Analysis Based on Management Status
It seemed that the next minute they would discover a solution.
Yet it was clear to both
of them that the end was still far, far off and the hardest
and most
complicated part was only just beginning. -A. Chekhov
5.1 Background
Gap analysis provides information on the current management of two elements of biodiversity - land cover types and terrestrial vertebrate species - as a first step in planning for the conservation of biological diversity. For this analysis, we make the assumption that lands in management status 1 and 2 (see Chapter 4 for definitions) provide adequate protection to elements such that long-term viability of the elements may be maintained. We identify land cover types and terrestrial vertebrates that do not occur on protected lands (i.e., "gaps") and summarize how much area occupied by each element is protected in Wyoming. In addition, we summarize the stewardship of lands occupied by each land cover type and vertebrate species to provide land stewards with a perspective on their current and potential role in biodiversity conservation. We identify cover types and vertebrate species as candidates for further protection if 1% or 50,000 ha of their occupied area or habitat in Wyoming is currently protected. These criteria are preliminary guidelines, and we recognize that a more detailed analysis of area requirements, distribution, disturbance regimes, and other ecological factors will be needed in planning for the long-term maintenance of biodiversity. In the future, other components of biodiversity, such as the distribution of selected groups of invertebrates, rare plants, and aquatic organisms, can be incorporated into the WY-GAP database, and similar analyses can be conducted.
Information on current protection of land cover and terrestrial vertebrate species was generated by overlaying GIS maps of land cover types and predicted habitat of vertebrate species described in Chapters 2 and 3 with the land management status map described in Chapter 4. We highlight the results of these analyses in the sections below and present the detailed summaries in the appendices. Management implications of the results are provided in Chapter 6.
5.2. Land Stewardship and Management Status
Less than 10% of the state of Wyoming falls within status 1 and 2 lands. Most of these lands (90%) occur in the western portion of the state and are aggregated in 2 National Parks, 10 wilderness areas, 11 state Wildlife Habitat Management Areas (WHMA), 1 National Wildlife Refuge, and several other minor conservation areas in the Greater Yellowstone Ecosystem (GYE) (Table 5.1, Appendix 5.5). In contrast, most of the eastern third of the state is in private hands where the climate supports grassland vegetation, and dry-land farming is sometimes possible. Public lands in the eastern portion of the state are limited and are rarely in status 1 and 2 (Map 4.1). The only private lands that currently are designated as status 1 and 2 lands are TNC lands and private easements on national wildlife refuges. We recognize that we do not have a comprehensive representation of private lands in management status 1 and 2 because we were limited to voluntary submission of information about management of these lands.
Table 5.1. Area (ha) and percent (%) of Wyoming's land stewardship categories by land management status. Total area under public and private jurisdictions are bolded. Total area under the 8 major stewards in Wyoming are in parenthesis The miscellaneous category includes areas such as open water that are not under specific jurisdictions. Accuracy of these numbers is discussed in section 4.2.1. (table not available in html)
Approximately 39% of the state of Wyoming is classified as management status 3 and these lands are largely in multiple use under the jurisdiction of the BLM (28.4%) and the USFS (9.8%). Just under half of the state is classified as status 4 because it occurs on lands under the stewardship of private citizens or Native Americans.
5.3 Land Cover
Anthropogenic types including irrigated cropland, dry-land cropland, human settlement, and mining operations were mapped as land cover types in Wyoming, but their conservation is not discussed in our gap analyses because they are not natural plant communities. Clearcuts are areas that are also modified by man, but are included in our analysis because they represent early successional stages of natural communities. Conservation of open water habitat is not emphasized in our analyses, even though it provides habitat for vertebrate species, because water resources will be addressed in the Aquatic Gap Program in more detail (P. Crist, personal communication). For the purpose of this discussion, we consider "minor" land cover types as those occupying < 50,000 ha (< 0.1%) of the state.
5.3.1 Land Cover and Land Stewardship
With the exceptions of ponderosa pine, limber pine woodland, and forest-dominated riparian, most forested land cover types found in Wyoming are under federal jurisdiction (Table 5.2). A high percentage of lands occupied by ponderosa pine (62%), limber pine (39%), and forest-dominated riparian (75%) are under private stewardship because they occur at low elevations, and in linear strips along mountain foothills, rocky ridges, or streams, About 3 times as much of the forested lands under federal stewardship in Wyoming are administered by the USFS as by either the NPS or the BLM (Appendix 5.1). The State of Wyoming administers relatively more forested areas occupied by limber pine, juniper woodland, and Douglas fir than other forest types for the same reasons described for private lands.
High elevation cover types, such as subalpine meadows, tundra meadows and grass-dominated wetlands, fall largely under federal jurisdiction. In contrast, grasslands occurring at low elevations (primarily in the eastern portion of the state) usually are privately owned (Table 5.2). Generally, shrubland cover types are more evenly distributed among public and private lands than are forested or grassland cover types (Table 5.2). Mesic and xeric upland shrubs are more prevalent on private and Native American lands than on federal or state lands, while basin big sagebrush and saltbush fans and flats exist primarily on federal lands. With the exception of unvegetated playas, most other natural land cover types occur on federal lands.
Table 5.2. Area and percent of land cover types within major
land stewardship categories. The miscellaneous category includes
areas such as open water that are not under specific jurisdictions.
Accuracy of these numbers is discussed in section 4.2.1.
(this table not available in html)
5.3.2 Land Cover and Management Status
Seven natural land cover types have > 50% of their land area protected (Table 5.3) and are the best protected among all Wyoming land cover types. Subalpine meadow, alpine exposed rock, meadow tundra, whitebark pine, and permanent snow are well protected because they occur at the highest elevations (Fig. 5.1), where most protected lands are found (Table 5.3). Of these types, whitebark pine deserves further conservation attention because of its limited extent (Table 5.3) and its vulnerability to pine bark beetle attack (Kendall 1995). The burned conifer type is 99% protected because, with one exception in the Bighorn Mountains, burned areas mapped at our 100-ha MMU occurred only in and adjacent to Yellowstone National Park (Merrill et al. 1996a) and resulted from the widespread fires of 1988.
Figure 5.1. Percent of land cover types in management status 1 and 2 in relation to mean elevation (m) of the area occupied by cover types.
Our analysis also indicates that grass-dominated wetland is well protected (73%), but this result is biased because information on wetlands in Yellowstone National Park was incorporated directly into our map from Despain (1990). Wetlands are distributed more widely in other areas of the state than the land cover data indicate, but because they usually occur in small patches, they were not readily distinguishable at our MMU. Given their ecological importance, especially in arid areas, and the limitations of our large MMU for delineating wetlands, further analysis is needed to adequately address their conservation.
Six land cover types have over 10% but less than 50% of the land they occupy in status 1 and 2 lands (Table 5.3). Because they are widespread and have > 50,000 ha in protected lands, the principal concern for conserving 4 of these types (spruce-fir, lodgepole pine, Douglas fir, and mountain big sagebrush) is the maintenance of their structural characteristics originally maintained by fire (Loope and Gruell 1973, Britton and Ralphs 1979, Romme and Knight 1981), rather than their continued existence in Wyoming (Knight 1987, Ferry et al. 1995). For example, areas of lodgepole pine that are not in status 1 and 2 lands largely undergo clearcut management, developing block patterns of more or less even-aged trees, separated by a relatively dense network of roads. Whether or not clear-cutting simulates wildfires in maintaining the integrity of this ecosystem is debatable (Knight 1994). Even in status 1 and 2 lands, fire management policy is subject to political forces and fire regimes are influenced by roads and special area management (Knight and Wallace 1989).
Table 5.3. Area (ha) and percent of land cover types by management
status. Accuracy of these numbers is discussed in section 4.2.1.
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In contrast, Great Basin foothills grassland is a relatively uncommon type in Wyoming because it occurs only in the foothills of mountains and only 21% (4,125 ha) of the area occupied is in management status 1 or 2. Most of this occurs along the base of the Tetons and in the Bighorn mountains. The Great Basin foothills grassland cover type is similar in floristic composition to the Palouse prairie of eastern Washington (Barbour et al. 1987), a vegetation type that has largely been converted to agriculture. Additional protection of this type is important, and could be accomplished along with other foothills environments, through judicious selection of management areas in coordination with conservation efforts in Montana and Idaho.
Seven of the land cover types have between 1 and 10% of their areas protected. Mesic upland shrub has the smallest area protected (< 2,000 ha). This type most commonly occurs in small, mesic, micro-environments (Knight 1994) that are often smaller than the GAP MMU. For this reason they are probably under-represented in their distribution on the WY-GAP land cover map. Mesic upland shrub communities are vulnerable to grazing disturbance, but less vulnerable to mining, logging or agriculture because they are widely scattered and occur in foothill areas where the latter land management practices are not as economically viable. Greasewood fans and flats and basin exposed rock and soil are widely distributed (> 350,000 ha), yet these types also are relatively unprotected. Greasewood fans and flats have little agricultural value and this type is mainly grazed by sheep and cattle, but within limits, because of the protective spines and toxic foliage of this species (Robertson 1983, Smith et al. 1992). The only foreseeable threat to this type would be destruction through oil and gas exploitation (Bureau of Land Management 1990, 1992). Grazing could be a threat to the graminoids and forbs that are associated with the greasewood. Basin exposed rock and soil is also relatively unprotected. From a biological point of view, the 1.28% protected may be adequate because this type is widely distributed across an extensive area and is unlikely to become vegetated due its innate instability. Some badland areas may be of greater interest for their esthetic values.
Although only 1.1% of the juniper woodlands in Wyoming is protected, there is little concern over its future because it is abundant both in Wyoming (> 500,000 ha) and in neighboring states to the south and west (Kuchler 1964). In the latter areas, the juniper type is, itself, a threat through its rapid expansion in the absence of fire (Ferry et al. 1995). In contrast, aspen is usually a successional type and whether current protection (3%) is sufficient depends on the maintenance of natural disturbance regimes through fire management (Schier and Campbell 1978, Bartos 1991, Knight 1994), clearcutting (Schier and Campbell 1978, Shields 1981), or compensatory cutting to stimulate regeneration (Greenway 1990).
Riparian types are only moderately protected in Wyoming (Table 5.3), but are of great importance for the maintenance of biodiversity on both local and landscape scales because the features they provide in arid environments are unique for a variety of species (Auble 1995). The situation with riparian cover types is similar to that described for grass-dominated wetlands above because they occur in small, often linear areas that are generally less than the MMU and are likely to be under-represented in the land cover data. In particular, protection is inadequate in the dry, western basins and in the eastern Great Plains. Because of their ecological importance, as well as their vulnerability to grazing and exotic invasions (Busch and Scott 1995), additional efforts to estimate the extent and condition of riparian zones throughout the state should be a high priority for future assessment of habitat conditions in Wyoming.
Sixteen land cover types have 1% of the land they occupy in status 1 and 2 lands (Table 5.3), indicating a need to further protect these land cover types in Wyoming. Two of these land cover types, Wyoming big sagebrush and mixed grass prairie, are widely distributed (> 4 million ha) in Wyoming, and in adjacent states (West 1983), and are probably not a high priority for conservation efforts overall. Nevertheless, the structure and functioning of the Wyoming big sagebrush type may be altered by grazing, fire regimes, exotic invasions and development of oil and gas (Miller et al. 1996, Young 1983, West and Hassan 1985, Bureau of Land Management 1990, 1992). Mixed grass prairies are primarily concentrated in the eastern third of the state where they are mainly used for cattle grazing, which does not pose a threat to this type in Wyoming as long as the grazing is moderate. Where extensive flat areas occur in this type, some of the area has been converted to dry-land farming for wheat, while in other cases sites have been plowed and reseeded to exotic range grasses. Should this conversion process continue, it could have serious consequences (Laurenroth et al. 1994), but no data on the extent or rate at which this conversion is taking place exist.
Saltbush fans and flats, along with desert shrub, greasewood fans and flats, and unvegetated playas have <1% of their areas in protection status 1 and 2. These four land cover types are part of topographic sequences in the lower portions of the western Wyoming basins. Collectively they amount to a very large area, but they are not well protected because they typically have received little ecological or conservation attention, especially compared with more mesic land cover types in the mountainous areas. If the currently proposed BLM wilderness study areas are formalized, it will only increase the amount of protected saltbush fans and flats and desert shrub by 1.4% and 0.91%, respectively, and will not increase the amount of protected area for unvegetated playa and greasewood fans and flats. All four of these basin types are vulnerable in equal or lesser degrees to many of the same kinds of threats as described for Wyoming big sagebrush. Changes in fire regimes or invasion by exotic plants are perhaps more serious considerations for desert shrub (West 1983) than the more xeric saltbush and greasewood types. Xeric saltbush and greasewood types are less likely to ever have carried fire, and the extreme edaphic sites occupied by these types are less vulnerable to exotic plant invasion. Saltbush fans and flats are also less likely to be threatened by grazing because the dominant species, saltbush (Atriplex gardneri (Moq.) D. Dietr.), is protected by high concentrations of salt (Knight 1994) and oxalic acid (Ellern et al. 1974) and rebounds well after grazing (West 1988).
Although ponderosa pine is also fairly widespread in Wyoming, over much of its extent it has been altered by logging and natural fire suppression so that natural, open stands of ponderosa pine are rare (Knight 1994, Ferry et al. 1995). Fire suppression in ponderosa pine areas has resulted in crowded stands, highly susceptible to drought, disease and insect attack, and to severe stand-destroying fires (Mutch et al. 1993). Maintenance of this type within protected lands requires prescribed ground fires due to the demographics of the species, and to vulnerability of old growth stands to pine bark beetle attack (Knight 1994). Despite long-standing requests by environmental groups for setting aside part of the finest stands in the Laramie Range in southeastern Wyoming, none have achieved protection status. Further protection of natural stands of ponderosa pine should remain a priority in the overall program for maintaining ecosystems in Wyoming.
The xeric upland shrub type and limber pine forests are not restricted in Wyoming but have < 650 ha protected. The xeric upland shrub type occurs on rocky outcrops, particularly on sandstone and limestone ridges of southeastern and southwestern Wyoming and on the fringes of the Bighorn Mountains (Map 2.1). This type is currently protected in small areas under 3 different jurisdictions (Appendix 5.1). The limber pine woodland cover type is found on dry slopes of central and southern Wyoming and in mountain ranges throughout the state with the exception of the Black Hills (Map 2.1), but is protected only in the Laramie Peak WHMA. Because these 2 types are fairly extensive in Wyoming and occur in rocky, dry land areas that are not likely to be developed, they are not of highest conservation priority, but their long-term management nevertheless merits further consideration. Public stewardship of most of the areas occupied by xeric upland shrub (20%) and limber pine (40%) is under the jurisdiction of BLM (Appendix 5.1). With formalization of the BLM wilderness areas, the percent of protected limber pine woodland would not increase, and xeric upland shrub will increase only by 0.64% (1270 ha).
The remaining 8 cover types have little to no protection in Wyoming (Table 5.3), indicating a high priority for conservation. Several of these types, even though they are restricted in Wyoming, are found extensively in other states. For example, < 10,000 ha (none protected) of unvegetated playa is mapped within Wyoming. These areas are extensive throughout the Great Basin as a result of the lakes that covered this area during the Pleistocene but are now dry, saline playas (West 1983). These types could be protected within topographic sequences of western Wyoming basins as described for saltbush flats above with little effort and loss of productive lands. BLM has jurisdiction over most of the public lands occupied by unvegetated playas (51%), saltbush fans and flats (82%), desert shrub (56%), and greasewood fans (44%) (Appendix 5.1).
Similarly, shortgrass prairie, which also has no protection in Wyoming, reaches the northern and western extent of its range in the extreme southeast corner of Wyoming and consequently is a peripheral type in this state (Knight 1994). The cover type extends across large areas southward through Colorado, Kansas, and into the panhandles of Oklahoma and Texas, where warmer temperatures favor it over the mixed grass prairie species that are more common in Wyoming (Barbour et al. 1987). However, unique community associations may exist in the peripheral areas of its range, meriting further management considerations. In Wyoming, this type occurs in a climate which supports dry-land wheat farming (Map 2.1) and wherever land in this cover type is flat enough to permit large-scale mechanical operations, it is vulnerable to conversion to agricultural land use. Since shortgrass prairie occurs on rougher topographic positions in southeastern Wyoming, a more detailed analysis is needed to indicate whether these areas are sufficient to conserve this type over the long term. Most (19%) of the shortgrass areas on public lands are under the stewardship of the State of Wyoming (Appendix 5.1).
Four land cover types are probably of lower conservation concern than our analysis indicates because they are patchily distributed and probably under-represented in the WY-GAP land cover map. Black sagebrush steppe often is intermixed with Wyoming big sagebrush and, as a result, it may be protected within the enormous extent of Wyoming big sagebrush. In addition, it is common throughout the southwestern states (Zamora and Tueller 1973) and typically occurs on poor, often shallow, soils that are not likely to be used for agriculture. Likewise, bitterbrush shrub steppe is widely distributed as small inclusions in other types in Wyoming, often around rocky outcrops which are not likely to be developed. Bitterbrush communities, though rarely extensive, also are fairly widespread from New Mexico to British Columbia and west from California to Oregon and Washington at elevations from sea level to close to 11,000 feet (Giunta et al. 1978). Basin big sagebrush very rarely exists in areas large enough to comprise a GAP MMU, but this cover type is quite extensive as a narrow, linear feature along the lower terraces of many perennial and ephemeral streams in western Wyoming at low elevations. Because of their typically linear configuration, these stands are unlikely to comprise an entire 100 ha MMU. Should these terraces undergo flood irrigation development, this type would be highly vulnerable to loss (Ganskood 1986). On the other hand, it probably will always be present as small inclusions in draws in Wyoming big sagebrush terrains.
Dune complexes are scattered throughout Wyoming but are most common along a path across the central Great Divide basin near Casper (Map 2.1). While active dunes are easily recognized, and, therefore, probably accurately identified, vegetated dunes are not easily recognized on satellite imagery or even on the ground, and may be under-estimated. In Wyoming, these types are often mosaics of both vegetated and active forms that require careful protection from disturbance due to the unstable soils. We estimate < 300 ha of vegetated dunes are currently protected and this protection occurs at Pathfinder Wildlife Refuge. Active sand dunes currently do not occur on any status 1 or 2 lands. With the formalization of BLM's Sand Dunes and Buffalo Hump Wilderness Study Areas, an estimated 4,527 and 381 additional hectares would be protected, corresponding to a 26.5% increase in protection. Although BLM is the primary steward (56%) of areas occupied by vegetated dunes, this type would not increase with formalization of any of the BLM wilderness study areas.
Finally, bur oak woodland in Wyoming is found only in the Black Hills of the northeastern corner of the state where it occurs as part of a complex mosaic with ponderosa pine, aspen, and mixed grass prairie (Knight 1994). This type extends into the South Dakota Black Hills, but nowhere is it a common type. In fact, this type is of phytogeographic interest as a Pleistocene remnant of eastern deciduous forest elements in the Great Plains (Daubenmire 1978), and undoubtedly contributes to habitat quality through its associated shrub and acorn production (Knight 1994). Although there are no evident threats to this type at this time, it clearly deserves priority for conservation because it is unprotected. Most lands occupied by this type in Wyoming occur on USFS lands (78%) and efforts to conserve this type may require coordination among jurisdictions in Wyoming and South Dakota.
5.4 Terrestrial Vertebrate Species
In summarizing information on the distribution of terrestrial vertebrate species by management status, it is important to identify special characteristics of some species' distributions (peripheral, disjunct, endemic) which may influence how they should be viewed within a statewide context. We defined peripheral species in Wyoming as those species which have < 10% of their total range distribution in Wyoming and occupy < 10% of the state (B. Csuti, personal communication). Because birds were not mapped from range maps, their habitat is more fragmented than other taxa (see Chapter 3) and frequently constituted < 10% of the state of Wyoming even when they were well distributed throughout the state. Therefore, we considered birds as peripheral if they were listed as peripheral, rare migrants, or uncommon migrants by Oakleaf et al. (1992). We designated a species as disjunct if its habitat in Wyoming was considerably disconnected from the major portion of its range. Species or subspecies were designated endemic if they occurred only in Wyoming or primarily in Wyoming and adjacent portions of other states. Four primary sources other than WY-GAP databases were used to determine whether a species was considered peripheral or disjunct (Robbins et al. 1993, Baxter and Stone 1985, Clark and Stromberg 1987, Oakleaf et al. 1992). Rankings as to species' sensitivity are based on federal (U.S. Fish and Wildlife), state (WGFD), and private (TNC) listings (Garber 1995, Wyoming Game and Fish Dept. 1996).
5.4.1 Species Distribution and Land Stewardship
Habitat of amphibians and reptiles generally occurred more under private stewardship than federal stewardship because they are concentrated in the eastern portion of Wyoming (Table 5.4). In contrast, habitats of birds and mammals were more equally distributed among federal and private stewardships because they are distributed more evenly across the state (Table 5.4). Stewardship of the potential habitat of each species is listed in Appendix 5.2.
Table 5.4. Average percent of the total habitat area (ha) of
species within taxonomic groups by major land stewardship categories.
The miscellaneous category includes areas such as open water
that are not under specific jurisdictions.
5.4.2 Species Distributions and Management Status
A smaller percentage of potential habitat of amphibians (8.8%) and reptiles (2.6%) occur on average in status 1 and 2 lands than either birds (14.4% ) or mammals (14.5%) (Appendix 5.3).
Amphibians
None of the 12 amphibians occurring in Wyoming had > 50% of their state-wide potential habitat in status 1 and 2 lands, and only 3 species, the spotted frog (Rana pretiosa) (49%), the boreal chorus frog (Pseudacris triseriata maculata) (20%), and the boreal western toad (Bufo boreas boreas) (15%) had >10% of their habitat protected (Table 5.5, Appendix 5.3). The spotted frog and the boreal chorus frog occur at relatively high elevations (Fig 5.2A) including areas in northwestern portion of the state (Merrill et al. 1996b) where 90% of the status 1 and 2 lands occur (Map 4.1).
Table 5.5. Number (No.) and percent (%) of species with 0%, > 0 - 1%, > 1%-10%, > 10-50% and >50% of their potential distribution within management status 1 and 2.
Four amphibians have between 1 - 10% of their habitat in protected areas (Table 5.5). Two of these species, the Wyoming toad (Bufo hemiophrys baxteri) and the wood frog (Rana sylvatica), have a very limited amount of potential habitat in status 1 and 2 lands (Table 5.6). The Wyoming toad is a subspecies of the Manitoba toad and is a federally listed endangered subspecies. In recent years, much of the potential habitat of the toad mapped by WY-GAP in the Laramie basin has been surveyed (Young 1994), and the toad has been found only in ponds within the Mortenson Lake National Wildlife Refuge. An intensive program is currently underway to recover the Wyoming toad under the Endangered Species Act (Stone 1991). Populations of the wood frog in Wyoming are considered part of the disjunct populations of this species in the central Rocky Mountains. In Wyoming, these populations occur in two separate mountain ranges, the Medicine Bow and Bighorn Mountains, where < 3,500 ha are protected in about equal amounts in each range. The populations of wood frog in Wyoming are glacial relic populations (Bagdonas and Pette 1976) and controversy surrounds their taxonomy (Bagdonas 1971). Studies on the wood frog in Colorado qualified the future of these disjunct populations as uncertain because of their dependence on ephemeral habitat and poor dispersal capabilities, apparently a consequence of the relatively xeric montane forest compared to the more lush conditions of northeastern North America (Haynes and Aird 1981).
Fig. 5.2(A). Percent of species habitat in management status 1 and 2 in relation to mean elevation (m) of the species habitat for amphibians and reptiles.
Four out of five amphibian species that have < 1% of their total habitat in status 1 and 2 lands (Table 5.6) are found primarily in the eastern portion of Wyoming. In particular, the bullfrog (Rana catesbeiana) and Great plains toad (Bufo cognatus) have a very limited amount of potential habitat protected. The bullfrog ranges from southern Canada to Mexico, but is considered a peripheral species in Wyoming that has spread up the North Platte River from Nebraska (Baxter and Stone 1985). In contrast, the Great Plains toad is listed as a common species (Baxter and Stone 1985) but has very limited protected habitat (208 ha). About half of the Great Plains toad's habitat is mapped in Devils Tower National Monument and the other half in Sand Creek Wildlife Habitat Management Area in northeast Wyoming (Appendix 5.2). Potential habitat that could be managed for this species occurs primarily on state lands along tributaries of the Belle Fourche River (Merrill et al. 1996b).
The Great Basin spadefoot toad (Scaphiopus intermontanus) also has < 1 % of its total habitat in status 1 or 2 lands (Table 5.6). This species is the only amphibian in Wyoming with a range limited to the southwestern sagebrush and desert shrub communities of the state. Official designation of the BLM wilderness areas in this portion of the state, particularly the Honeycomb Buttes and Sand Dunes WSAs, would nearly double (0.77% to 1.54%) the amount of protected habitat for this species. Establishment of BLM's proposed wilderness areas would not considerably increase the protection of other amphibian species.
Table 5.6. State range, state and federal rankings, area (ha)
and percent habitat of 7 amphibian and 24 reptilian species which
have < 1 % or < 50,000 ha of their total potential habitat
within management status 1 and 2 lands.
(this table not available in html)
Reptiles
None of the 26 reptiles found in Wyoming have > 50% of their habitat protected and only three reptiles, the wandering (Thamnophis elegans vagrans) and common (Thamnophis sirtalis) garter snakes and rubber boa (Charina bottae), have > 10% of their potential habitat occurring in status 1 and 2 lands (Table 5.6). The habitat of these species is relatively well protected because they are the only reptiles that have a significant amount of their potential habitat at high elevations, particularly in the Greater Yellowstone Ecosystem (GYE) (Merrill et al. 1996b). Although our results indicate considerable habitat is protected, Baxter and Stone (1985) consider the rubber boa rare and suggest its habitat warrants conservation. Others suspect that the nocturnal and fossorial habits contribute to its apparent rarity (Koch and Peterson 1995).
All of the remaining reptiles in Wyoming have < 2.5 % of their habitat in status 1 and 2 lands (Table 5.6) because they occur primarily at low elevations (Fig. 5.2A) which are not well protected in Wyoming. Four species are widely distributed (> 11 million ha total habitat) and have > 50,000 ha of potential habitat in protected lands (Appendix 5.3). Two of these species, the northern sagebrush lizard (Sceloporus graciosus graciosus) and eastern short-horned lizard (Phrynosoma douglassi brevirostre) are wide-spread and common in Wyoming, and the opportunities to contribute to the species' conservation with further habitat protection are great. The bullsnake (Pituophis melanoleucas sayi) and the prairie rattlesnake (Crotalus viridis viridis) are both common species in Wyoming, but their habitat may warrant further protection because of intrusive land development (Baxter and Stone 1985, Koch and Peterson 1995).
The remaining 19 species have either < 1% or < 50,000 ha of their total habitat in status 1 and 2 lands. Thirteen of these species, however, meet our definition of peripheral species in Wyoming (Table 5.6), and none are federally listed or candidates for federal listing. Conservation of these species may need to be evaluated on a regional basis rather than within state boundaries alone. Of the six remaining species, the plains hognose snake (Heterodon nasicus nasicus), eastern yellowbelly racer (Coluber constrictor flaviventris) and pale milk snake (Lampropeltis triangulum multistrata) occur primarily on private land (> 65%) in eastern Wyoming, but opportunities for further habitat protection also occur on BLM and State of Wyoming lands (Appendix 5.2). Populations of the smooth green snake (Opheodrys vernalis) in the western states, including Wyoming, are isolated from its more eastern populations. The currently protected habitat of the species in Wyoming occurs primarily in three areas under the stewardship of the State of Wyoming and the U.S. Forest Service. Most of the unprotected habitat on public lands occurs in the Medicine Bow and Black Hills National Forests. The U.S. Forest Service is also the principle land steward of unprotected habitat of the Black Hills redbelly snake (Storeria occipitomaculata pahasapae) in Wyoming (Appendix 5.2).
Establishment of BLM wilderness areas would not protect sufficient additional habitat of any reptiles to remove them from our list of under-protected species. Habitat of the majority (62%) of the 26 reptiles in Wyoming did not overlap with the proposed WSA. Three of the four species occurring exclusively in the southwestern portion of the state where the WSA exist are considered peripheral to Wyoming. The fourth species, the midget faded rattlesnake (Crotalus viridis concolor), occurs primarily in the vicinity the lower Green River, with approximately 50% of its unprotected habitat occurring under the stewardship of BLM. Official designation of the BLM wilderness areas would increase the protected habitat for this species to only 5,006 ha (1.1 %), based on the two WSAs, Devil's Playground and Twin Buttes, which occur in the lower Green River area.
Mammals
Nine (8%) of the 116 mammals of Wyoming currently have > 50% of their potential habitat in status 1 and 2 lands (Table 5.5). These include the lynx (Lynx canadensis) (50%), American pika (Ochotona princeps) (51%), mountain goat (Oreamnos americanus) (57%), Yuma myotis (Myotis yumanensis) (64%), grizzly bear (Ursus arctos) (60%), American bison (Bos bison) (63%), gray wolf (Canis lupus) (73%), fisher (Martes pennanti) (96%), and Preble's shrew (Sorex preblei) (99%) (Appendix 5.3). With one exception, the potential habitat of all of these species is well protected because it occurs primarily in the GYE in the northwestern portion of the state (Merrill et al. 1996b). The exception is the Yuma myotis, which has 64% of its potential habitat protected in the Bighorn Canyon National Recreation Area. The actual presence of this species in Wyoming is questionable since previous documentation has been refuted based on misidentification of the species (R. Luce, pers. communication). Thirty mammals (26%) have 10 - 50 % and 40 (35%) have > 1 - 10% of their potential habitat in protected lands (Table 5.5, Appendix 5.3). These species occur more broadly across the state, but because protected lands occur at high elevations, species with high elevation habitat preferences are more protected (Fig. 5.2B).
Fig. 5.2(B). Percent of species habitat in management status 1 and 2 in relation to mean elevation (m) of the species habitat for mammals.
Five mammals (4%) have no habitat and 32 mammals (28%) have < 1% of their habitat located in status 1 or 2 lands (Table 5.5) and are considered species in need of further habitat protection. Distributions of 15 of these species are peripheral to Wyoming, although so little is known about the distribution of 10 of these species in Wyoming that their peripheral status is questionable (Table 5.7). WGFD (1996) has designated 4 of the peripheral species as Species of Special Concern (Table 5.7). The importance of habitat in Wyoming to the long-term conservation of these species may need to be assessed at a broader scale. The remaining 22 species with < 1% of protected habitat occur primarily in the low elevation grasslands and basins in the eastern half of the state and their habitat falls under private (> 50 %) stewardship. Exceptions are the Wyoming pocket gopher (Thomomys clusius), and pygmy rabbit (Brachylagus idahoensis) which are restricted to southwestern Wyoming. Over 65% of their unprotected habitat occurs under the stewardship of BLM (Appendix 5.2). Although the amount of protected habitat for these two species would be doubled with the establishment of the BLM wilderness areas, < 1 % and < 50,000 ha of their habitat would still be protected and they would remain on the gap list. Only two of the mammals, the thirteen-lined ground squirrel (Spermophilus tridecemlineatus) and Ord's kangaroo rat (Dipodomys ordii), would be removed from the gap list if BLM WSAs were included as status 1 lands. The majority of additional protected habitat for both of these species would occur in the Honeycomb Buttes and Sand Dunes WSAs.
Three other species may be considered gap species because they have < 50,000 ha of protected habitat and are not considered peripheral to Wyoming (Table 5.7). We consider the habitat of two of these, Allen's 13-lined ground squirrel (Spermophilus tridecemlineatus alleni) and the pygmy shrew (Sorex hoyi), as needing additional protection. Most of the unprotected habitat of the pygmy shrew falls under the stewardship of the U.S. Forest Service (88%) while that of the Allen's 13-lined ground squirrel occurs under a number of stewardships including private landowners (31%), BLM (29%), State of Wyoming (8%) and U.S. Forest Service (13%). In contrast, we do not consider the eastern fox squirrel (Scurius niger), which also has < 50,000 ha (1.5%) protected, as a species whose habitat is high priority for conservation. The species does not meet our criteria for a peripheral species, but it reaches its western limit in Wyoming and is considered an exotic species since many of the fox squirrels in Wyoming today are descended from individuals introduced into cities by humans (Clark and Stromberg 1987).
Table 5.7. State range, state and federal rankings, area (ha)
and percent habitat of 43 mammalian species which have < 1
% or < 50,000 ha of their total potential habitat within management
status 1 and 2 lands.
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Birds
Seventeen (6%) of the 291 birds in Wyoming had > 50% of their potential habitat in status 1 and 2 lands (Table 5.5). These are all birds associated with open water and all but one have restricted (< 250,000 ha) distributions that occur primarily in the GYE (Merrill et al. 199b). A high proportion of the habitat of these species is protected because it includes Yellowstone and/or Jackson Lakes which are large bodies of water contained in National Parks. Habitat of the American (water) pipit (Anthus spinoletta) is widespread (> 1,500,000 ha) because it includes a wide variety of high elevation land cover types (Merrill et al. 1996b) and it occurs in the Bighorn and the Medicine Bow Mountain ranges as well as the GYE (Merrill et al. 1996b).
One hundred thirteen (39%) birds have 10 - 50%, and 130 (45%) birds have 1 - 10% of their potential habitat protected (Table 5.5). Similar to mammals, the protection of avian habitat is related to its elevational distribution (Fig. 5.2C), but unlike mammals, two distinct patterns emerge among bird species. First, birds associated with open water habitats (e.g., waterfowl, shorebirds, gulls) have a higher proportion of their habitat protected than other species at the same elevations (Fig. 5.1C) because they are associated with open water which is generally well (45%) protected in Wyoming (Table 5.3). Second, birds associated with forests in Wyoming are more protected compared to birds associated with basin shrublands and prairie grasslands because forests generally occur at higher elevations and have a higher percentage of lands within management status 1 and 2 (Table 5.3).
Fig. 5.2(C). Percent of species habitat in management status 1 and 2 in relation to mean elevation (m) of the species habitat for birds
Two birds had no habitat and 29 (10%) birds had < 1% of their potential habitat in status 1 and 2 lands and are considered gap species whose habitat is in need of further protection (Table 5.8). Habitat of these species is unprotected because they generally occur at low elevations (< 2200 m: Fig. 5.1C) where few protected lands occur. About half (15) of these species are located in the eastern half of the state and > 70% of their habitat occurs on private lands, about one third of the species (10) occur in the Green River area and > 50% of their habitat is under BLM stewardship, and about one fifth (6) of the species occur more broadly across the state in the foothills and basins with their habitat under both private and BLM stewardship. Twelve of these species are peripheral, rare, accidental, or uncommon migrants in Wyoming (Table 5.8) and, as such, their habitat from a species conservation perspective may not receive the highest priority for conservation in the state. An exception is the piping plover which is listed as endangered (Garber 1995).
Table 5.8. State range, state and federal rankings, area (ha)
and percent habitat of 74 avian species which have
< 1 % or < 50,000 ha of their total potential habitat within
management status 1 and 2 lands.
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Of the remaining non-peripheral species with < 1% of their habitat protected, thirteen have <50,000 ha in status 1 or 2 lands (Table 5.8) and these species deserve high priority for further habitat protection. Most of these species, including the Cassin's kingbird (Tyranannus vociferans), the chimney swift (Chaetura pelagica), the blue-gray gnatcatcher (Polioptila caerulea), the Baird's sparrow (Ammodramus bairdii), and the northern bobwhite (Colinus virginianus) are either rare or uncommon residents of Wyoming (Oakleaf et al. 1992. In contrast, McCown's longspur (Calacrius maccownii) is a common summer resident that is broadly distributed (> 3.7 million ha) in Wyoming.
An additional 22 species that are not considered peripheral in Wyoming have <50,000 ha of potential habitat protected and, as a result, we include these species in our list of vertebrate species in need of further habitat protection. In particular, 4 species (blue grosbeak (Guiraca caerulea), purple finch (Carpodacus purpureus) , Columbian sharp-tailed grouse (Tympanuchus phasianellus columbianus), and the white-tailed ptarmigan (Lagopus leucurus)) have the least amount of habitat in status 1 and 2 lands (<10,000 ha). In Wyoming, the blue grosbeak and purple finch are considered a rare summer resident and an uncommon winter resident, respectively (Oakleaf et al. 1992), but in terms of their overall range, they might be considered peripherals to the state (Robbins et al. 1983). The white-tailed ptarmigan is a high elevation species considered a rare resident of the state (Oakleaf et al. 1992) that has been seen recently only in the Medicine Bow Mountains (Merrill et al. 1996b). However, other suitable habitat exists in other areas of the state primarily under the stewardship of the U.S. Forest Service (98%). Habitat of the Columbian sharp-tailed grouse is protected in three wilderness areas in the Sierra Madre and Medicine Bow mountains, and the potential for additional protection occurs on U.S. Forest Service (22%) and BLM (34%) land.
Eight birds, representing 20% of the bird species on the gap list that are not peripheral, would be removed from the gap list by official designation of the BLM WSAs. These include the sage grouse (Centrocercus urophasianus), mountain plover (Charadrius montanus), Eastern screech owl (Otus asio), short-eared owl (Asio flammeus), canyon wren (Catherpes mexicanus) and sage sparrow (Amphispiza belli). The remaining two species, the gray partridge (Perdix perdix) and ring-necked pheasant (Phasianus colchicus), are exotic game species which are not considered a priority for biodiversity management in Wyoming.
5.5 Summary
Less than 10% of the state of Wyoming is classified as status 1 and 2 lands, and 90% of these lands occur in the Greater Yellowstone Ecosystem (GYE) in the northwestern portion of the state. Seven of the 41 land cover types occur at high elevations and are well (> 50%) protected in Wyoming because they occur in national parks and wilderness areas. Sixteen of 36 natural (non-anthropogenic) land cover types have < 1% or < 50,000 ha of the area they occupy in status 1 and 2 lands, though only 11 (31 %) of these are actually considered to be gaps. Wyoming big sagebrush and mixed grass prairie are not included as gaps because of their wide distribution in the state. Black sagebrush steppe and bitterbrush shrub steppe are also not included as gaps because their actual distribution was probably underestimated in our analysis, due to mapping difficulties. Finally, clearcut conifer is not included because of its anthropogenic nature. In addition to the 11 gap cover types, Great Basin foothills grasslands, mesic upland shrub, and all the riparian/wetland types are also considered to be underprotected in Wyoming, even though they have > 1% of the area they occupy in status 1 and 2 lands.
Habitats of 6 (50 %) amphibians, 8 (31%) reptiles, 25 (22 %) mammals, and 41 (14%) birds that are not considered peripheral in Wyoming merit increased management attention. There are an additional 12 mammals and 9 birds with < 1% or < 50,000 ha of habitat in status 1 and 2 lands that are designated as uncertain peripherals, since not enough is known about their distribution to determine whether they should be considered as gaps. The habitat of most of these species is primarily at low elevations in the eastern portion of the state or in the Green River area where status 1 and 2 lands are uncommon. Species that are most protected occur in the northwestern portion of the state and are associated with either open water or forests.