Southern High Plains Of Texas Research Articles

Methane Emissions from a Beef Cattle Feedyard during Winter and Summer on the Southern High Plains of Texas.

Methane (CH) emissions from enteric fermentation by livestock account for about 2.1% of U.S. greenhouse gas emissions, with beef and dairy cattle being the most significant sources. A better understanding of CH emissions from beef cattle feedyards can help build more accurate emission inventories, improve predictive models, and meet potential regulatory requirements. Our objective was to quantify CH emissions during winter and summer at a typical beef cattle feedyard on the southern High Plains in Texas. Methane emissions were quantified over 32 d in winter and 44 d in summer using open-path lasers and inverse dispersion analysis. Methane per capita emission rate (PCER) ranged from 71 to 118 g animal d in winter and from 70 to 130 g animal d in summer. Mean CH PCER was similar in January, February, and May (average, 85.0 ± 0.95 g animal d) and increased to 93.4 g animal d during the June-July period. This increase coincided with increased dietary fiber. Methane loss ranged from 9.2 to 11.4 g CH kg dry matter intake, with lower values during winter. Gross energy intake (GEI) ranged from 135.2 to 164.5 MJ animal d, and CH energy loss ranged from 4.5 to 4.9 MJ animal d. Fraction of GEI lost as CH (Y) averaged 2.8% in winter, 3.2% in summer, and 3.0% overall. These values confirm the Y value currently recommended by the Intergovernmental Panel on Climate Change for Tier 2 estimates of enteric CH from feedlot fed cattle.

Nesting ecology and nest survival of lesser prairie‐chickens on the Southern High Plains of Texas

ABSTRACTThe decline in population and range of lesser prairie‐chickens (Tympanuchus pallidicinctus) throughout the central and southern Great Plains has raised concerns considering their candidate status under the United States Endangered Species Act. Baseline ecological data for lesser prairie‐chickens are limited, especially for the shinnery oak‐grassland communities of Texas. This information is imperative because lesser prairie‐chickens in shinnery oak grasslands occur at the extreme southwestern edge of their distribution. This geographic region is characterized by hot, arid climates, less fragmentation, and less anthropogenic development than within the remaining core distribution of the species. Thus, large expanses of open rangeland with less anthropogenic development and a climate that is classified as extreme for ground nesting birds may subsequently influence nest ecology, nest survival, and nest site selection differently compared to the rest of the distribution of the species. We investigated the nesting ecology of 50 radio‐tagged lesser prairie‐chicken hens from 2008 to 2011 in the shinnery oak‐grassland communities in west Texas and found a substantial amount of inter‐annual variation in incubation start date and percent of females incubating nests. Prairie‐chickens were less likely to nest near unimproved roads and utility poles and in areas with more bare ground and litter. In contrast, hens selected areas dominated by grasses and shrubs and close to stock tanks to nest. Candidate models including visual obstruction best explained daily nest survival; a 5% increase in visual obstruction improved nest survival probability by 10%. The model‐averaged probability of a nest surviving the incubation period was 0.43 (SE = 0.006; 95% CI: 0.23, 0.56). Our findings indicate that lesser prairie‐chicken reproduction during our study period was dynamic and was correlated with seasonal weather patterns that ultimately promoted greater grass growth earlier in the nesting season that provided visual obstruction from predators. © 2014 The Wildlife Society.

The Predicted Influence of Climate Change on Lesser Prairie-Chicken Reproductive Parameters

The Southern High Plains is anticipated to experience significant changes in temperature and precipitation due to climate change. These changes may influence the lesser prairie-chicken (Tympanuchus pallidicinctus) in positive or negative ways. We assessed the potential changes in clutch size, incubation start date, and nest survival for lesser prairie-chickens for the years 2050 and 2080 based on modeled predictions of climate change and reproductive data for lesser prairie-chickens from 2001–2011 on the Southern High Plains of Texas and New Mexico. We developed 9 a priori models to assess the relationship between reproductive parameters and biologically relevant weather conditions. We selected weather variable(s) with the most model support and then obtained future predicted values from climatewizard.org. We conducted 1,000 simulations using each reproductive parameter’s linear equation obtained from regression calculations, and the future predicted value for each weather variable to predict future reproductive parameter values for lesser prairie-chickens. There was a high degree of model uncertainty for each reproductive value. Winter temperature had the greatest effect size for all three parameters, suggesting a negative relationship between above-average winter temperature and reproductive output. The above-average winter temperatures are correlated to La Niña events, which negatively affect lesser prairie-chickens through resulting drought conditions. By 2050 and 2080, nest survival was predicted to be below levels considered viable for population persistence; however, our assessment did not consider annual survival of adults, chick survival, or the positive benefit of habitat management and conservation, which may ultimately offset the potentially negative effect of drought on nest survival.

Integrating Cotton and Beef Production in the Texas Southern High Plains: III. An Economic Evaluation

Economic viability of an agricultural economy is dependent on the availability of soil and water resources and how these resources are allocated within production systems. The semiarid Texas High Plains has highly productive soil and water resources from the southern Ogallala aquifer. Sustainability of its agricultural economy is threatened by depletion of the Ogallala aquifer, which underlies much of the region. The predominant production system within the region is monoculture cotton (Gossypium hirsutum L.). Long‐term (1999–2008), replicated research compared water use, productivity, and energy efficiency of a cotton monoculture system and an integrated cotton–forage–beef cattle (Bos taurus) system. Evaluation of the two production systems using mean input and output prices indicated that profitability during the 10‐yr period was not significantly different. During the last 6 yr, however, the cotton monoculture was more profitable due to the introduction of higher yielding cotton cultivars. The integrated system used 24% less applied irrigation, with irrigation efficiency similar to the cotton monoculture as measured by gross margin per hectare. Results indicate that where water availability is adequate, the cotton monoculture system has higher profitability than the integrated system, primarily due to the introduction of higher yielding cotton cultivars. The integrated system could be a viable alternative in areas of the region where irrigation is limited due to aquifer depletion and/or pumping regulation. The integrated system had less economic risk associated with the variation in profitability and added ecological diversity that benefited soil health and wildlife populations.

Seasonal Variation in Offspring Sex Ratio in the Snowy Plover

The Snowy Plover (Charadrius nivosus) is unique in being a determinate layer of an odd modal clutch size and in having a variable mating system in which female brood desertion occurs regularly. These traits make determining Snowy Plover offspring sex ratios important not only for long-term population stability, as the species is of conservation concern, but also for application to sex allocation theory. In this study, we determined Snowy Plover offspring sex ratios, examined differential costs of producing male and female offspring, and evaluated sex ratio variation in relation to maternal condition, habitat condition, and time during the nesting season on saline lakes of the Southern High Plains of Texas. Examination of 245 chicks from 118 clutches during 1999–2000 and 2008–2009 showed that male offspring were more costly to produce than female offspring; however, offspring sex ratio did not differ from parity, but was slightly male-biased in most years. The probability of producing a male offspring was greater both earlier and later in the breeding season than in the middle. As the availability of saline lake surface water and the subsequent availability of food vary unpredictably throughout the breeding season, depending on precipitation events, we suggest that sex ratio adjustment in unpredictable environments may not be straightforward and may follow nonlinear models and/or vary annually The effects such changes in sex ratios may have on population growth and stability remain unknown.

Recent Declines in Apparent Survival and Survey Counts of Snowy Plovers Breeding in the Southern High Plains of Texas

Abstract We quantified changes in long-term Snowy Plover (Charadrius nivosus) survey counts and return rates, estimated current sex and age-specific apparent survival and encounter rates, and calculated recruitment thresholds needed to maintain a stable population in the Southern High Plains of Texas. Mean survey counts of adult Snowy Plovers decreased by 78% at one saline lake (from 80 adults/survey to 18 adults/survey) from 1999–2000 to 2008–2010 but remained consistent at an alternate lake (from 45 adults/survey to 41 adults/survey). Adult and juvenile return rates have similarly declined within this time frame by 25 and 62%, respectively. Long-term declines in return rates may be the result of increased mortality from declining habitat conditions either within or outside the breeding season. Current estimates of adult (65%) and juvenile (12%) apparent survival are lower than most other estimates for Snowy Plovers throughout their range. Current estimates of adult and juvenile apparent survival and ret...

Grain sorghum response to saflufenacil applied preemergence

Field studies were conducted in 2008 and 2009 at three locations on the Texas Southern High Plains to evaluate grain sorghum response to saflufenacil alone or in combination with dimethenamid. Hybrids ‘Pioneer 85G01’ and ‘Dekalb 44-20’ were planted and saflufenacil at 0.5–0.70 kg ai ha−1 or saflufenacil + dimethenamid at 0.05 + 0.44 to 0.2 + 1.75 kg ai ha−1 was applied preemergence. Injury to sorghum increased with increasing rates at all locations. Saflufenacil + dimethenamid was less injurious than saflufenacil applied alone at similar rates. ‘Pioneer 85G01’ was more susceptible to herbicide injury than ‘Dekalb 44-20.’ Differences in soil texture and organic matter likely contributed to saflufenacil-induced injury across locations. Rainfall within 10 days after planting appeared to increase sorghum injury.

Modeling Resource Use Responses to Macroeconomic Changes: Water in the US Southern Great Plains

This study addressed the impacts of the 2008 US recession on water extraction rates from the Ogallala Aquifer in the Southern High Plains of Texas by examining the differences in projected macroeconomic variables and how they impact agricultural production and irrigation water use. The approach used pre- and post-recession FAPRI-based projections of commodity markets and an economic optimization model formulated for the Ogallala Aquifer to simulate water use adjustments. Results indicate that, based on the projections used, the 2008 recession decreased, then increased water use slightly in the representative counties, ceteris paribus, with minimal cumulative effect, and water use responsiveness to economic forces within the region was variable. This analysis also demonstrates that relating policy and economic changes to resource use changes is possible.

Migration and Habitat Preferences of Swainson's Hawks at an Autumn Stopover Site in Northwestern Texas

Unlike most raptors, the Swainson's Hawk (Buteo swainsoni) migrates long distances between breeding and wintering ranges, which elevates the importance of stopover sites for foraging. We conducted three years of fall surveys in the Southern High Plains of Texas. Migrant Swainson's Hawks moved through the area mostly between July and mid-October, peaking in September. Subadults tended to migrate earlier than adults, and light morphs before dark morphs. Favored foraging habitats included silage corn, green beans, and alfalfa, but the hawks foraged primarily where ongoing agricultural activities disturbed prey and made them more available.A diferencia de la mayoría de las rapaces, Buteo swainsoni migra largas distancias entre sus áreas de reproducción e invernada, lo que aumenta la importancia de los sitios de parada para forrajear. Realizamos muestreos durante tres otoños en las Southern High Plains de Texas. Los individuos de B. swainsoni migrantes se desplazaron a través del área generalmente entre julio y la mitad de octubre, con el nivel más alto en septiembre. Los sub-adultos tendieron a migrar antes que los adultos y las formas claras antes que las formas oscuras. Los hábitats de forrajeo favoritos incluyeron silos de maíz, judías verdes y alfalfa, pero los halcones forrajearon principalmente donde las actividades agrícolas en desarrollo disturbaron a las presas y las hicieron más disponibles.

Evaluation of the Precision Agricultural Landscape Modeling System (PALMS) in the Semiarid Texas Southern High Plains

Accurate models to simulate the soil water balance in semiarid cropping systems are needed to evaluate management practices for soil and water conservation in both irrigated and dryland production systems. The objective of this study was to evaluate the application of the Precision Agricultural Landscape Modeling System (PALMS) model to simulate soil water content throughout the growing season for several years and for three major soil series of the semiarid Texas Southern High Plains (SHP). Accuracy of the model was evaluated by comparing measured and calculated values of soil water content and using root mean squared difference (RMSD), squared bias (SB), squared difference between standard deviations (SDSD), and lack of correlation weighted by the standard deviation (LCS). Different versions of the model were obtained by modifying soil hydraulic properties, including saturated hydraulic conductivity (Ks) and residual (θr) and saturated (θs) soil volumetric water content, which were calculated using Rosetta pedotransfer functions. These modifications were combined with updated routines of the soil water solver in PALMS to account for rapid infiltration into dry soils that often occur in the SHP. Field studies were conducted across a wide range of soil and water conditions in the SHP. Soil water content was measured by neutron attenuation and gravimetrically throughout the growing seasons at each location to compare absolute values and the spatial distribution of soil water with PALMS calculated values. Use of Rosetta calculated soil hydraulic properties improved PALMS soil water calculation from 1% - 13% of measured soil volumetric water content (θv) depending on soil type. Large-scale models such as PALMS have the potential to more realistically represent management effects on soil water availability in agricultural fields. Improvements in PALMS soil water calculations indicated that the model may be useful to assess long-term implications of management practices designed to conserve irrigation water and maximize the profitability of dryland and irrigated cropping systems in the SHP.

A 250,000-year record of lunette dune accumulation on the Southern High Plains, USA and implications for past climates

A concentration of lake/playa basins occurs on the Southern High Plains (SHP) of northwest Texas and eastern New Mexico. Associated with these lake/playas are lee-side lunettes positioned on their southeast margins ranging in height from 1.5 to >10 m. An OSL dating program was applied to 30 samples from lunettes associated with large lakes and small playa basins. Samples were extracted from trenched dune sections or from deep cores. Earlier SHP lunette investigations show depositional ages primarily in the late Wisconsin and Holocene. This research extends the timing of lunette accretion to the middle Pleistocene, the earliest recorded deposition for these features. The expanded chronology permitted investigation into dune morphology on nested lunettes built on contracting lake margins. Outer lunettes formed prior to inner dunes, but simultaneous deposition occurred on downwind ridges as younger lee-side dunes were constructed. Large lake lunettes were inactive during discreet SHP pluvial episodes from early Wisconsin to LGM. Conversely, these lunettes accreted when climatic conditions promoted basin desiccation and aeolian deflation. This suggests their mode of formation contrasts with lunette models recognized for other regions. From post LGM to earliest Holocene, active lunette accretion occurred from 16 to 11 ka followed by a significant period of lunette construction during the mid-Holocene. Late Holocene-lunette deposition was interrupted by intervals of landscape stability. Lunette deposition between 1300s and 1700s corresponds with drought intervals recognized in tree-ring records from adjacent regions. Recent lunette activity on the plateau is contemporary with the 1930's ‘dust bowl’. Further insight into SHP response to changing climatic conditions was given by comparing lunette depositional events with previous investigations on sedimentation intervals for draws, lake/playa basins, and sand sheets.

Integrating Cotton and Beef Production in the Texas Southern High Plains: I. Water Use and Measures of Productivity

Texas High Plains agriculture, largely dependent on water from the Ogallala aquifer for irrigation, exemplifies semiarid agricultural regions where irrigation is used at nonsustainable rates of extraction. Integrating crop and livestock systems has been suggested to conserve water and to achieve other environmental and economic goals compared with monoculture systems. From 1998 to 2008, two large‐scale systems, with three blocks in a randomized block design, compared irrigation water, productivity, chemical inputs, and specific pests of (i) a cotton (Gossypium hirsutumL.) monoculture, and (ii) an integrated three‐paddock system that included cotton in a two‐paddock rotation with grazed wheat (Triticum aestivumL.) and rye (Secale cerealeL.) and the perennial variety WW‐B. Dahl old world bluestem (OWB) [Bothriochloa bladhii(Retz) S.T. Blake] in a third paddock for grazing and seed production. All paddocks were irrigated by subsurface drip. Angus crossbred beef steers (Bos taurus; initial BW 229 kg; SD = 33 kg) grazed 185 d from January to mid‐July each year. During the 10 yr following the establishment year, cotton lint yield was similar and averaged 1370 kg ha−1for both systems. Bluestem seed yield averaged 25 kg pure live seed (PLS) ha−1. Steers gained 139 kg on pasture and 0.79 kg d−1. Per hectare, the integrated system used 25% less (P< 0.001) irrigation water, 36% less N fertilizer, and fewer other chemical inputs than monoculture cotton. Integrated production systems that are less dependent on irrigation and chemical inputs appear possible while achieving goals of sustainability, fiber production, and food security.

Integrating Cotton and Beef Production in the Texas Southern High Plains: II. Fossil Fuel Use

Agriculture relies on fossil fuel inputs for production processes, but their use is also problematic because of finite supplies, release of associated CO2, and energy price fluctuations. In the Texas High Plains, integrated crop–livestock systems were proposed to reduce soil erosion, N‐fertilizer use, and reliance on the Ogallala aquifer, a source of irrigation water that is being rapidly depleted. We compared fossil fuel use and associated C emissions of an integrated crop–livestock system and a cotton (Gossypium hirsutum L.) monoculture system in a randomized block design evaluated for 10 yr. Energy use and C emissions ha−1 by the integrated system were less than the monoculture system when only one group yr−1 of beef stocker steers (Bos taurus) grazed the integrated system. When stocking rate increased, energy required by the integrated system rose due to additional cost required to support a larger off‐site cow herd that provided stockers. The monoculture system used more energy than the integrated system for irrigation, fertilizer, pesticides, and mechanical operations. Energy efficiency of producing cotton lint (25 MJ kg−1) was similar between the two systems. The integrated system's perennial grass WW‐B. Dahl old world bluestem [Bothriochloa bladhii (Retz) S.T. Blake] was more efficient at producing grazing days (32 MJ animal d−1) than the annuals wheat (Triticum aestivum L.) and rye (Secale cereale L.; 80 and 48 MJ animal d−1, respectively). As the aquifer is depleted and water is pumped from greater depths, the integrated system's lower water use will save energy relative to the monoculture.

Relationship between cotton yield and soil electrical conductivity, topography, and Landsat imagery

Understanding spatial and temporal variability in crop yield is a prerequisite to implementing site-specific management of crop inputs. Apparent soil electrical conductivity (ECa), soil brightness, and topography are easily obtained data that can explain yield variability. The objectives of this study were to evaluate the spatial and temporal variability in cotton (Gossypium hirsutum L.) yield and determine the relationship between yield and soil ECa, topography, and bare soil brightness at a field level in multiple growing seasons. A 50-ha field grown with cotton from 2000 to 2003 and 2005 on the Southern High Plains of Texas was selected for this study. Yield was negatively correlated with bare soil brightness (−0.47 < r < −0.33 for red band) and positively correlated with ECa (0.08 < r < 0.29 for 30-cm ECa and 0.28 < r < 0.44 for 90-cm ECa). Yield had stronger correlation with relative elevation and slope than with profile curvature and planar curvature. Combined, ECa, topographic attributes, and bare soil brightness explained up to 70.1 % of cotton yield variability. Bare soil brightness and ECa were strongly related to soil texture. Brighter soils with low ECa values had lower clay content. Yield and soil properties had stronger correlation in dry growing seasons than in wet growing seasons. Cotton yield variability pattern was relatively stable across different growing seasons. Soil texture was one of the greatest factors influencing cotton yield variability. Results of this study provide a basis for site-specific management of yield goals and variable rate application of water, fertilizers, seeds, and other inputs.

Primed acclimation of cultivated peanut (Arachis hypogaea L.) through the use of deficit irrigation timed to crop developmental periods

Water-deficits and high temperatures are the predominant factors limiting peanut production across the U.S., either because of regional aridity or untimely rainfall events during crucial crop developmental periods. In the southern High Plains of west Texas and eastern New Mexico, low average annual rainfall (450mm) and high evaporative demand necessitates the use of significant irrigation in production systems. In this west Texas study, the primary objective was to develop irrigation schemes that maximized peanut yield and grade while reducing overall water consumption. Therefore, a large-scale field experiment was established in 2005 and 2006 that utilized 15 treatment combinations of differing rates of irrigation (50, 75, and 100% of grower applied irrigation) applied at different periods of peanut development (early, middle, and late season). Precipitation patterns and ambient temperatures showed greater stress levels in 2006 which likely reduced yields across all treatments in comparison to 2005. Yields were reduced 26 (2005) and 10% (2006) in the lowest irrigation treatment (50% full season) compared with full irrigation (100% full season); but early-season water deficit (50 and 75% in the first 45days after planting) followed by 100% irrigation in the mid- and late-seasons were successful at sustaining yield and/or crop value. Root growth was significantly enhanced at 50% irrigation compared with 100% irrigation, through greater root length, diameter, surface area, and depth, suggesting greater access to water during mid- and late-season periods. These results suggest that early to mid-season deficit irrigation has the potential to maintain peanut yield without altering quality, and to substantially reduce water use in this semi-arid environment.

Modeling simultaneous exceedance of drinking-water standards of arsenic and nitrate in the Southern Ogallala aquifer using multinomial logistic regression

The occurrence of elevated levels of arsenic and nitrate in aquifers impacted by agricultural activities is common and can result in adverse health effects in rural areas. Numerous wells located in the Ogallala aquifer in the Southern High Plains of Texas have tested positive for both arsenic and nitrate MCL exceedance. To model the simultaneous exceedance of both chemicals, two types of Logistic Regression (LR) models were developed by (a) treating arsenic and nitrate independently and combining the marginal probabilities of their exceedance, and (b) treating the two exceedances together by using a multinomial model. Influencing variables representative of both soil and aquifer properties and data for which was readily available were identified. The predictive capacities of the two models were evaluated using Received Operating Characteristics (ROCs) and spatial trends in predictions were studied. The LR model constructed from the marginal probabilities had lower overall accuracy (59% correct classifications) and was extremely conservative by over-predicting outcomes. In contrast, the multinomial model showed good overall accuracy (79% correct classifications), made the correct predictions 90% of the time when both arsenic and nitrate MCL exceedances were observed, and was a good fit for wells located in agricultural areas. The results of the multinomial model also confirm previous studies that attributed shallow subsurface arsenic to anthropogenic activities. Based on the insights provided by the model it is recommended that where agricultural areas are concerned, the occurrence of arsenic and nitrate are better evaluated together.

Clinical Variables of Scaled Quail (Callipepla squamata) in the Southern High Plains of Texas

We report packed-cell volume and values of aspartate aminotransferase, calcium, creatine kinase, lactate dehydrogenase, total protein, triglycerides, and uric acid in plasma of 154 scaled quail (Callipepla squamata) captured during February-April 1999 and 2000 in Cochran County, Texas. Values for packed-cell volume, calcium, total protein, and uric acid were in the normal range for birds. Aspartate aminotransferase, creatine kinase, and lactate dehydrogenase were elevated as a result of stress experienced while in the trap.Se presenta el volumen de contenido celular el y los valores de la aspartato aminotransferasa, calcio, creatina quinasa, lactato deshidrogenasa, proteínas totales, triglicéridos, y ácido úrico de 154 codornices escamosas (Callipepla squamata) capturadas durante febrero-abril de 1999 y 2000 en el condado de Cochran, Texas. Los valores del volumen de contenido celular, calcio, proteínas totales, y ácido úrico se encontraron en el rango normal para aves. Aspartato aminotransferasa, creatina quinasa y lactato deshidrogenasa se elevaron a consecuencia del estrés mientras las codornices estuvieron en la trampa.

Spatial Distribution and Morphology of Sediments in Texas Southern High Plains Playa Wetlands

Playas are depressional geomorphic features on the U.S. High Plains. About 20,000 Southern High Plains playa wetlandsserve as runoff catchment basins, which are thought to be focal points of Ogallala aquifer recharge. Sediments in playas can alter biodiversity services, impede aquifer recharge, and increase evaporative water losses. The purpose of this study was to evaluate the effects of watershed cultivation systems on post-cultural sediment deposition in 3 pairs of cropland/native grassland playas in Briscoe, Floyd, and Swisher counties of Texas. A hydraulic probe was used to collect soil cores to 2 m or to refusal depth at 25 possible locations in each playa. Particle size distribution and soil color effectively identified sediment additions to the playas. Soil color transitions with depth from very dark grayish brown (10YR 3/2) to very dark gray (10YR 3/1) were always found in cropland playas but not in grassland playas. Particle size distribution was more useful in identifying sediment distribution than type. Using a kriging model, sediment volume in each playa was calculated from sediment thicknesses at the sampling locations and from sediment thicknesses interpolated between sampling locations. Sediment volume was directly related to watershed land use with more accumulated sediment in cropped playas than in grassland playas. Erosion of cultivated watersheds near playas contributes sediments that decrease playa depth and can result in increased evaporative water losses and decreased aquifer recharge. Citation: Villareal CJ, Zartman RE, Hudnall WH, Gitz D, Rainwater K, Smith LM. 2012. Spatial distribution and morphology ofsediments in Texas southern high plains playa wetlands. Texas Water Journal. 3(1):1-13. Available from: https://doi.org/10.21423/twj.v3i1.2070.

Snowy plover nest site selection, spatial patterning, and temperatures in the Southern High Plains of Texas

AbstractSnowy plover (Charadrius nivosus) populations have declined throughout their range, in part because of habitat degradation and poor nest success, making information regarding regionally specific nest site selection and spatial patterns important when considering habitat conservation and management guidelines. We determined nest site selection characteristics (n = 180) and examined spatial patterns (n = 215) of snowy plover nests in saline lakes in the Southern High Plains (SHP) of Texas. At 104 nests, we examined the influence of substrate type on nest temperatures and heat mitigation. Snowy plover nests were more likely to be found near an object, on pebble substrate, and with fewer plants than random sites. High use areas were generally located in areas with pebble substrate and on human‐made or natural islands, berms, and peninsulas. Overall, nests placed on pebble substrate had lower temperatures during the day than nests placed on sand substrates. Nest placement on pebble substrate may be valuable to nesting snowy plovers, providing thermal advantages to incubating adults and depressing potentially high nest predation rates. Management guidelines for this region should emphasize the importance of addressing key elements of snowy plover nesting habitat including the presence of pebble substrate and reducing vegetation encroachment. © 2012 The Wildlife Society.

Raptor community composition in the Texas Southern High Plains lesser prairie‐chicken range

AbstractPredation can be a factor in preventing prey population growth and sustainability when prey populations are small and fragmented, and when predator density is unrelated to the density of the single prey species. We conducted monthly raptor surveys from February 2007 to May 2009 in adjacent areas of the Texas Southern High Plains (USA) that do and do not support lesser prairie‐chickens (Tympanuchus pallidicinctus), a candidate for protection under the Endangered Species Act. During the summer period corresponding to prairie‐chicken nesting and brood‐rearing, Swainson's hawks (Buteo swainsoni) were the most abundant raptor. During the lekking and overwintering period, the raptor community was diverse, with northern harriers (Circus cyaneus) being the most abundant species. Raptor abundance peaked during the early autumn and was lowest during the spring. Utility poles were a significant predictor of raptor density at survey points and Swainson's hawks and all raptors, pooled, were found in greater densities in non‐prairie‐chicken habitat dominated by mesquite (Prosopis glandulosa). Avian predation risk on prairie‐chickens, based on presence and abundance of raptors, appears to be greatest during winter when there is a more abundant and diverse raptor community, and in areas with utility poles. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.