MDF Projects
Mapping Mule Deer Habitat
A Guide to Restoring Habitat Capacity
By: Jim deVos
Chair, Mule Deer Working Group
Arizona Game and Fish Department
Mule deer are an important species from many standpoints. Since this species is so widely distributed in North America, many young hunters have harvested a mule deer as their first big game. Also, who hasn’t experienced a thrill as they see a herd of mule deer slipping quietly through an aspen thicket, or a rolling sagebrush covered hillside, or even crossing a saddle in the Sonoran desert. The point is that mule deer are widely distributed and most folks have had positive experiences with them.
One challenge mule deer managers face is that over the last several decades there have been a number of mule deer population cycles; sometimes we have many deer and sometimes, like now, deer are pretty scarce. In looking at these fluctuations, one fact jumped out: when deer numbers were up, they were not as high as in previous highs, and the lows were lower than previous lows. Concerned with this decades-long decline, the Directors of the western states appointed a Working Group to help identify causes and remedies to reverse the decline in mule deer.
Early in our deliberations on the cause of the current mule deer decline, we reached agreement in the group that long- and short-term changes in habitat capacity contributed to the direction mule deer populations were headed. Our next step was to look at what options existed to better manage mule deer habitat. One problem with habitat management is that many factors, such as fire suppression or the introduction of invasive species such as cheatgrass, have allowed most mule deer habitat to undergo huge changes that don’t favor high mule deer survival.
The Working Group felt that until we were able to implement large-scale habitat restoration programs, we would never be able to achieve sustained increases in mule deer numbers. Recognizing the diversity of habitat in which mule deer are found, the Working Group began discussing how we could prioritize areas to begin restoration treatments that would have the highest return for the investment.
Here the plan became murky. Although most states and provinces had existing maps of mule deer habitat, there were essentially no mapping efforts that crossed state/provincial boundaries; therefore, the goal of large-scale restoration was hampered. Further, we found that maps were completed at different scales and with different mapping conventions, which made them hard to use. There was another limitation to the existing maps that the Working Group thought was an important limitation: few of the maps actually identified what factors imposed limitations on the quality of the mule deer habitat. So while we were able to tell that an area was important winter range, we could not tell how functional the area was.
During our search for mule deer maps, we found a map the Rocky Mountain Elk Foundation had done that covered North America. It not only mapped the areas by habitat type, but also included a listing of the limiting factors for each area mapped. It was exactly what we were looking for, only it was for elk and not deer.
The Working Group then began to look for organizations that could develop a similar map for mule deer. We found that Utah State University had the capacity to do this work for us. Unfortunately, the Working Group had no budget, so we began to look for agencies and organizations that could support this work. The first fishing trip was to the state/provincial wildlife agencies in the West, and they came up with about 25 percent of what was needed. The National Fish and Wildlife Foundation found the project of interest and put up half of the funding required, leaving us to find another 25 percent, or a little over $32,000.
Fortunately, the leadership of the Mule Deer Foundation shared the Working Group’s vision of the need for a range-wide map that not only lists habitats by type, but also identifies the limiting factors for each mapped area. After some discussions, the Mule Deer Foundation agreed to provide $32,000 for the project. Now we had the funding and the organization to do the work, and in early summer of 2003, the project was launched.
Over the last year, researchers from Utah State have visited the states/provinces with mule deer to work with the biologists to draw lines on the maps and attribute each area with a list of limiting factors. This done, the hand-drawn maps are taken to the lab in Utah and converted to digital format, printed and returned to the coordinators in the wildlife agencies to review and make minor tweaks based on re-evaluation by the biologists. Through a stroke of luck, we were able to include the mule deer habitat in Mexico; so at this time, all mule deer habitat in North America has been mapped.
Let’s explore how this map will benefit mule deer management. The Working Group is looking for opportunities to initiate landscape scale restoration projects, and we can use the output of the map to identify priority areas. Let’s say for example that we want to work on winter habitat on the west slope of the Rockies. The underpinning of the map is a database that contains all the information on the location and limiting factors for winter range. We can ask the computer to identify and map all of the winter range that is threatened by woody invasion, and with a little computational time, out comes a map that shows all of the areas that fit these two classes.
From a Mule Deer Foundation standpoint, this map will allow local chapters to do the same exercise outlined above. When looking for high priority projects, a chapter can query the database for their area, request a given habitat class and a specific limiting factor, and the database will identify all of the areas that meet those classifications.
The uses of the database are limitless. I can see a biologist working with a planning and zoning commission in Colorado to highlight important fawning areas so urban expansions can avoid critical habitat impacts.
It is important to note that there were many contributors to this project. Without the great technical assistance from researchers at Utah State, it is likely we would not have been able to complete the project. Every wildlife agency in the West stepped up and contributed to the project. Finally, without the helping hand extended by the Mule Deer Foundation, the project would likely still be a dream yet to be fulfilled. Hopefully, the products produced will be used to guide restoring the habitat capacity and in turn return mule deer populations to a sustainable, productive level.