Eric T. Thacker

Evaluation of brood detection techniques: recommendations for estimating Greater Sage-Grouse productivity.

ABSTRACT. Obtaining timely and accurate assessment of sage-grouse (Centrocercus spp.) chick survival and recruitment is an important component of species management and conservation. We compared the effectiveness of walking, spotlight, and pointing-dog surveys to detect radio-marked and unmarked chicks within broods of radio-marked hens in Utah. Walking surveys detected 72% of marked chicks, while spotlight and pointing-dog surveys detected 100% and 96%, respectively. We found no difference between spotlight and pointing-dog counts in number of marked and unmarked chicks detected (P = 0.57). Spotlight counts were slightly more time efficient than pointing-dog surveys. However, spotlight surveys were nocturnal searches and perceived to be more technically arduous than diurnal pointing-dog surveys. Pointing-dog surveys may offer greater utility in terms of area searched per unit effort and an increased ability to detect unmarked hens and broods.

Thermal patterns constrain diurnal behavior of a ground-dwelling bird

Recently, gaining knowledge about thermal refuges for vulnerable species has been a major focal point of ecological studies, and this focus has been heightened by predicted temperature increases associated with global climate change. To better understand how organisms respond to thermal landscapes and extremes, we investigated the thermal ecology of a gallinaceous bird species (northern bobwhite; Colinus virginianus, hereafter bobwhite) during a key life history period. Specifically, our study focused on the brood-rearing period of precocial bobwhite chicks associated with brood-attending adults. We measured site-specific black bulb temperatures (Tbb) and vegetation characteristics across 38 brood tracking days and 68 random landscape sites to assess thermal patterns at scales relevant to broods. We observed that the landscape was thermally heterogeneous, exhibiting variation in Tbb up to 40°C during peak diurnal heating demonstrating a wide array of thermal choices available to broods. At 15:00 h, broods...

Invasion of Broom Snakeweed (Gutierrezia sarothrae) Following Disturbance: Evaluating Change in a State-and-Transition Model

Abstract Broom snakeweed (Gutierrezia sarothrae [Pursh] Britt. & Rusby) is an aggressive native invasive species that thrives after disturbance in semiarid rangelands of the western United States. A 5-yr (2002–2006) study was initiated following grazing and fire disturbances on an Upland Gravelly Loam ecological site in the sagebrush steppe of northern Utah, to evaluate broom snakeweed invasion in different plant communities. The study site originally had two plant communities: a sagebrush/bunchgrass community that received alternate-year, fall cattle grazing, and was dominated by bluebunch wheatgrass (Elymus spicatus) and an open stand of Wyoming big sagebrush (Artemisia tridentata subsp. wyomingensis), and a sagebrush community that received continuous, annual, spring cattle grazing that removed the bunchgrasses, leaving a dense stand of Wyoming big sagebrush with an understory of Sandberg bluegrass (Poa secunda). Portions of these two plant communities were burned in a wildfire in 2001, removing the sagebrush, and creating two additional communities. The burned portion of the sagebrush/bunchgrass community became a bluebunch wheatgrass–dominated community, and the burned portion of the sagebrush community became a snakeweed-dominated community. Foliar cover, aboveground biomass, and sagebrush and snakeweed densities were compared among the four communities. Mature snakeweed plants that existed in the sagebrush/bunchgrass community were eliminated in 2003, because of drought conditions. Snakeweed was eliminated in the bluebunch wheatgrass community by the wildfire in 2001, and there was no reestablishment. Snakeweed density and cover remained constant in the sagebrush community. Snakeweed cover increased from 2% to 31% in the snakeweed community, despite the presence of Sandberg bluegrass. The data were used to evaluate and update the current Upland Gravelly Loam (Wyoming big sagebrush) ecological site description in the Great Salt Lake Major Land Resource Area and its state-and-transition model to reflect vegetation changes associated with snakeweed invasion.

Seeding Cool-Season Grasses to Suppress Broom Snakeweed (Gutierrezia sarothrae), Downy Brome (Bromus tectorum), and Weedy Forbs

Abstract Broom snakeweed (snakeweed) is an aggressive native range-weed found throughout arid and semiarid areas of the western United States, that increases following disturbances such as overgrazing, drought, or wildfire. Ecologically based strategies that include controlling snakeweed and reestablishing desirable herbaceous species are needed to restore productivity and diversity to invaded areas. The objective of this study was to compare the ability of selected introduced and native grass species and prostrate kochia (kochia) to prevent reinvasion of snakeweed, downy brome, and annual forbs following control. This field study was replicated at two sites (Howell and Nephi, Utah) within the sagebrush-steppe biome. Snakeweed and downy brome were controlled by picloram (0.25 kg/ha [0.22 lb/ac]) and glyphosate (1.5 kg/ha [1.3 lb/ac]). The seeding treatments were comprised of three introduced grasses and a mix of these species, three native grasses and a mix of these species, and kochia. The treatments were seeded into 3 by 15-m (10 by 50 ft) plots in October 2003. Frequency and biomass of seeded species, snakeweed, downy brome, other grasses, and annual forbs were measured in 2004, 2005, and 2008. Seeded species were evaluated for success of establishment and persistence, and their ability to restrict reinvasion of snakeweed, downy brome, and annual forbs. Crested wheatgrass and big squirreltail had the best initial establishment at both locations (>u200975%). In contrast, kochia and Russian wildrye did not establish well at either site, and western wheatgrass did not establish well at Nephi. Snakeweed reestablishment was restricted in all treatments except the kochia treatments, in which kochia did not establish well. Frequency of downy brome increased at both sites, and annual forb frequency increased at Nephi to near 100%, but the better established grasses suppressed biomass production of these weedy species. Crested wheatgrass established best, had the greatest production, and provided greatest suppression of downy brome and annual weeds. Nomenclature: Glyphosate; picloram; broom snakeweed, Gutierrezia sarothrae (Pursh) Britt. & Rusby GUESA; downy brome, Bromus tectorum L.; big squirreltail, Elymus multisetus (J.G. Sm.) Jones ‘Sand Hollow’; crested wheatgrass, Agropyron cristatum (L.) Gaertner × A. desertorum (Fisch. Ex Link) Schultes ‘Hycrest’; prostrate kochia, Kochia prostrata (L.) Schrader ‘Immigrant’; Russian wildrye, Psathyrostachys junceus (Fisch.) Nevski ‘Bozoisky’; western wheatgrass, Pascopyrum smithii (Rybd.) A. Löve ‘Rosanna’.

Greater Sage-Grouse and Range Management: Insights from a 25-Year Case Study in Utah and Wyoming☆

ABSTRACT Conservation of sagebrush (Artemisia spp.) systems is one of the most difficult and pressing concerns in western North America. Sagebrush obligates, such as greater sage-grouse (Centrocercus urophasianus; hereafter sagegrouse), have experienced population declines as sagebrush systems have degraded. Science-based management is crucial to improve certainty in range management practices. Although large-scale implementation of management regimens within an experimental design is difficult, long-term case studies provide opportunities to improve learning and develop and refine hypotheses. We used 25 years of data across three large landscapes in northern Utah and southwestern Wyoming to assess sage-grouse population change and corresponding land management differences in a case study design. Sage-grouse lek counts at our Deseret Land and Livestock (DLL) study site increased relative to surrounding populations in correspondence with the implementation of small-acreage sagebrush treatments designed to reduce shrub cover and increase herbaceous understory within a prescriptive grazing management framework. The higher lek counts were sustained for nearly 15 years. However, with continued sagebrush treatments and the onset of adverse winter conditions, DLL lek counts declined to levels consistent with surrounding areas. During summer, DLL sage-grouse broods used plots of small, treated sagebrush mosaics more than untreated reference sites. We hypothesize that sagebrush treatments on DLL increased availability of grasses and forbs to sagegrouse, similar to other studies, but that cumulative annual reductions in sagebrush may have reduced availability of sagebrush cover for sage-grouse seasonal needs at DLL, especially when extreme winter weather occurred.

Behavioral Responses at Distribution Extremes: How Artificial Surface Water Can Affect Quail Movement Patterns☆

ABSTRACT Supplementing wildlife populations with resources during times of limitation has been suggested for many species. The focus of our study was to determine responses of northern bobwhite (Colinus virginianus; Linnaeus) and scaled quail (Callipepla squamata; Vigors) to artificial surface-water sources in semiarid rangelands. From 2012–2014, we monitored quail populations via radio telemetry at Beaver River Wildlife Management Area, Beaver County, Oklahoma. We used cumulative distribution functions and resource utilization functions (RUFs) to determine behavioral responses of quail to water sources. We also used Program MARK to determine if water sources had any effect on quail vital rates. Our results indicated that both northern bobwhite and scaled quail exhibited behavioral responses to the presence of surface-water sources. Northern bobwhite selected for areas < 700 m and < 650 m from water sources during the breeding and nonbreeding season, respectively. However, the nonbreeding season response was weak ( = -0.06, SE = < 0.01), and the breeding season ( = 0.01, SE = 0.02) response was nonsignificant on the basis of RUFs. Scaled quail selected for areas < 650 m and < 250 m from water sources during the breeding and nonbreeding season, respectively. The breeding season RUF ( = -0.31, SE = 0.07) indicated a stronger response for scaled quail than bobwhite. Conversely, there was no direct effect of surface water on quail vital rates or nest success during the course of our study. Although water may affect behavioral patterns of quail, we found no evidence that it affects quail survival or nest success for these two species.

A Comparison of Inter- and Intraspecific Interference on Broom Snakeweed (Gutierrezia sarothrae) Seedling Growth

Abstract Broom snakeweed (snakeweed) is a native range shrub found throughout semiarid rangelands of the western United States, which increases and dominates plant communities after disturbances such as overgrazing, drought, or wildfire. The objective of this study was to compare the ability of selected grass species and prostrate kochia to restrict establishment and growth of snakeweed seedlings in potted-plant and replicated field studies within two sagebrush ecological sites. In the potted-plant studies, single snakeweed seedlings were grown with seedlings (seedling neighbor study) and established plants (established neighbor study) of three cool-season grasses (crested, pubescent, and bluebunch wheatgrass), prostrate kochia, and snakeweed at increasing densities (1, 3, 5 plants/pot). Interference from crested wheatgrass in the seedling neighbor study, and both crested and bluebunch wheatgrass in the established neighbor study, induced the greatest mortality of snakeweed seedlings, and snakeweed growth was suppressed more by interspecific (grass) than intraspecific (snakeweed) neighbors in both potted-plant studies. Snakeweed establishment was also evaluated at two field sites: Howell and Nephi, UT. Snakeweed and downy brome were controlled by picloram (0.25 kg ae/ha) and glyphosate (1.5 kg ae/ha), then three native and three introduced grasses were drill-seeded, and prostrate kochia was dribble-seeded in replicated plots (3 m by 15 m) at both sites in October 2003. Snakeweed seedlings were transplanted into seeded plots and a bare ground control plot in autumn 2004. Snakeweed mortality was greatest (73%) in crested wheatgrass plots at Howell, but there were few differences among species treatments at Nephi. Of the snakeweed seedlings that survived, there was relatively little growth in any of the seeded plots compared to those in the bare ground control plots. These results indicate that seeded cool-season grasses interfered with and reduced establishment of snakeweed seedlings. Nomenclature: Glyphosate; picloram; bluebunch wheatgrass, Pseudoroegneria spicata Pursh ‘Goldar’; broom snakeweed, Guterrezia sarothrae (Pursh) Britt. & Rusby GUESA; crested wheatgrass, Agropyron cristatum (L.) Gaertner × A. desertorum (Fisch. Ex Link) Schultes ‘Hycrest’; downy brome, Bromus tectorum L; prostrate kochia, Kochia prostrata (L.) Schrader ‘Immigrant’; pubescent wheatgrass, Elytrigia intermedia ssp. trichophorum (Host) Beauv. ‘Luna’.

Sage-Grouse Habitat Monitoring: Daubenmire versus Line-Point Intercept

On the Ground Evaluation of range/habitat projects for sage-grouse require careful monitoring to measure their impact. Daubenmire canopy cover and line-point intercept did not yield similar results. As herbaceous canopy cover increased, the differences between the cover estimates increased. Adoption of both techniques by both groups may be the only feasible solution since institutional constraints limit either group from changing monitoring techniques.

Does the presence of Oil and gas infrastructure potentially increase risk of harvest in northern bobwhite

Beyond organisms experiencing direct impacts (mortality) from the presence of anthropogenic features, interactive relationships may exacerbate the effects of anthropogenic disturbance within the context of these features. For example, mortality risk may be affected by the road infrastructure associated with energy development by influencing space use of predators including human hunters. To assess these relationships, we conducted research on northern bobwhite Colinus virginianus across a hunted and non-hunted area of Beaver River Wildlife Management Area, Oklahoma, using radiotelemetry from 2012–2015. We found that bobwhite mortality risk decreased as the distance from primary roads (m) increased across weeks (hazard ratio [HR] = 1.008, 95% confidence interval [CI] = 1.0003 to 1.0013). The interaction between unit (hunted and non-hunted) and distance from primary roads was not significant (HR = 1.00, 95% CI = 0.999 to 1.001) indicating that hunting pressure was not a likely explanation for the observed decrease in survival related to primary roads. Bobwhite on the hunted unit avoided exposed soil/sparse vegetation ( = -0.01, CI = -0.02 to -0.002) and bare ground ( =-0.01, CI =-0.02 to -0.002) more than bobwhite on the non-hunted unit, however these were weak relationships. No other differences in bobwhite space use were detected related to hunting. Though we were limited to estimating theoretical rather than empirical amounts of hunting pressure during our study, we were unable to detect any negative compounding effects of anthropogenic development and hunting pressure on bobwhite ecology during the hunting season.

Development and characterization of 23 microsatellite loci for scaled quail ( Callipepla squamata )

The scaled quail (Callipepla squamata) is a common but declining game bird found throughout large portions of the arid southwest region of the United States. Range-wide population declines have been linked to long term drought and land use changes and have led to a resurgance in research investigating various aspects of scaled quail ecology. In order to facilitate future research on scaled quail, we have developed and characterized 23 polymorphic microsatellite loci. Among 16 individuals from populations located throughout scaled quail range, the number of alleles per locus ranged from 3 to 14 with an average of 7. Polymorphic information content ranged from 0.210 to 0.899 with an average of 0.654, indicating that these loci have high applicability for future scaled quail genetic studies.