Many wildlife species rely on or require access to daily free (surface) water. However, the proliferation of water developments for domestic livestock across our arid and semi-arid rangelands has resulted in the capture and containment of many natural water sources though spring developments, pipeline and trough systems, storage tanks and bladders, reservoirs and dugouts, and other artificial delivery or storage facilities. Water resources may remain tied up in storage facilities or within facilities that do not allow for wildlife access. In many instances, wildlife may actually be risking their lives to obtain life-giving waters in what were once natural habitats with natural surface waters.

This report section has been divided into subsections - each representing major wildlife access or safety issues associated with livestock water developments. The three subsections are: Lack of Cover and Predation, Wildlife Access, and Wildlife Escape Mechanisms. Graphic examples of failures of public agencies to actually provide for wildlife escape from livestock water developments will be presented in Section 4.2.

Lack of Cover and Predation

Livestock removal of native vegetation may exert a profound influence on the overall presence and on the reproductive viability of wildlife species within a particular habitat. Years of field observations by many scientists, including the author of this report, reveal that water and trees are rarely the major limiting factor for wildlife. The most observable limiting factor for many if not most wildlife species (from invertebrates to vertebrates) is the presence or lack of understory or groundcover values. Vegetative groundcover or understory values are directly related to foraging values, prey base presence, nesting cover, and thermal cover. Additional major functions of groundcover and understory values are the provision of hiding and escape cover. (Nest or brood parasitism is another critical impact with a high correlation to both regional and local livestock grazing disturbance - but is associated with livestock grazing in general as well as near developments and is not discussed in any particular detail within this report.)

Wildlife species entering open areas or areas supporting minimal cover values are vulnerable to predation. Wildlife may be reluctant to utilize water or even taller vegetative structures when such resources are not associated with ample groundcover or understory vegetation. Obviously, as biological needs intensify (e.g. thirst) the natural reluctance of many species to cross or enter open areas may be abandoned. Some wildlife species, particularly large birds of prey, may capitalize on habitats fragmented by water developments and other range "improvements" As was noted in Section 3.1 regarding sage grouse:

Construction of roads, power lines, fences, reservoirs, ranches, farms, and housing developments has resulted in sage grouse habitat loss and fragmentation. Structures such as power lines and fences pose hazards. (Connelly and others 2000)

Not only do such human structures represent actual physical hazards or impediments to wildlife movements (refer to pronghorn killed in fence accident, Figure 3.1-60,), these structures also provide increased perches for raptors. While this may benefit the raptors in some instances, the additional predation pressure may also create artificial hardships for sensitive or TES species; particularly when open, denuded watering areas gain popularity as "local diners" for area raptors. Figures 4.1-1 and 4.1-2 illustrate this concept well.

Raptor perching on or near water developments substantially increases risk of predation for smaller wildlife attempting to access the water source. As many water developments have wooden posts and structures placed around, on, or over them- raptors may actually perch directly on the water developments themselves. This phenomenon can be evidenced by flight or other feathers dropped singly into a trough during preening activities, and through the observation of portions of prey (such as portions of a rabbit carcass) dropped into troughs.

Approaching a trough may result in increased risks of predation for many species of wildlife. Simply crossing large open spaces (regardless of actual numbers of predators present) may represent an instinctual barrier just as much as a physical barrier. Many wildlife species faced with broad open areas may attempt crossings to water sources under cover of darkness or at other hours of the day when risks of predation may be instinctually perceived as being minimized. For species with particular habitats for different hours of the day, such as small birds or small mammals, the presentation of a desired water source without cover or other substantial resource values such as the denuded area around water developments (in some instances up to several square miles) may limit species presence as well as overall population densities (reproductive success) within that respective habitat.

Observations and comparisons of troughs with moderate to heavy cover values to troughs with very little or no cover values immediately reveals differences in wildlife behavior regarding the water resources. Observations and comparisons between sites with and without substantial cover values may reveal the presence of a greater variety of wildlife species for troughs with substantial cover, as opposed to the presence of few if any species of wildlife at troughs with little or no cover. The reader/viewer needs to realize that relative abundance and diversity are also dependent upon other site and habitat characteristics. However, for general comparison purposes, the activity and presence of wildlife at a trough with heavy cover versus one with no close cover is still revealing of startling differences in wildlife presence.

Figures 4.1-9 and 4.1-10 are representative of a trough with substantial nearby cover and a trough without any substantial nearby cover. In order to provide a more realistic comparison of wildlife values, these examples were selected because they share a similar elevation and plant community type. The troughs are also within the same mountain range and are managed by the same agency - Sawtooth National Forest. These troughs were both visited in the late afternoon in September of 2002. One trough is a round metal tank and one is a rectangular metal tank; both troughs have free surface waters available to wildlife in addition to the troughs. Both troughs have large aspen trees nearby. Weather was sunny and air temperatures were warm during both survey visits. The major difference between the two troughs is the presence or lack of substantial groundcover and understory vegetation due to grazing (or the lack of grazing) by domestic livestock.

Wildlife were present and active at the above trough with substantial cover - even on a late fall afternoon. Ruffed grouse and the presence of a variety of songbirds (e.g. White-crowned Sparrow, Spotted Towhee, Song Sparrow, Dark-eyed Junco) were observed in the immediate vicinity. Small mammals were present and active - including mice, pocket gophers, and voles. Many kinds of insects were visible or had left sign of their presence. Fresh deer and elk tracks were observed in the vicinity of the trough with substantial cover (figure 4.1-9).

The trough without substantial cover (figure 4.1-10, area grazed by domestic livestock) had no observable wildlife species present and active in the immediate vicinity - with the exception of a few types of insects- during the survey visit. There were no small mammals or songbirds observed in the immediate vicinity. There were no deer or elk tracks in the immediate vicinity of the trough, although three mule deer were observed about one mile north of the grazed trough (in an area with much heavier cover values) on the same day as the survey visit.

Grazing utilization levels as well as the potential for predation can seriously impact the presence or overall success of many wildlife species in a habitat that contains a water development. Removal of cover occurs either by grazing or through trampling/bedding and the constant use of a single location.

As was previously discussed in Section 3.1 Ecological Costs of Livestock Water Developments, Subsection Impacts to Native Plant Community Values, the following language provides examples of language appearing in various state BLM Standards & Guides in relation to livestock grazing and maintenance of plant community values (plants provide critical ground cover and understory values for wildlife):

  • Apply grazing management practices and/or facilities that maintain or promote the physical and biological conditions necessary to sustain native plant populations and wildlife habitats in native plant communities. (Idaho BLM 1997 Guidelines for Livestock Grazing Management #12)
  • Grazing management practices will be implemented that: a) Maintain sufficient residual vegetation and litter on both upland and riparian sites to protect the soil from wind and water erosion and support ecological functions; c) Meet the physiological requirements of desired plants and facilitate reproduction and maintenance of desired plants to the extend natural conditions allow; d) Maintain viable and diverse populations of plants and animals appropriate for the site (Utah BLM 1997 Guidelines for Grazing Management #1)
  • Manage grazing to maintain or improve watershed vegetation, biodiversity… Maintain or improve riparian vegetative cover and structure (Montana BLM 1997 Butte District Guideline #1, Lewistown District Guideline #2, Miles City District Guideline #2, Dakotas Guideline #2)
  • Grazing will be managed to promote desired plants and plant communities of various age classes (Montana BLM 1997 Lewistown District Guideline #5)

Based upon field observations, it is quite evident that a great many (if not most) livestock water developments do not support appropriate native (or seeded) plant community values; and represent overall as well as point-in-time violations of state BLM Standards & Guides.

Obviously, if a trough is utilized by large hoofed, heavy, and relatively clumsy animals (e.g. cattle) some trampling damage is bound to occur to area vegetation as well as corresponding utilization impacts. Sheep use also exerts substantial trampling and use impacts - based largely on the dogged persistence of "close-herding" practices. In other words - each trough, if used in conjunction with grazing activities during a season, is going to represent a sacrifice zone at varying scales of duration and intensity.

Some troughs may have been placed on cement or rock pads, or on lumber or some other material that maintains (or results in) a permanent but very limited bare area immediately around the trough itself. Depending on the duration and intensity of livestock utilization of the water development and associated pasture or allotment forage; impacts may range from minimal to moderate, to severe or even extreme. Most troughs or other types of water developments are utilized for extended periods of time by large numbers of livestock- resulting in substantial habitat disturbance.

Brief livestock utilization resulting in minimal to moderate impacts (also dependent on actual numbers), will leave some residual cover in place, and will allow for a reasonable amount of vegetative recovery following timely removal of the livestock (although weeds may eventually tend to comprise a higher percentage of the plants around the trough area than within the surrounding plant community). However, use and stocking rates that exceed the carrying capacity of either the forage or water resources are going to result in substantial area impacts - in extreme cases of up to several square miles in extent.

Minimal to moderate livestock use of water developments and adjacent habitat, while representing a measurable disturbance, still preserves many critical wildlife habitat values such as hiding and escape cover, forage values, and prey base values. Heavy, severe, and extreme use levels correspondingly and increasingly impair and eventually eliminate wildlife habitat values. This is completely counter to longstanding and recommended range management practices. As Vallentine (1974) has observed:

  • Stocking rates cannot be evaluated only in terms of forage since it must be accompanied by adequate drinking water for the grazing animals.
  • Stockwater problems arise on the range:
  • When there are too few watering places.
  • When the water yield or storage, or both, is inadequate.
  • When water sources are poorly distributed.
  • When water developments are wasteful because of leakage or high evaporation.
  • When there are erosion problems at present facilities.

Bell (1973) succinctly admonishes and warns the livestock grazing industry with these statements:

To insure proper distribution and uniformity of grazing, a range requires both careful management of the range and the livestock. It is more difficult to achieve this particular objective than almost any other phase of range management. This is due primarily to the fact that the livestock have to be managed and manipulated more by persuasion and inducement than by direct control. Whatever the cost and trouble, proper distribution and uniformity of grazing are among the most rewarding achievements in range management. Without them, the loss in production can be twofold. First, there is loss from forage production that would be otherwise unused; second, there is loss through continued overuse and progressive expansion of that part of the range used by choice. Improper distribution of grazing, especially when induced by selective use, becomes a continuing and expanding deterioration of a range. Areas of selectivity continue to grow and eventually will engulf the entire range, resulting in severe overuse and poor condition of all the range.

Reasonable management preserves at least functional wildlife habitat values - if not desired ideals. Figures 4.1-13 and 4.1-14 provide an example of the visible (and measurable) differences between a water development that has been grazed, but not to extremes; and a site that has been severely grazed, where wildlife cover and forage values have been substantially impaired. Both are reservoir developments; and though differing in size and site characteristics, both locations were being grazed in 2002 when these photos were taken. The sites are physically separated by approximately 12 air miles.

The formulation of grazing management recommendations as well as regulatory procedures does not insure that implementation will be carried out or "enforced." Figures 4.1-15 and 4.1-16 represent some of the more severe examples of failures to adhere to reasonable standards and guides in relation to water developments; and very obviously illustrate the overstocking and resultant overgrazing issues as described by Vallentine (1974) and Bell (1973).

Wildlife Access and Availability

Wildlife access to water developments and the actual seasonal availability of water are major issues that have not yet been presented in detail within this report. Wildlife access to water developments is rarely if ever discussed in agency planning documents or in agency meetings with the public. As many western surface waters may be completely captured and then stored or provided solely within livestock water developments, the issue of wildlife access to and the seasonal availability of these waters can be critical. It is also important for managers, permittees, and the public to realize that even in instances where water developments (troughs or tanks) are adjacent to a remnant or otherwise functional surface water source - wildlife (particularly birds) will still be biologically attracted to the deeper troughs or tanks. Without the provision of some sort of physical access - trough or tank waters may remain completely out of reach or may represent serous drowning dangers to area wildlife.

Some kinds of water developments are more accessible to wildlife than others. In the case of developments such as dugouts, reservoirs, or similar ground-level impoundments wildlife would typically be able to access the waters in approximately the same manner as a natural lotic or lentic system. Problems may arise due to removal of area plant community values with a corresponding loss of nesting, hiding, escape cover, and of forage or prey-base values. Ground nests or the young of some avian species, as well as small mammals, amphibians, or reptiles may be physically trampled if the impoundments remain heavily occupied (or are frequently accessed) by domestic livestock. Fences or other objects placed in or across impoundments can impede wildlife access or movements.

Water quality may also become a serious issue for impoundments, as water levels decline and the resource is loaded with animal waste products or suffers eutrophication processes. Water quantity may become an issue if livestock exceed the water capacity of the facility - leaving wildlife with no surface water resources. However - wildlife are not likely to physically drown while attempting to utilize impoundments any more than if using a natural lotic or lentic system. Wildlife coming into contact with the waters would hopefully be able to swim to shore or to emergent vegetation (if any exists). Reservoirs or dugouts emptied down to mud could also represent hazards to wildlife such as big game or others that (similar to domestic livestock) can become mired and trapped.

Water troughs and tanks, including large open storage tanks, may be difficult for wildlife to utilize as water resources. Many wildlife species may not be able to physically access the waters within these types of livestock developments. Sides of developments may be too high off the ground for some or even all wildlife to reach over; or may simply be made of materials too smooth (slick) for wildlife to climb up to, hang onto the sides or other structures (e.g. stand pipes) of, or climb out of should they accidentally fall in. (Escape issues will be discussed in greater detail in the following subsection, Wildlife Escape Mechanisms.)

Sherrets (1989) makes the following statements and recommendations for providing wildlife access to watering troughs and tanks:

  • If all available water is captured and the only water outlet source is a trough, wildlife water should be provided through an alternative water outlet. If sufficient water is available, an overflow outlet a little distance from the livestock trough will normally meet wildlife needs. It is best to fence overflow areas so livestock do not trample the outlets.
  • Immature wild ungulates (fawn deer, bighorn sheep lambs, calf elk, antelope kids, etc.) cannot utilize watering facilities that exceed 20 inches above ground level (Illustration 1). Whenever ground-level wildlife drinking facilities are not provided in association with other water developments, the height of livestock troughs or other containers must not exceed 20 inches. Larger troughs may be set below ground level to reach the desired height.

Figures 4.1-17 and 4.1-18 provide portions of Sherret’s illustrations (1989) regarding trough heights.

Sherrets (1989) also notes:

  • If the quantity of water is insufficient to provide separate livestock and wildlife developments, the livestock facility must serve a dual role. This can be accomplished by constructing wildlife ladders which lead into water facilities. These ladders can be constructed of expanded metal or rebar and hardware cloth and should be protected by posts or protective fencing.
  • An alternative method of providing access by small animals to raised troughs is to construct concrete or rock ramps topped with concrete. Advantages of such ramps include minimal maintenance and decreased chance of injury to livestock. Protective fencing would be optional if concrete/rock ramps are used.

During five years of field surveys (1998-2003) across Idaho, Nevada, and Utah this report’s author has never once come upon a livestock trough that was designed or modified specifically to allow access (ingress) by small wildlife species. In fact- the design of a number of guzzlers constructed for wildlife and observed in Idaho do not facilitate use by small species - including birds! A few livestock troughs observed in southern Idaho have been constructed so as to meet the 20-inch access required by young native ungulates. Quite a few troughs observed have been outfitted with escape devices of widely varying designs and efficacy.

However, troughs and tanks outfitted only with escapes do not facilitate or encourage access by small mammals, reptiles, or amphibians. Birds and bats may be able to utilize some troughs and tanks - as some species (e.g. swallows, bats) can drink "on the wing." However - most bird species require a perch (or substrate surface such as soil or rock) from which to drink or bathe. In some instances small wildlife such as mammals or reptiles may be able to physically climb up the braces or sides of some types of troughs - but whether or not they can then physically reach the water presents another obstacle. This scenario is likely one of the causes of accidental drownings in facilities not equipped with adequate escape devices.

Birds can make some use of floatation devices placed in troughs and tanks as perches from which to drink. Unfortunately, these devices are rarely suitable as escapes - by virtue of the fact that they are not placed so as to intercept the paths of drowning wildlife. Tanks and troughs with flotation devices routinely drown a wide variety of bird species (discussed in detail in following subsection, 4.2). In addition, floating wire-wrapped boards, platforms, and other flotation devices are completely useless to small mammals and other terrestrial species such as reptiles. They cannot access these devices to drink from, and even if actually found and accessed by animals that have fallen into a tank or trough terrestrial species must then remain marooned until they die of either starvation or predation.

Figures 4.1-19 through 4.1-22 illustrate some of the access issues discussed above for troughs.

Figure 4.1-23 illustrates access issues for a guzzler - this one apparently intended for game bird or wild ungulate use. The fiberglass catchment basin has not been cleaned or maintained properly, and the surfaces surrounding the water basin are too slick for most small species to negotiate. The water catchment basin was littered with feathers on the visit date - indicating a possible drowning. However, the water within was of such poor quality and clarity that it was impossible to determine if bones (or a carcass) were on the bottom. This is a perfect example of why many researchers and members of the public feel that water developments for wildlife are ineffectual; and at best may be useful to only a very small number of wildlife (or introduced wildlife) species.

Vallentine (1974) notes, "Ramps are often needed to allow livestock, game animals, and birds safe access to water." Sherrets (1989) provides an illustration (figure 4.1-24) of how a trough can be constructed or modified so as to allow for the access (ingress) and safe escape (egress) of smaller wildlife species.

Another wildlife safety concern associated with troughs is the presence of structures that may prevent wildlife from safely accessing livestock water developments - particularly flying species such as birds and bats. Species that drink on the wing typically require an open area free of objects that would hinder approaches to (and movements away from) an open water source. Other barricades and junk may simply prevent safe or easy ground access to a water site - even for larger terrestrial species. Objects may extend the overall reach to water - or if appearing "trap-like" may deter or eliminate use by some species.

Field observations reveal that aerial access to a great many troughs and tanks are blocked by many kinds of foreign structures or objects - ranging from posts and metal bars to barbed wire. While it is recognized that some of these objects have been placed or constructed around, over, or in troughs in an attempt to keep livestock from jumping, falling, or climbing into the water developments - they nonetheless present substantial impediments to use of the facilities by wildlife.

In some cases, drowning victims observed may well have ended up in troughs or tanks after colliding with structures placed over or around the water facilities. Wire can be difficult for many species (including bats) to detect in flight or during pursuit of prey - and may inadvertently be leading to increased fatalities at certain developments. While bats have the ability to echolocate - they do not always use it during flight. Under poor light conditions - such as after dark, during storms, or in the early dawn or late evening hours - wires and other very thin obstructions may not be identified by wildlife in time to avoid a collision. These types of hazards are rarely if ever mentioned in literature or planning documents. Figures 4.1-25 through 4.1-32 illustrate some of the obstructions that may be commonly encountered by wildlife while attempting to utilize livestock water troughs on western rangelands.

The final issue discussed within this subsection is the seasonal availability of waters for wildlife in livestock developments. If developments are only used to provide water resources when domestic livestock are present (which typically varies from early spring to late fall in cooler climates), wildlife that are forced to rely upon the artificial systems (or have grown accustomed to their presence and availability at certain times of the year) may be faced with an unexpected loss of water during critical time periods - such as during migration, during the nesting season, while wildlife are nursing young, or during extremely hot or dry conditions.

Sherrets (1989) makes the following statement and recommendation for providing wildlife with water when cattle are not in a grazing unit:

"The primary beneficiaries of the livestock water should agree to provide wildlife waters during times livestock is not present (except for winter months)."

Although agency planning and regulatory documents may occasionally contain language regarding the availability of water for wildlife when livestock are not physically present in a grazing unit - Sherrets’ guideline does not appear to be routinely carried out in the field. This may create unusual hardships for wildlife - particularly when part or all of natural surface waters have been captured and placed within water development systems.

Figures 4.1-33 through 4.1-40 (all obtained in 2003) illustrate a lack of water in livestock developments during a variety of time periods and/or under extreme conditions critical for a variety of wildlife species - ranging from birds and bats to native ungulates.

A lack of water in water developments is not reserved just for livestock troughs - this problem also extends to those developments created specifically for wildlife. It is not unusual to find wildlife drinker boxes on western rangelands without any water in them. Perhaps no one has turned the system on perhaps the system is not working, or perhaps the wildlife are only allowed water in their developments when domestic livestock are within that grazing unit. Figure 4.1-41 illustrates this concern.

Wildlife Escape Mechanisms

When open containers of water are placed within wildlife habitats, a wide variety of species may be attracted even if natural sources still exist within the region. If natural sources are artificially captured, dry up, are severely contaminated, or otherwise become unavailable to wildlife; species of all kinds may make desperate attempts to access artificial troughs and tanks for the life-giving waters they hold. When waters are only present in troughs and tanks - the danger of accidental drowning of wildlife can reach critical proportions. As thirst increases, the biological needs of wildlife may overcome their natural caution- leading a variety of species to take risks of drowning they would not take under more ordinary circumstances. For biological reasons not fully understood, birds in particular are drawn to the deeper waters of troughs and tanks. In some cases, this may occur because existing surface waters have become so filled with livestock wastes as to be rendered unpalatable.

Other wildlife may inadvertently, through collision with objects or other miscalculations, simply end up falling into a tank or trough. For example, the report author walked up to a trough in Pixley Basin (within the Owyhee BLM Field Office Area in SW Idaho) surprising a large fence lizard. The lizard was apparently catching insects from one of the trough’s wooden braces. The startled reptile jumped off the brace in a panic, landing within the trough. While an excellent swimmer - there was no escape device present in the trough, and had the author not rescued the unfortunate animal - death would have resulted from exhaustion and drowning. (see figure 4.1-42)

It is important to recognize that almost without exception - wildlife species of all sorts (from birds and bats to reptiles and mammals) are excellent swimmers. However, if an animal is unable to escape from a particular situation - such as from waters within a smooth-sided container - they are doomed to eventual exhaustion and drowning. Hypothermia may also play a significant role - depending on water temperatures.

Some waterfowl may be able to gain the air directly from aquatic surfaces; while the Ouzel is adapted to watery environments. However, most passerines (perching birds) and others including raptors (both diurnal and nocturnal -such as hawks and owls) must have dry feathers in order to fly away from danger. If these birds cannot climb onto a safe substrate in order to fluff and dry saturated feathers - even after natural bathing - they are unable to fly to safety. Bats cannot "rise up" from the water and fly away either. While bats typically drink on the wing, if their wings catch the water or if they strike a foreign object they may tumble into the water. Bats are excellent swimmers just like other wildlife - but they are also doomed without some way to escape a container such as a livestock trough. Large animals are also at risk of drowning under some conditions. Sherrets (1989) notes:

  • Often cattle, domestic sheep, wild horses, and other large ungulates will push, crowd, or fight adjacent to a water facility. With the lip of the trough 20 inches above ground level there is the possibility of some ungulates (e.g., domestic sheep, calves, fawn deer, antelope, etc.) falling into the trough. If the water level exceeds 20 inches, the animal may not be able to reach the bottom and stand. Consider installing safety barricades in all livestock watering developments to prevent accidental entry and possible drowning.
  • In addition, escape from a trough by a large ungulate may be more difficult than an accidental entry. Consider installation of concrete blocks and/or rocks to form escape ramps in all livestock water facilities where water depth exceeds 20 inches.

Although not considered by Sherrets, caution must be exercised in attempting to exclude larger animals - as barriers may then impede other kinds of wildlife or result in collision-related drownings of birds and bats. Decisions on how best to allow for wildlife entry and escape or other safety issues, including for livestock, need to be made by utilizing site specific information: such as season of livestock use, wildlife species present, and the potential for alternative water sources for wildlife. In other words - managers need to evaluate the potential use as well as potential risks when considering, constructing, and maintaining any - including those designed primarily for wildlife use.

While this report deals almost exclusively with public rangelands - these same drowning issues apply to troughs or tanks on private lands, and to other bodies of water such as children’s wading pools. For example - the author has received several reports of owls becoming trapped in children’s wading pools. (Owls have a particular penchant for bathing and are attracted to open waters - the author has found several drowned owls in rangeland troughs.) Corral troughs and even buckets represent drowning hazards for birds and other small wildlife. As was mentioned previously, even when natural or surface waters are present - birds may still be drawn instinctively to the deeper containers of water.

Another drowning hazard not specifically discussed by Sherrets is the fact that submerged surfaces quickly become extremely slippery due to the presence of algae, slime molds, and other aquatic organisms. Larger animals may not be able to stand even in shallow water on slippery surfaces or climb rocks or ramps; and smaller wildlife may not be able to climb many kinds of surfaces - including those of escape devices if not properly constructed/installed or properly cleaned and maintained.

In attempts to prevent the drowning of wildlife, a wide variety of escape devices have been created and used in rangeland troughs. Some styles work fairly well, some are excellent, some are highly ineffective, and some are actually dangerous to wildlife. Agency and other researchers have carried out efforts to determine behaviors to be expected from a drowning animal, the most effective designs for providing escape, and methods of retrofitting troughs originally constructed without escapes.

Sherrets (1989) in the BLM Technical Bulletin entitled "Wildlife Watering and Escape Ramps on Livestock Water Developments" notes "Perhaps the most important open trough modifications to small wildlife are escape ladders and ramps installed inside troughs." Sherrets provides the following observations and recommendations:

  • Birds, lizards, rodents, rabbits, and other small animals generally swim the circumference of a tank trying to find a way out. Therefore, wildlife escape ladders must be constructed and installed to intercept the line of travel around the edge of the tank.
  • All wildlife escape ladders should be attached to the watering facility by a hinge or bracket to facilitate trough and ladder cleaning and to reduce the possibility of the ladder being removed. Brackets have proven to be more effective than hinges. If not installed properly, hinges tend to bind and break with prolonged use.
  • Wildlife escape ladders should have a minimum slope of 30 degrees and a maximum of 45 degrees. The more gradual the slope of an escape ladder the more effective it will be.
  • A minimum of one escape ladder per 30 linear feet of trough perimeter should be installed. Information suggests that many small animals become exhausted and drown if forced to swim more than 30 feet. Where troughs are connected in a series (such as 3-10ft troughs), each trough must have escape ladders.

  • It is possible to make wildlife escape ramps serve purposes other than wildlife protection. In water facilities where float valves are installed, the escape ramp may provide a protective cover for the valve, as well as a landing from which animals can drink and a method by which trapped animals can escape.
  • In many grazing areas large open water storage tanks are used. The majority are out of reach of livestock, big game animals, and most small wildlife species (except birds and bats). The livestock trough modifications described are impractical, and usually unnecessary in storage tanks. Some provision to allow trapped birds to escape the deep water is needed. A floating wildlife platform should be installed in all large open water storage tanks. Such a platform will allow birds to escape or to drink. (see figures 4.1-45 through 4.1-48)

However, Sherrets (1989) has failed to recognize a couple of issues that survey efforts for this report have identified in the field. Floating platforms do not necessarily intercept the paths of drowning birds in tanks any more than in troughs - as is been evidenced by the discovery of dead birds and bats floating in large tanks provided with rafts. Big game animals do occasionally access large tanks and face entrapment and/or drowning. Therefore, some additional recommendations are made by this report.

  • Provide multiple rafts in very large storage tanks, as well as one or more escape devices (depending on tank circumference) that are situated so as to intercept the path of drowning birds or bats seeking the tank’s edge. Rafts and other escape devices must be cleaned and maintained on a regular basis.
  • When large, open storage tanks exist - particularly if sides are between 4 and 5 feet in height - immediately adjacent and alternative water resources must be provided for big game species. Otherwise, they may attempt to access the tank- with the possibility of disastrous results, not only for the wildlife but for the water facility as well. (see figures 4.1-49 and 4.1-50)
  • Sherret’s designs show escapes extending to the bottoms of troughs for accessibility at varied water levels. The importance of this should be re-emphasized - as it may not be self-evident. The author has viewed dozens of troughs on western rangelands, where escape devices are either left high and dry (or are fully submerged) as water levels change during the season.
  • Devices must extend fully from the rim to the floor of each livestock trough or tank in order to provide for escape regardless of the water level. This also remedies the plight of hapless small mammals or reptiles and amphibians that fall into a dry tank. While they may not necessarily drown, they still cannot escape the trap if it is constructed of materials that do not provide any climbing traction or other means of escape.

In an apparent effort to cut costs - agencies have been observed to only partially copy a recommended design, without realizing that their actions may result in additional drownings. The attitude that something is better than nothing does not excuse public lands failures to properly install and maintain functional wildlife escapes. Many wildlife escape devices may serve limited purposes- such as wire wrapped pieces of boards floating in troughs or tanks. However, these may not be intercepted by drowning wildlife, and do not provide an adequate substrate for use by larger bird species. The author has observed drowned birds, bats, and small mammals in troughs where these boards have been provided. Tire troughs- made from large tractor tires are one of the more difficult to provide with escapes due to the curved surfaces and lip at the top rim. Sherrets (1989) provides numerous examples of how to retrofit a variety of trough designs, including tractor tires, to make them safer for wildlife. (see figures 4.1-51 through 4.1-57)

Occasionally accidents will happen - even with properly installed and maintained escapes. Just like humans who have an auto accident, fall off a ladder, or slip on an icy sidewalk - wildlife have accidents too. Some organisms may simply have less natural caution than others; others simply end up in the wrong place at the wrong time. However, the provision of properly constructed, properly installed, and properly maintained escapes will prevent most if not nearly all potential drownings from occurring. Unfortunately, as is the case with so many management plans and recommendations, provision and maintenance of wildlife escapes may not actually be occurring at the field level.


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*Figure 4.1-57

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