August 1, 2009

East Mojave Mule Deer Research Project

Kelley M. Stewart, Assistant Professor, University of Nevada Reno

Vernon C. Bleich, Adjunct Professor, University of Nevada Reno

Debra J. Hughson, National Park Service

Neal Darby, National Park Service

California Deer Association

A mule deer doe released after capture. (Kelley Stewart)

Water is thought to be an 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 a component of management of wildlife habitats in arid and desert regions since the 1940s.

Considerable effort, from state agencies and sportsmen’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, Nevada that had provided water for populations of wildlife, have not done so for the last 10+ years.

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.

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 sportsmen 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 more than 100 years, and ranchers used a system of wells to provide water for livestock. Many of those artificial sources of water were present in the Preserve when it was created in 1994. From 1998 to 2002, grazing allotments in MojaveNational 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 a century. Loss of those water sources generated controversy among sportsmen’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 (DFG), Quail Unlimited, California DeerAssociation, 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 DFG, we designed an experiment to address the effects of provision of water for mule deer and other wildlife. We reactivated six 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 to 5 will include the comparison of areas with and without permanent sources of water, and those that have water available all year. During phase 2 of the project, years 6 to 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 provide both the National Park Service and California DFG 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 its 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-year portion of the study began in 2008. Six wells were turned on in the “water available” study areas during September and October. The movements and reproduction of mule deer in those two study areas and the ‘control’ area will be compared. 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.

Using the helicopter, deer were brought back to base camp where we collected data and placed radio collars on them. The radio collars are used to determine movement patterns and use of water sources in the Preserve. 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 that 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 nonwatered area. Some of the 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 captured deer 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.

In January 2008, we captured 18 mule deer: 15 does, 2 bucks, and a 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 checked for the 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.

This project is the result of years of effort by concerned sportsmen’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 Grateful Nation 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.