Chain Tanks Bighorn, 1999
Q1 How has drought impacted the size of the bighorn sheep population?
A1 Severe drought years have typically been followed by a drop in sheep numbers. On the Kofa, the 1994 survey estimated 811 bighorn on the refuge. The next (1997) survey immediately after the 1996 drought year estimated 600 sheep on the refuge. Similarly, the 2000 Kofa survey estimated 812 bighorn on the refuge, while the next (2003) survey, immediately after the 2002 severe drought year, estimated 620 bighorn. Despite somewhat improved rainfall patterns after 2003, the 2006 survey estimated 390 bighorn in the Kofa NWR population. However, while some bighorn populations elsewhere in the Kofa Mountains Complex (KMC) stabilized or even improved during the 2000-2006 timeframe, that portion of the herd on the Kofa National Wildlife Refuge has shown a steep, decline even when measured against declining populations elsewhere in the KMC. On the Kofa, the 1994 survey estimated 811 bighorn on the refuge. The next (1997) survey immediately after the 1996 drought year estimated 600 sheep on the refuge. Similarly, the 2000 Kofa survey estimated 812 bighorn on the refuge, while the next (2003) survey, immediately after the 2002 severe drought year, estimated 620 bighorn. Despite somewhat improved rainfall patterns after 2003, the 2006 survey estimated 390 bighorn in the Kofa NWR population. This suggests that other factors other than drought may be involved in the decline. This suggests that factors other than drought may be involved in the decline.
Q2 Why does drought have such an effect on desert bighorn sheep population size?
A2 Drought has certainly been a normal part of the evolution of the Kofa ecosystem for hundreds if not thousands of years. The length of the current drought is exceeding any previous drought for which we have records. Besides the obvious drying up of water sources, drought also significantly reduces quantity, palatability and diversity of the plants bighorn feed on. As a drought intensifies, it may also result in the concentration of animals around the remaining sources of food and water. Among other factors, this can make the animals more susceptible to disease, predation, and human disturbance.
Q3 Are there manmade water catchments on the Kofa that Bighorn can use?
A3 Over the past several decades 48 water catchments have been improved or established on the Kofa. These include modified natural catchments, so-called “ring tanks, 12 windmill/well tanks, and buried fiberglass/PVC pipe systems, which represent a newer and generally preferred design. While available to all species on the refuge, many of these were built specifically to suit bighorn needs, while others were constructed with mule deer in mind. In addition, many of the older catchments were built prior to the existence many now available technologies and materials and are less durable and productive than new developments. The manmade sources supplement the hundreds or, in wet years, thousands of naturally occurring rock potholes and other water sources on the refuge. The majority of these last only a short period of time and even some of the nine natural springs found on the refuge are known to go dry during droughts. Prolonged drought may also result in even long-established natural tanks becoming “death traps” for desperate sheep and other wildlife that become trapped in natural pockets in their efforts to reach the last available water. In wetter years, the mix of manmade and natural sources has proven capable of supporting high bighorn sheep populations, but is still not considered sufficient to maximize bighorn use of all the suitable habitat. The extent of the current drought has eliminated many of the naturally occurring water sources and severely taxed the entire water supply.
Q4 How often are surveys conducted?
A4 From 1992 to 2000, the Kofa surveys were jointly conducted every three years by the U.S. Fish and Wildlife Service (USFWS) and Arizona Game and Fish Department (AGFD) as part of the department’s overall survey of desert bighorn sheep populations throughout southwestern Arizona. As a result of the findings of the 2006 survey, annual surveys of the Kofa herd began in October of 2007 and continued through 2010. After 5 years of relative stability, surveys are now scheduled to be frown every other year.
Q5 How large is the bighorn sheep habitat on the Kofa NWR?
A5 435 square miles.
Q6 Why is the Kofa Mountains Complex bighorn herd so important?
A6 At its historic average of approximately 800 animals, the Kofa mountains complex herd represents the largest population of this subspecies in the United States. Bighorn from the Kofa have been a critical source of animals for the reestablishment and maintenance of bighorn populations across Arizona and throughout the southwestern United States, to include New Mexico, Colorado, and Texas. The first successful transplant in 1957 moved Kofa bighorns to the Black Gap Wildlife Management Area, Texas, an area from which bighorn had been exterminated, but that now boasts a healthy herd. The last translocation of sheep from the Kofa was in 2005 when 30 sheep were captured and transported to the San Andres Wildlife Refuge in New Mexico as part of the effort to restore that refuge’s bighorn herd.
Q7 How many bighorn have been transplanted from the Kofa NWR?
A7 Transplanting (or translocation) efforts began in 1955, but the first successful transplant occurred in 1957. Records for some years do not include numbers and some other years combined data from other locations. However, to date at least 513 bighorn sheep have been translocated.
Q8 In light of the population decline, should translocations from the Kofa be stopped?
A8 The last translocation was in 2005. Translocations were suspended after the 2006 survey and none are currently scheduled. Throughout their history on the Kofa, translocations have been adjusted based on the assessment of the herd size and their potential impact on it. The protocols established for the actual conduct of translocations were designed to further reduce any negative impact by limiting chase times and precluding the chasing of any bighorn group more than once during a translocation, thus limiting the take from any one group to no more than two animals. It should also be noted that, in the 50 years since the first successful translocation in 1957, there were 25 years during which there were no translocations, and during the most active translocation period from 1992-2002, the bighorn population reached the highest numbers ever recorded.
Q9 Recreational use of the refuge has been mentioned as possibly having a negative impact on the bighorn herd. How does that use affect the population?
A9 Like many species, there are parts of desert bighorn sheep habitat that are especially important to the reproductive cycle and may be disrupted by human activity during certain times of the year. With desert bighorn it is possible that human activity in the high-mountain lambing grounds during the January-April lambing season could result in lower lamb survival. Illegal OHV use may also have some affect on the population.
Q10 Will recreational use of the Kofa be stopped or reduced?
A10 No decision has been made and additional research will likely be necessary to determine the actual human impact, if any. It would be premature to speculate in advance of further study of the situation, but the Department will work with the USFWS as it sorts through the issue. It is likely that any restrictions would be limited to key lambing areas and key lambing seasons.
Q11 How many mountain lions are on Kofa NWR?
A11 The refuge estimates that in 2006 at least five lions (three adults and two sub-adults) included parts of the refuge in their home ranges. Five individual lions were specifically identified through the use of camera monitoring of waterholes. Genetic sampling of captured lions and scts collected on the refuge indicated that at least 11 different lions had used the refuge during a 2-year period (2007-2009).
Q12 Are these lions dangerous to recreational users of the refuge?
A12 In all but the most unusual circumstances, no. As the largest natural predator commonly found in the state, lions should always be treated with respect, but they will almost always seek to avoid people. On very rare occasions lions have attacked and seriously injured or killed humans.
Q13 How many desert bighorn sheep are lions killing?
A13 Given the size of the refuge and the way lions hide their prey when taken, no definitive count is possible. The mix of male/female/young/mature lions, which is still unknown, would also impact the numbers of animals taken. That said, the most current lion research indicates that an adult lion will take as many as one large mammal (mule deer and bighorn in the case of the Kofa) every seven days. With at least five resident lions on the Kofa, that could result in as many as 260 large mammal (mule deer or bighorn sheep) kills a year. For the three collared lions about which we have solid data, 71% of the known large mammal kills of one lion (KM01), 25% of the known large mammal kills of the second lion (KM02), and 45% of the large mammal kills documented for the third lion (KM03) – a total of 10 bighorn -- were bighorn sheep. While the information from these lions is a limited sample size, it is the best lion predation data ever collected from the Kofa Mountains Complex herd and the implications for bighorn herd restoration are troubling.
Q14 Are mountain lions having an adverse effect on the Kofa NWR desert bighorn sheep population?
Q14 The data from our collared lions coupled with existing mountain lion research tells us that the estimated five lions now including parts of the refuge in their home ranges are adding important mortality to a population already significantly stressed by the long-term, ongoing drought. What we know about mountain lion history in the Kofa mountains complex further supports that conclusion. While it is true to say that lions are native to Arizona, all the available data and research tell us that it is equally true to say that a resident population does not appear to have been a natural component of the Kofa in historical times. As late as 1995, an intensive mountain lion survey using trained dogs was conducted in all the mountain ranges that make up the Kofa mountains complex and found no evidence of any mountain lion presence. The record of the refuge tells us that, previously, even transient lions were a very rare part of the Kofa ecosystem. With an expected recruitment into the Kofa herd of 17 yearling bighorn sheep per 100 ewes, recruitment at the current herd size is approximately 40 yearling bighorns a year. Given that lions could be taking as many as 260 large mammals a year from the refuge, the math and our experience with the two lions about which we have solid data is very concerning. Based on the data we have collected on the three lions collared to date (January 2008), it is possible that total predation on bighorns could exceed their annual recruitment into the herd, and this is cause for serious concern.
Q15 Is sport lion hunting part of the predatory management plan?
A15 No. Sport lion hunting has not proven effective for taking mountain lions in low desert habitat.
Bighorn lamb at water catchment on Kofa NWR
Q16 Will lions be eradicated from the refuge?
A16 There is no plan to eradicate lions from the refuge. Lions that focus their predatory activity on bighorn and that are subject to the sole authority of the Department, will be removed under the auspices of the “Kofa Mountains Complex Predator Management Plan.” Data tells us lions have not historically been a part of the Kofa ecosystem. Even transient lions were rare.
Q17 What is the definition of an “offending” lion?
A17 The criteria for “offending” mountain lion is one that has demonstrated a focus on bighorn sheep by killing at least two in a six-month period. The “offending lion” criteria selected for both the investigative report and the Kofa Mountains Complex Predation Management Plan is among the most conservative of the existing management plans for other at risk bighorn sheep populations. For example:
- The “Mountain Lion Management to Protect the State Endangered Desert Bighorn Sheep – New Mexico” final environmental assessment defines an offending lion as any lion that kills “one desert bighorn sheep.”
- The “Recovery Plan for Bighorn Sheep in the Peninsular Range, California” removal criteria is a lion “known to be, or suspected of, preying on bighorn sheep.”
Q18-- Why was the killing of two bighorn sheep within a six-month period chosen as the standard for an “offending” mountain lion?
A18-- This definition was based on research and modeling done by Ernest et al. (2002) as well as guidelines established in recovery plans for bighorn sheep in other areas. The definition for Kofa allows for more sheep in a smaller time period to be killed before a lion is considered “offending”. This was done to avoid removing a lion that is not a regular predator of bighorn sheep. There is evidence that an individual mountain lion may specialize on a single prey species and that this behavior is learned and can be passed on to offspring. Therefore, the Kofa definition was designed to target only lions that had established a pattern of regularly preying on bighorn sheep.
Q20 Given the population decline, shouldn’t bighorn hunting be stopped?
A20 Only the ram segment of the bighorn sheep population is subject to hunting. We have detected a slight decline (85 to 72) in the number of rams between the 2003 and 2006 surveys and, in fact, there are as many senior class rams in the largest segment (GMU 45) of the Kofa herd as were found during the 2000 survey when the herd was at its historic high. The number of permits is adjusted annually based on the number of mature rams in the herd. Hunting has been critical to the resurrection of this species throughout the southwestern United States with hunters and sportsmen’s groups and individual sportsmen providing a majority of the funding for bighorn management. Most of this funding is spent to the benefit of animals that will never be hunted. We will monitor the population, including ram numbers, and adjust permits in accordance with Department species management guidelines. For 2007 the number of permits that include parts of the refuge is 12, the lowest number issued since 1981. Even under current conditions, some level of continued hunting of older rams will still be important to the management of the health of the herd in order to reduce competition with ewes for food resources and to reduce ewe stress caused by excess rams battling for reproductive access to them. For the purposes of hunt management, Arizona Game and Fish has long divided the state into a series of Game Management Units. In the case of the Kofa NWR, the refuge is divided into three GMUs: Unit 45 A comprises roughly the northwestern third of the refuge, Unit 45B the southeastern third, and Unit 45C the southwestern third. Other surrounding GMUs contain the remaining sections of the greater Kofa Mountains Complex.
Q21 Is human encroachment negatively affecting the Kofa bighorns?
A21 There has been no significant human encroachment on the Kofa herd since the construction of Interstate 10 some 40 years ago and encroachment is not considered to be a contributor to the current state of the herd. However, as the state continues to grow, there is the possibility that surrounding development could have a major impact on the Kofa. Possible roadway construction associated with nearby development could have an important negative affect on the species.
Q22 Is illegal immigration having a negative affect on the Kofa bighorns?
A22 There is no current evidence suggesting illegal immigration is having any negative affect on the herd.
Q23 Is disease reducing the Kofa bighorn sheep herd?
A23 Disease is a common element of the Sonoran desert ecosystem and several diseases are known to occur in bighorn. Although current data is insufficient to determine the exact role of disease in the Kofa herd, blood analyses from bighorns handled during transplant operations do not indicate a significant change in disease exposure in this herd. However, one situation that is known to increase disease problems is the concentration of animals whose disease resistance has been lowered by resource stress. Certainly as the drought continues, this becomes a greater concern to the extent drought-stressed Kofa bighorn become concentrated to the point were disease is more easily spread.
Q24 What is the Department’s position on the proposed Devers-Palo Verde #2 power transmission line route across the Kofa NWR?
A24 The Department is on record opposing new disturbance of bighorn sheep habitat. The Department positions is that the line should be built within the existing utility corridor. Given the existing Harquahala-Hassayampa line’s historical lack of significant impact on Kofa NWR bighorn sheep, we believe construction of the new line would not significantly change the situation. Our analysis of the other proposed route involving use of wholly new habitat indicates it would have the potential for significantly greater impact as it passes through the Plomosa Mountains bighorn sheep habitat.
Q25 Doesn’t the Kofa NWR oppose this transmission line?
A25 The refuge manager deemed the power line to be incompatible with refuge objectives, but the Arizona Corporation Commission’s vote against any construction of such a line would appear, for now, to make the issue moot.
Q26 How do you respond to opposition to the Department’s removal of lions in the vicinity of the Kofa NWR?
A26 It would be hard to find an animal more symbolic of the Sonoran Desert than the desert bighorn sheep, which is prominently displayed in the logos of the Center for Biological Diversity, the Animal Defense League of Arizona, and other organizations. The Kofa NWR bighorn sheep herd has proven to be an invaluable resource in the reestablishment of the species in areas from which they had been eliminated and in the maintenance of the genetic and reproductive health of existing populations. Bighorn from the Kofa have been critical to the health of bighorn populations across Arizona and throughout the southwestern United States, to include New Mexico, Colorado, and Texas. The Kofa, which, until quite recently had no historical record of resident lions, is not critical to the health of the Arizona mountain lion population. If continued research confirms the preliminary results of earlier research to the effect that lion predation is adding new and unsustainable mortality to the bighorn sheep population, then we believe management decisions should favor the bighorn.
Q27 What is the status of the “Yuma Puma”?
A27 Recent mitochondrial DNA studies (Culver et.al., 1995 and 2000) indicate that, in fact, there is not, nor has there ever been, a “Yuma Puma” subspecies. We believe the Culver studies to be definitive on the issue. It is worth noting that an exhaustive 1995 morphological study of all available specimens (McIvor et.al.) reached the same conclusion.
Q28 How many bighorn sheep will be hunted on the Kofa NWR this year?
A28 Six permits were issued in 2011 for game management units that include at least part of the Kofa NWR. The Kofa NWR is also available to the holder of the annual auction tag, which could result in a 7th tag on the Kofa, although that tag has not been used there for several years.
Q29 Why did the Department kill a collared lion in June 2007?
A29 The lion met the Department definition of “offending lion” (two bighorn killed within six months) having clearly focused its predatory behavior on bighorn sheep by taking five bighorn sheep during the 96 days the lion was collared. Four of those sheep were killed within a 50-day period. Global Positioning System (GPS) locations obtained via satellite put the lion precisely at the site of nine ungulate kills: five bighorn, two mule deer, and two other as yet unidentified large ungulates (either bighorn or mule deer). A tenth kill appears most likely to have been a coyote. The lion was physically observed at three of the kill sites. When taken, the lion was found in a small clump of trees with the carcasses of a mule deer and two bighorn sheep ewes cached within the same clump of trees. All kills appeared to have occurred within no more than four days, with the freshest probably killed within 24 hours. It was noted that two of the three kills appeared to have been fed on only once and one not at all. Both ewes appeared to be of prime reproductive age. The collar recovered at the time of the lion’s removal provided daily location data which field biologists used to visit suspected “kill clusters” to further determine this lion’s predation pattern. All sites have been visited.
Q30 How do you know lions killed the dead sheep you have found and attributed to lion predation?
A30 The sites of the dead prey animals are characteristic of mountain lion kills: tracks, scat, blood stains, signs of violent struggle, drag marks caching under trees, covering of the carcass, tooth marks, broken neck, manner of feeding, etc. Given the weather stability in the Sonoran desert, even drag marks may still discernable months after a kill. Since mountain lions do not eat spoiled meat (and thus are rarely, if ever, feeders on carrion) finding dead prey animals exhibiting the characteristic signs of lion predation is almost definitive proof they were killed by mountain lions. In the case of the lion killed in June 2007, all five kills attributed to him prior to his removal, his Global Positioning System (GPS) collar indicated he was returning to the exact same location, multiple times over a period of one-three days.
Q31 Are there any other collared lions on the Kofa?
A31 As of April 2012 there are 3 radio-collared mountain lions on the Kofa, the capture and collaring of lions is an ongoing process and the number of lions with collars will change from year to year.
Q32 Why is the U.S. Fish & Wildlife Service being sued?
A32 The question as to the intent and desires of the organizations that filed the suit (i.e., the Montana-based Wilderness Watch, Incorporated, and the Arizona Wilderness Coalition) would be best directed to those organizations. That said, the suit against the U.S. Fish and Wildlife Service is aimed at the recent redevelopment of two Kofa NWR water catchments: McPherson Tank and Yaqui Tank. From the language in the suit it appears these organizations believe the categorical exclusion and minimum tool analysis process conducted by the refuge in advance of these two projects was insufficient. In the words of the suit, they seek to “(1) stop further construction of artificial water sources inside the Wilderness Area; and (2) remove any artificial water source that have thus far been constructed under this secret and illegal authorization.” While not a subject of the suit, the Arizona Game and Fish Department believes the program history of human-assisted water development indicates its significant value in supporting wildlife in both wilderness and non-wilderness habitat and that the process followed by the refuge for these redevelopments is in keeping with established wilderness act and NEPA requirements. On July 6, 2007, the Arizona Game and Fish Commission voted unanimously to request the court’s permission to intervene in the lawsuit and become a co-defendant with the U.S. Fish and Wildlife Service. As of October 2007, the court has not acted on the Commission’s request, but has permitted the Department to participate in the lawsuit and file briefs as if it was a party.
Q33 Were Yaqui and McPherson tanks redeveloped secretly?
A33 No. Wildlife water developments and redevelopments have become such a routine activity that media interest has become almost nonexistent and press releases announcing their start or completion are rare. Ironically, of the 50 Region IV water projects completed by the Arizona Game and Fish Department on national wildlife refuges, national monuments, and Bureau of Land Management lands since January 2006, the Yaqui and McPherson tanks redevelopments were the only ones that were announced via the media. In the Department’s June 12, 2007, press release announcing the signing of the “Investigative Report”, the release noted that “In keeping with the recommendations of the report, actions have already been initiated, to include the June 3 completion of an 11,000 gallon buried underground system at Yaqui Tank in the Kofa Mountains . . . . A second water project is scheduled for later in June.” An exception to the announcement of these projects is that we routinely inform those non-governmental organizations (NGOs) that have demonstrated their willingness to support these projects with essential volunteer labor and equipment about those projects for which volunteers are needed. Volunteers and equipment was needed for both redevelopments and an appeal for volunteers was made at the May 2, 2007, regular monthly meeting of the Yuma Valley Rod and Gun Club. This club has helped install dozens of wildlife in southwestern Arizona.
Q34 Does the Arizona Desert Wilderness Act of 1990 prohibit man-made wildlife water development on the refuge?
A34 No. Perhaps the best expression of Congress’s intent is contained in Arizona Congressman Morris K. Udall’s report submitted to accompany the Act: “I am pleased the delegation and the Committee [on Interior and Insular Affairs] accepted the statutory language I proposed, along with explanatory Report language, to make sure the public land managers recognize wildlife and wildlife habitat as a wilderness resource. During our work on this bill, we were told that some federal policy makers believed the maintenance and construction of wildlife habitat improvements, such as simple watering facilities in the wilderness, were not compatible with the wilderness resource. By including this statutory and Report language, the Committee refutes any such contention. Wildlife water facilities and other habitat improvements can be maintained, repaired and reconstruction in accordance with the wilderness management plan developed by the land and wildlife managers.” Appendix B of the Act provides additional amplification.
Q35 Why were Yaqui and McPherson Tanks expanded with manmade water catchments?
A35 These tanks are two of the 24 waters identified as “critical” bighorn sheep waters in the investigative report. They were redeveloped to provide a more reliable, low maintenance, low footprint water source for the bighorn sheep in that part of the Kofa NWR. The Yaqui redevelopment added 11,280 gallons of capacity and the McPherson redevelopment added 9,392 gallons of capacity. Bighorn sheep were using Yaqui Tank within days of its installation. The original catchments are modified natural tinajas whose construction reflects a less efficient design first used in the state several decades ago. Arizona Game and Fish’s extensive experience with these waters tells us that they require some of the highest levels of maintenance of any of the waters the Department maintains due to the need for frequent water hauling, sediment removal, and resealing. When such projects began in the 1950s, the modifying of natural tinajas made sense given the then limited technology. Such projects often took weeks to complete and, in some cases, involved blasting to make the necessary modifications. Post-construction maintenance and support was very significant, with the frequently isolated locations making them difficult to check or replenish, and the unpredictable and often violent rainfall runoff damaging or destroying improvements. By contrast, the redeveloped, buried tank systems (a California design first used in southwestern Arizona in 1995 in the Maricopa Mountains) provide the opportunity to provide wildlife in the area with a more reliable water supply due to our ability to site the catchment to best take advantage of natural flow while simultaneously reducing the maintenance and evaporation problems common to natural catchments. The redeveloped waters also present a much smaller footprint resulting in considerably less visual intrusion. A 20,000 gallon redevelopment can be installed in as little as two days and the soil disturbance is quickly restored to a natural surface within a few rainy seasons. These tanks provide special advantages in wilderness (McPherson tank is sited approximately 450 yards inside wilderness) since they require less water hauling and sediment removal activity, and are usually repaired without resorting to mechanized means. Normally, water catchments are installed in cool weather due to the significant amount of hand labor they require. These two were redeveloped at the beginning of the Summer because it is important to eliminate those factors reducing bighorn sheep numbers. These two tanks were selected because of their potential to have an immediate impact on reducing water stress on bighorn sheep.
Q36 Why are these considered “redevelopments” rather than “new” water catchments?
A36 It would be very difficult to avoid simply duplicating the defects of an existing natural or modified natural tinaja if a redeveloped water was installed within the exact footprint of the existing tank. Put another way, a redevelopment is placed close enough to the existing tank to serve the same wildlife resource, while also enabling us to site the new tank so as to correct the old tank’s deficiencies, thus reducing the amount of maintenance and replenishment activity. In the case of the redeveloped McPherson Tank, for example, one of the plantiff affidavits in the recent lawsuit against the U.S. Fish and Wildlife Service notes the importance of reliable water sources to wildlife habituated to them, observes that “the old McPherson Tank rarely held water long-term”, and then opposes as “new” a redeveloped catchment installed specifically to remedy this defect in a critical bighorn sheep water and thus reliably serve the same wildlife resource that has been repeatedly failed by the natural tinaja. Redevelopments can also permit us to further reduce human intrusion by being sited closer to existing access roads. Continuing with the McPherson Tank example, the modified tinaja is located approximately 1.4 miles (2,430 yards) into wilderness, versus .26 miles (450 yards) for the redeveloped McPherson which is adjacent to the existing McPherson Pass Road, a public access route. Conversely, new catchments/tanks are installed to serve areas currently lacking a reliable source of wildlife water.
Bighorn sheep dead of thirst at Red Tank on Kofa NWR
Q37 What is a water “catchment”?
A37 As the name implies, water catchments (also referred to as “tanks” or “waterholes”) are sites that “catch” or collect water. Catchments fall into three broad categories: Natural temporary or intermittent, Natural modified, and manmade. In wet rainfall years the Kofa probably contains thousands temporary natural catchments that vary from mere puddles lasting no more than a few hours, to deep solid rock catchments that may be many feet deep and may last for years. Modified natural tanks are naturally occurring tanks that are altered to improve wildlife access, increase the storage capacity, or reduce evaporation. Manmade catchments are constructed of manmade materials at sites that have little or no likelihood of providing useful natural water storage. These range from simply earthen dams and metal stock tanks to more elaborate “ring tanks” with sometimes large concrete collection aprons that feed a circular (“ring”) covered tank that fills a wildlife drinking trough. The current state of the art for manmade tanks is the buried tank system that uses existing runoff channels to feed buried fiberglass or PVC tanks that provide water to prefabricated drinkers. When complete, buried systems have almost no above-ground components.
Q38 What is a “death trap” catchment?
A38 Wildlife can become trapped in naturally occurring water catchments and either drown or die of hunger when they cannot escape. Many tanks with a capacity for long-term water storage are able to do so due to the presence of deep, steep sided, solid rock pockets. Many natural tinajas have the ability to become “death traps” during extended droughts when the water level drops so low that the established access points no longer permit access to remaining water. Animals can become desperate enough to climb or jump down into these tanks in the search for water. If they cant escape, they either drown or die of hunger. Most known “death trap” waters have been modified to include steps to enable wildlife to get and out of them. The current drought has driven some tanks not previously known as “death traps” to such low levels that they have become potentially deadly to wildlife.
Q39 Is it true that there is opposition to the Kofa transplant program within the U.S. Fish and Wildlife Service?
A39 There is no opposition to transplanting bighorn sheep from a healthy Kofa population among current U.S. Fish and Wildlife Service staff at Kofa NWR. A former refuge biologist has indicated he opposes the program, but while still a member of the refuge staff he was enthusiastic in his support of the last (2005) transplant: “This capture was perhaps the most organized and logistically efficient I have been involved with on the Kofa since my first capture in 1979. The shade structure was a good addition. Bob Henry and others had the handling protocol, staff, and staging area set up perfectly. The veterinary support was excellent, as usual. All involved in the planning and execution of this effort should be commended for their efforts. This is the first time I was able to stand back to watch the complete operation in progress and I was impressed with all aspects of it. Oh, I forgot to mention the food and the efforts of the cooks and bakers! I was scheming up a plan to spread the remaining 10 bighorn we still “owe” SANWR/NMGFD [San Andres National Wildlife Refuge/New Mexico Game and Fish Department] over at least a 2 year period just to reap the benefits of the camping experience.”
The impact of wildlife waters on expanded raven (which, unlike lions, have long been a component of the native fauna of the refuge) predation on desert tortoises has also been brought up in the context of the Kofa. Speculation about the single Mohave Desert study of raven use of livestock watering sites from which such concerns appear to be derived, ignores the fact that the waters studied bear almost zero resemblance to the waters or habitat in the Kofa Mountains Complex.
Q40 Does the addition and improvement of wildlife waters cause predators to expand their range?
A40 The available science does not support it. In the case of mountain lions, the Kofa history would seem to refute such speculation. As one example, during the 60+ year history of active water development on the Kofa, a resident, reproducing lion population did not become established until sometime within the past seven years. The scale of lion use of the habitat – their home ranges of as much as 500 square miles far exceed those of their prey species – seems clearly indicative of an animal for whom water availability is neither a significant limiting factor or attractant. For lions, the answer to the questions: Why here? Why now? . . . remain the subject of intense research and conjecture. The impact of wildlife waters on expanded raven (which, unlike lions, have long been a component of the native fauna of the refuge) predation on desert tortoises has also been brought up in the context of the Kofa. Speculation about the single Mohave Desert study of raven use of livestock watering sites from which such concerns appear to be derived, ignores the fact that the waters studied bear almost zero resemblance to the waters or habitat in the Kofa Mountains Complex.