Research Projects

East Mojave Mule Deer Research
by Dr. Kelley Stewart, Assistant Professor, University of Nevada, Reno
Vern Bleich, Adjunct Professor, University of Nevada, Reno
Debra Hughson, National Park Service
Neal Darby, National Park Service

Mule deer buck with radio collar in Mojave National Preserve, CA January 2008. (K. Stewart).

Water is thought to be an important resource for wildlife species in desert ecosystems.  If water is limiting, then provision of water must increase survival or reproduction for individuals in areas with free standing water available all year.  State and federal agencies in the western United States have used water developments as an important component of management of wildlife habitats in arid and desert regions since the 1940’s.  To this day considerable effort, from stage agencies and sportsman’s organizations, is focused on providing water in areas where it is believed to be limited and may benefit populations of wildlife.  With increases in urbanization and demand for water by human populations many springs that once were available for wildlife have run dry and no longer provide free standing water.  For example some springs near Las Vegas, NV that had provided water for populations of wildlife and in the last 10+ years no longer provide water.  Water developments are likely becoming more important for sustaining populations of wildlife in arid regions of the western United States.  There is controversy associated with water developments, some people claim that they do not benefit wildlife or are detrimental to populations of wildlife by concentrating animals and providing opportunities for predators. 

Water development for wildlife in Mojave National Preserve, CA. November 2009

Mule deer occur throughout Western North America and require relatively large areas for viable populations, especially in desert ecosystems where resources such as food and water are scarce and widely distributed.  Certainly the distribution, abundance, and seasonal availability of water affect the distribution of mule deer across the landscape.  Mule deer are an important game species for sportsman and have aesthetic value for those who enjoy observing wildlife.  Mule deer also are good indicator species of changes in habitat quality and ecosystem health, which is in part why we selected mule deer for the species to study with this project. 

Cattle have been grazed in the Mojave Desert for over 100 years, and ranchers used a

Windmill used to pump groundwater to tanks for use by wildlife in Mojave National Preserve, CA. November 2009.

system of wells to provide water for livestock.  Many of those artificial sources of water were present the in Preserve when it was created in 1994.  From 1998 to 2002 grazing allotments in Mojave National Preserve were purchased, retired, and donated to the National Park Service.  When those allotments were retired, numerous water sources for livestock were deactivated within the Preserve.  Many of those water sources had been available to native wildlife for periods in excess of 100 years.  Loss of those water sources generated controversy among sportsman’s and environmental organizations about how loss of those wells affected populations of wildlife.  In 2004, Safari Club International (SCI) in cooperation with California Department of Fish and Game (CDFG), Quail Unlimited, California Deer Association, Mule Deer Foundation, Desert Wildlife Unlimited, and the Foundation for North American Wild Sheep proposed to reactivate 12 retired wells to provide water for mule deer and other species of wildlife.  The National Park Service (NPS) undertook an environmental assessment to address whether to grant the permit to retrofit those wells.  The result of the environmental assessment was for a science‑based research project to determine the existence and extent of benefit for artificial water sources for mule deer and other species of wildlife. 

The University of Nevada Reno answered the call for proposals for the research project.  In cooperation with NPS, SCI, and CDFG, we designed an experiment to address the effects of provision of water for mule deer and other wildlife.  We reactivated 6 wells and included several developed springs in an area designed to have permanent water available to compare with another area where the wells were kept off.  We will compare areas with and without permanent sources of water and examine movement patterns, reproduction, body condition, and food availability in each of those experimental areas.  We also included a ‘control area’ that will be monitored, but remain unchanged throughout the study.  The study has a 10 year duration, years 1-5 will include the comparison of areas with and without permanent sources of water, those that have water

Mule deer doe released after capture in Mojave National Preserve, January 2008 (K. Stewart).

available all year.  During phase 2 of the project, years 6-10, we will turn on the wells in the area without permanent water and will compare effects on the mule deer herd before and after water was made available.

With this study we hope to answer the question of whether provision of water in Mojave Preserve is beneficial to mule deer populations and to provide both the National Park Service and California Department of Fish and Game with information regarding the value of continuing to provide artificial sources of water in the Preserve and other arid regions of the west.   Many western states spend many hours and dollars providing water for wildlife, and management agencies from several states are interested in the results of this project.  Indeed the Nevada Department of Wildlife felt that this research was relevant to their needs and provided funding for a portion of the project.  Support also has been received from California Deer Association and the Golden Gate Chapter of SCI.

The first 5 years portion of the study began in 2008, we turned on 6 wells in the “water available” study areas during September and October.  We will compare movements and reproduction of mule deer in those two study areas and the ‘control’.  During January of 2008 and 2009 we captured mule deer with a netgun fired from a helicopter.  Netguns are an effective way to catch mule deer, and in Mojave National Preserve the “gunner” has his work cut out for him when trying to catch deer while avoiding cactus and Joshua trees.  Deer were brought back to our established base camp with the helicopter where we collect data and place radio collars.  Deer were equipped with radio collars to look at movement patterns and use of water sources in the Preserve. 

Tim Glenner (California Dept. Fish and Game) with a netgun used to capture deer.  January 2008.

 

We are using GPS type collars in Mojave Preserve.  Those collars obtain highly accurate locations of mule deer about 7 times a day.  So we have very detailed data on movements of deer in the Preserve.  The only drawback is that the collars store all of the locations on the collar, known as store-on-board collars, so we have to get the collar back at the end of the year to have access to those data.  Collars are programmed to drop off the deer at a specified time and then they transmit a signal so technicians are able to go out into the Preserve and find the collars.  We have just recently obtained the collars from last year and next winter we will locate the collars that we placed in January to examine movements of deer in relation to the recently reactivated water sites.

We have a remote camera located at each water site that is monitored with this study and several sites in the non-watered area.  Some of those cameras were purchased by NPS for their ongoing camera study, which we have incorporated into this project.  Several of the cameras were purchased by SCI, and are currently in use on the Preserve for this study.  The cameras record use of our treatment areas by mule deer so we can use them throughout the year to identify our deer at the water sites.  The cameras also record use of the wells by other species of wildlife, such as many species of birds, including hawks and owls, and several small mammals and reptiles.  Another criticism of water developments is that they only benefit ‘game’ species, although to date many non-game species have been photographed using these water sources.

We examined those animals for physical condition and pregnancy using ultrasound technology.  Using ultrasound we are able to measure the amount of fat on several areas of the body which is a good index to how good or poor condition the animal is in.  Using ultrasound we also determined if females were pregnant and if they were carrying twins or single fetuses.  We are able to get accurate measurements of fetuses to determine health of the offspring and determine the stage of gestation, similar to human women visiting the doctor for ultrasound during pregnancy.  By determining physical condition and numbers of offspring we are able to assess the health of the mule deer herds in the different study areas.

Example of a fetus of a mule deer from ultrasonography.  The fetus is circled in black and the head length is measured with the two “+” signs. January 2008.

In January of 2008 we captured 18 mule deer, 15 does, 2 bucks, and 1 yearling doe.  We captured 6 deer in the control area 7 in the study area that will have water provided, and 5 in the no permanent water study area.  Since the experiment had not yet been set up, water sources were turned on later in the year, we used the initial data to obtain an overall idea of demography.  We looked at pregnancy of those females and 94% (15 of the 16 females, including the yearling) were pregnant.  Of those 15 females, 73% were carrying twins.  Twinning is an excellent indicator of overall quality of the habitat and health of the population.

During January 2009, we captured 30 does, and 1 juvenile (born spring 2008). Several of those deer were recaptured from last year to remove old radio collars.  We captured 27 new individuals, 9 does were captured in the control area, 10 in the watered area, and 8 does in the area without permanent sources of water.  We tested 28 of those deer for pregnancy, and 93% of those females (26 of 28) were pregnant, but only 14% were carrying twins.  We suspect that because 2008 was a very dry autumn, compared with 2007, fewer sources of food were available for deer as they entered the breeding season, and possibly resulted in a lower twinning rate.  We need to examine more years of data following future captures to determine the relationship between water developments, precipitation, and availability of food to understand those effects of pregnancy rates, twinning rates, and condition of deer in this population.  Since data on deer in 2008 were collected before the experiment was fully set up, we cannot compare the different study areas yet.  We are looking forward to examining differences among deer in the different study areas next winter.

University of Nevada Reno is primarily a place of learning and one of the attributes of this study is that students receive training on handling of wildlife, collection of data, and design of experiments.  We are currently training a Master’s level graduate student on this project, and several undergraduates have accompanied us on our captures to gain experience handling wild deer in a field setting. 

Chris McVicars, undergraduate student in Wildlife Ecology and Conservation at University of Nevada Reno, catches a mule deer that has been brought to base camp with a helicopter for data collection and to receive a radio collar. January 2009.

This project is the result of years of effort by concerned sportsman’s groups to restore historical water sources to areas from which they had been removed.  Safari Club International, California Deer Association, and the Society for the Conservation of Bighorn Sheep have led this effort.  The project is necessary because restoration of historical water sources as described in the environmental assessment approved for that action must be fully evaluated in terms of the responses of mule deer to the provision of water.

Deer Hunt Zone (D-17), in which the study area is located produces on average the largest trophies (as determined by proportions of 3-point, 4-point, and 5 or more point bucks) of all zones in California.  Hunter success is not the highest in California, but trophy quality is outstanding and the zone sells out on an annual basis.  Restoration of water sources in the study area has important implications for conservation of mule deer, and maintaining high-quality recreational hunting in that area.  Finally, collaboration is the key to any successful venture and this project has evolved into a huge collaborative effort.  Collaborators include state agencies: University of Nevada Reno, California Department of Fish and Game, Nevada Department of Wildlife; a federal agency: National Park Service; and Conservation Organizations: Safari Club International, Golden Gate Chapter Safari Club International, and California Deer Association.   

Capture crew, January 2008.