CWD is infectious lets take a look at some statistics and possible scenarios. Although CWD has only occurred at the rate of about 1 percent of the elk, and 1-13 percent of the deer in Colorado (where deer densities range from 2-5 deer per square mile) since 1981, no one knows how rapidly CWD may spread in areas where white-tailed deer numbers exceed 75+ deer per square mile (conservative estimate from the Wisconsin Department of Natural Resources). Wildlife managers are also more worried about the spread of CWD in the eastern states, because white-tailed deer appear to be more susceptible to CWD than either mule deer or elk. And no one is sure what long-term affect CWD will have on a white-tailed deer herd of over 1.5 million in Wisconsin or 1 million in Minnesota. Since CWD was first discovered in Wisconsin in 2002, forty-one infected deer have been found in the state. And some of those deer have been found outside of the 370 square mile endemic area in the south-central portion of the state. CWD infected deer and elk are also showing up in areas that are far removed from the endemic area of northeastern Colorado/southeastern Wyoming/southwestern Nebraska. In Colorado they have occurred as far away as the western slope of the Rocky Mountains. Management Considerations
A second thing to consider is how young deer, particularly young bucks between 8 and 18 months of age, often disperse from their mother's home range. During his study on the movement activities of white-tailed deer on the Desoto National Wildlife Refuge in Nebraska, Kurt VerCauteren found that dispersing yearling deer traveled as far as 12-15 miles from their former home range; some of the sub-adult does traveled as far as 40 to 50 miles. Chris Rosenberry and others found that 70 percent of the 6-18 month old bucks dispersed from their 3,300-acre study area; 50 percent dispersed an average of 3.7 miles, with some animals traveling as far as 36 miles. One yearling buck tagged in central Minnesota was shot 165 miles from where it was tagged; an adult doe was found 85 miles from where it was tagged. A third thing to consider is how far bucks may travel during the rut. Dr. James Kroll is reported to have said that bucks in Alberta may occupy a 3,000 -acre core area, and they may travel circuits of 20-25 miles during the rut. We must also consider the fact that CWD may linger in contaminated soil for years. Scientists have found that scrapies can stay in the soil of infected areas for up to three years. This means that, even after the complete removal of infected animals, some areas (particularly wintering areas, and areas where deer are supplied with feed bait, or minerals) may cause new infections several years later. We may have a sense of what can happen in white-tailed deer herds by what happened in the cattle herds in Great Britain. Mad Cow Disease was first observed in Great Britain in April, 1984, and was diagnosed in 1985. By June of 1990, there were 14,000 confirmed cases of Mad Cow Disease out of 10 million cattle. Since 1986 nearly 200,000 cases of Mad Cow Disease have been identified, and between 1992 and 1993, when the epidemic peaked, 1,000 cases a week were reported. What deer managers have thought about (and what deer hunters need to think about) when they consider the possible effects of CWD on migrating, dispersing or rutting deer, is how easily CWD can be spread to other areas when deer migrate or disperse, and how many deer will contract CWD when deer come in contact with each other during migration and the rut. Another thing to think about is that the incubation period of CWD in whitetails is thought to be from 3-16 months. It may take up to a year or more from the time CWD is first reported in an area before wildlife managers can assess the impact of CWD on the animals in the surrounding areas. If CWD is infectious how easily can
it spread in the Midwest and East?
NEXT: Responsible Deer Management For more information on specific seminar titles and times contact; T.R. Michels, Trinity Mountain
Outdoors / T.R. Michels Guide Service, PO Box 284, Wanamingo, MN 55983,
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