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MONTROSE-Colorado Division of Wildlife (DOW) research biologists will be taking the next step to further understand the dynamics of the Uncompahgre Plateau deer herd when they begin an experimental nutritional study in December. The study will involve feeding a supplement to deer on DOW property south of Montrose then observing them during the following winter to check the survival of their offspring.
According to DOW researcher Chad Bishop, “The fawn/doe ratios on the Plateau have been low for nearly a decade indicating over-summer survival is a problem. We’re trying to better understand several factors affecting the deer population and identify the cause of low fawn survival.” The DOW began a fawn survival in 1998 and preliminary results indicate there might be a health problem, either disease or nutrition, affecting fawn survival.
This winter, the DOW will be feeding a supplement that consists primarily of wheat middlings, brewers grains, cottonseed hulls, and alfalfa. It also includes a number of vitamins and minerals. It is the supplement the DOW uses when it is necessary to feed deer populations during abnormally severe winters. Prior to feeding, 40 of the deer will be trapped and fitted with radio collars.
Another group of 40 deer that will not be given the supplement will also be trapped in a different area and fitted with radio collars. Then biologists will compare the two herds in terms of the fawn/doe ratio in December 2001. Research biologists are theorizing that if nutrition is a problem, the deer being fed the supplement will be healthier and have healthier fawns that will be better able to survive over the summer. The DOW annually does trend and sex-ratio counts in December to keep track of the growth and health of deer herds.
“Since the two herds use similar wintering areas and occupy the same summer range, any disease and predation factors should be the same,” Bishop added. “The supplemental feed will be the only factor different between the two herds. So if we observe a difference in fawn survival next year, we will be fairly certain the problem is poor nutrition.”
Biologists think nutrition could be a problem on the Uncompahgre Plateau because of the condition of the deer winter range caused by fire suppression. According to DOW biologist Bruce Watkins, the pinon pines and junipers have slowly invaded traditional sagebrush areas and formed a closed canopy under which very little can grow. In addition, as the mountain shrub communities continue to mature, they provide less nutritive value for deer.
“What we need to do is change these habitats to get both a wider variety of forbs and shrubs as well as more varied age classes,” Watkins said.
Watkins is currently working with the Uncompahgre Ecosystem Restoration Project, an amalgamation of state, federal, and private interests, to look at various ways to improve the habitat. Possibilities include prescribed fires, roller chopping, hydro-axing, reseeding and prescribed grazing.
While it could be several years before biologists pin down the problem and then begin to try to solve it, DOW biologists are optimistic they are on the right track. The studies on the Uncompahgre Plateau are slated to continue for the next several years.
Uploaded: 11/26/2000
Uploaded: 11/26/2000