Written by Jack Bauer Edited by David Wetzel “Landscape-Scale Conservation” – A large-scale conservation initiative encompassing all the peoples, flora, and fauna of a region in an effort to insure diversity and the sustainability of an interconnected ecosystem indefinitely. 
Victorio Canyon in the Sierra Diablo Mountains north of Van Horn, Texas. The Baylor Mountains are in the background. Note the shinny wildlife water guzzler on top of the ridge, left, center. For nearly a decade I was fortunate to be directly involved in habitat acquisition for the Wildlife Division and State Parks Division of Texas Parks and Wildlife (TPW). My task was to develop and implement land conservation strategy to meet identified priorities in land conservation needs through coordination with field staff, senior staff in Austin and the Texas Parks and Wildlife Commission. Relative to the desert bighorn sheep program, that usually meant helping staff at Sierra Diablo Wildlife Management Area (WMA), Black Gap WMA, and the West Texas Big Game Program Manager solve facility management problems. These were opportunistic separate transactions that would improve access to the area for the recreational public or purchase from willing sellers privately owned land residing within the boundary of the facility (in-holding). Many of the larger strategic goals were not met. Unfortunately, I was unaware of Texas Bighorn Society’s (TBS) close relationship with TPW and the landowners of the Big Bend. Partnering with TBS could have greatly increased the likelihood of success in sheep habitat conservation by facilitating strategic public and private land purchases in the Trans-Pecos and northern Mexico. The landowners, wildlife biologists, natural resource managers and technicians working the wildlife management areas in the region and Big Bend Ranch State Park had great ideas for conservation, and I took every opportunity to listen to these professionals about conservation schemes that would provide effective “landscape-scale conservation” for wildlife, especially desert bighorn sheep in the Big Bend. The mountain ranges are the critical habitat elements because their vertical stratification provides the variability in geology, vegetation, climate and aspect that contribute to habitat diversity. Because of this increased habitat diversity, mountain ranges naturally function as habitat islands while intermountain ridge lines and valleys serve as corridors for wildlife migration. When viewed from the air, the opportunity to provide for protection connectivity between the mountain ranges of the Trans-Pecos is very apparent, especially between Texas and Mexico along the Rio Grande River in the southern Big Bend. If one could have the ability to manage all of the habitat islands and the travel corridors by some method of land ownership or management agreement between multiple landowners for the benefit of a unified set of management objectives, “landscape-scale conservation” would be the potential result. The image below represents satellite photography processed to display slope greater than 60%. These slope angles estimate the critical cover and escape habitat required by bighorn sheep as one component of many habitat and land-use attributes needed to improve the odds for bighorn restoration. The connection between the mountainous, rugged bighorn habitat and travel corridors is revealing. 
Mountains of the southern Big Bend of Texas and Northern Mexico either side of the blue-tinted Rio Grande River This article is a story of the development of a concept for conservation in the Trans-Pecos and northern Mexico that developed simultaneously among TPW biologists, the TBS Board of Directors, and Cemex Corporation land conservation staff at Maderas del Carmen Preserve in Coahuila, Mexico. The concept has come to be known as the “EL Carmen / Big Bend Conservation Corridor Initiative”. It represents a slightly broader approach to realizing the TBS charter goal “to restore desert bighorn sheep to their native range in Texas”, but an approach that is as directly connected to desert bighorn restoration (and all other native plants and animals contributing to the ecosystem) as the annual work projects. As a basis for starting the story, the current and historic range of the desert bighorn sheep in Texas is represented by the map below. The blue text identifies facilities or mountain ranges currently occupied at some level by sheep. 
Map of Historic and Current Bighorn Sheep Habitat and Occupation As another reference, I have summarized the critical-to-optimal attributes for successful desert bighorn sheep restoration as referenced in the “habitat and human interaction checklist” in the TPW publication, “A Historical Review of Reports, Field Notes, and Correspondence on Desert Bighorn Sheep in Texas.” Habitat characteristics preferred by desert bighorn sheep - Landscape topography: steep, rocky, canyons, bluffs, shelters
- Size: Very large, remote desert mountain ranges, interconnected by travel corridors
- Plant Association: yucca/pinion-juniper savanna – sotol-lecheguilla association
- Water: permanent and well-dispersed
- Other wildlife: no exotic sheep, minimal natural predation by felines
Land-use characteristics optimum to desert bighorn sheep - Human interaction: minimal infrastructure development or fragmentation of habitat by roads, pipelines, etc. Minimal human recreational use.
- Long range land use: adjacent public/private land managed by agreement between participating landowners for unified management objectives.
In order to insure the attributes of this country for bighorn sheep and the other wildlife present, it is important to consider how the land is used and what effects that land-use has on the ecosystem as a whole. The flora and fauna of the Chihuahuan desert is very susceptible to intrusion by man and his machines. Wounds heal slowly here if at all, and it can take many years to recover from the effects of over grazing, resource extraction, or excessive recreational development. Survival in this environment is dependant upon the ability to freely access the scarce resources available when needed, and what may seem to be in abundance at one time, may in fact be barely enough to insure survival during tougher times. It is important that we take a very long-term view of management practices and involve all area landowners and managers in a cohesive effort to manage these lands. Bighorn sheep make a good barometer for this work given their tendency to expand their range into suitable habitat given the opportunity and a workable environment. An excellent example of this concept is the Sierra Diablo/ Baylor/ Beach Mountain meta-population that developed from an intensively managed core area, the Sierra Diablo WMA. Following the re-introduction of a small bighorn herd into Sierra Diablo WMA and with the overwhelming help and support of surrounding private landowners, the population has spread to become the largest single population in the state! PUTTING THEORY INTO ACTION In 2003, TPW and the Texas General Land Office (GLO) were directed by the Texas Legislature to evaluate their land holdings across the state and consider a land exchange transaction to consolidate each agency’s land holdings at locations where TPW and GLO (permanent school fund managed to maximize revenue for the state school system) parcels were inter-mingled. In 2005, TPW and GLO staff had prepared a plan that would have significant conservation benefits at Black Gap WMA, Sierra Diablo WMA and Big Bend Ranch State Park (BBRSP). At Black Gap WMA, approximately 30,000-acres of GLO permanent school fund land were checker-boarded by section throughout the WMA. A similar but less severe situation also existed at BBRSP. As a result of the exchange that finally took place, TPW acquired the GLO land at issue at BBRSP and Sierra Diablo WMA. At Black Gap WMA, priority habitat was consolidated into a new boundary containing over 90,000-acres of contiguous priority habitat. GLO permanent school fund land was aggregated nearest the border community of La Linda, a historic mining operation of primarily commercial interest. For Black Gap WMA, the land exchange consolidated priority habitat based upon landscape-scale objectives for desert bighorn sheep, mule deer, Mexican black bear, upland game birds, and river recreation. TBS played a significant role in facilitating the land exchange by contributing $200,000 to TPW. These funds allowed TPW to acquire approximately 2,700 acres of permanent school fund land as sheep habitat for Black Gap WMA. Most importantly, the inter-agency land exchange provided the land ownership arrangement to motivate conservation-based landowners on both sides of the Rio Grande to further partner to bridge habitat lands with natural travel corridors between Black Gap WMA, Big Bend National Park, and BBRSP with conservation lands in Mexico. For instance, following the land exchange involving Black Gap WMA, Cemex Corporation, a global concrete manufacturer and conservation owner of Maderas del Carmen Preserve in northern Mexico, acquired the Adams Ranch situated directly between Black Gap WMA, Big Bend National Park, and the Cemex Corporation preserve in Mexico. Cemex Corporation is dedicated to desert bighorn sheep restoration in Mexico and the Trans-Pecos and remains an exceptional partner to TBS and TPW. As an example, the Cemex Corporations purchase of the Adams Ranch left TPW the recipient of a conservation easement of the Adams Ranch and a partner in the unified management of Adams Ranch with Black Gap WMA for the benefit of desert bighorn sheep and many other species of interest. This type of management contract outlives personalities and facility managers, assuring that long-term future management will remain for the sheep and other flora and fauna that benefit from the management investments. This relationship could serve as a model of cooperative conservation; it provides a long-term mechanism to implement critical management strategies across ownership boundaries that have significant implications to the success of bighorn production by the control of land-use. Land-use characteristics that control domestic livestock, non-native wildlife (especially exotic sheep), bighorn predators, etc. are critical to the recovery of the species and the expansion of their populations into historic habitat. We know desert bighorn sheep, black bear and many other species of desert wildlife migrate between Mexico and the Trans-Pecos through the Del Carmen Mountain range and beyond. The TPW desert bighorn sheep program would greatly benefit by developing management agreements between adjacent landowners of quality contiguous sheep habitat. Facilitated cooperatively by TPW staff and TBS Board of Directors and Advisors, these agreements could assure human interaction and land-use attributes critical to sheep production are dealt with prior to sheep introductions and during the early critical years of growing sustainable populations of sheep in an area. 
Margaret Basin, wildlife travel corridor between Black Gap WMA and Maderas del Carmen Preserve, Coahuila, Mexico The map schematic below identifies some of the areas of Texas and Mexico that were historically occupied by bighorn sheep but that do not currently support bighorn. The establishment of new populations somewhat isolated from current stable or increasing populations of desert bighorn may provide increased probability of surviving an almost inevitable crash of a population induced by a disease vector or other natural event. According to CEMEX Corporation wildlife biologist Bonnie McKinney, meta-populations of bighorns in adjacent Coahuila, and in western Texas will combine to form sustainable herds (over 100 animals) that are greater than 25 miles apart, thus adding the potential for interbreeding to insure genetic diversity for many years. 
Schematic of conservation areas in the southern Big Bend and northern Mexico that represent “Areas of Opportunity” for desert bighorn population expansion The conservation and land management actions between TPW at Black Gap WMA and Maderas del Carmen Protection Area, the conservation efforts of Cemex Corporation and TPW demonstrates a conservation strategy that can be duplicated by other landowners in west Texas and northern Mexico. Big Bend Ranch State Park is excellent desert bighorn sheep habitat, as is Canyon Santa Elena Protection Area just across the border. Big Bend National Park is also committed to conservation in the area in the form of partnerships. Key elements to implementing a landscape-scale conservation strategy in the Big Bend include: - connecting the habitat islands and travel corridors through land purchase, conservation easement, or long-term lease within the prime desert bighorn habitat regions;
- implementing management agreements among all adjacent landowners to assure that long-term land-use and human interaction situations are complimentary to desert bighorn sheep and other desert species of interest;
- cooperating to reintroduce the species of concern;
- managing for population increases to sustainable levels.
Texas Bighorn Society is well suited to facilitate these types of landowner partnerships and management agreements for the benefit of desert bighorn sheep. TBS’s non-profit, volunteer conservation organization status is non-threatening to the independent-minded landowner typical of the Trans-Pecos. The TBS membership includes people highly motivated and skilled in dealing with landowners, government institutions, and political stakeholders. The organization has a history of demonstrating generous and effective actions, a catalyst to getting things done. As a result of hard work by its volunteers, TBS has earned the level of credibility necessary among governmental entities, conservation organizations and landowners to be positioned as a leader in facilitating future landscape-scale conservation for desert bighorn sheep in the Trans-Pecos and northern Mexico. 
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