Mule Deer in the Mojave


Water. Every living thing needs it. It covers 70% of the Earth’s surface, but only 1% is potable.  But what about deserts?  Where does wildlife find water in the desert?

Most deserts have rivers, natural springs, seeps, and natural depressions where freshwater is available at certain times of the year.  In some desert landscapes, humans create ways to provide surface water consistently throughout the year. Artificial water sources, such as wells and catchment basins commonly called guzzlers, are installed to support livestock ranching.

A long history of cattle ranching and grazing goes back over 100 years in the East Mojave Desert where artificial water developments were used to support livestock. Opportunistically, wildlife used and became accustomed to these artificial water sources.

A man-made water source in Mojave National Preserve.
A man-made water source in Mojave National Preserve.

Then in 1994, the National Park Service (NPS) formed the Mojave National Preserve (MNP) within the East Mojave Desert. The preserve encompasses 1.6 million acres of land in Southern California and the NPS created regulations that restricted new human developments on the preserve.  When ranchers living in the desert stopped grazing livestock, they abandoned their homesteads and the artificial water developments. At request of the NPS, these developments were supposed to be removed.

The NPS wanted the wells and other manmade features removed from the preserve in order to return the land to what they considered a “natural state.”  The guzzlers were installed for livestock, and without livestock present, they could be removed because they no longer served a purpose.

However, hunters familiar with the area were concerned for mule deer and other wildlife populations that were using the water developments. Since the water sources on cattle ranches were active for many years, hunters anticipated that the removal of surface water would have negative impacts to wildlife, such as mule deer. Hunters brought their concerns to the attention of NPS officials and biologist with the California Department of Fish and Game.  Initially, the NPS officials refused to listen to the concern and decided that MNP should be a natural area free of manmade objects.

Wildlife biologists with the California Department of Fish and Game (CDFG) disagreed.  In 2004, CDFG attempted to reactivate 12 of the wells in the preserve because they believed that wildlife depended upon these water sources for survival.  As a result, injunctions were filed to stop the reactivation of the wells and all progress on the matter halted.  It seemed as if none of the wells would be reactivated.

Fortunately, the Safari Club International Foundation got involved. The SCI Foundation set up a meeting between all parties involved.  It was brought to light that no one really knew the impact of these water sources on wildlife populations.  Therefore, in 2006 it was decided that a scientific-based research project was to be initiated to understand how these water sources were impacting wildlife.  The NPS agreed to partner on the research project, and Mule deer were chosen as the focal species because of their prominence in the system.

By late 2007, professor, Dr. Kelley Stewart of the University of Nevada-Reno joined the project.  Dr. Stewart’s research at the MNP focuses on the response of mule deer to water manipulations.  The research has been set up in three areas of MNP.  In one area, which is the control, wells were never deactivated and the deer in this area have had uninterrupted access to water for a quarter of a century.   In the second area, all wells were deactivated and deer only had access to springs. In the third area, wells were deactivated, but are systematically being turned back on.  Through the systematic reactivation of certain wells, researchers can determine how mule deer are impacted by the availability of water.

Since the research began in 2008, seven wells were reactivated the MNP.  The SCI Foundation made significant financial contributions to their reactivation. SCI Foundation has and continues to financially support this research effort.  More than 50 mule deer have been captured and monitored using radio collars and trail cameras.  They are looking at overall survival, fawning rates, body condition, and movement patterns of deer within the three areas.  When deer are captured, blood, hair, and body measurements are taken to test for health. Researchers are also monitoring weather conditions, vegetation, and water availability because these variables can all impact survival and movement of animals in their environment.

A researcher receiving a mule deer from a helicopter.
The research team working on the captured deer.
A newly collared mule deer in the Mojave National Preserve.

The results are still preliminary, but there are trends in the data that point to mule deer surviving better when they have access to more water sources.  In the area where wells were never deactivated, the collared mule deer have about a 93% annual survival; an 81% annual survival of collared mule deer was determined in the other two areas. Long-term availability of water, habitat conditions, or a lack of adequate ambush terrain for local predators may all be reasons for this difference in survival.  Over a ten year period, the research may show a significant difference in survival, condition and movements of mule deer between the study areas.

Another part of the study installed game cameras near water the sources to determine frequency of use by mule deer.  But, the cameras also showed a variety of other species using these water sources.  Everything from endangered bats and tortoises to bobcats and coyotes are using these water sources on a regular basis.  The researchers were surprised to find an abundance of species using these water sources, but it further establishes their importance to wildlife.

Mule deer at a spring. Taken with one of the many game cameras.

Research projects like this are important for conservation of species and their habitats.  But they also give us a glimpse into larger issues.  Initially the NPS wanted the wells removed to bring the preserve back to what they considered a natural state. But in reality, the natural state of the ecosystem known to wildlife included the additional water provided by humans.


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