Conservation and Ecology of Bird – Game Birds III

Contributed Paper
ROOM: Rooms 18 – Cochiti and 30 – Taos Combined

1:10PM Identifying Disturbance Thresholds to Assess Effectiveness of Core Area Conservation Metrics for Greater Sage-Grouse
Kurt T. Smith; Christopher P. Kirol; Jeffrey L. Beck; Nicholas E. Graf; Jonathan B. Dinkins; Chad W. LeBeau; Thomas L. Maechtle; Andrew L. Sutphin
The Wyoming Core Area Policy for greater sage-grouse (Centrocercus urophasianus) limits surface disturbance at 5% to constrain landscape change within areas of high sage-grouse population densities. We designed our study to evaluate effectiveness of the 5% disturbance cap on sage-grouse nest and brood survival in relation to habitat use by female grouse during nesting and brood-rearing. To explore these relationships we used nest (n = 1,049), brood-rearing (n = 2,810), and random (to represent available habitat; n = 19,595) locations from VHF- and GPS-marked females compiled from 6 distinct study areas across Wyoming including from 2008-2011. Female grouse were exposed to differing types of energy development and surface disturbance. We quantified surface disturbance for each study area with the Wyoming Density and Disturbance Calculation Tool and explored different functional relationships (e.g., linear, quadratic) between nest and brood survival and disturbance using a mixed effects Cox proportional hazard model. Nest survival was best explained by a linear relationship at the 0.25-km2 scale. As percent surface disturbance exposure at this scale increased the risk of nest failure also gradually increased. When a nest was exposed to more than one type of disturbance at the 0.25-km2 scale the risk of nest failure increased at a greater rate. We did not detect a direct relationship between percent disturbance exposure and brood survival. However, across consecutive brooding locations, broods exposed to disturbance at the 1-km2 scale were at greater risk of brood loss compared to broods not exposed to disturbance at this scale. Most nest (79.9%) and brood-rearing (83.3%) locations were located in areas with 0-3% disturbance. The minimal number of nest and brood-rearing locations that were within areas that had disturbance values greater than 3%, likely restricted our ability to detect survival consequences of habitat use in higher disturbance areas.
1:30PM Effects of Spring Cattle Grazing on Nest Survival of Greater Sage-Grouse in Southern Idaho.
Andrew R. Meyers; Courtney J. Conway; David D. Musil; Karen Launchbaugh; Shane Roberts
Cattle grazing is a land use practice that occurs across much of the western United States’ publicly-managed rangelands. The range of the greater sage-grouse (Centrocercus urophasianus) overlaps with much of these rangelands. Many people have firm opinions regarding the effects of cattle grazing on greater sage-grouse populations, but limited research has addressed the topic. In 2014, we began recording grazing practices and monitoring greater sage-grouse nesting success at study sites in southern Idaho. We used Program Mark to assess the relative influence of the following variables on greater sage-grouse nest survival: grazing intensity, weather variables, nest initiation date, female age, and a suite of vegetation and anthropogenic characteristics surrounding the nest site. We monitored 255 greater sage-grouse nests across four study sites in southern Idaho. Apparent nest success was 43% (n = 53) in 2014, 46% in 2015 (n = 106), and 34% in 2016 (n = 96). Successful nests were located in areas with more grass cover and greater grass height. Our results should help land managers implement grazing practices that minimize impacts to greater sage-grouse.
1:50PM Short-Term Demographic Response of Greater Sage-Grouse to Habitat Treatments
Jason R. LeVan; Kurt T. Smith; Jeffrey L. Beck
Loss and fragmentation of sagebrush (Artemisia spp.) habitats have triggered declines in greater sage-grouse (Centrocercus urophasianus) populations over the past several decades leading to unparalleled conservation efforts. Sagebrush treatments pre-1990s were used to increase livestock forage, but are now applied by managers to enhance habitat quality for sage-grouse and other species. Reducing sagebrush cover may release herbaceous understory from shrub competition, thus providing important food and cover resources for nesting and brood-rearing sage-grouse. Some studies have examined sage-grouse use of treated areas; however, use alone may be a misleading indicator of treatment success as habitat quality is a function of use and an individual’s ability to survive and reproduce. Research examining sage-grouse demographic response to treated areas is sparse, but is necessary to assess the effectiveness of sagebrush habitat treatments for sage-grouse. Our objective was to evaluate demographic response of sage-grouse to mowing and tebuthiuron (Spike® 20P) treatments in Wyoming big sagebrush (A. tridentata wyomingensis). Our before-after-control-impact study in central Wyoming, USA included 2 untreated control (17 and 61 km2), 2 mowed (34 and 50 km2) and 2 tebuthiuron (25 and 45 km2) study areas. We collected pre-treatment (2011-2013) and post-treatment (2014−2016) nest and brood survival data from 444 radio-marked female grouse. In 2014 we implemented mowing and aerial-broadcast tebuthiuron treatments totaling 4.9 and 6.1 km2, respectively. Treatment prescriptions followed Wyoming Game and Fish Department guidelines for sage-grouse core areas. We found no differences in nest survival between mowing and herbicide treatments or between treatment and control study areas. Brood survival was not influenced by distance to treatment nor were differences in brood survival detected between mowed and tebuthiuron treatment study areas. Our results suggest that mowing and tebuthiuron treatments may not provide uplift to sage-grouse nest or brood survival in Wyoming big sagebrush.
2:10PM Prey for Sage-Grouse: Impacts of Livestock Grazing
David M. Gotsch; Courtney J. Conway; David D. Musil; Shane B. Roberts
Insects are an essential component in the diet of greater sage-grouse (Centrocercus urophasianus) chicks. Livestock grazing is common within sage-grouse breeding habitat and grazing may affect insect abundance and, thereby, affect growth and survival of sage-grouse chicks. We evaluated the relationship among vegetation characteristics, intensity of cattle grazing, and relative abundance and biomass of insects in southern Idaho. We used pitfall traps and sweep nets to sample insects at 60 sampling locations in 2015 and 120 sampling locations in 2016 within four study sites. We also measured a suite of vegetation characteristics (e.g., grass height), estimated herbivore removal of perennial bunchgrasses, and estimated abundance of cow dung at each sampling location. We identified insects to at least their taxonomic Order and recorded body length of each individual insect. We used allometric equations to convert body length into estimates of biomass. We also counted the number of ant mounds along a 50-m transect at each of the sampling locations and used Program Distance to estimate the density of ant mounds at each sampling location. Results from two study sites showed higher ant and grasshopper biomass and lower beetle biomass within grazed pastures compared to rested pastures (those that were ungrazed during the season of sampling). We used general linear models to examine whether variation in ant mound density, insect abundance, or insect biomass could be explained by three measures of grazing intensity (percent grass biomass removed by herbivores, grazing treatment, and relative abundance of cow dung) after controlling for vegetation characteristics, sampling date, and study site.
2:30PM Greater Sage-Grouse Habitat and Demographic Response to Grazing by Non-Native Ungulates
Phillip A. Street; Tessa L. Behnke; Levi Jaster; James S. Sedinger
Within the Great Basin, the effects of grazing by feral horses or livestock on Greater Sage-grouse demographics are poorly understood because horses and livestock often occur together. We investigated these effects in Northern Nevada and Southern Oregon using historic and contemporary datasets. Our study sites allowed for isolation of feral horse and livestock grazing. The timing of the study allowed for four levels of grazing including no grazing, grazing by feral horses only, grazing by livestock only, and grazing by feral horses and livestock combined. On one site, we observed evidence for increased adult survival of female sage-grouse following the removal of livestock. There was little evidence of a response of nest success following the removal of grazing. With the contemporary dataset, we further evaluated the effects of grazing as a continuous covariate of grazing intensity. Grazing intensity was estimated using distance sampling targeting feces of livestock and feral horses. We sampled 364km of fecal transects conducted at the end of each sage-grouse breeding season, and using resource selection functions, we built a predictive surface of grazing intensity for each year within the contemporary dataset. We observed higher success of nests with a combination of higher grass heights and greater sagebrush cover. We observed lower values of these covariates in areas with higher grazing intensities by either feral horses or livestock during the breeding season. We observed a similar relationship for chicks of a young age. Combined, these results suggest high rates of grazing by non-native ungulates during the nesting or early brood rearing period may negatively impact Greater Sage-grouse populations.
2:50PM Refreshment Break
3:20PM Sharp-tailed Grouse Occupancy Dynamics in Areas Open and Closed to Hunting in Michigan
David R. Luukkonen; David Jentoft
In response to widespread forest clearing, sharp-tailed grouse (Tympanuchus phasianellus) expanded across most of northern Michigan by the 1950’s. Sharp-tailed grouse then declined and are now more restricted, but a stronghold remains in the eastern Upper Peninsula. The sharp-tailed grouse hunting season was closed in Michigan in 1998 due to uncertainty about sustainability of harvest. Working together with an advisory group composed of State and Federal agencies, tribes, universities, and private partners, the Michigan Department of Natural Resources (DNR) established an occupancy survey in the eastern Upper Peninsula in 2009 and the sharp-tailed grouse hunting season was reopened in a limited area in fall 2010. We surveyed 1 mi2 sections 3-4 times each spring 2009-2014 in portions of the study area open (n = 14) and closed (n = 23) to sharp-tailed grouse hunting. We used occupancy modeling to account for imperfect detection while estimating effects of year and hunt area on localized extinction, colonization and resulting occupancy probabilities. Estimates of occupancy varied from a low of about 53% in 2009 to a high of 87% in 2010. Among 7 models fit to occupancy data, the top 2 models captured almost all weight of evidence; the top model (w = 0.73) supported year-varying colonization and extinction probabilities but unrelated to hunt area. The second-ranking model (w = 0.24) also indicated dynamic occupancy among years, but also suggested slightly higher occupancy at sites in the area opened to hunting. Both models indicated relatively stable detection probability. Occupancy dynamics pre- and post-reopening of hunting and in open and closed areas suggested little impact of hunting on sharp-tailed grouse occupancy dynamics; the hunting season was expanded in 2015 to include the area previously closed to hunting and we will assess the impact of this expansion via analysis of occupancy data through spring 2017.
3:40PM Effect of Wind Turbine Presence on Pheasant Distribution in Central Iowa
James N. Dupuie Jr.; Stephen J. Dinsmore; Julie A. Blanchong
Iowa ranks third among all states in number of wind turbines (3,957), with at least 1,000 more turbines currently scheduled for construction by 2020. Wind turbines have been shown to have negative effects on upland game birds such as prairie-chickens and grouse. The Ring-necked Pheasant (Phasianus colchicus) is an economically and recreationally important Iowa gamebird. Pheasant numbers, based on roadside counts and reported hunter harvest, have shown long-term declines in Iowa. There is growing concern that wind turbines could cause habitat fragmentation in pheasant habitats, thereby exacerbating long-term declines. We conducted male crowing surveys during the peak breeding season (April 15- May 30) on one central Iowa wind farm in 2015 and on four central Iowa wind farms in 2016 to assess pheasant densities and detection probabilities relative to proximity to wind turbines. We had 577 detections of roosters across 300 surveys in 2015 and 1,816 detections of roosters across 920 surveys in 2016 (average of 1.96 ± 0.05 [SE]) birds per survey across both years). Linear regression showed a small, but statistically significant positive relationship (β = 0.00007, P = 0.01) between the average number of detections and distance from the survey point to the nearest wind turbine. There was a negative relationship (β = 0.13, P = <0.001) between the average number of detections and turbine density within 2 km of the survey point. These results suggest a statistically (but perhaps not biologically) significant avoidance of wind turbines by male Ring-necked Pheasants in the study area. Based on our crowing survey data, at least at the landscape level, wind energy development appears to have minimal influence on pheasant distribution. Future studies should focus on local-scale movements and reproduction of individual pheasants in relationship to wind turbines.
4:00PM Assessing the Umbrella Effect of Greater Sage-Grouse Management on Golden Eagles in the Western United States
Jason D. Carlisle; Geoffrey Bedrosian; Trent L. McDonald
Landscape-scale conservation strategies are underway to protect Greater Sage-Grouse (Centrocercus urophasianus) across vast areas of the western U.S. Golden Eagles (Aquila chrysaetos) co-occur with Greater Sage-Grouse in much of their range, and the two species face many of the same threats (e.g., habitat loss due to anthropogenic disturbance, invasive annual grasses, and altered fire regimes). Therefore, management actions taken on behalf of Greater Sage-Grouse may provide a conservation umbrella to Golden Eagles by preserving key habitat resources that may otherwise be lost without proactive management. Our objective was to determine the amount and suitability of Golden Eagle habitat within federally designated Priority Areas for Conservation (PACs) managed for Greater Sage-Grouse. We analyzed data from spatially explicit habitat suitability models for Golden Eagles during the breeding and winter seasons within seven ecoregions spanning the western U.S. We found that Greater Sage-Grouse PACs contained nearly one-fifth of Golden Eagle breeding (mean = 21.3%) and winter (mean = 19.6%) habitat, but that the amount of overlap varied widely among ecoregions (breeding range = 3.3 – 44.7%, winter range = 1.6 – 45.3%). To further understand the effectiveness of PACs at capturing high-suitability Golden Eagle habitat, we created 250 simulated PACs within each ecoregion that were the same size as the established PACs, but sited with no respect to Greater Sage-Grouse. We found that the established PACs outperformed the simulation-based expectation for only four of the possible 14 ecoregion-season combinations tested. Our findings suggest that Golden Eagle conservation may be substantially augmented by efforts to protect Greater Sage-Grouse in some, but not all, western ecoregions. Additionally, the large size of the PACs, and not concordance in each species’ preferred habitat, may be the key mechanism to the success of the conservation umbrella provided by Greater Sage-Grouse.
4:20PM Factors Affecting Nesting Propensity in Greater Sage-Grouse
Tessa L. Behnke; Phillip A. Street; James S. Sedinger
Breeding propensity, here defined as attempting at least one nest in a given year, may be an important contribution to population dynamics in Greater sage-grouse (Centrocercus urophasianus). As demonstrated in many avian species, breeding propensity can be influenced by individual characteristics, population level dynamics, and a suite of environmental factors. Sage-grouse have an intermediate life-span, which creates the opportunity for trade-offs between survival and current and/or future reproduction. Female sage-grouse can have multiple nests in a season, if the first nest fails while the breeding grounds, called leks, are still active. In this study, we followed 520 radio-marked female sage-grouse between 2013 and 2016 in northern Nevada and southern Oregon. Hens were monitored every 2-3 days during the nesting season, from late March to early June. We used the transition probabilities from a multistate model to calculate rates of nesting and renesting for each year of the study. The transition from pre-nesting to nesting supported a quadratic trend, and failed to renesting supported a linear trend. Effects of age and year, treated as individual covariates, were also supported in the top model. We will be investigating the environmental factors that may contribute to annual variation in future analyses.
4:40PM Species Distribution Models for the Dusky Grouse in the American Southwest: Implications for Conservation and Climate Change
Joseph A. Youtz; Reza A. Goljani; Jennifer K. Frey
The dusky grouse (Dendragapus obscurus) is a game bird that occurs in boreal forests from southern Canada and Alaska south to isolated mountaintops in Arizona and New Mexico. This species has been ill-studied in the American Southwest where it is a protected game species. Recent largescale fires in both states have greatly impacted dusky grouse habitat, but the extent has not yet been investigated. Our study aims to develop a habitat suitability map of dusky grouse in New Mexico and Arizona using Maximum Entropy Modeling (MaxEnt). We collected occurrence records of dusky grouse from museum collections, eBird, iNaturalist, professional observations, and the New Mexico Ornithological Society database. We assigned observation error based on the observer’s knowledge and location precision. We constructed habitat models, based on 8 biophysical variables (elevation, heat load index, terrain ruggedness index, GAP landcover, slope, aspect, Normalized Difference Vegetation Index, distance to water) and 19 standard bioclimatic variables. We optimized the background extent, variables and beta parameter. We also modeled the impact of future climate conditions on grouse habitat according to Representative Concentration Pathway 4.5 and 8.5 scenarios. The final model suggested elevation (69.3%), precipitation of the driest quarter (20.5%), and precipitation of driest month (7.2%) as the most influential variables in predicting dusky grouse habitat. The largest and most suitable areas of grouse habitat were the northern mountains of New Mexico with significant areas of suitable habitat also found on the Kaibab Plateau. Suitable habitat in the southern part of both states was small and fragmented. Dusky Grouse can be affected by recent land cover changes and the effects of climate change. Future research will need to be undertaken in order to better understand this species and its current status in the American Southwest.


Contributed Paper
Location: Albuquerque Convention Center Date: September 27, 2017 Time: 1:10 pm - 5:00 pm