Sand Sagebrush Research Articles

Chemical Control of Sand Sagebrush: Implications for Lesser Prairie-Chicken Habitat

Abstract Traditional management of sand sagebrush (Artemisia filifolia) rangelands has emphasized sagebrush control to increase forage for livestock. Since the 1950s shrub removal has been primarily achieved with herbicides. Concerns over declining lesser prairie-chicken (Tympanuchus pallidicinctus; LPC) populations have led to increased scrutiny over the use of herbicides to control shrubs. The objective of our research was to describe changes to LPC habitat qualities following chemical control of sand sagebrush in northwest Oklahoma. Study pastures ranged in size from 10 to 21 ha. Five pastures were sprayed with 2,4-dichlorophenoxyacetic acid (2,4-D) in 2003 (RECENT), five were sprayed with 2,4-D in 1984 (OLD), and four received no treatment (SAGE). We measured habitat structure (sagebrush cover, sagebrush density, visual obstruction [VO], and basal grass cover), and dietary resources (forb density, forb richness, and grasshopper density) in all pastures from 2003 to 2006. OLD and RECENT pastures had le...

Effects of sand sagebrush control in southern mixed-grass prairie rangeland on cattle performance and economic return

<h2>ABSTRACT</h2> To evaluate the effects of sand sagebrush (Artemisia filifolia Torr.) control in native rangelands on cattle performance, 15 pastures (10 to 21 ha each) were selected in northwest Oklahoma. Eleven pastures had been sprayed with 2,4-dichlorophenoxyacetic acid in 1984 or 2003 to establish differences in sagebrush cover. The pastures were categorized into 3 sagebrush cover levels: 1) high (27 ± 2.7% cover, n=4), 2) medium (10 ± 2.7% cover, n=6), and 3) low (5 ± 2.7% cover, n=5). From 2003 to 2008, steers (BW = 202 ± 6.1 kg) were stocked annually in late January and grazed until mid-August. The high, medium, and low pastures were stocked at 47, 69, and 69 animal-unit-d/ha, respectively. Cattle were supplemented with oilseed-based cubes (41% CP) from January through April at a rate of 0.68 kg/ steer daily. From January to April, ADG did not differ (P = 0.96) among treatments, but from April to August steers grazing the high pastures gained BW faster (P < 0.01; 1.03 kg) than did steers grazing medium pastures (0.96 kg) or low pastures (0.98 kg). Gain of BW and net return per hectare were greatest (P < 0.01) for low pastures (102 kg, $123.20) compared with high (67 kg, $88.71) or medium (81 kg, $97.74) pastures. These results suggest that increasing levels of sagebrush control coupled with appropriate adjustments in stocking rates may be most profitable for stocker cattle production, but this removal of sagebrush could limit the ecological services that rangeland provides because of loss of protective cover for wildlife.

Restoration of the fire–grazing interaction in Artemisia filifolia shrubland

Summary1. Patterns of landscape heterogeneity are crucial to the maintenance of biodiversity in shrublands and grasslands, yet management practices in these ecosystems typically seek to homogenize landscapes. Furthermore, there is limited understanding of how the interaction of ecological processes, such as fire and grazing, affects patterns of heterogeneity at different spatial scales.2. We conducted research in Artemisia filifolia (Asteraceae) shrublands located in the southern Great Plains of North America to determine the effect of restoring the fire–grazing interaction on vegetation structure. Data were collected for 3 years in replicated pastures grazed by cattle Bos taurus where the fire–grazing interaction had been restored (fire and grazing = treatment pastures) and in pastures that were grazed but remained unburned (grazing only, no fire = control pastures). The effect of the fire–grazing interaction on heterogeneity (variance) of vegetation structure was assessed at scales from 12·5 m2 to 609 ha.3. Most measurements of vegetation structure within treatment pastures differed from control pastures for 1–3 years after being burned but were thereafter similar to the values found in unburned control pastures.4. Treatment pastures were characterized by a lower amount of total heterogeneity and a lower amount of heterogeneity through time.5. Heterogeneity of vegetation structure tended to decrease as the scale of measurement increased in both treatment and control pastures. There was deviation from this trend, however, in the treatment pastures that exhibited much higher heterogeneity at the patch scale (mean patch size = 202 ha) of measurement, the scale at which patch fires were conducted.6. Synthesis and applications. Vegetation structure in A. filifolia shrublands of our study was readily altered by the fire–grazing interaction but also demonstrated substantial resilience to these effects. The fire–grazing interaction also changed the total amount of heterogeneity characterizing this system, the scale at which heterogeneity in this system was expressed and the amount of heterogeneity expressed through time. Land managers seeking to impose a shifting mosaic of heterogeneity on this vegetation type can do so by restoring the fire–grazing interaction with potential conservation benefits similar to what has been achieved in other ecosystems where historic cycles of disturbance and rest have been restored.

Topoedaphic Variability and Patch Burning in Sand Sagebrush Shrubland

Patch burning is the deliberate application of fire to a management unit in a heterogeneous manner, resulting in the heterogeneous distribution of grazing animal impact. The application of patch burning typically has been discussed within a framework of imposing heterogeneity on a homogeneous landscape or management unit, yet most landscapes and management units are actually distinguished by an inherent level of heterogeneity. Within landscapes and management units, differing topography and soils interact to create patterns of contrasting patches, also known as topoedaphic sites. Thus, introduction of a heterogeneous disturbance such as patch burning on a landscape or management unit is more accurately described as the imposition of one layer of heterogeneity onto a pre-existing layer of heterogeneity. We examined effects of patch burning on vegetation structure and animal distribution across contrasting topographical sites in sand sagebrush (Artemisia filifolia Torr.) shrubland of the southern Great Plains in North America. Landscapes at our study site were characterized by an inherent amount of heterogeneity in vegetation structure due to variability in topoedaphic sites, and the patch burning treatment superimposed additional heterogeneity that was constrained by topoedaphic characteristics. Shrub-dominated sites were more dependent on patch burning for heterogeneity of vegetation structure than sites dominated by short grasses. Distribution patterns of cattle (Bos taurus) were not significantly different across treatments, though they followed patterns similar to previous studies. We demonstrated that heterogeneity was dependent on topoedaphic patterns and the application of patch burning management for heterogeneity was dependent on the inherent variability of a landscape.

Fire tolerance of a resprouting Artemisia (Asteraceae) shrub

In North America, most Artemisia (Asteraceae) shrub species lack the ability to resprout after disturbances that remove aboveground biomass. We studied the response of one of the few resprouting Artemisia shrubs, Artemisia filifolia (sand sagebrush), to the effects of prescribed fires. We collected data on A. filifolia density and structural characteristics (height, canopy area, and canopy volume) in an A. filifolia shrubland in the southern Great Plains of North America. Our study sites included areas that had not been treated with prescribed fire, areas that had been treated with only one prescribed fire within the previous 5 years, and areas that had been treated with two prescribed fires within the previous 10 years. Our data were collected at time periods ranging from ½ to 5 years after the prescribed fires. Density of A. filifolia was not affected by one or two fires. Structural characteristics, although initially altered by prescribed fire, recovered to levels characteristic of unburned areas in 3–4 years after those fires. In contrast to most non-sprouting North American Artemisia shrub species, our research suggested that the resprouting A. filifolia is highly tolerant to the effects of fire.

Aboveground Macroinvertebrate Diversity and Abundance in Sand Sagebrush Prairie Managed With the Use of Pyric Herbivory

Through pyric herbivory (i.e., fire-induced grazing patterns), native grasslands were historically a spatially heterogeneous environment. It is hypothesized that the mosaic of habitats created by pyric herbivory supports a more diverse invertebrate community compared to modern range management. Patch-burn management, a pyric herbivory technique, is an application of prescribed fire and grazing whereby the timing and location of the burned and grazed patches is varied, creating a diversity of habitat conditions. Although disturbance in sandsage (Artemisia filifolium Torr.) prairie historically included fire and grazing, fire disturbance has been nearly eradicated from this ecosystem in western Oklahoma. We compared patch-burn management to traditional management (i.e., moderate grazing with no fire) in sandsage prairie to evaluate the impact of these two management regimes on aboveground invertebrates. We sampled invertebrates at 44 points in each of 3 mo (May, June, and July) with the use of Dietrick vacuum sampling. Diversity, total abundance, and abundance of seven invertebrate orders (Araneae, Diptera, Hemiptera, Homoptera, Hymenoptera, Lepidoptera, and Orthoptera) were similar between patch-burn and traditional pastures. When examined on a patch level, five invertebrate orders were also similar between their respective time since burn patch and the traditional patches. Araneae and Coleoptera abundance were higher in traditional patches, and Hemiptera abundance was higher in current-year burn patches. Our results suggest a heterogeneity-based management scheme based on pyric herbivory does not negatively impact the overall invertebrate community and may benefit a wider variety of invertebrates by providing areas of varying levels of disturbance. In comparison, homogeneous landscapes such as those created by traditional management may only benefit segments of the invertebrate community that have habitat associations with moderately disturbed or undisturbed areas. Therefore, a disturbance regime involving the interaction of fire and grazing may be valuable for maintaining biodiversity and productivity within sandsage prairie ecosystems.

Spatial Ecology and Factors Influencing Movement Patterns of Desert Massasauga Rattlesnakes (Sistrurus catenatus edwardsii) in Southeastern Colorado

The Massasauga Rattlesnake (Sistrurus catenatus) occurs from extreme southeastern Canada to northern Mexico, and most populations are highly threatened due to habitat loss and fragmentation. Although their range is reduced from historical levels, they may be locally abundant in appropriate habitat. We studied movement patterns, home range and core activity centers, habitat use, and prey abundance in a robust population of Desert Massasauga Rattlesnakes (S. c. edwardsii) in southeastern Colorado by radiotracking 36 snakes over four active seasons (May–October). In the spring, snakes made long-distance directed movements (mean = 1.89 km) from the hibernacula (shortgrass, compacted clay soils) to summer foraging areas (mixed-grass/Sand Sagebrush, sandhills). Summer activity was characterized by short distance non-directional movements, and snakes were most often observed at the base of Sand Sagebrush (Artemisia filifolia). Home ranges and core activity centers were significantly larger for males than for females, but daily movements, total distance moved, and range length did not differ significantly between sexes. Prey base surveys indicated a significantly higher abundance of both rodents and lizards in summer foraging grounds than at hibernation sites. Snakes returned to the hibernaculum area in October and appeared to hibernate individually in rodent burrows. Migration patterns exhibited by S. c. edwardsii are likely resource driven, with the migratory movements observed in the spring resulting in utilization of summer foraging habitat with more abundant prey. Conversely, hibernacula with greater thermal and structural stability in the shortgrass habitat (perhaps due to the compacted clay soils versus loose sandy soils) favor migratory return for torpor in the fall. At present, the main populations in Colorado occur far from developing regions in the state, but due to habitat loss and fragmentation resulting from projected agricultural expansion and urbanization, these populations may be threatened in the future.

Biomass Not Linked to Perennial Grass Mortality Following Severe Wildfire in the Southern High Plains

In March 2006 the East Amarillo Complex (EAC) wildfires burned over 367 000 ha of short and mixed grass prairie of the southern High Plains, USA. We studied EAC wildfire effects on perennial grass mortality and peak standing crop on Deep Hardland and Mixedland Slopes ecological sites. Deep Hardlands were dominated by blue grama ( Bouteloua gracilis H.B.K. [Griffiths]) and buffalograss ( Buchloe dactyloides [Nutt.] Engelm.); common species on Mixedland Slopes were little bluestem ( Schizachyrium scoparium [Michx.] Nash.) and sideoats grama ( Bouteloua curtipendula [Michx.] Torr.) with scattered sand sagebrush ( Artemisia filifolia Torr.) sometimes present. We hypothesized that perennial grass mortality would increase and standing crop would decrease following severe wildfire, and that these responses would be greater than documented prescribed fire effects. Frequency of perennial grass mortality was higher on both sites in burned areas than nonburned areas through three growing seasons following wildfire; however, standing crop was minimally affected. Results suggest that post-wildfire management to ameliorate wildfire effects is not necessary, and that wildfire effects in this area of the southern High Plains are similar to prescribed fire effects. En Marzo de 2006 los incendios del Complejo del Este de Amarillo (CEA) quemaron más de 367.000 ha de estepas de pastos cortos y mixtos del sur de las Altas Planicies de EE.UU. Estudiamos los efectos del incendio del CEA sobre la mortalidad de pastos perennes y la biomasa total acumulada en dos sitios ecológicos denominados Deep Hardland (DH) y Mixedland Slopes (MS). Las especies dominantes en el sitio DH fueron Bouteloua gracilis H.B.K. [Griffiths] y Buchloe dactyloides, mientras que las especies comunes en el sitio MS fueron Schizachyrium scoparium [Michx.] Nash.y Bouteloua curtipendula [Michx.] Torr. con la presencia esporádica de individuos de Artemisia filifolia Torr. Nuestra hipótesis predijo que los incendios severos aumentarían la mortalidad de pastos perennes y disminuirían la biomasa en pie y que dichas respuestas serian mayores a las documentadas en quemas prescriptas. En ambos sitios, la frecuencia de mortalidad de pastos perennes fue mayor en áreas quemadas que en áreas no quemadas a lo largo de tres estaciones de crecimiento posterior al incendio; no obstante, la biomasa en pie fue mínimamente afectada. Los resultados sugieren que el manejo post-incendio tendiente a atenuar los efectos del mismo no es necesario, y que los efectos de los incendios en esta región sur de las Altas Planicies es similar a la de las quemas prescriptas.

The Sex Pheromone of the Sand Sagebrush Carpenterworm, Holcocerus artemisiae (Lepidoptera, Cossidae)

(Z)-5-dodecen-1-ol (Z5-12:OH), (Z)-5-dodecenyl acetate (Z5-12:Ac), and (Z)-5-tetradecenyl acetate (Z5-14:Ac) were found in the extracts of the female sex pheromone gland of the carpenterworm moth Holcocerus artemisiae Chou et Hua, a pest of Artemisia filifolia. The average amounts of Z5-12:OH, Z5-12:Ac, and Z5-14:Ac in a single sex pheromone gland of a calling moth were (7.14 +/- 0.73) ng, (54.20 +/- 0.34) ng, and (38.70 +/- 0.46) ng, respectively. Electroantennography (EAG) of these compounds and their analogues demonstrated that Z5-12:Ac excitated the largest male EAG response, followed by Z5-14:Ac. Traps baited with rubber septa impregnated with Z5-12:Ac (500 microg/septum) and Z5-14:Ac (300 microg/septum) were more effective than traps with other baits or virgin females. Addition of Z5-12:OH to rubber septa did not enhance the trap catches, but (E,Z)-3,5-dodecadienyl acetate (E3,Z5-12:Ac) enhanced the trap catch.

Breeding and Non‐Breeding Survival of Lesser Prairie‐Chickens Tympanuchus pallidicinctus in Texas, USA

Lesser prairie‐chickens Tympanuchus pallidicinctus have declined throughout their range because of loss or fragmentation of habitat from conversion of native prairie to agricultural cropland, exacerbated by overgrazing and drought. We used data from radio‐marked lesser prairie‐chickens to determine whether differences in survival existed between populations occurring in two areas dominated by different vegetation types (sand sagebrush Artemisia filifolia vs shinnery oak Quercus havardii) in the Texas Panhandle from 2001 through 2005. We used a model‐selection approach to evaluate potential generalities in lesser prairie‐chicken survival. Our results indicated that survival of lesser prairie‐chickens differed between breeding and non‐breeding periods, and between study populations. We estimated annual survival of lesser prairie‐chickens at 0.52 (95% CI: 0.32–0.71) in the sand sagebrush and 0.31 (95% CI: 0.12–0.58) in the shinnery oak vegetation type. Our results suggest that demographic differences in lesser prairie‐chicken within sand sagebrush and shinnery oak vegetation types throughout the Texas Panhandle should be evaluated, especially during the breeding season. Based on our results, higher mortality of birds during the breeding season illustrates the need to manage for vegetation components such as sand sagebrush and residual bunchgrasses as opposed to shinnery oak such that potential breeding season mortality may be lessened.

Land cover associations of nesting territories of three sympatric Buteos in shortgrass prairie

Abstract Three species of Buteo hawks nest sympatrically in the southern Great Plains of the United States. Dietary overlap among them is broad and we tested the hypothesis these species partition their breeding habitat spatially. We compared land cover and topography around 224 nests of the three species breeding in shortgrass prairie in 2004 and 2005. Red-tailed Hawks (Buteo jamaicensis) nested almost exclusively in riparian timber surrounded by prairie (95% prairie land cover around nests) and disproportionately used areas with greater topographic relief within prairie landscapes. Swainson's Hawks (B. swainsoni) commonly nested in low-relief areas dominated by small-grain production agriculture but generally used habitats in proportion to availability. Most nest sites of Ferruginous Hawks (B. regalis) were in prairie (78% prairie land cover around nests), but some were in areas that were at least partially agricultural. Ferruginous Hawks had at least two times more sand sagebrush (Artemisia filifolia) ...

Management Implications of Cover Selection Data: Northern Bobwhite Example

Abstract: We derived a method of estimating the direction and magnitude of cover changes for potentially maximizing wildlife abundance on an area. We illustrate the method with data on cover selection by northern bobwhites (Colinus virginianus) collected in the Texas Panhandle from 2000 to 2003. We used radiotelemetry to determine use of cover associations, Geographic Information System analysis to determine their availability, and logic related to use‐availability analysis to collapse 95% kernel home ranges to usable space. Bobwhites selected mixed‐shrub cover consisting of sand plum (Prunus angustifolia) and fragrant sumac (Rhus aromatica), and they avoided or neutrally used 8 other cover associations. However, grass upland and sand sagebrush (Artemisia filifolia) associations occurred in ≥86% of home ranges (n = 96 bobwhites with ≥30 radiolocations). Usable space averaged 54.2% ± 1.72 SE of kernel home ranges. The data indicated that adding about 226 ha of mixed‐shrub cover or a structural homologue while simultaneously reducing the quantity of most other cover associations would maximize bobwhite abundance. An area with 30–60% mixed‐shrub cover, with the balance in grass upland and sand sagebrush, and with cover dispersed such that no point was &gt;30 m from mixed‐shrub cover was hypothetically optimal for bobwhites in our region. Within certain constraints (e.g., financial, social, edaphic), managers can apply this method by manipulating cover types through relevant management practices (e.g., planting, prescribed burning, mechanical removal of vegetation). This method, with minor modification, could also be used to decrease usable space on an area, and thus decrease wildlife densities, should that be the manager's objective.

Stocking Rate and Weather Impacts on Sand Sagebrush and Grasses: A 20-Year Record

Abstract Understanding how stocking rate or grazing intensity affects the abundance of common plant species is fundamental to the sustainable management of rangelands. We had the unique opportunity to determine the impact of stocking rate on shrub canopy cover and grass basal cover in a sand sagebrush (Artemisia filifolia Torr.) grassland of the Southern Plains, United States. Treatments were imposed over a 20-year time span that included an entire precipitation cycle from wet to dry and back to wet conditions. From 1941 until 1951, continuous stocking treatments of 41, 53, and 82 animal-unit-days ha−1 (AUD·ha−1) were imposed with straight-bred Hereford steers (initial weight of 213 kg ± 11 SE) for about 320 days from mid-November to late September of the next year. From 1952 through 1961, the experimental pastures were grazed yearlong by cow-calf pairs at 45, 60, and 87 AUD·ha−1. Canopy cover of shrubs and basal cover of grasses were measured by the line-intercept method in 1940, 1942, 1949, 1955, 1958, ...

NESTING ECOLOGY OF LESSER PRAIRIE-CHICKENS IN SAND SAGEBRUSH PRAIRIE OF SOUTHWESTERN KANSAS

Despite the fact that the Lesser Prairie-Chicken (Tympanuchus pallidicinctus) is a species of conservation concern, little is known about its nesting ecology, particularly in sand sagebrush (Artemisia filifolia) habitats. To find and monitor nests, we captured and equipped 227 female Lesser Prairie-Chickens with transmitters (87 yearlings, 117 adults, and 23 of unknown age) from 1997 to 2002 in southwestern Kansas. Apparent nest success was similar for yearlings (31%, n = 74) and adults (27%, n = 97) but differed marginally (P = 0.090) between first nests (29%) and renests (14%). An estimated 31% of females that were unsuccessful in their first nesting attempt initiated a second nest. The probability that a female would initiate a second nest after failure of the initial attempt was negatively influenced by the day of incubation on which the initial attempt failed. Over 95% of all nests were initiated and completed between 5 May and 2 July. The primary cause of nest failure was predation by coyotes (Canis latrans) and gopher snakes (Pituophis melanoleucus). Mean clutch size, egg fertility, hatching success, nesting and renesting frequency, and incidence of interspecific parasitism were all similar across years and between yearlings and adults. Distances between nest sites were used as an index to nest-site fidelity between first nests and renests and for across-year nesting attempts. Mean distances between first nests and renests were similar for yearlings (1,071 m) and adults (1,182 m). Mean distance between nests constructed by the same female in subsequent years (918 m) did not differ between age classes or success of the first year's nest. Most females (80%) nested closer to a lek other than the lek where they were captured.

Stocking Rate and Weather Impacts on Sand Sagebrush and Grasses: A 20-Year Record

Understanding how stocking rate or grazing intensity affects the abundance of common plant species is fundamental to the sustainable management of rangelands. We had the unique opportunity to determine the impact of stocking rate on shrub canopy cover and grass basal cover in a sand sagebrush (Artemisia filifolia Torr.) grassland of the Southern Plains, United States. Treatments were imposed over a 20-year time span that included an entire precipitation cycle from wet to dry and back to wet conditions. From 1941 until 1951, continuous stocking treatments of 41, 53, and 82 animal-unit-days ha-1 (AUD ha-1) were imposed with straight-bred Hereford steers (initial weight of 213 kg +/- 11 SE) for about 320 days from mid-November to late September of the next year. From 1952 through 1961, the experimental pastures were grazed yearlong by cow-calf pairs at 45, 60, and 87 AUD ha-1. Canopy cover of shrubs and basal cover of grasses were measured by the line-intercept method in 1940, 1942, 1949, 1955, 1958, and 1961. Canopy cover of sand sagebrush was not affected by stocking rate. Individual grass species exhibited positive and negative responses to stocking rate in some years, but no grass species responded to stocking rate in a single direction over the entire length of this long-term study. Stocking rate effects were most obvious under favorable conditions of high precipitation, but these effects were absent during drought. Climatic variability and slope gradient exerted the primary controlling influences on sand sagebrush-grasslands in the Southern Great Plains when stocking rates were within the bounds tested in this study.

Lesser prairie-chicken brood habitat in sand sagebrush: invertebrate biomass and vegetation

Invertebrates are an important food source for grouse chicks, especially within the first 2 weeks of life. Invertebrate abundance is highly patchy and dependent upon herbaceous cover and vegetation structure. We examined the relationship between invertebrate biomass (from sweepnet samples) and habitat structure at lesser prairie-chicken (Tympanuchus pallidicinctus) brood-use and non-use areas during 2001 and 2002 in a sand sagebrush (Artemisia filifolia) prairie vegetation community of southwestern Kansas. We delineated use and non-use areas from paired sampling points within and outside 95% utilization distributions of radiomarked brood females, respectively, during the first 60 days post-hatch. We measured vegetation cover and invertebrate biomass (Acrididae and “other” invertebrates) at 71 paired points on 2 study sites (Site I=4 broods, Site II = 12 broods). Both Acrididae and other invertebrate biomasses were greater at brood areas than non-use areas on both study sites, suggesting this food source likely had a greater influence on brood habitat use than vegetation type. Vegetation structure described brood-use areas better than vegetation type because brood-use areas had greater visual obstruction readings (VORs) than non-use areas regardless of dominant cover type. We also examined the predictive relationship between vegetation type and invertebrate biomass. Sand sagebrush density was the best linear predictor of Acrididae biomass, with lower densities having the greatest Acrididae biomass. We propose experiments to determine best management practices that produce abundant invertebrate biomasses for lesser prairie-chicken brood habitat, using our study as a baseline.

Fire and Grazing Effects on Wind Erosion, Soil Water Content, and Soil Temperature

Selective grazing of burned patches can be intense if animal distribution is not controlled and may compound the independent effects of fire and grazing on soil characteristics. Our objectives were to quantify the effects of patch burning and grazing on wind erosion, soil water content, and soil temperature in sand sagebrush (Artemisia filifolia Torr.) mixed prairie. We selected 24, 4-ha plots near Woodward, OK. Four plots were burned during autumn (mid-November) and four during spring (mid-April), and four served as nonburned controls for each of two years. Cattle were given unrestricted access (April-September) to burned patches (<2% of pastures) and utilization was about 78%. Wind erosion, soil water content, and soil temperature were measured monthly. Wind erosion varied by burn, year, and sampling height. Wind erosion was about 2 to 48 times greater on autumn-burned plots than nonburned plots during the dormant period (December-April). Growing-season (April-August) erosion was greatest during spring. Erosion of spring-burned sites was double that of nonburned sites both years. Growing-season erosion from autumn-burned sites was similar to nonburned sites except for one year with a dry April-May. Soil water content was unaffected by patch burn treatments. Soils of burned plots were 1 to 3 degrees C warmer than those of nonburned plots, based on mid-day measurements. Lower water holding and deep percolation capacity of sandy soils probably moderated effects on soil water content and soil temperature. Despite poor growing conditions following fire and heavy selective grazing of burned patches, no blowouts or drifts were observed.

EFFECTS OF MICROHABITAT AND MICROCLIMATE SELECTION ON ADULT SURVIVORSHIP OF THE LESSER PRAIRIE-CHICKEN

Populations of the lesser prairie-chicken (Tympanuchus pallidicinctus), an endemic grouse of the south-central United States, have declined precipitously. This species occurs in short- and mixed-grass prairies with sandy soils. Apart from perennial grasses of short stature, prairie-chicken habitat is characterized by dryland shrubs of the sand shinnery community, particularly the shinnery oak (Quercus havardii) and sand sagebrush (Artemisia filifolia). We measured microhabitat and microclimate characteristics at bird-centered and random points at the southwestern (New Mexico) and northeastern (Oklahoma) edges of the species' range. We estimated survival by locating radio-tagged prairie-chickens (n = 544) from April 1999 to June 2003. We found that lesser prairie-chickens used sites within the sand shinnery community that had a higher cover and greater density of shrubs (ANOVA: P < 0.0001). Microclimate differed substantially between occupied and random sites (MANOVA: P < 0.0001), and prairie-chicken survival was higher in microhabitat that was cooler, more humid, and less exposed to the wind. Survivorship was higher for adults that chose microhabitat with a higher cover of shrubs and grasses and a higher density of vegetation. Survivorship was higher for prairie-chickens that used sites with >20% cover of shrubs than for those choosing 10–20% cover; in turn, survivorship was higher for prairie-chickens choosing 10–20% cover than for those choosing <10% cover (Cox regression: P < 0.05). Whereas vegetation may recover following moderate habitat disturbance, land managers applying herbicides or otherwise removing shrubs should understand the potentially negative effects of reduced shrub cover on adult survivorship of lesser prairie-chickens.

LOCATION AND SUCCESS OF LESSER PRAIRIE-CHICKEN NESTS IN RELATION TO VEGETATION AND HUMAN DISTURBANCE

Lesser prairie-chicken (Tympanuchus pallidicinctus) populations have declined rangewide, and one of the principal causes is thought to be low nest success. Little is known about the relationship of vegetation structure and human intrusion to lesser prairie-chicken nest location and success. We conducted our study from 1997 to 2002 in southwestern Kansas, USA, on 2 sand-sagebrush (Artemisia filifolia) prairie areas managed for livestock production. We determined apparent nest success (26%) for 200 of 209 lesser prairie-chicken nests located. Nest sites had taller grass, greater sand-sagebrush density, and higher visual obstruction than random locations in the surrounding prairie. We recorded the distances from nests to 6 anthropogenic features (wellheads, buildings, improved roads, unimproved roads, transmission lines, center-pivot irrigation fields) to determine whether the features were related to nest location and success. Sand-sagebrush habitat around 5 of 6 features (all except unimproved roads) was avoided for 80 m (wellheads) to >1,000 m (buildings) by nesting lesser prairie-chickens, but distances to the features were not substantial predictors of apparent nest success. Grass height, sagebrush plant density, and sagebrush height were the most important vegetation characteristics influencing nest success.

HABITAT USE AND NEST SITE SELECTION BY NESTING LESSER PRAIRIE-CHICKENS IN SOUTHEASTERN NEW MEXICO

Abstract Lesser prairie-chickens (Tympanuchus pallidicinctus) occur in shinnery oak (Quercus havardii) and sand sagebrush (Artemisia filifolia) grassland habitats in New Mexico, Texas, Oklahoma, Kansas, and Colorado. Range-wide population reductions since the 1800s have been attributed to habitat loss, especially of nesting habitat. Using radio-telemetry and a vegetation map of the study area, we investigated habitat use by lesser prairie-chicken hens during the nesting season in herbicide-treated and untreated pastures (each about 1,000 ha in size). Herbicide treatment was effective in reducing shinnery oak cover. The most common vegetation types in hen home ranges were those dominated by shinnery oak. Hens were detected more often than randomly in or near untreated pastures. Although hens were detected in both treated and untreated habitats, 13 of 14 nests were located in untreated pastures, and all nests were located in areas dominated by shinnery oak. Areas immediately surrounding nests had higher shr...