• Book Review: The Economics of Non-Convex Ecosystems, Partha Dasgupta, Karl-Goran Maler (Eds.)

      Batabyal, Amitrajeet A. (Society for Range Management, 2005-07-01)
    • An Unmanned Aerial Vehicle for Rangeland Photography

      Hardin, Perry J.; Jackson, Mark W. (Society for Range Management, 2005-07-01)
      Because of its perceived impracticality and expense, aerial photography from unmanned aerial vehicles (UAVs) remains virtually unused as a rangeland management tool. This underuse suggested 2 objectives. The first was to develop a UAV from off-the-shelf components that could acquire low-altitude large-scale photography for rangeland documentation. The second was to assess the UAV flight characteristics. A remotely controlled UAV suitable for 35-mm photography was built in 56 hours at a cost of 1 480. In a 2-year test period, the UAV successfully completed 100+ sorties at elevations ranging from 10 m to 1 000 m above ground. The average distance required for takeoff is 18.2 m whereas landing requires an average of 22.5 m. Average UAV airspeed at takeoff is about 11.4 m s-1. Typical cruise speed during photograph acquisition is 13.8 m s-1, resulting in 6.9 mm of blur from forward-image motion. The UAV is an inexpensive tool for monitoring rangeland condition from an aerial perspective. It is currently being used to map squarrose knapweed (Centaurea virgata Lam. ssp. squarrosa Gugl.) density at several rangeland sites in Utah.  
    • A Visual Obstruction Technique for Photo Monitoring of Willow Clumps

      Boyd, Chad S.; Svejcar, Tony J. (Society for Range Management, 2005-07-01)
      Quantifying woody plant biomass has often proven difficult in the field for reasons that include irregular plant morphology, between-observer variability, and lack of standardized techniques. One potential solution to these challenges is the use of ground-based photographic technology. Our objective was to develop a photo-based technique that could be used to monitor changes in willow (Salix spp.) biomass over time and estimate changes in biomass associated with herbivory. We focused on young willows (2 m in height) because this size class represents a critical life history stage for establishment of willow clumps. In August 2000 and 2001, we harvested 25 willow (Salix boothii Dorn.) clumps and clamped them in front of a fluorescent orange photoboard (150 X 200 cm). Clumps were defoliated of leaves and tips of current annual stem growth (referred to as ‘‘biomass’’) by hand in 4 to 7 increments and photographed before and after each removal. Images were scanned to digital format and the degree of photoboard obstruction was determined with Adobe® Photoshop® 4.0 software. Regression analysis indicated that visual obstruction of the photoboard was a good predictor of total clump biomass (r2 = 0.89, P < 0.01) as well as biomass remaining following sequential defoliations (r2 = 0.92, P < 0.01). These results suggest our technique provides a reliable index of both willow biomass and utilization within the size class of willow tested. Results might differ with larger willows and increased woody biomass. The technique minimizes observer bias and provides a permanent photo record that can be reanalyzed at a later date if necessary.  
    • Feeding Value of Singed Walkingstick Cholla

      Sawyer, Jason E.; Endecott, Rachel L.; Löest, Clint A.; Petersen, Mark K. (Society for Range Management, 2005-07-01)
      Walkingstick cholla cactus (Opuntia imbricata [Haw.] DC) has been used in New Mexico as an emergency feed during drought for more than 100 years. Most reports present only the chemical composition of walkingstick cholla, and limited data exist regarding its feeding value. Three wethers (avg wt 65 +/- 7 kg) were fed a basal diet of mature blue grama hay (Bouteloua gracilis [HBK] Lag. ex Steud., 9.0% crude protein [CP] and 69.0% neutral detergent fiber [NDF], organic matter [OM] basis) in a replicated 3 X 3 Latin square to determine digestibility of singed walkingstick cholla and to measure nitrogen balance. Treatments consisted of 0%, 15%, and 20% walkingstick cholla in the diet on a dry matter (DM) basis. Walkingstick cholla contained 20.3% DM, 79.6% OM, 36.4% NDF, and 9.0% CP (OM basis). Walkingstick cholla clippings, consisting of green, nonwoody cladodes, were harvested in September. Cactus was singed with a propane torch until no spines remained, chopped, and added to the diet each day. Walkingstick cholla and hay were sampled daily and compiled by period. Total fecal and urine collections were subsampled and frozen for later analysis. Feed and fecal samples were analyzed for DM, OM, NDF, and nitrogen (N); urine samples were analyzed for N. Nutrient digestibilities and N-retention values were calculated. Walkingstick cholla digestibilities were determined by difference. Mean walkingstick cholla DM, OM, NDF, and CP digestibilities averaged 32.6%, 44.3%, 27.9% and 67.6%, respectively. Diet OM and CP digestibilities were similar for all treatments. Diet DM digestibility tended (P = 0.08) to decrease linearly with increasing dietary walkingstick cholla. As walkingstick cholla increased in the diet, NDF digestibility decreased linearly (P = 0.04). Because of its poor feeding value and low DM content, use of walkingstick cholla as an emergency feed should be carefully considered.  
    • New Mexico Blue Grama Rangeland Response to Dairy Manure Application

      Stavast, Lanson J.; Baker, Terrell T.; Ulery, April L.; Flynn, Robert P.; Wood, M. Karl; Cram, Douglas S. (Society for Range Management, 2005-07-01)
      New Mexico supports over 290 000 dairy cattle. These cattle produce large quantities of manure. It has been suggested excess dairy manure could be applied to rangelands as an organic fertilizer to increase soil fertility and herbaceous production. Manure was applied June 2000 to a rangeland in New Mexico dominated by blue grama (Bouteloua gracilis (Willd. ex Kunth) Lag. ex Griffiths) according to phosphorus (P) content: a recommended (light) rate (54 kg P ha-1) to enhance blue grama growth and a gross overapplication (heavy) rate (493 kg P ha-1) to determine their effects on vegetation. The actual application rate of manure on a dry weight basis was 0, 11 739, and 107 174 kg ha-1. Four replications of control, light, and heavy rates were established. Herbaceous standing crop (kg ha-1) was similar 1 growing season after manure application, and greater 2 and 3 growing seasons after application on the light treatment compared with the control. Initially the heavy treatment suppressed herbaceous standing crop; thereafter, standing crop responded in a linear fashion to rainfall. Three growing seasons after manure application, basal cover was similar between light and control treatments, whereas the heavy treatment continued to be characterized principally by manure/litter cover. Heavy disposal-oriented treatments are not suitable for blue grama rangelands because of persistent declines in herbaceous cover and changes in soil salinity. A light manure application rate that is based on P content can increase forb and in particular grass standing crop on arid blue grama rangelands. Successful rangeland manure applications will depend on proper management to insure objectives are met while minimizing any hazards to the environment.  
    • Fall-Prescribed Burn and Spring-Applied Herbicide Effects on Canada Thistle Control and Soil Seedbank in a Northern Mixed-Grass Prairie

      Travnicek, Andrea J.; Lym, Rodney G.; Prosser, Chad (Society for Range Management, 2005-07-01)
      Prescribed burning in Theodore Roosevelt National Park has played an important role in maintaining a natural ecosystem. However, changes in plant community dynamics caused by burning may have led to an invasion of weedy species such as Canada thistle (Cirsium arvense L.). The objectives of this research were to evaluate the effect of a fall burn before spring herbicide application on Canada thistle control and to evaluate the soil seedbank within Canada thistle infestations. Canada thistle stem densities initially were higher in the burned compared with the nonburned areas because plants were slower to emerge in the nonburned treatments. However, the effect was short-lived, and Canada thistle densities were similar in the burned and nonburned treatments by the second season following the prescribed burn. Canada thistle control averaged 78% 60 days after treatment with clopyralid, clopyralid plus triclopyr, or picloram when spring applied whether or not application was preceded by a prescribed burn. Control declined to less than 60% by 363 days after application. Grass cover increased from an average of 5% before treatment to 37% and 46% 60 and 425 days after herbicide application, respectively, regardless of burn treatment. Forb cover increased following a prescribed burn but was unaffected by herbicide treatment. Overall the number and variety of species in the soil seedbank was not affected by a prescribed burn. A total of 74 species (56 forbs, 13 grasses, and 5 other mesic species) were found in the soil seedbank. However, the majority of the soil seedbank consisted of nondesirable low seral and invasive species including Canada thistle and Kentucky bluegrass (Poa pratensis L.), which accounted for over 80% of the total germinated seed. Although a prescribed burn caused an initial increase in Canada thistle density and cover, the greater long-term concern may be the lack of desirable species present in the seedbank to replace Canada thistle once the weed is controlled.  
    • Remote Sensing Assessment of Paspalum quadrifarium Grasslands in the Flooding Pampa, Argentina

      Herrera, Lorena P.; Hermida, Vanina Gómez; Martínez, Gustavo A.; Laterra, Pedro; Maceira, Néstor (Society for Range Management, 2005-07-01)
      The knowledge of the distribution, area, and current conservation status of relict natural grasslands dominated by the tall-tussock grass Paspalum quadrifarium Lam. (‘‘pajonal’’) in the Flooding Pampa (Argentina) is relevant for the identification of conservation sites and sustainable management and land-use planning. Since European settlement, vast areas of pajonal were converted to croplands and short-grass prairies. The only available vegetation map of these grasslands was made in the mid-20th century. We evaluated 2 methods of land-cover classification (supervised and unsupervised) using a Landsat TM satellite image over an area of 2 258.21 km2 in Ayacucho county, where pajonal still persists as an important ecosystem. At the paddock scale, this grassland community presents a complex structure in which the pajonal is not a pure category but a mosaic of tall and short grasses. Six categories of land cover were adopted (crops, sown pastures, short grasses, pajonal, wetlands, and urban areas). A very good overall accuracy was obtained for both classifications (86.9% and 87.9% for supervised and unsupervised classifications, respectively). However, both producer’s and user’s accuracies for the pajonal and short grasses were better for the unsupervised classification than for the supervised classification. The pajonal class occupied only 20% of the study area with patch size ranging between 0.09 and 1 653 ha. This work suggests an important replacement of tall-tussock grass by short-grass matrix, which represents noticeable structural and functional changes. The unsupervised classification of Landsat image seems a particularly suitable method for mapping complex vegetation units like the highly fragmented pajonal of the Flooding Pampa and should be an important tool for management and tracking future changes.  
    • Silver Sagebrush Community Associations in Southeastern Alberta, Canada

      Jones, Paul F.; Penniket, Roy; Fent, Livio; Nicholson, Joel; Adams, Barry (Society for Range Management, 2005-07-01)
      Greater sage-grouse (Centrocercus urophasianus) habitat in southeastern Alberta is limited by the distribution of silver sagebrush (Artemisia cana Pursh). We conducted a landscape assessment of silver sagebrush throughout the current range of sage-grouse in southeastern Alberta. Black-and-white aerial photography acquired in the fall of 2001 was used to map silver sagebrush. Contact print stereo pairs were interpreted using a stereoscope and initially classified into 1 of 13 site classes based on soil type and landscape feature (e.g., recent agriculture). Each site polygon was further broken down into smaller polygons based on the percentage of silver sagebrush occupancy, density distribution, and height. A total of 4 626 site polygons were identified and classed into 1 of 13 site classes. To ensure all assumptions of statistical tests were met, the data set was reduced to 9 site classes. The mean percentage of silver sagebrush occupancy was significantly different between the 9 site classes (F = 285.00, df = 8, P < 0.001). The lotic site class had the highest mean percentage of occupancy, followed by overflow and old cultivated site classes. The frequencies of density distribution were not equal for all site classes (Pearson’s chi-square = 5 727.09, df = 72, P < 0.001). Lotic had greater than expected occurrences in distribution classes 8 through 12 whereas overflow had greater than expected occurrences in distribution classes 8 and 10. The frequencies of height class were not equal for all site classes (Pearson’s chi-square = 4 382.15, df = 24, P < 0.001). Lotic and overflow sites had greater than expected occurrences in the mixed and tall height classes, whereas blowouts, loamy and saline lowlands had greater occurrences in the small height class. Understanding the occupancy, density distribution, and height of silver sagebrush across the landscape will assist in understanding the resource selection patterns and management of sage-grouse in Alberta, Canada.  
    • Interspecific Competition Interacts with the Spatial Distribution of a Palatable Grass to Reduce Its Recruitment

      Cipriotti, Pablo A.; Aguiar, Martín R. (Society for Range Management, 2005-07-01)
      Most arid and semiarid ecosystems around the world have been grazed by domestic herbivores. In many cases, grazing has degraded vegetation and soil. The possibility of restoring rangeland’s good condition depends, partially, on the ability of remaining populations of desirable species to recover. In this work, we studied the exact spatial distribution of remaining palatable adult plants in fields with different grazing history (i.e., seed sources) and quantified the effect of interspecific competition with less palatable grasses on seedling emergence and survival (i.e., regeneration constraints). We worked in a Patagonian steppe composed of shrubs and perennial tussock grasses that has been grazed by sheep for >100 years. In order to evaluate the location of seed sources, we mapped the location of a palatable species (Bromus pictus Hook.) in paddocks with different long-term grazing intensity. In addition, we sowed seeds of B. pictus close to 2 dominant, less palatable grasses in 2 different years to evaluate the role of interspecific interactions on regeneration and the effects of climate variability. The proportion of B. pictus plants growing in protected places near less palatable species significantly increased with grazing intensity. Competition effects on emergence, survival, and growth depended on the year’s moisture regime. During the dry year, competition with less palatable grasses reduced the emergence, survival, height, and number of leaves of palatable grass seedlings by 30%, 55%, 48%, and 40%, respectively. In the wet year, there were no effects of competition on emergence and height, and the effects on survival depended on the species of the less palatable neighbors. Our study supports the idea that management for recovering degraded rangelands in this ecosystem may benefit from considering the spatial distribution of remaining plants. It also indicates that the susceptibility of demographic processes to interspecific competition depends on the year and neighbor species.  
    • Spring Growth and Use of Cool-Season Graminoids in the Nebraska Sandhills

      Volesky, Jerry D.; Schacht, Walter H.; Reece, Patrick E.; Vaughn, Timothy J. (Society for Range Management, 2005-07-01)
      Upland sites in the Nebraska Sandhills are dominated by warm-season grasses, although cool-season graminoids often produce from 10% to 40% of the herbage. The grazing season on uplands traditionally begins when warm-season grasses have initiated rapid growth, which coincides with declining nutrient density of cool-season plants. Earlier initiation of grazing would improve the efficiency of use of cool-season plants. A study was conducted in 2001 and 2002 to characterize the growth of cool-season species on upland range and to determine the use and herbage production in response to spring grazing date and stocking rate. Grazing dates were 10 April, 1 May, and 22 May, combined with stocking rates of 3, 6, and 9 AUD (animal unit days) ha-1. Needleandthread (Stipa comata Trin. Rupr.) and sedges (Carex spp.) accounted for an average of 48% of the spring herbage yield. Amount of total current-year herbage ranged from 114 to 472 kg ha-1 over the grazing dates. Overall, paddock use of needleandthread and sedges averaged 11% and 4%, respectively. Use on 10 April averaged 61% of that observed on 1 and 22 May, likely because of short plant height (5 cm). Residual (prior-year) herbage probably was a substantial component of animal diets on 10 April. Increasing stocking rate resulted in greater herbage use (% weight removed) and percentage of plants grazed (P < 0.1). Total herbage yield in mid-June (1 130 kg ha-1) and mid-August (1 350 kg ha-1) was greatest when paddocks were grazed in April, and it declined by approximately 20% when grazed in May (P < 0.1). Overall, upland grazing strategies that include a grazing period in early May will result in greater utilization of cool-season species, but summer yield will be reduced. However, utilization of cool-season species in the spring would be advantageous, because they are being consumed at a time when their nutritive value and palatability are greater.  
    • Consequences of Selecting Rambouillet Ewes for Mountain Big Sagebrush (Artemisia tridentata ssp. vaseyana) Dietary Preference

      Seefeldt, Steven S. (Society for Range Management, 2005-07-01)
      A dense mountain big sagebrush (Artemisia tridentata Nutt. ssp. vaseyana [Rydb] Beetle) canopy suppresses understory vegetation. Rambouillet ewes with high and low dietary preferences for mountain big sagebrush were tested for their ability to reduce the cover of dense stands of sagebrush. Eighty ewes with high and low preferences for mountain big sagebrush were grazed in October on 8 pastures with a 33% shrub cover for 3 years. Even though near infrared reflectance spectroscopy measurements of feces indicated that high-preference ewes consumed up to twice as much mountain big sagebrush than did low- preference ewes (P < 0.005), there was no difference in the reduction of sagebrush canopy between the high- and low- preference ewes (P = 0.46). Indeed, grazing did not reduce mountain big sagebrush more than in the ungrazed pastures. However, ewes with a high preference for mountain big sagebrush consumed more antelope bitterbrush (Purshia tridentata [Pursh] DC.) (P < 0.05) than did low-preference ewes (length reductions of 30 cm and 10 +/- 3.7 cm [mean +/- SE], respectively). In this study, the selection of ewes with a dietary preference for mountain big sagebrush had the unintended consequence of selecting ewes with a dietary preference for antelope bitterbrush. Antelope bitterbrush is a desirable shrub in sagebrush steppe ecosystems, and reductions in antelope bitterbrush as a result of altered livestock preferences will reduce rangeland health. Animals selected with a dietary preference for one plant species must be screened to determine what other plants they will preferentially select to limit potential negative consequences for plant communities and ecosystems.  
    • Diets of Prairie Dogs, Goats, and Sheep on a Desert Rangeland

      Mellado, Miguel; Olvera, Abundio; Quero, Adrián; Mendoza, Germán (Society for Range Management, 2005-07-01)
      Diets of prairie dogs, goats, and sheep were examined by microhistological fecal analysis during 4 periods of a year in a desert rangeland in northern Mexico. Prairie dogs selected more grasses (79% across all seasons; P < 0.05) than goats and sheep during most of the year. Total grasses in goat diets were consistent (20%) in all seasons, whereas this forage class was highest during winter (72%) and lowest during summer (62%) in sheep diets. The diet of goats was predominantly shrubs (45%-62%) in all seasons, whereas sheep and prairie dogs ate little browse throughout the study. All 3 species preferred forbs, which contributed about one-third to the composition of the prairie dog (winter), goat (summer), and sheep (spring) diets. Acacia greggii Gray and Opuntia rastrera Weber were the most preferred species by goats, whereas prairie dogs and sheep showed particular preference for Buchloe dactyloides (Nutt.) Engelm. and Bouteloua gracilis (Willd. ex Kunth) Lag. ex Griffiths. During summer and spring, concentration of nitrogen in the feces of sheep was 36% and 17% higher (P < 0.05) than in the feces of goats. There was a high overlap in diets between prairie dog and sheep in all seasons, whereas diets of prairie dogs and goats, and goats and sheep were significantly different from each other in all seasons. These results showed that competition was keen between prairie dogs and sheep for a limited quantity of forage in this arid zone pasture, whereas goats were better able to use common resources with prairie dogs.  
    • Elk and Mule Deer Diets in North-Central New Mexico

      Sandoval, Leonard; Holechek, Jerry; Biggs, James; Valdez, Raul; VanLeeuwen, Dawn (Society for Range Management, 2005-07-01)
      Botanical composition of mule deer and elk diets in winter, spring, summer, and autumn was studied during 1998 and 1999 on woodland rangeland in north-central New Mexico using microhistological analysis of fecal samples. Our study area had no livestock grazing for 60 years but was moderately grazed by mule deer and elk. Elk and mule deer shared 3 of the top 5 key forage species when diets were pooled across seasons and years. These 3 species were oak (Quercus sp.), ponderosa pine (Pinus ponderosa Dougl.), and mullein (Verbascum thapsus L.). When data were pooled across seasons and years, overall dietary overlap between mule deer and elk was 64%. Diet overlaps of 50% or more occurred between mule deer and elk in all 4 seasons in both years of study. Throughout both years, mule deer and elk diets were dominated by browse. Mountain mahogany (Cercocarpus montanus Raf.) was the most abundant browse plant in mule deer diets; ponderosa pine was most abundant in elk diets. Both animals selected forbs, which were in low supply during the study. Scarlet globemallow (Sphaeralcea coccinea Pursh), a nutritious forb, was common in both mule deer and elk diets. Our study and others from woodland rangelands in New Mexico show high potential for forage competition between mule deer and elk. Elk are more dietarily adaptable to changing forage availability than are mule deer. Our study indicates that diets of mule deer and elk are not complementary on woodland rangelands in New Mexico. Therefore, grazing capacity is not increased by common-use grazing of the 2 animals. Both mule deer and elk herds have been increasing on our study area. Therefore, if use of common forage species is kept at moderate levels on southwestern woodland rangelands, mule deer herds can be maintained or increased when elk are present.  
    • Rainfall, Temperature, and Forage Dynamics Affect Nutritional Quality of Desert Mule Deer Forage

      Marshal, Jason P.; Krausman, Paul R.; Bleich, Vernon C. (Society for Range Management, 2005-07-01)
      Forage quality affects physiological condition, population dynamics, habitat use, and distribution of ungulates. We studied how rainfall, temperature, forage biomass, and forage growth are related to water content, crude protein (CP), and in vitro dry- matter digestibility (IVDMD) of some common forage species of desert mule deer (Odocoileus hemionus eremicus Mearns) in the Sonoran Desert, California. We established vegetation transects in desert washes to collect forage samples and to measure forage biomass, growth, rainfall, and temperature on a quarterly basis. Percent water and CP were positively associated with forage growth (P < 0.001) and with rainfall (P < 0.025). There were positive relationships between IVDMD and forage growth (P < 0.001), forage biomass (P < 0.001), and the combination of temperature and rainfall (P < 0.001). These findings suggest that the highest quality landscapes for deer are those with rapidly growing forage where forage water, CP, and IVDMD are greatest. With the quantified relationships between rainfall, temperature, and forage characteristics presented here, the nutritional constituents for deer forage can be predicted.  
    • The Effects of Livestock on California Ground Squirrels (Spermophilus beecheyii)

      Fehmi, Jeffrey S.; Russo, Sabrina E.; Bartolome, James W. (Society for Range Management, 2005-07-01)
      Understanding the impacts of livestock grazing on wildlands is important for making appropriate ecosystem management decisions. Using livestock exclosures, we examined the effects of moderate cattle grazing on the abundance of California ground squirrels (Spermophilus beecheyii Richardson) and the spatial distribution of active burrows within their colonies in grassland and blue oak (Quercus douglasii Hook. Arn.) savanna habitats in the coastal range of California over a 3-year period (1991-1994). Overall, relative population densities of California ground squirrels declined significantly throughout the experiment, but did not differ between grazed and ungrazed colonies or between habitats. There was also no significant interaction between these 2 factors. The spatial distribution of burrows, as measured by the mean nearest neighbor distance of active entrances within a colony, did not differ significantly between grazed and ungrazed colonies or between habitats, nor was the interaction significant. Thus, low to moderate levels of cattle grazing did not appear to have a strong effect on the population dynamics of California ground squirrels, and grazing may be compatible with maintenance of ground squirrel populations. Based on multivariate analysis of variance of 1994 data, live plant cover, native plant cover, and standing biomass were lower where the number of burrows was higher on grazed colonies but were little affected on ungrazed colonies. Ground squirrels may increase the impact of livestock grazing and thus reduce the capacity of the land to support other activities. However, it is clear that the effects of livestock grazing are complex and that detailed studies of potential mechanisms by which grazing impacts California ground squirrel populations are necessary.  
    • Arizona Permittee and Land Management Agency Employee Attitudes Toward Rangeland Monitoring by Permittees

      Fernandez-Giminez, Maria E.; McClaran, Susan Jorstad; Ruyle, George (Society for Range Management, 2005-07-01)
      Ongoing conflicts over the management of western rangelands can be attributed in part to the lack of reliable information about current ecological conditions and their causes due, in turn, to insufficient monitoring. To meet the monitoring shortfall, land management agencies increasingly are enlisting permittees to monitor their grazing allotments. We surveyed grazing permittees in 5 Arizona counties and land management agency employees throughout Arizona to compare their attitudes toward permittee monitoring on public rangelands, the role of government in rangeland management, rangeland conditions in Arizona, and the credibility of information sources about rangelands. Permittees and agency employees differed in most of the attitudes measured by our survey. However, both populations agreed that permittees should participate in monitoring their allotments, and many respondents agreed with making permittee monitoring mandatory. Many respondents in both groups also agreed that collaboration can be beneficial. Joint monitoring, which can be considered a type of ‘‘joint fact-finding,’’ may help improve agency-permittee relationships and bridge the gap in attitudes and underlying values. Permittee-monitoring programs deserve careful evaluation to determine their impacts on social relationships, management decisions, and ecological conditions 
    • Survivorship and Causes of Mortality for Livestock-Guarding Dogs on Namibian Rangeland

      Marker, Laurie L.; Dickman, Amy J.; Macdonald, David W. (Society for Range Management, 2005-07-01)
      This paper reports upon the survivorship of 143 livestock-guarding dogs placed on Namibian rangeland between January 1994 and January 2002 as part of a study of techniques that could be used to reduce stock losses on commercial ranches and communal farms. During the study period, 61 (42.7%) of the dogs placed were removed from working situations. Deaths accounted for 49 (80.3%) of removals, while the remaining 12 (19.7%) were transfers out of the program. Causes of death varied by both farm type and age group. The most common cause of death for working dogs, especially young ones, was accidental, which accounted for 22 reported deaths, while culling of the dog by the owner was the reason for 12 working dog deaths, all of which occurred on commercial ranches. The mean survival time as a working dog was estimated as 4.16 (+/-0.40) years for males, 4.65 (+/-0.45) years for females, and 4.31 (+/-0.31) years for all dogs placed. Survival distributions differed slightly (P = 0.049) between farm types, with adult mortality less common on communal farms than on commercial ranches. There was no significant difference (P = 0.612) between the sexes regarding survival distributions. With good care of the dogs and sufficient information provided to farmers, guarding dogs can act as an effective and economically beneficial method of livestock protection, with implications for range management both in Namibia and elsewhere.