• Using the Green and Ampt infiltration equation on native and plowed rangeland soils

      Hutten, N. C.; Gifford, G. F. (Society for Range Management, 1988-03-01)
      Soil textural relationships were used on 3 soil series on both plowed and native rangeland to predict Green and Ampt infiltration equation parameters. Infiltration rates predicted from the Green and Ampt soil texture relationships were regressed against field infiltration rates. Good predictability was found on only 4 of 94 plots, all of which were in the agricultural area. Results indicate that current soil texture relationships developed for estimating infiltration rates may not be sufficient for use in either agricultural or rangeland semiarid environments. At this point in time, if infiltration values are important, then they should be measured (not estimated) using appropriate methodologies.
    • Using Unmanned Helicopters to Assess Vegetation Cover in Sagebrush Steppe Ecosystems

      Breckenridge, Robert P.; Dakins, Maxine; Bunting, Stephen; Harbour, Jerry L.; Lee, Randy D. (Society for Range Management, 2012-07-01)
      Evaluating vegetation cover is an important factor in understanding the sustainability of many ecosystems. Remote sensing methods with sufficient accuracy could dramatically alter how biotic resources are monitored on both public and private lands. Idaho National Laboratory (INL), in conjunction with the University of Idaho, evaluated whether unmanned aerial vehicles (UAVs) are sufficiently accurate and more efficient than the point-frame field method for monitoring vegetative cover and bare ground in sagebrush steppe ecosystems. These values are of interest to land managers because typically there are limited natural resource scientists and funding for comprehensive ground evaluations. In this project, unmanned helicopters were used to collect still-frame imagery to determine vegetation cover during June and July 2005. The images were used to estimate percent cover for six vegetative cover classes (shrub, dead shrub, grass, forbs, litter, and bare ground). Field plots used to collect imagery and on-the-ground measurements were located on the INL site west of Idaho Falls, Idaho. Ocular assessments of digital imagery were performed using SamplePoint, and the results were compared with field measurements collected using a point-frame method. The helicopter imagery evaluation showed a high degree of agreement with field cover class values for grass, litter, and bare ground and reasonable agreement for dead shrubs. Shrub cover was often overestimated, and forbs were generally underestimated. The helicopter method took 45% less time than the field method. This study demonstrates that UAV technology provides a viable method for monitoring selective types of cover on rangelands and could save time and resources./Evaluar la cobertura vegetal es un importante factor para entender la sustentabilidad de muchos ecosistemas. Métodos de teledetección con suficiente precisión pueden considerablemente alterar la manera en como los recursos bióticos son monitoreados tanto en propiedad privada y pública. El laboratorio Nacional de Idaho (INL), en conjunto con la universidad de Idaho, evaluaron si vehículos aéreos no tripulados (UAVs) son suficientemente precisos y más eficientes que los métodos de campo basados en punto de referencia para monitorear la cobertura de las vegetación y el suelo desnudo en los ecosistemas de pastizales de Artemisia. Estas evaluaciones son de interés para los manejadores de tierra ya que normalmente hay poco scientíficos dedicados al estudio de los recursos naturales así como escasos recursos monetarios para evaluaciones integrales. En este proyecto, helicópteros no tripulados fueron usados para recolectar imágenes usadas para determinar la cobertura vegetal durante junio y julio de 2005. Las imágenes fueron usadas para estimar el porcentaje de cobertura de seis clases de cubierta vegetal (arbustos, arbustos muertos, pastos, herbáceas, hojarasca y suelo desnudo). Parcelas de campo que fueron usadas para recolectar las imágenes así como las mediciones en campo fueron localizadas en el sitio INL al oeste de Idaho Falls, Idaho. Evaluaciones oculares de imágenes digitales fueron realizadas usando SamplePoint y los resultados fueron comparados con las mediciones de campo recolectadas usando el método de point-frame. La evaluación de las imágenes recolectadas por el helicóptero mostró un alto grado de correlación con respecto a las evaluaciones de campo para pastos, hojarasca, y suelo desnudo, y una razonable relación para plantas muertas. Las cobertura de los arbustos fue regularmente sobrestimado y para las herbáceas fueron generalmente subestimadas. El método del helicóptero tomo 45% menos tiempo que el método de campo. Este estudio demostró que la tecnología UAV proporciono un método viable para monitorear los tipos selectivos de cobertura en los pastizales y podría salvar tiempo y recursos.
    • Using Very-Large-Scale Aerial Imagery for Rangeland Monitoring and Assessment: Some Statistical Considerations

      Karl, Jason W.; Duniway, Michael C.; Nusser, Sarah M.; Opsomer, Jean D.; Unnasch, Robert S. (Society for Range Management, 2012-07-01)
      The availability of very-large-scale aerial (VLSA) imagery (typically less than 1 cm ground-sampling-distance spatial resolution) and techniques for processing those data into ecosystem indicators has opened the door for routinely using VLSA imagery in rangeland monitoring and assessment. However, for VLSA imagery to provide defensible information for managers, it is crucial to understand the statistical implications of designing and implementing VLSA image studies, including consideration of image scale, sample design limitations, and the need for validation of estimates. A significant advantage of VLSA imaging is that the researcher can specify the scale (i.e., spatial resolution and extent) of the images. VLSA image programs should plan for scales that match monitoring questions, size of landscape elements to be measured, and spatial heterogeneity of the environment. Failure to plan for scale may result in images that are not optimal for answering management questions. Probability-based sampling guards against bias and ensures that inferences can be made to the desired study area. Often collected along flight transects, VLSA imagery lends itself well to certain probability-based sample designs, such as systematic sampling, not often used in field studies. With VLSA image programs, the sample unit can be an entire image or a portion of an image. It is critical to define the sampling unit and understand the relationship between measurements and estimates made from the imagery. Finally, it is important to statistically validate estimates produced from VLSA images at selected locations using quantitative data of the same scale and more precise and accurate than the VLSA image techniques. The extent to which VLSA imagery will be useful as a tool for understanding the status and trend of rangelands depends as much on the ability to build the imagery into robust programs as it does on the ability to quickly and relatively easily collect VLSA images over large landscapes./La disponibilidad de imágenes aéreas a gran escala (IAGE) (normalmente menos de un cm de de distancia de resolución espacialen el terreno) y técnicas que procesen esos datos dentro de indicadores del ecosistema han abierto la puerta para que de manera rutinaria se use IAGE en pastizales en monitoreo y evaluación. Sin embargo, para IAGE proveer información defendible para administradores es crucial para entender las implicaciones estadísticas para diseñar e implementar estudios de IAGE que incluyan consideraciones de escala de la imagen, limitaciones en el diseño de muestreo y la necesidad de validación de los estimadores. Una ventaja significativa de IAGE es que el investigador puede definir la escala (ejm. resolución espacial y extensión) de la imagen. Los programas de IAGE deberían planear escalas que empaten preguntas de monitoreo, el tamaño delos elementos del paisaje a ser medidos y la heterogeneidad espacial del medioambiente. Fallas en planear la escala puede resultar en imágenes que no son optimas en resolver las preguntas del administrador. Muestreos basados en probabilidad protegen contra sesgo y aseguran que la inferencia puede ser hecha para la area de estudio deseada. Seguido, recolección a lo largo de vuelos en transectos, IAGE permite bien a cierto diseño de muestra basado en probabilidad como diseño sistemático nousado a menudo en estudios de campo. Con programas IAGE la unidad de muestreo puede ser la imagen completa o una porción de ésta. Es fundamental definir la unidad de muestreo y entender la relación entre medidas y estimaciones hechas de la imagen. Finalmente, es importante validar estadísticamente los estimadores producidos de IAGE es lugares seleccionados usando datos cuantitativos de la misma escala y más precisos y certeros que las técnicas de IAGE. La amplitud a la cual IAGE será de utilidad como herramienta para entender el estatus y tendencia de los pastizales, depende en gran medida en la habilidad para construir imágenes en programas robustos sino también con la habilidad de recolectar imágenes IAGE rápidamente y relativamente fácil sobre grandes paisajes.
    • Using Weather Data to Explain Herbage Yield on Three Great Plains Plant Communities

      Smart, Alexander J.; Dunn, Barry H; Johnson, Patricia S.; Xu, Lan; Gates, Roger N. (Society for Range Management, 2007-03-01)
      Understanding the drivers that account for plant production allows for a better understanding of plant communities and the transitions within ecological sites and can assist managers in making informed decisions about stocking rates and timing of grazing. We compared climatic drivers of herbage production for 3 plant communities of the Clayey ecological site in southwestern South Dakota: the midgrass community dominated by western wheatgrass (Pascopyrum smithii [Rybd.] A. Love); the mixed-grass community codominated by western wheatgrass, blue grama (Bouteloua gracilis [H.B.K.] Lag. Ex Griffiths), and buffalograss (Buchloe dactyloides [Nutt.] Engelm.); and the shortgrass community dominated by blue grama and buffalograss. We used herbage yield and weather data for the period 1945-1960 collected at the South Dakota State University Range and Livestock Research Station near Cottonwood, South Dakota, to develop stepwise regression models for each plant community. Midgrass herbage production was best predicted by current-year spring (April-June) precipitation, number of calendar days until the last spring day with minimum temperature 18C, and previous-year spring precipitation (R2 = 0.81). Mixed-grass herbage production was best predicted by current-year spring precipitation and days until the last spring freeze (R2 = 0.69). Shortgrass herbage production was best predicted by current-year spring precipitation (R2 = 0.52). Midgrass plant communities were, overall, 650 kg ha-1 (SE = 92 kg ha-1) more productive (P < 0.01) than mixed- or shortgrass plant communities given the same climatic inputs. Our study enables managers to make timely informed decisions regarding stocking rates and timing of grazing on this ecological site in western South Dakota. 
    • Using Weather Records with a Forge Production Model to Forecast Range Forage Production

      Wight, J. R.; Hanson, C. L.; Whitmer, D. (Society for Range Management, 1984-01-01)
      This paper describes a method for calculating site specific forecast yields and their associated probabilities of occurrence. A physically based range forage model, which utilizes beginning soil water content and daily precipitation, mean air temperature, and solar radiation as inputs, calculates the ratio of actual transpiration (T) to potential transpiration (Tp) as a yield index. Annual yield is calculated by the relationship: yield = potential site yield (yield when water is nonlimiting) × T/Tp. By using the current year's beginning soil water content and weather data for a number of years, a population of yields is generated (one yield for each year of weather data). From the population of yields, a mean and various confidence intervals around the mean can be calculated as the forcast yield and its associated confidence intervals. The forecast procedure was tested using 55 years (1917-1971) of weather records and 12 years (1967-1978) of actual yield and soil water data for an upland range site in eastern Montana. An expected two thirds of the field measured yields were within a standard deviation of the forecasted yields for the April, May, and June forecasts.
    • Utah's Big Game, Livestock, and Range Relationship Research

      Julander, O. (Society for Range Management, 1951-09-01)
    • Utilization and grazing distribution of cattle at 4 stocking densities

      Burboa-Cabrera, F. R.; Schacht, W. H.; Anderson, B. E. (Society for Range Management, 2003-07-01)
      The relationship between stocking density and grazing distribution was studied in eastern Nebraska pastures seeded to a warm-season, tall-grass mixture and grazed at 4 stocking densities: 9, 18, 27, and 54 steers ha-1. Each of 4 pastures was divided into 4 paddocks ranging in size from 0.18 to 1.12 ha. Paddocks within each pasture were grazed rotationally by 10 steers averaging 282 kg during 3 consecutive cycles (12, 36, and 24 days) from early June to late August in 1995 and 1996. Transects 12-m long were established in a grid pattern in each paddock. Six tillers each of big bluestem (Andropogon gerardii Vitman) and switchgrass (Panicum virgatum L.) were marked permanently in each transect. Height and leaf length of marked tillers were measured before and after grazing in the last 2 grazing cycles in both years. Utilization was estimated by the reduction in tiller height or leaf length. Estimates of grazing distribution were based on a uniformity index, which was calculated by summing the absolute differences of tiller height or leaf length between adjacent transects. Stocking density generally did not affect (P > 0.05) tiller height reduction which ranged from 19 to 22 cm and from 29 to 38 cm among the stocking densities in 1995 and 1996, respectively. In most grazing cycles, leaf length reduction for big bluestem was greater (P < 0.05) than for switchgrass while tiller height reduction was similar between species. Spatial grazing distribution was not affected (P > 0.05) by stocking density but big bluestem was grazed more evenly (P < 0.05) than switchgrass in the last cycle in each year. Stocking densities as high as 54 steers ha-1 on warm-season, tall-grass mixtures do not appear to be a major factor in affecting spatial grazing distribution or forage plant selection.
    • Utilization of Fringed Sagewort on a Winter Sheep Range

      Spang, E. F. (Society for Range Management, 1954-03-01)
    • Utilization of globemallow (Sphaeralcea) taxa by sheep

      Rumbaugh, M. D.; Mayland, H. F.; Pendery, B. M.; Shewmaker, G. E. (Society for Range Management, 1993-03-01)
      Globemallows (Sphaeralcea spp.) are well adapted to semiarid and arid environments. They are potentially useful as the forb component of seeding mixtures for rangeland improvement in the western states. However, the degree of acceptability of globemallow forage to livestock has not been well established. We tested 13 globemallow accessions representing 4 species and compared their utilization by sheep (Ovis aries) with that of crested wheatgrass [Agropyron cristatum (L.) Gaertn. X A. desertorum (Fisch.) Schult.] and alfalfa (Medicago sativa L.) during fall 1988 and 1989, and spring 1990 and 1991. Alfalfa consistently produced more forage per plant than wheatgrass or globemallows, and a greater portion of the alfalfa was eaten than of the other species. Sheep utilized wheatgrass more than globemallows in the fall, but the converse was true during spring pasturing. Over the 4 years, sheep ate similar proportions of wheatgrass and individual globemallows. The percentage of S. coccinea (Pursh) Rydb. forage consumed equaled that of crested wheatgrass or alfalfa in the fall but did not equal the percentage of alfalfa consumed in spring. However, S. coccinea produced much less total forage than the other species evaluated. Pre-grazing plant dry weight, dry matter content, and the occurrence of rust caused by Puccinea sherardiana Korn were negatively associated with globemallow utilization. Over-winter mortality of grazed globemallow exceeded that of ungrazed plants. Crested wheatgrass and alfalfa stands were not reduced by grazing. Globemallows are acceptable, but not highly preferred, forbs which can be seeded in environments where alfalfa and other more desirable species are not adapted.
    • Utilization of Grasslands in the Flint Hills of Kansas

      Kansas. , Utilization Of. (Society for Range Management, 1953-03-01)
    • Utilization of larkspur by sheep

      Ralphs, M. H.; Bowns, J. E.; Manners, G. D. (Society for Range Management, 1991-11-01)
      Sheep are more resistent to larkspur (Delphinium spp.) poisoning than are cattle, and may be used as a biological tool to graze larkspur prior to cattle turn-in to reduce the risk of cattle poisoning. Sheep utilization of 3 species of larkspur was measured at 3 phenological growth states (vegetative, bud, and flower) at 5 locations. Utilization of waxy larkspur (D. glaucescens Wats), varied among years at Ruby, Mont. Use of duncecap larkspur (D. occidentals. Wats) at Oakley, Ida., was uniformly higher in all 3 growth stages due to closed herding practices. Use of tall larkspur (D. barbeyi Huth) increased as it matured. Trailing sheep through larkspur patches, or bedding them in patches greatly increased trampling of larkspur stalks and utilization of heads and leaves.
    • Utilization of linear prediction procedures to evaluate animal response to grazing systems

      Winder, J. A.; Beck, R. F. (Society for Range Management, 1990-09-01)
      Best linear unbiased prediction (BLUP) procedures were used to separate genetic merit from environmental effects on 205-d weight (205-d wt) of calves produced by cows grazing 2 pasture systems. Phenotypic measures of 205-d wt were statistically partitioned into genetic effects (breeding value) and environmental effects. Means were regressed on year of birth of calf. Analysis of covariance was used to test difference in slope and elevation (means) of the regression lines. The continuously grazed pasture (CC) produced higher 205-d wt than did the rotationally grazed pastures (RG) (P<.10). Rate of change in 205-d wt was similar in the 2 grazing systems. Genetic merit was similar among the animals in the 2 grazing systems. The rate of change per year in genetic merit (genetic trend) was also similar. Means tended to vary sharply from year to year, indicating inequality of genetic merit should be taken into account in this type of data. Mean environmental effects resulted in greater (P<.10) 205-d weight in CG than in RG. Rate of change of environmental quality was similar in the 2 systems. These results indicate, from the animals perspective, the RG system did not improve productivity when compared to CG. The CG system was of higher nutritional quality, but the rate of change was similar to that of the RG system.
    • Utilization of the Major Plant Communities in the Similkameen Valley, British Columbia

      McLean, A.; Lord, T. M.; Green, A. J. (Society for Range Management, 1971-09-01)
      The plant communities of the ponderosa pine zone in southern British Columbia offer best returns from grazing by domestic and wild ungulates. The communities of the douglasfir zone should usually be considered integrated-use areas, having significant values for both grazing and timber production. The subalpine fir zone has its main value for timber production although grazing values usually persist for many years in the lower part of the zone after logging or burning. However, the upper part of the above zone is suited mainly for grazing. Although the alpine tundra has very limited forage production it sometimes provides summer range for bighorn sheep. Since the climate is usually favorable below 3000 feet elevation, arable agriculture should be considered where soils are not restrictive.
    • Utilization of White Locoweed (Oxytropis sericea Nutt.) by Range Cattle

      Ralphs, M. H.; James, L. F.; Pfister, J. A. (Society for Range Management, 1986-07-01)
      Utilization studies conducted on a high mountain range determined the quantity and timing of white locoweed (Oxytropis sericea Nutt.) consumption by cattle. Paired plots (one caged and one grazed) were clipped at the end of the grazing season to determine seasonal utilization. Biweekly visual appraisals were used to estimate percentage leaf grazed and number of reproductive stalks grazed and thus determine utilization patterns as the season progressed. Loco comprised 26% of the standing crop. Thirty-four percent of the available loco was utilized during the grazing season. Loco flower and pods (heads) were preferred to leaves. Utilization of loco heads increased linearly as the season progressed. Loco leaves were not consumed until the last 3 weeks of the grazing season. Loco heads also contained the highest concentration of the toxic alkaloid, swainsonine.
    • Utilization of Winter Range Forage by Sheep

      Green, L. R.; Sharp, L. A.; Cook, C. W.; Harris, L. E. (Society for Range Management, 1951-07-01)
    • Utilization patterns by Angora goats within the plant canopies of two Acacia shrubs

      Owens, M. K. (Society for Range Management, 1991-09-01)
      Uneven distribution of livestock in large pastures results in some areas receiving more use than the average and some areas receiving little or no use. Six 2-ha experimental pastures on a shallow ridge site were stocked with 2, 4, or 6 Angora goats per ha to reflect different levels of use found in large pastures of south Texas. Two additional pastures on a sandy loam site were stocked with 2 goats per ha. Utilization estimates were made in each pasture using a twig diameter-weight relationship. Estimates of utilization of guajillo (Acacia berlandieri) and blackbrush (A. rigidula) were made in canopy strata which the goats could reach in a quadrupedal stance (low), a bipedal stance (middle), and from the zone above the bipedal stance (high). These measurements were repeated 3 times during the grazing season. Nonlinear regressions of diameter on weight (Y = aXb) collected from plants in control pastures provided a better fit than log-log regressions in almost every instance. Fit index values, which are analogous to R2 values for linear equations, ranged from 0.82 to 0.94 for nonlinear equations and from 0.62 to 0.88 for the log-log regressions. Goats exhibited different grazing strategies by using the canopy strata differently for the 2 plant species. Percent utilization in the middle strata was higher than in either of the other 2 canopy strata within each grazing treatment and for each plant species. Cumulative use in the middle strata for guajillo was 79% compared to 63% in the low and 28% in the high strata. Blackbrush also had highest use in the middle strata with 39% use compared to 27 and 9% for the low and high canopies, respectively. By the third sampling period, use of guajillo in the 2 lowest canopy strata declined and use of blackbrush increased over the first 2 sampling periods. Average grazed twig diameter within each grazing treatment did not vary significantly in the low strata throughout the growing season. On heavily used sites, averaged grazed twig diameter increased in the 2 highest canopy layers as the season progressed. The size of grazed twigs in the middle zone on the heaviest grazed sites was significantly higher than in any other canopy strata.
    • Utilization Practices and the Returns from Seeding an Area to Crested Wheatgrass

      Godfrey, E. B. (Society for Range Management, 1979-05-01)
      Numerous studies have estimated the benefits and costs of various types of range improvements, including seedings. However, the results reported have varied widely. One of the reasons why these estimates have varied is that the effect of utilization (season and amount) has generally not been explicitly considered. In an effort to provide some insight into the effect utilization has on returns, a study of the Point Springs seedings in south-central Idaho was undertaken. This study indicated that: (1) spring utilization of crested wheatgrass seedings is a necessary prerequisite to favorable net returns; (2) grazing patterns involving heavy utilization had the shortest life, but the highest net returns; (3) fall only utilization had the lowest net returns; (4) the net returns from seeding the area were greater than the investment costs for nearly all utilization patterns considered; and (5) seeding an area to crested wheatgrass can yield returns which may be greater than the returns from investing scarce investment dollars in other range improvement alternatives.
    • Utilizing National Agriculture Imagery Program Data to Estimate Tree Cover and Biomass of Piñon and Juniper Woodlands

      Hulet, A.; Roundy, B. A.; Petersen, S. L.; Bunting, S. C.; Jensen, R. R.; Roundy, D. B. (Society for Range Management, 2014-09)
      With the encroachment of piñon (Pinus ssp.) and juniper (Juniperus ssp.) woodlands onto sagebrush steppe rangelands, there is an increasing interest in rapid, accurate, and inexpensive quantification methods to estimate tree canopy cover and aboveground biomass. The objectives of this study were 1) to evaluate the relationship and agreement of piñon and juniper (P-J) canopy cover estimates, using object-based image analysis (OBIA) techniques and National Agriculture Imagery Program (NAIP, 1-m pixel resolution) imagery with ground measurements, and 2) to investigate the relationship between remotely-sensed P-J canopy cover and ground-measured aboveground biomass. For the OBIA, we used eCognition® Developer 8.8 software to extract tree canopy cover from NAIP imagery across 12 P-J woodlands within the Sagebrush Steppe Treatment Evaluation Project (SageSTEP) network. The P-J woodlands were categorized based on the dominant tree species found at the individual sites for the analysis (western juniper, Utah juniper, and mixed P-J community). Following tree canopy cover extractions, relationships were assessed between remotely-sensed canopy cover and ground-measured aboveground biomass. Our OBIA estimates for P-J canopy cover were highly correlated with ground-measured tree canopy cover (averaged across all regions r=0.92). However, differences between methods occurred for western and Utah juniper sites (P<0.05), and were more prominent where tree canopy cover was >40%. There were high degrees of correlation between predicted aboveground biomass estimates with the use of remotely-sensed tree canopy cover and ground-measured aboveground biomass (averaged across all regions r=0.89). Our results suggest that OBIA methods combined with NAIP imagery can provide land managers with quantitative data that can be used to evaluate P-J woodland cover and aboveground biomass rapidly, on broad scales. Although some accuracy and precision may be lost when utilizing aerial imagery to identify P-J canopy cover and aboveground biomass, it is a reasonable alternative to ground monitoring and inventory practices. © 2014 The Society for Range Management.
    • Utilizing Remote Sensing and GIS to Detect Prairie Dog Colonies

      Assal, Timothy J.; Lockwood, Jeffrey A. (Society for Range Management, 2007-01-01)
      The locations of black-tailed prairie dog (Cynomys ludovicianus [Ord]) colonies on a 550-km2 study site in northeastern Wyoming, United States, were estimated using 3 remote sensing methods: raw satellite imagery (Landsat 7 ETM+), enhanced satellite imagery (integration of imagery with thematic layers via a Geographic Information System), and aerial reconnaissance (observations taken from a small plane). A supervised classification of the raw satellite imagery yielded an overall accuracy of 64.4%, relative to ground-truthed locations of prairie dog colonies. The enhanced satellite imagery, resulting from a filtering of the data based on an index derived from the sum of weighted ecological factors associated with prairie dog colonies (slopes, land cover, soil, and ‘‘greenness’’ via the Normalized Difference Vegetation Index) yielded an overall accuracy of 69.2%. The aerial reconnaissance method provided 65.1% accuracy. The highest rate of false positives resulted from the aerial reconnaissance method (39.9%). The highest rate of false negatives resulted from the raw satellite imagery (60.0%), a value that was markedly reduced via the enhancement with ecological data from thematic layers (45.8%). Given the accuracy, interpretability of results, repeatability, objectivity, cost, and safety, the enhanced satellite imagery method is the recommended approach to large-scale detection of black-tailed prairie dog colonies. If a greater accuracy is required, this method can be employed as a coarse filter to narrow the scale and scope of a more costly and laborious fine-scale analysis effectively.