Opinion ID: 181487
Heading Depth: 2
Heading Rank: 2

Heading: Decline in Population of Bighorn Sheep, and the Service's Response

Text: As the Management Plan described, the Kofa Wilderness historically has been home to the desert bighorn sheep. In recent decades, the estimated population of the bighorn sheep in the Kofa Wilderness and Refuge remained relatively stable, with fluctuations between 600 and 800 sheep. Surveys done in 1991 and 1997 (the period shortly after the refuge was first designated as a wilderness area and while the Service was preparing the Management Plan) revealed that the population remained relatively stable at around 700 sheep, and the Service determined that the carrying capacity of the area was about 800 sheep. In 2000, the estimated population registered on the high end of the range, at 813 sheep. Due to the population's stability, the Service and other government agencies have permitted certain activities that generally are viewed as inconsistent with population conservation. For example, since 1979, the area has served as a primary source of sheep for translocation programs to re-establish populations of bighorn sheep in Arizona, Colorado, New Mexico, and Texas. For decades, the Service translocated sheep from the refuge on a nearly annual basis. [3] The area also has been a hunting ground for bighorn sheep, and the Service has issued a limited number of hunting licenses (between 9 and 17) each year. The Service also permits hiking in known lambing areas, despite the sheep's strong aversion to human disturbance. One factor historically benefitting the bighorn sheep within the Kofa Refuge was the absence of predators such as mountain lions. Studies conducted in the 1990s found no evidence of mountain-lion presence within the Kofa Refuge. In 2003, the estimated population of bighorn sheep in the refuge was 623. Although this marked a decline since 2000, the estimated population nevertheless remained comfortably within the acceptable range of 600 to 800 sheep. Unconcerned, the Service continued issuing hunting permits, allowed hiking, and, encouraged by abundant rainfall in 2005, translocated 31 sheep that year. In 2006, however, surveys indicated that the population of bighorn sheep had suffered an unexpected declineto 390 sheep, or approximately 30% to 50% fewer sheep than in recent decades. In response, the Service and the Arizona Game and Fish Department prepared a document in 2007 titled Investigative Report and Recommendations for the Kofa Bighorn Sheep Herd (Investigative Report). The report came to no concrete conclusions concerning the recent decline in population. Instead, the comprehensive document examined the wide range of mortality factors of bighorn sheep and, for each factor, it presented prescriptive strategies intended to aid successful recovery of their population. The most prominent factors identified by the report are availability of water, predation, translocation, hunting, and human disturbance.
The report identified availability of water as a critical habitat variable. Investigative Report at 8. The report concluded that, [i]n addition to a need for better monitoring and maintenance of existing waterholes, a better distribution of permanent water supplies is needed to provide water in all areas of suitable sheep habitat. Id. at 9. The report identified strategies such as identifying existing permanent water sources that could be improved by hauling water during low-water seasons, identifying existing water sources that could be redeveloped to improve capacity and efficiency, and identifying locations for new water sources. Id. at 10. With respect to new water sources, the report stated that [n]ew water developments can likely be constructed outside of wilderness, although construction in wilderness should remain an option if a wilderness location best meets wildlife management needs. Id. at 9. Plans for ... new water developments will require an environmental assessment and minimum requirement analysis/minimum tool analysis. Id. at 10.
The report examined predation, primarily by mountain lions. Id. at 11-15. The report noted that, until 2003, no mountain lions were known to exist within the Refuge. Id. at 11-12. Beginning in 2003, however, there have been mountain-lion sightings and confirmed mountain-lion kills of bighorn sheep. Id. at 12. The overall impact of mountain lion predation on the sheep population is unknown. It is unlikely that lion predation alone accounts for the decline observed, but it may be additive to other sources of mortality or sufficient to prevent sheep population recovery. Predation by bobcats or coyotes may also be a contributing factor.... Id. at 13. Limited removal of individual lions identified as regularly preying on sheep may help the bighorn population recover to historical levels. Id. Determining the cause of bighorn sheep mortality is another vital part of assessing the effect of predation on the Kofa population. Id. The report recommended the strategies of determining the extent of predation and reducing predation by the removal of offending lions until the sheep population fully recovers. Id. at 14-15.
The report discussed the high demand by other natural areas for translocated bighorn sheep and the history of translocations from the Refuge to distant natural areas. Id. at 18-19. The report discussed the translocation of 31 sheep in 2005 despite the relatively low population estimate in 2003. Id. at 18. The report found that, [w]hile not the ultimate cause of the population decline, the 2005 transplant may have contributed to the low numbers seen in [one region of the Refuge] on the 2006 survey. Id. The report concluded that no additional translocations will occur until the population of sheep returns to historical levels. Id. at 18-19.
Hunting for desert bighorn sheep in Arizona is a once-in-a-lifetime opportunity and the demand for bighorn sheep hunting exceeds the allowable harvest. Id. at 19. The report described the very restrictive limits on permitted hunting and the financial benefit to certain conservation groups, which are granted a small number of annual permits for auction at fundraisers. Id. The government agencies have issued anywhere from 5 to 17 bighorn sheep permits for the Kofa [Refuge] ... since 1960. Id. The report recommended, without explanation, that the agencies [c]ontinue to offer bighorn sheep hunting opportunities consistent with sheep conservation. Id. at 20.
Bighorn sheep tend to use the highest, most rugged areas within their home ranges for lambing. Id. at 16. Signal Peak and Castle Dome Peak are two of the most distinctive features of the refuge and as such are popular destinations for hikers. Id. Most use of these areas occurs in the cool winter months (November-March), which strongly overlaps the peak lambing season of January-March. Id. The report cited documentation of strong reactions (immediate running, left area and did not return) from Kofa sheep in response to 1 or 2 people. Id. at 17. Frequent human disturbance of ewes may cause them to abandon these areas for less optimal habitat, which could in turn affect lamb survival. Id. The report recommended [r]educ[ing] the negative impacts of human recreational activities on bighorn sheep by monitoring sheep usage during lambing season and, if necessary, closing popular hiking trails during lambing season. Id.
The report contained no overall summary and came to no conclusions about the causes of the decline in the population of bighorn sheep, nor did it make a reasoned comparison among the different potential causes and recovery strategies. The report's discussion of water does not mention the development of the two water structures at issue in this casethe Yaqui and McPherson tanks. Those structures are listed only in a cost comparison chart near the end of the report. Id. at 23. The report lists projects in priority order though the reasons for the priorities are unstated. Id. at 23 (capitalization omitted). In that list, the development of the Yaqui and McPherson tanks is listed sixth out of 14, below four strategies aimed at monitoring mountain lions and reducing mountain-lion predation and one overall strategy for recovery of bighorn sheep. Id. The Service prepared two other documents before initiating work on the new water structures within the Kofa Wilderness. The first document, titled Kofa National Wildlife Refuge Minimum Requirements Analysis, is a two-page document that contains a series of yes/no questions and requires the preparer to circle, with a pen or pencil, either YES or NO. The questions on the second page provide a very small space for an explanation of a yes/no answer, but the first page contains no such area. The preparerwhose identity is unknowndutifully circled answers to the questions and, on the second page, provided very short explanations for the selected yes/no answers to those questions. The final question asks if there are potential adverse effects on wilderness. The preparer circled YESPROCEED TO MINIMUM TOOL ANALYSIS. The second document, titled Kofa National Wildlife Refuge Minimum Tool Analysis, is a detailed explanation of the proposed action, an explanation for why it is necessary, alternative action plans (including the no action alternative), an analysis of the effects of the alternative action plans, and a summary description of the chosen alternative. In a section titled Why Project Is Necessary, the Minimum Tool Analysis states, in full: Kofa NWR was established, in part, for the conservation of desert bighorn sheep and other wildlife, and the maintenance of this population of desert bighorn sheep is very important regionally for the conservation of sheep and as a source for transplants to other locations in order to establish and re-establish other sheep herds. Wildlife is an important component of Wilderness. The three alternatives are (1) no action, (2) constructing the two structures with mechanized means, and (3) constructing the two structures without mechanized means. The Service selected alternative number 2: constructing the two structures with mechanized means. The Service rejected the no-action alternative because it would not help the sheep. The Service rejected the alternative that used non-mechanized means because it would increase the time needed to complete the project, resulting in increased disturbance to wildlife and human visitors alike. Over a three-day period in 2007, the Service built the new Yaqui and McPherson water structures, consisting mostly of aerated PVC pipe buried underground. Designed to catch rainwater and run that water into small concrete weirs or troughs, each system is capable of holding approximately 13,000 gallons of water. The Service decided to enter the two areas with motorized vehicles and equipment because it concluded, in its Minimum Tool Analysis, that using motorized equipment was safer for the workers and would reduce the amount of time the workers would be in the wilderness. The workers used existing roads and removed tracks left by the vehicles. The workers also covered the troughs with local sand and rocks to blend the structures into the natural environment, so that only the troughs and small vent pipes are visible above ground. The Yaqui tank is located in the refuge, just outside the wilderness, but two or three water diversion weirs fall within the wilderness. The McPherson tank is located well inside the wilderness, but within 0.1 mile of a designated road in the area.