South of Interstate 40 Mule Deer

The South of Interstate 40 mule deer reside in Game Management Units (GMUs) 8 and 6B in Arizona. The herd summers in high-elevation open meadows and Pinus ponderosa (ponderosa pine) habitat southwest of Flagstaff, Arizona. In late October, the herd migrates west to lower elevation Pinus spp. (pinyon pine)-Juniperus spp. (juniper) and shrub habitats near the junction of Interstate 40 and U.S. Highway 89 (fig. 6). With funding support by the DOI through SO 3362, research on this herd’s migration began in February 2020. Additional GPS collars were deployed in January 2022 with support from the FS, Mule Deer Foundation, and other partners. Primary threats to the herd’s migration involve high-volume roads including Interstate 40 and U.S. Highways 89 and 89A.

Blue Canyon Mule Deer

The Blue Canyon mule deer herd winters in the western foothills of the Sierra Nevada south of Interstate 80. The winter range includes dense conifer and oak woodland that is shared with a resident portion of the herd on a mix of public and private lands. In the spring, the Blue Canyon herd migrates from their winter range eastward along two main paths located on the north and south sides of the Forest Hill Divide to higher elevation terrain near Soda Springs and the crest of the Sierra Nevada (fig. 7). The summer range includes primarily mixed-conifer forests opening up to high alpine granite near the crest of the Sierra Nevada. The population size is not well known because of limited surveys, but is considered stable to declining, affected primarily by increasingly dense overstory and habitat loss. This GPS collaring project was designed as part of a region-wide effort to obtain abundance estimates for deer using fecal DNA and home range analyses, with pinpointing migration routes and identifying winter ranges a secondary priority. Because of the small sample of GPS-tagged mule deer, additional migration routes and winter ranges probably exist beyond the extent of our model output.

Bucks Mountain-Mooretown Mule Deer

The Bucks Mountain-Mooretown mule deer herd winters in the western foothills of the Sierra Nevada. The winter range includes vernal pool grassland, oak woodland, and dense-conifer that is shared with a resident portion of the herd on a mix of public and private lands. In the spring, the Bucks Mountain-Mooretown herd migrates along the U.S. Highway 70 corridor and high-elevation locations of the Sierra Nevada east and south to higher elevation terrain in the surrounding national forest lands east of the Sierra Nevada near Quincy and La Porte, California (fig. 8). The summer range is primarily mixed-conifer forests opening up to high alpine granite near the crest and transitioning to a mix of conifer and shrub communities on the eastern side of the Sierra Nevada. Although the population size is not well known, it is considered stable to declining, affected primarily by increasingly dense overstory, environmental stressors, and habitat loss. This GPS collaring project was designed as part of a region-wide effort to obtain abundance estimates for deer using fecal DNA and home range analyses, with pinpointing migration routes and identifying winter ranges a secondary priority. Because of the low sample size, additional migration routes and winter ranges probably exist beyond the extent of our model output.

Downieville-Nevada City Mule Deer

The Downieville-Nevada City mule deer herd winters in the western foothills of the Sierra Nevada range. The winter range includes dense conifer and oak woodland that is shared with a resident portion of the herd on a mix of public and private lands. In the spring, the migratory component of the herd migrates north and east of Nevada City on both sides of the middle fork of the Yuba River, staying north of Interstate 80, to high-elevation summer range along the crest of the Sierra Nevada (fig. 9). The summer range is primarily mixed-conifer habitat opening up to high alpine granite near the crest of the Sierra Nevada. The population size is unknown because of limited survey capacity, but the population is considered stable to declining, affected primarily by dense overstory, environmental stressors, and habitat loss. This GPS collaring project was designed as part of a region-wide effort to obtain abundance estimates for deer using fecal DNA and home range analyses, with pinpointing migration routes and identifying winter ranges a secondary priority. Because of the small sample size, additional migration routes and winter ranges probably exist beyond the extent of our model output.

East Tehama Mule Deer

The East Tehama herd is the largest migratory population of mule deer in California (Hill and Figura, 2020). Population numbers peaked in the 1960s but have declined in recent decades (Ramsey and others, 1981). These mule deer migrate from a lower elevation winter range in the foothills east of the Sacramento Valley to upper elevation summer ranges in the southern Cascades and northern Sierra Nevada (fig. 10). Although portions of the herd winter on the California Department of Fish and Wildlife’s Tehama Wildlife Area and other public lands, the herd’s winter range also comprises many private ranchlands. The herd’s summer range includes significant portions of surrounding national forest lands as well as Lassen Volcanic National Park and private timberlands. Primarily oak woodlands and annual grasslands characterize the winter range, while the summer range consists of conifer forests, montane meadows, and montane chaparral. Potential threats to the herd include habitat changes resulting from fire management (including fire suppression and catastrophic wildfires), forest succession, vegetation management, and climate change. A small percentage of the herd are residents, inhabiting areas along the Sacramento River and areas of irrigated agriculture.

Grizzly Flat Mule Deer

The Grizzly Flat herd winters in the western foothills of the Sierra Nevada near Grizzly Flats, California. The winter range includes conifer forests, vineyards, and oak woodland that is shared with a resident portion of the herd on a mix of private and public lands. In the spring, the Grizzly Flat herd migrates east to higher elevation terrain in the surrounding national forest, staying south of Interstate 50 and primarily north of U.S. Highway 88, to the crest of the Sierra Nevada (fig. 11). The summer range contains primarily mixed-conifer forests opening up to high alpine granite near the crest of the Sierra Nevada. Although the population size of the Grizzly Flat herd is unknown because of limited surveys, it is considered stable to declining, affected primarily by dense overstory, environmental stressors, and habitat loss. This GPS-collaring project was designed as part of a region-wide effort to obtain abundance estimates for deer using fecal DNA and home range analyses, with pinpointing migration routes and identifying winter ranges a secondary priority. Because of the small sample size of GPS-tagged mule deer, additional migration routes and winter ranges probably exist beyond the extent of our model output.

Kern River Mule Deer

The Kern River deer herd abundance peaked in 1949, but numbers have decreased in recent decades. The population size estimate is now considered stable, owing primarily to habitat expansion by the 2001 McNally fire (California Department of Fish and Wildlife, 2022). The Kern River herd winters in regional national forest lands north of Johnsondale and east of Slate Mountain. In the spring, the herd migrates northward to an area by Redrocks Meadows and along the Kern Canyon ridgeline to their summer range in Sequoia National Park (fig. 12). The herd’s annual range spans the watersheds of the Kern and Little Kern Rivers in eastern Tulare County. Elevations range from 2,500 ft (762 m) on the southern slopes of the winter range to above 11,000 ft (3,353 m) on the northern summer range. Telemetry data during the past two decades show considerable mixing between this herd and the Manache herd on their summer ranges. Further research may support the hypothesis that these herds are subherds of a larger population. This GPS-collaring project was designed as part of a statewide deer-monitoring effort to obtain abundance estimates, demographic rates, and movement datasets.

Manache Mule Deer

The Manache mule deer herd predominantly covers the eastern slopes and crest of the Sierra Nevada. Elevation stretches from 3,200 ft (975 m) on the Owens Valley winter range to above 11,000 ft (3,353 m) on the summer range in Sequoia National Park. The Manache herd migrates from winter ranges just west of U.S. Highway 395 on the steep slopes and valleys of the Sierra Nevada near Dunmovin and Haiwee west to some of the highest elevations in the continental United States in the surrounding national forests (fig. 13). Deer numbers have fluctuated since 1900, attributed largely to livestock allotments, fire regimes, and timber-harvest practices. The population size in 2022 was unknown because of limited data. This GPS-collaring project was designed as part of a statewide deer-monitoring effort to obtain abundance estimates, demographic rates, and movement datasets.

Salt Springs Mule Deer

The Salt Springs herd winters in the western foothills of the Sierra Nevada predominantly on private property from Tylers Corner south to Sheep Ranch. The summer range is in high-elevation terrain near Lower Bear River Reservoir and Salt Springs Reservoir (fig. 14). The winter range consists of mainly oak woodland habitat, and the summer range includes primarily mixed-conifer forests opening up to high alpine granite terrain near the crest of the Sierra Nevada. The population size is unknown because of limited data. This GPS-collaring project was designed as part of a region-wide effort to obtain abundance estimates for deer using fecal DNA and home range analyses, with pinpointing migration routes and identifying winter ranges a secondary priority. Therefore, other winter range and migration corridor routes probably exist apart from what the limited sample size revealed. Future work will help pinpoint the boundaries of this herd. The Salt Springs herd is particularly important for comparison to the Railroad Flat herd, which overlaps on the winter range with the Salt Springs herd (though the Railroad Flat herd uses a unique summer range).

Siskiyou Mule Deer

The Siskiyou mule deer herd migrates from winter ranges primarily north and east of Mount Shasta (for example, Lake Shastina, Mount Dome, Mount Hebron, Tionesta, and Wild Horse Mountain) to sprawling summer ranges within regional wilderness areas in the west and the Burnt Lava Flow Geological Area to the east (fig. 15). A small percentage of the herd are residents, residing largely within winter ranges across the central and northeast areas of the herd’s annual distribution. The total population size of the Siskiyou herd is unknown, but adult deer densities averaged 6.01 deer per square kilometer (15.4 deer per square mile) on summer ranges in 2017 and 5.16 deer per square kilometer (13.23 deer per square mile) on winter ranges in 2019 (Wittmer and others, 2021). Some deer from the Siskiyou herd, including individuals not collared from this dataset but moving within herd boundaries, cross major highways during their seasonal migrations (U.S. Highways 97 and 89), and road mortalities of telemetered deer have been recorded (Cristescu and others, 2022). The summer range poses few concerns to the health of the herd, although limited water availability and recent forest fires may affect deer to some extent. Possible risks to deer population health on the winter range are relatively unknown. While recreational (hunting) opportunities have declined, the herd’s status is considered stable.

Albion Mountains Mule Deer

Albion Mountains mule deer winter on the lower south- and west-facing aspects of the Albion Mountains (fig. 16). However, the majority of deer that summer in the Albion Mountains migrate east to the Albion and Jim Sage Mountains and, to a lesser extent, north to the Cotterel Mountains. In 2017, an estimated 4,000 mule deer wintered in the southern portions of the Albion and Jim Sage Mountains. The Albion Mountain range is a small, isolated mountain range surrounded by private agricultural land. The Cotterel Mountains and Jim Sage Mountains are other isolated ranges, separated by private agricultural valleys spanning a few miles between ranges. On average, the Albion Mountains mule deer migrate 15 mi (24 km) between their summer and winter habitats. There is low risk of conversion of private agricultural lands to habitat unsuitable for mule deer. Because many of these deer have to cross private lands to reach their winter range, it is important to maintain private land as agricultural so migrations are not inhibited.

North Hansel Mountains Mule Deer

North Hansel Mountains mule deer winter east of Stone, Idaho, along the border of Idaho and Utah (fig. 17). Recent aerial abundance surveys indicate that 1,600–2,200 mule deer winter here. Below-average winter snow depths result in deer dispersing throughout the North Hansel Mountains and the Pleasantview Hills to the north. In contrast, above-average snow depths force deer farther south into Utah. In the spring, deer migrate north−northeast and north−northwest into the Pleasantview Hills and Deep Creek Mountains, respectively. On average, these mule deer travel 27 mi (43 km) between their summer and winter ranges. Livestock fencing, wildfires, and the proliferation of exotic annual grasses all have the potential to negatively affect migration and seasonal habitats for this herd.

Sand Creek Mule Deer

Approximately 3,800 mule deer winter on the slightly rolling terrain surrounding Sand Creek (this area is regionally known as the Sand Creek Desert), located in GMU 60A (fig. 18). Human entry restrictions across much of the area during winter provide mule deer with undisturbed access to high-quality sage steppe habitats. The area primarily consists of sagebrush or bitterbrush overstory with grass and forb understory. In certain areas, these brush communities are interspersed with stands of juniper, Prunus virginiana (chokecherry), and other shrub species, which provide both cover and browse for mule deer. Pseudotsuga menziesii (Douglas fir) and Pinus contorta (lodgepole pine) communities become common throughout Big Bend Ridge as elevation increases to the north of the Sand Creek Desert. In the summer, Sand Creek mule deer largely disperse north and east into forested habitats (often east of U.S. Highway 20) to GMUs 60, 62, and 62A, with some individuals traveling to Wyoming. Two main challenges these mule deer face during migration include an extensive network of fencing and traffic on U.S. Highway 20.

South Hills Mountains Mule Deer

South Hills mule deer primarily winter on the northern end of the South Hill and spend the summer on national forest lands to the south-southeast (fig. 19). The lower south-facing slopes are generally free from significant snow, and an abundance of bitterbrush provides forage for more than 6,000 mule deer. The South Hill area is popular for off-road and all-terrain vehicle enthusiasts because of the extensive motorized-use trails and roads in the area. Some seasonal access restrictions protect mule deer on their winter range. On average, these mule deer migrate 20 mi (33 km) between their winter range and summer ranges in the higher elevations of the region. Several large wildfires have burned hundreds of thousands of acres in the South Hills in the last decade, affecting winter range distributions.

Stone Hills Mule Deer

Stone Hills mule deer winter west−southwest of Stone, Idaho, and north of Snowville, Utah, between Interstate 84 and Stone (fig. 20). Aerial abundance surveys in 2015 and 2022 documented more than 1,900 mule deer wintering in the Stone Hills. In the spring, these deer migrate north−northwest and north−northeast into the Sublett Range and Deep Creek Mountain, respectively. On average, these mule deer migrate 26 mi (42 km) between their summer and winter ranges. Prior to the construction of Interstate 84 in 1969, many deer from the summer range in the Sublett Range migrated to the winter range along the Black Pine Mountains; that migration no longer exists. Transportation infrastructure, wildfires, and the proliferation of non-native annual grasses negatively affect the winter and summer habitats for these deer.

Canyon de Chelly Mule Deer

The Canyon de Chelly population is one of several mule deer herds that winter in the foothills of the Chuska Mountains, a mountain range measuring 80 mi (129 km) long within the southeast Colorado Plateau in the Navajo Nation Reservation. The winter ranges and migration corridors of the Canyon de Chelly mule deer herd lie just 7 mi (11 km) south of the Ram Pasture herd but are separated geographically by Canyon del Muerto and Black Rock Canyon (fig. 21). These canyons are part of a larger canyon system known as the Canyon de Chelly National Monument. The Canyon de Chelly National Monument is one of four parks in the Federal park system comanaged with a Native American Tribe, though the United States government owns none of the parklands (National Park Service, 2021). Members of the Navajo Nation continue to live inside the Canyon de Chelly National Monument and the surrounding canyons where they maintain livestock (cattle and sheep) and grow crops. Although there are routes into the canyon and perennial streams throughout the bottom of the canyon, the collared mule deer spend most of their winter season on top of the canyon mesas. Windmills installed for livestock use by the Navajo Nation Department of Water Resources are an important source of water for mule deer during winter. During spring and fall migrations, the Canyon de Chelly herd’s migration corridors cross Indian Route 12, a busy rural highway along the Arizona and New Mexico border. Vehicular collisions, urban development, and overgrazing by livestock are the herd’s predominant challenges within this migration corridor. Because of the small sample of GPS-tagged mule deer, additional migration routes and winter range areas may exist beyond the extent of our model output.

Ram Pasture Mule Deer

The Ram Pasture population is one of several mule deer herds that winter in the foothills of the Chuska Mountains, a mountain range measuring 80 mi (129 km) long within the Navajo Nation Reservation (fig. 22). These mule deer winter in pinyon-juniper and sagebrush foothills, migrate east to higher elevations in the spring, and summer in habitats comprised of mixed-conifer, aspen, high alpine meadows, and ponderosa pine. Both winter and summer ranges remain entirely within Tribal trust lands managed by the Navajo Nation Department of Fish and Wildlife. Similar to the Canyon de Chelly mule deer herd, every spring and fall, the Ram Pasture herd must cross Indian Route 12, a busy rural highway along the Arizona and New Mexico border. Vehicular collisions are a continuous problem in these areas during migration seasons. Aerial surveys in 2020 estimated 1,583 mule deer as the minimum number known to be alive throughout the herd’s winter ranges in the Chuska Mountains. The limiting factors for this herd include low-quality habitat caused by overgrazing and resource competition with feral horses and unregulated livestock (Davies and Boyd, 2019; Wallace and others, 2021). Furthermore, extended drought and habitat fragmentation driven by urban development have accelerated the decline of habitat suitability (Redsteer and others, 2013; Nania and others, 2014).

Crow Mesa Mule Deer

The Crow Mesa Mule Deer study was initiated in 2019 to identify the seasonal movements and distribution patterns of mule deer in the eastern half of GMU 2C. This GPS study builds on nearby studies of mule deer and elk conducted by the BLM, the Southern Ute Tribe, the Jicarilla Apache Nation, and the New Mexico Department of Fish and Game. Migration corridors extended 20–75 mi (32–110 km) from the winter ranges in GMU 2C to various summer ranges on national forest lands to the northeast near Dulce, and to the southeast near Cuba (fig. 23). The Crow Mesa herd relies largely on winter ranges administered by the BLM, where approximately 70 percent of the population remains year round (Sawyer, 2021). The other 30 percent of the herd migrates through and summers on an assortment of private, Tribal, and FS lands. Notably, all recorded mule deer migration corridors crossed Jicarilla Apache Nation Reservation immediately east of this herd’s winter range. Key management challenges with this deer herd include fence barriers, highway crossings, and habitat loss and human disturbance associated with energy development.

Rio Chama Mule Deer

The Rio Chama mule deer herd has one of the highest-density populations of any herd in New Mexico. The herd migrates from north-central New Mexico along the Continental Divide and through the San Juan Mountains, with some individuals moving to summer ranges in southern Colorado (7,871–11,500 ft [2,399–3,505 m] elevation; fig. 24). These deer migrate through a mosaic of private, public, and Jicarilla Apache Nation Reservation lands. The herd winters south and east of Heron Reservoir and El Vado Reservoir in habitat consisting primarily of sagebrush steppe, grasslands, pinyon-juniper mesas, and oak woodlands. The mule deer use two primary migration corridors: One corridor follows the Rio Chama to the northeast and a shorter corridor heads east across U.S. Highways 84 and 64. The shorter corridor initially follows Rio de los Ojos before branching into separate corridors north and south of U.S. Highway 64. Interspersed agricultural lands along the Rio Chama and U.S. Highways 84 and 64 may serve as stopover sites for some mule deer during their spring migration. Ponderosa pine, mixed-conifer, and Populus tremuloides (quaking aspen) forests characterize the corridors and stopovers within mid-elevation landscapes. As the Rio Chama mule deer continue northeast, they travel through subalpine spruce-fir forests and montane meadows until reaching their high-elevation summer range, which consists of mixed-conifer and aspen forests. Challenges the herd faces include crossing U.S. Highways 84 and 64, increasing density of housing subdivisions in some areas along the routes, and fencing, especially taller fencing that mule deer cannot jump.

Book Cliffs Mule Deer

Framed by Interstate 70 to the south, the Book Cliffs region is a barren, wild landscape of the Colorado Plateau and is critical to the survival of wildlife in Utah. The area begins in the northern desert shrub zone of the Uinta Basin and, to the south, rises gradually to aspen and fir zones in the Tavaputs Plateau, averaging 6,000 ft (1,829 m) elevation. The Book Cliffs mule deer herd uses the roadless backcountry terrain to migrate annually between their summer and winter ranges (fig. 25). The Book Cliffs mule deer are summer range limited, where habitat consists primarily of oak, sagebrush, Douglas fir, and Utah juniper vegetation types. Areas of high winter use by the Book Cliffs herd include open pinyon-juniper woodland and sagebrush (Karpowitz, 1984). Many economic activities occur within these habitats, such as oil and gas extraction and cattle grazing (U.S. Department of Agriculture, 2005; Utah Division of Wildlife Resources, 2020). The Utah Division of Wildlife Resources collaborates with partners and land management agencies that make up the patchwork of the Book Cliffs region to balance mule deer herd and human needs.

Eagle Mountain Mule Deer

Eagle Mountain is located in central Utah on the northwest side of Utah Lake. In the early 1990s, the area was relatively undeveloped. Now, there are approximately 30,000 residents, and the population is projected to triple by 2040 (State of Utah, 2014). Prior to 2018, the Utah Division of Wildlife Resources had a small amount of data, which showed that mule deer migrated from winter ranges in the Lake Mountains to summering areas in the Oquirrh Mountains. The migration crosses State Route 73, which connects Eagle Mountain, Utah with the suburbs of Salt Lake City. In December 2018, 38 mule deer were captured and fitted with GPS tracking devices. Tracking data indicate that there are two major migration routes in the area (fig. 26): one eastern route and one western route. The western route crosses State Route 73 at Fivemile Pass in an area with substantial recreational use but not at risk for development. The eastern migration route passes through Eagle Mountain in an area that will probably be developed in the near future. The Utah Division of Wildlife Resources is working with Eagle Mountain, Utah Department of Transportation, BLM, the Mule Deer Foundation, and others to preserve migration corridors in response to the rapid changes occurring in the area.

Morgan-South Rich Mule Deer

The Morgan-South Rich herd is located in northern Utah, northeast of Park City, and is made up of nearly 10,000 mule deer (Bernales and others, 2020). From collaring efforts started in 2020, GPS tracking data indicate mule deer migrate from higher elevations in the Wasatch Range to the winter-range habitats on the north slopes of Weber River, Lost Creek, and Echo Canyon (fig. 27). A detached, smaller wintering area lies on the south-facing slopes above Cottonwood Creek. However, the available area of low-elevation winter habitat is severely limited. Mule deer heavily use the lower elevation habitat types of sagebrush and mountain browse, but in severe winters, browsing availability is greatly reduced (Utah Division of Wildlife Resources, 2017).

Traditional winter-range habitats are at high risk of habitat loss and degradation, threatened by increasing development and urbanization in Morgan Valley and Henefer areas (Utah Division of Wildlife Resources, 2017). In addition, highway mortality presents a significant concern in this migration corridor and winter range. Two major interstates, Interstates 80 and 84, form the southwest boundary of this population and pose a threat to its migratory and wintering mule deer. Cooperative efforts with the Utah Department of Transportation are underway to construct highway fences and wildlife warning signs to allow for safer crossing.

North Slope Mule Deer

Stretching across northeastern Utah along the Utah−Wyoming border and east to the Colorado state line, the North Slope herd is home to nearly 5,800 mule deer (Bernales and others, 2020). The peaks of the Uinta Mountains span the southern border of this region, with elevations ranging from 8,000 ft (2,438 m) to 13,000 ft (3,658 m), with hundreds of high alpine lakes scattered between the summits. The North Slope mule deer herd predominantly migrates east and west, traversing the northern perimeter of the Uinta Mountains and crossing the national forest lands (fig. 28). Beginning in 2018, 70 migratory mule deer have been tracked traveling short distances of almost 3 mi (5 km) to longer stretches of 73 mi (118 km). Seventeen of the GPS-tracked mule deer migrated from Utah into Wyoming or Colorado.

San Juan Mule Deer

The San Juan mule deer reside in the southeast corner of Utah. The summer range for these mule deer occupies higher elevations in the Abajo Mountains, and a majority of the deer migrate to winter ranges at lower elevations in Alkali Point and Harts Draw areas (fig. 29). Habitat types in the summer range include conifer, aspen, alpine, and mountain shrubs. The herd’s winter-range habitats include sagebrush steppe, pinyon-juniper woodlands, and salt desert shrub that support valuable browse in mild to moderate winters (Utah Division of Wildlife Resources, 2015). Highway mortality is a significant concern in this migration corridor because the mule deer must traverse two major roads: U.S. Highway 191 and U.S. Route 491. The Utah Division of Wildlife Resources, Utah Department of Transportation, San Juan County, Sportsman for Fish and Wildlife, and others collaborated and determined priorities for reducing WVC along these stretches of highway. As a result, six wildlife crossing structures and approximately 7 mi (11 km) of highway fencing have been constructed on U.S. Highway 191 near Monticello, Utah, allowing for safer wildlife crossings.

Chelan Mule Deer

The Chelan mule deer herd occupies a mix of private and public lands from the Columbia River to the crest of the Cascade Range in central Washington. U.S. Highway 2, northwest of Wenatchee, Washington, serves as the southern boundary for this herd, and Lake Chelan bounds the northern edge. The high-use winter range includes the southeastern shore of Lake Chelan, the breaks of the Columbia River, the lower Entiat River drainage, and the foothills east of Cashmere, Washington. In the spring, migratory individuals travel northwest into the Entiat and Chelan Mountains to their summer ranges in regional wilderness areas. A small sample of Chelan mule deer was captured near the Swakane Wildlife Area in January 2020 (n = 19 adult females). Thus far, most captured individuals have been migratory, although some individuals reside year round in the foothills east of Cashmere and along the Columbia River (fig. 30). On the winter range, residential development and disturbance from human recreation continue to be a concern. Semipermeable barriers to migration include U.S. Highway 97A, which overlaps the winter range along the Columbia River, and U.S. Highway 2, which bisects several individual migration routes.

Wenatchee Mountains Mule Deer

Along the eastern slope of the Cascade Range in Chelan and Kittitas Counties, the Wenatchee Mountains mule deer herd inhabits a matrix of private and public lands. Historically, the Wenatchee Mountains mule deer were separated into two subherds, Chelan and Kittitas; however, recent movement data from GPS-collared individuals associated with SO 3362 (U.S. Department of the Interior, 2018) revealed that the mule deer south of U.S. Highway 2 and north of Interstate 90 represent one population. Their high-use winter range extends along the foothills west and south of Wenatchee, Washington, and throughout the foothills of the Kittitas Valley outside Ellensburg, Washington. Their low-use winter range occurs along the foothills west of the Columbia River just north of Interstate 90. In the spring, migratory individuals travel west into the Wenatchee Mountains to their summer range, which includes regional wilderness areas (fig. 31).

The Wenatchee Mountains mule deer are partially migratory; a high proportion of migratory individuals occupy the northern winter range of the Wenatchee Mountains, and nonmigratory individuals more commonly inhabit the foothills of the Kittitas Valley. The increasing frequency of large-scale wildfires and residential developments continue to degrade and reduce available winter range. Disturbance from human recreation on the winter range continues to be a concern. Semipermeable barriers to spring and fall migration include U.S. Highway 97 and State Route 970, as both experience relatively high volumes of traffic in the region.

Jackson Mule Deer

Mule deer within the Jackson segment of the Sublette herd (fig. 32) winter mainly in the valley and south-facing slopes of the buttes. These geologic features are characteristic of the Jackson Hole area near Jackson, Wyoming. Winter ranges in the Jackson valley are a mixture of national forest public land as well as private urban and exurban land. The lower elevation, south-facing hillslopes are typified by stands of Juniperus scopulorum (Rocky Mountain juniper) or mixed mountain shrub communities of Artemisia tridentata (mountain big sagebrush), Artemisia tripartite (three-tip sagebrush), Purshia tridentata (antelope bitterbrush), Amelanchier alnifolia (Saskatoon serviceberry), Symphoricarpos albus (common snowberry), chokecherry, and various grasses and forbs. North-facing slopes are characterized by a mixture of Douglas fir and quaking aspen.

Half of the individuals originally marked in this study were migratory, while the other half were residents. Resident animals in this herd segment often rely on ornamental landscaping and other human food sources. During migration, animals tracked with GPS collars (n = 19 females) traveled an average one-way distance of nearly 6 mi (10 km), with some animals migrating more than 17 mi (27 km). This herd segment, which approximates a few hundred, has a variety of summer destinations. Most individuals migrate northwest into Grand Teton National Park and the southern Teton Range. Some individuals migrate west and southwest near Munger Mountain. A few mule deer migrate short distances to the hills near Hoback Junction. Summer ranges in higher elevations transition to stands of lodgepole pine, Pinus flexilis (limber pine), Abies lasiocarpa (subalpine fir), and Picea engelmannii (Engelmann spruce) interspersed with aspen, subalpine meadows, and tall forbs. Willows, Shepherdia canadensis (russet buffaloberry), Elaeagnus commutate (silverberry), Picea pungens (blue spruce), Populus balsamifera (balsam poplar), and Populus angustifolia (narrowleaf cottonwood) dominate the riparian habitats in this area. Roadways bisect much of the winter range of this herd segment, causing some animals to make daily movements across roads during the winter. Teton County contains one of the highest rates of WVC per mile of road in Wyoming, and road mortality significantly affects this population, especially during severe winters.

Since 2017, the Wyoming Department of Transportation has worked on several road improvements, including multiple wildlife underpasses and fencing on U.S. Highway 89, because of rising traffic volumes in the area (Kampschror, 2017). There are also plans for building future wildlife crossing structures on U.S. Highway 22 west of Jackson. Increasing residential, recreational, and urban development in Teton County has encroached on mule deer winter ranges and migration routes. Future development of historically open agricultural lands along migration routes is a concern. Managers are also concerned about rapidly growing pressures from human recreation and annual invasive grasses on public lands in important mule deer winter and summer ranges.

South Rock Springs Mule Deer

The South Rock Springs mule deer herd lives year round in the Greater Little Mountain Ecosystem in southwestern Wyoming, an arid landscape where desert badlands give way to aspen and mountain shrub communities at higher elevations. Approximately 4,000 mule deer occupy this landscape, which is one of the least developed in Wyoming. Likely owing to its aridity and lack of strong elevational gradients and high mountains, mule deer migrations in this herd are less pronounced and less structured than elsewhere in Wyoming. Instead of all animals congregating in a common winter range and following a shared narrow corridor to their summer range, mule deer in this herd migrate diversely. Some animals winter near Flaming Gorge Reservoir and then head east into the forested habitat of Little Mountain, while other animals winter farther east and migrate in all directions (fig. 33). Migrations tend to be relatively short for mule deer, averaging 10 mi (17 km). A few animals make longer movements south into Utah. The herd is threatened by competition from a growing elk population and ongoing risk of oil and gas development, which would fragment this otherwise intact landscape.

Selkirk White-Tailed Deer

The Selkirk White-Tailed Deer Management Zone (WDMZ) is home to the largest population of white-tailed deer in Washington and consists of seven GMUs (105, 108, 111, 113, 117, 121, and 124) located in northeastern Washington. Aside from the southern portion of GMU 124, which is dominated by the metropolitan area of Spokane, Washington, most of these GMUs have similar rural characteristics. Private landowners manage most of the Selkirk WDMZ (77 percent) and use it primarily for commercial timber harvest. The FS manages 16 percent of the land, and the U.S. Fish and Wildlife Service, Department of Natural Resources, and BLM manage the remaining 7 percent. White-tailed deer used in this analysis were captured on their winter range in GMUs 117 and 121 (fig. 34), where the habitat consists of conifer forest (65 percent of the total land cover within the area) and shrub land. Grassland, pasture, and cultivated crops make up the next highest land cover types (altogether comprising nearly 21 percent of the Selkirk WDMZ). Agriculture in the valley supports high densities of deer adjacent to U.S. Highway 395, which bisects the Selkirk WDMZ from north to south. This white-tailed deer population experiences some of the highest rates of deer-vehicle collisions in the state (Myers and others 2008; G. Kalisz, Washington Department of Transportation, written commun.). Currently, there are no crossing mitigations in place along U.S. Highway 395 or State Route 20 to curtail collisions with wildlife. Other wildlife-human management challenges for this herd include mitigating crop damage complaints, maximizing hunting opportunity, and encroaching human development on the deer’s winter range.

Big Lake Pronghorn

The Big Lake pronghorn herd resides in the White Mountains of eastern Arizona within GMU 1 (fig. 35). The herd begins spring migration mid-March, crossing the Little Colorado River approximately 4 mi (6 km) north of River Reservoir, to their high-elevation summer range. The summer range consists primarily of high-elevation grasslands and large alpine meadows near Big Lake. Some individuals continue several miles farther south to summer near Middle Mountain. Fall migration occurs in early to mid-October, when the herd moves north to low-elevation grassland habitats west of Eagar, Arizona. The primary threat to this migration corridor is State Route 260, which experiences high traffic volume and requires crossing for pronghorn to access seasonal ranges.

Shotgun Valley Pronghorn

The Shotgun Valley pronghorn population totals approximately 300 animals. Summer range distributions are largely east and north of Dubois, Idaho, ranging from the Camas Creek watershed to Shotgun Valley (fig. 36). These pronghorn winter in and around Dubois and Hamer, Idaho, often becoming dependent on haystacks as a food source once snow accumulations reach moderate levels. In winters with average snow accumulations, Shotgun Valley pronghorn often use railroad tracks as travel corridors and sleeping or loafing locations. Several collisions between pronghorn and trains have occurred in the past, with multiple collisions killing up to 100 pronghorn each (Bodie and others, 1979; Idaho Department of Fish and Game, unpub. data). Interstate 15 has a woven-wire right-of-way fence that restricts this herd to suboptimal winter habitat east of the interstate. Historically, these animals would have continued their fall migrations to the west and wintered in the desert areas near Mud Lake, Idaho. Shotgun Valley pronghorn face a number of challenges during their seasonal movements including numerous fences that decrease landscape permeability, the loss of native range, and seasonal range restrictions.

North Central Pronghorn

The North Central pronghorn herd is the only known consistently migratory pronghorn herd in New Mexico and is one of the few pronghorn herds in the west that migrate to higher elevations in the summer (from 7,400 ft [2,256 m] to 10,800 ft [3,292 m]; fig. 37). Their winter range includes primarily sagebrush steppe and stretches across the Rio Grande del Norte National Monument from the Rio Grande to the base of the San Juan Mountains. The pronghorn follow two primary migration corridors: a northern corridor that follows the Rio San Antonio southwest of the Pinabetal Mesa and a southern corridor that follows the arroyos southwest of San Antonio Mountain to Little Tusas Creek. As their migration continues west and overlaps with the San Antonio elk herd, the pronghorn travel through conifer, deciduous, and mixed forests interspersed with shrublands. High-elevation summer range for North Central pronghorn consists of montane meadows, particularly along the Rio Brazos.

Some of the herd crosses U.S. Highway 285 during migration, probably facilitated by the lay-down fence removed for the winter months and does not impede animal movement. Migration routes to higher elevations tend to occur in areas with sparse, woody plant cover; increased canopy cover and woody plant encroachment could affect pronghorn migrations in the future. Fence modifications are ongoing on BLM lands to facilitate pronghorn movements and use of the landscape.

Medicine Bow Pronghorn

The Medicine Bow pronghorn population is one of the largest herds in the United States with an estimated population of 38,400 animals. The herd summers in the sagebrush steppe and grasslands of Shirley Basin, north of Medicine Bow, Wyoming (fig. 38). Most pronghorn migrate either west to the southern edge of the Seminoe Reservoir or north to Bates Hole, an area south of Casper, Wyoming. During harsh winters, some pronghorn migrate 65–75 miles (105–121 km) as far west as Rawlins, Wyoming. The Shirley Basin is a mostly intact landscape that is dominated by private lands, with only limited public lands along some foothill habitats. During the early 2000s, several large wind energy facilities were developed; some are in high-use migration corridors and in areas designated as crucial pronghorn winter range. The effects of wind energy development on pronghorn are not well understood, but recent research in Shirley Basin revealed wind energy development causes pronghorn to avoid some preferred habitats. U.S. Highways 30 and 287 and Interstate 80 seemingly bound the movement of these pronghorn to the south. Other challenges Medicine Bow pronghorn face are crossing U.S. Highway 487 and miles of fencing, which can often be a barrier to movement.

Marble Mountain Elk

Little information exists regarding demographic rates and abundance of elk in the Marble Mountains in California. In the early 1990s and 2000s, elk were reintroduced from Oregon into the Marble Mountain, California area (CDFW, 2018). Since then, elk have been reintroduced throughout much of the area, but GPS collar data and information on movement are limited. Elk were collared from 2006 to 2013 to examine home-range use. Ongoing research that began in 2021 is examining how fire affects elk occupancy in the area. Data collection for this work was completed in 2021 and data interpretation and analysis continues. Based on resulting GPS location data, elk were separated into three distinct subherds (north: Ukonom, central: Wooley Creek, and south: South Fork) because of nonoverlapping GPS data points within these areas (fig. 39). The Marble Mountain elk do not migrate between traditional summer and winter seasonal ranges. Instead, the herd contains short-distance, elevation-based migrants displaying a nomadic migratory tendency to move up or down elevational gradients. Some elk used higher elevation areas throughout the summer, though this pattern was not ubiquitous. Therefore, annual home ranges were modeled using year-round GPS data to demarcate high-use areas in lieu of modeling the specific winter ranges commonly seen in other ungulate analyses in California. More GPS collars are being deployed within this elk population in collaboration with the Karuk Tribe, but these data are not included here.

Black Prince-Slate Creek Elk

Black Prince-Slate Creek elk winter north of the Saint Joe River, close to Erlmo, Idaho (fig. 40). The habitat is primarily mixed-conifer forest with agriculture in the valley. Much of their winter-range habitat lies on private timber company lands on south-facing slopes that were recently logged (Ellstrom and others, 2020). The Black Prince-Slate Creek elk migrate to FS lands in the spring and summer. They travel north−northeast and summer on the south side of the Saint Joe Divide, the divide between the Coeur d’Alene River and Saint Joe River drainages. On average, these elk migrate more than 9 mi (15 km) between their summer and winter ranges.

North Fork of St. Joe River Elk

North Fork of St. Joe River elk winter on the brushy, south-facing slopes near Avery, approximately 35 mi (56 km) east of Saint Maries, Idaho, between Slate Creek and the North Fork Saint Joe River (fig. 41). They migrate north−northeast and summer in mixed-conifer forests near the border of Montana and sometimes migrate as far as Interstate 90 in Montana. This elk population has the longest known migration in the Idaho panhandle, migrating an average of 16 mi (26 km) between the winter and summer ranges. The North Fork of St. Joe River elk population, part of GMUs 6 and 7, declined by more than half in 2009–2020 (Ellstrom and others, 2020). Interstate 90 may constrict migration distances, but seasonal routes are probably not affected as the migrations occur almost solely on public FS lands.

Rochat Creek-Ahrs Creek Elk

Rochat Creek-Ahrs Creek elk winter north of Saint Joe River, approximately 7 mi (11 km) east of Saint Maries, Idaho (fig. 42). The habitat is primarily mixed-conifer forest with agriculture in the valley. Much of the herd’s winter-range habitat lies on private timber company lands on south-facing slopes that were recently logged (Ellstrom and others, 2020). Most elk in this population migrate north and summer on the south side of the Saint Joe Divide. A few individuals continue north to the South Fork Coeur d’Alene River drainage, while others migrate south of the Saint Joe River. On average, these elk migrate almost 8 mi (13 km) between their summer and winter ranges. Rochat Creek-Ahrs Creek elk summer on a mix of BLM, FS, and private timber company lands. Land use (logged compared to unlogged) likely affects seasonal migration routes and seasonal ranges.

Sand Creek Elk

Approximately 4,500 elk from the Island Park population winter in the gentle, rolling terrain surrounding Sand Creek (this area is regionally known as the Sand Creek Desert) (fig. 43). In spring, the Sand Creek elk herd migrates to their summer range in GMUs 60, 61, and 62A. Winter restrictions on human entry across much of the area provide elk with undisturbed access to high-quality sage-steppe habitats. Sagebrush and bitterbrush with herbaceous understory are interspersed with stands of juniper, chokecherry, and other shrub species. Douglas fir and lodgepole pine communities are common in migratory habitats along Big Bend Ridge as elevation increases north of Sand Creek. Two main challenges these elk face during migration include an extensive network of fencing and traffic on U.S. Highway 20.

South of St. Joe River Elk

South of St. Joe River elk winter south of the Saint Joe River between Mica Creek and Marble Creek (fig. 44). Most elk in this population migrate south to southwest, but a few individuals migrate north of the Saint Joe River. On average, these elk migrate approximately 9 mi (14 km) between their summer and winter ranges. The habitat is primarily mixed-conifer forest with agriculture in the valley. South of Saint Joe River elk winter and summer primarily on managed forests (private timberlands and Idaho Department of Land property), but they also use FS lands. Land use (logged compared to unlogged) probably affects seasonal migration routes and seasonal ranges as there are large, clearcut areas within their migration routes.

Teton River Elk

The Teton River elk herd includes approximately 500 individuals and is managed as part of the larger Island Park population (fig. 45). Historically, these elk wintered in aspen and shrub communities associated with the Teton Canyon and migrated east to summer in forested habitats in the eastern portion of GMU 62 in Idaho and into Wyoming. This herd has shifted primarily to summer habitats associated with agriculture in GMU 62, with fewer individuals migrating to Wyoming. This shift has resulted in increased conflict with agricultural producers. Winter distributions have also shifted in response to habitat loss and human disturbance, with most individuals now wintering in the Hog Hollow area along the Teton River. In February 2019, approximately 300 of these elk moved west, crossed U.S. Highway 20, and wintered along Henrys Fork, Snake River, and Sand Creek near Sugar City, Idaho. Elk repeated this pattern in 2020 and 2021, raising concerns of increased WVC and increased conflict with livestock operations and associated fencing infrastructure.

Trout Creek-Big Creek Elk

Trout Creek-Big Creek elk winter north of the Saint Joe River, east of Saint Joe, Idaho (fig. 46). The habitat is primarily mixed-conifer forest with agriculture in the valley. Much of their winter-range habitat is private timber company lands on south-facing slopes that were recently logged (Ellstrom and others, 2020). Most elk in this population migrate north and summer on the south side of the St. Joe Mountains. A few individuals continue north to the South Fork of the Coeur d’Alene River drainage, while others migrate south of the Saint Joe River. On average, these elk migrate almost 9 mi (14 km) between their summer and winter ranges. Trout Creek-Big Creek elk summer on a mix of private timber company and FS lands. Land use (logged compared to unlogged) probably affects seasonal migration routes and seasonal ranges.

San Antonio Elk

The San Antonio elk herd migrates from the Rio Grande del Norte National Monument to the southern San Juan Mountains of north-central New Mexico and south-central Colorado (7,000–11,500 ft [2,134–3,505 m] elevation; fig. 47). Managed by the BLM, the Rio Grande del Norte National Monument contains the Taos Plateau and a portion of the Rio Grande. Data collected from the herd in 2020–2021 by GPS collars indicate that elk winter near San Antonio Mountain or east of U.S. Highway 285 on the Taos Plateau, with some elk wintering as far east as the Rio Grande. Other elk herds also winter on the Taos Plateau, including herds from the eastern side of the Rio Grande Gorge that are not featured in this report. Critical winter range consists primarily of sagebrush steppe, with pinyon-juniper dominating the volcanic cones of Cerro de la Olla, Cerro del Aire, Cerro Montoso, and Cerro Chiflo scattered across the monument land. The area north of the volcanic cones is rich in Ceratoides lanata (winterfat), providing nutrition high in protein during the harsh winters. Key terrestrial habitats across the herd’s ranges include intermountain basins, big sagebrush shrubland, Rocky Mountain alpine montane wet meadow, and Rocky Mountain montane mixed-conifer forest and woodland.

Within the Taos Plateau, 61,330 acres (24, 819 ha) have been identified as migration corridors, 218,962 acres (88, 611 ha) as winter range, and 100,191 acres (40,546 ha) as summer range for big-game species. Migrations typically begin in early spring, with elk taking extended stopovers in the eastern foothills and slopes of the San Juan Mountains, primarily along the Rio San Antonio. By late spring, many of the elk continue their migration towards the western slopes of the San Juan Mountains or north into Colorado. Some elk travel to lower elevation foothills along the western slopes of the San Juan Mountains before retracing some of their movements to settle on their high-elevation summer range. Summer range habitats are typically mid- to high-elevation mixed-conifer and aspen forests with interspersed montane meadows. The crossing of U.S. Highway 285 may create an obstacle to elk migrations, as 29 of 40 WVC in 2009–2018 involved elk.

Pend Oreille Elk

The Pend Oreille elk subherd is part of the larger Selkirk elk herd located in northeast Washington on nine GMUs: 101, 105, 108, 111, 113, 117, 121, 124, and 204. Elk used in this analysis were collared in GMUs 117 and 121 on winter ranges located east and west of Huckleberry Mountain, along the Colville River valley that splits the two GMUs, and west of the Pend Oreille River (fig. 48). In this area, private landowners manage 77 percent of the land (primarily for timber); the FS manages 16 percent; and the U.S. Fish and Wildlife Service, Washington State Department of Natural Resources, and BLM manage the remaining 7 percent. Montane conifer forests dominate the mid-to-higher elevations of the region, while agriculture predominates in the valley.

The Pend Oreille elk subherd is partially migratory, with three main migratory routes. A segment of the population traverses the northern portions of Huckleberry Mountain along Summit Valley, others migrate north of Chewelah Mountain following the South Fork Chewelah and Winchester Creeks, and another group migrates around Bald Mountain following the Buck Creek drainage. Elk move freely between GMUs 117 and 121, which is bisected by U.S. Highway 395 where some of the highest incidences of WVC are reported (G. Kalisz, Washington Department of Transportation, written commun.). Based on collared elk data, harvest and vehicle collisions are the primary and secondary causes of mortality, respectively, for adult females in this population. A large portion of the adult female harvest occurs on private property and in response to agricultural damage complaints.

Sierra Madre Elk

With substantial forest habitat in the Sierra Madre, the Sierra Madre elk population is one of the most productive elk herds in the state. Harvest from this herd typically accounts for approximately 10 percent of the total elk harvest in the state. The herd occupies typical year-round habitat for elk in Wyoming. They winter largely in expansive sagebrush growing in the foothills and at low elevations in the valley of the Little Snake River and its various drainages (fig. 49). In spring, most animals migrate to higher elevation forested habitat within the Sierra Madre. Like many elk herds, their seasonal migrations tend to be diffuse without a clear delineation of narrowly defined corridors; the average migration length is approximately 16 mi (25 km). Some animals migrate farther distances south across the border with Colorado, with a maximum length of 39 mi (62 km). The herd is estimated to be approximately 7,000 animals, although reliable population estimates are not available. The mountain pine beetle-epidemic has disturbed the herd’s summer habitat to a substantial degree, and has had a mixed effect on elk habitat. A recent study showed only a limited increase in forage in beetle-killed areas, although continued understory growth is expected (Lamont and others, 2019). Perhaps more importantly, elk and hunters alike tend to avoid the heavy downfall conditions created by dead and fallen snags (Lamont and others, 2020).

South Rock Springs Elk

This small herd of elk is steadily establishing itself in the Greater Little Mountain Ecosystem in southwestern Wyoming. Elk in this system occupy some of the most arid seasonal ranges in the state, which contrasts with the more forested habitat that elk typically occupy in Wyoming. The herd is small but growing, with 920 animals counted during surveys in 2020. The habitat is a mix of broad valleys dominated by sagebrush habitat, with aspen, mountain shrubs, and pinyon-juniper at higher elevations. Elk in this system are not strongly migratory; like the mule deer that occupy this same landscape, the elk migrations tend to be relatively short with an average distance of 11 mi (18 km). However, there is a clear pattern to their seasonal movements, with winter ranges in the lower elevation habitat just east of Flaming Gorge Reservoir and summer ranges in the higher, more mountainous country to the east (fig. 50). In general, the herd is growing and appears to have few threats; however, the region more broadly is at risk of oil and gas development that would bring considerable human effects to an otherwise intact landscape.