9 research outputs found
The Influence of Mitigation on Sage-Grouse Habitat Selection within an Energy Development Field
Growing global energy demands ensure the continued growth of energy development. Energy development in wildlife areas can significantly impact wildlife populations. Efforts to mitigate development impacts to wildlife are on-going, but the effectiveness of such efforts is seldom monitored or assessed. Greater sage-grouse (Centrocercus urophasianus) are sensitive to energy development and likely serve as an effective umbrella species for other sagebrush-steppe obligate wildlife. We assessed the response of birds within an energy development area before and after the implementation of mitigation action. Additionally, we quantified changes in habitat distribution and abundance in pre-and post-mitigation landscapes. Sage-grouse avoidance of energy development at large spatial scales is well documented. We limited our research to directly within an energy development field in order to assess the influence of mitigation in close proximity to energy infrastructure. We used nestlocation data (n = 488) within an energy development field to develop habitat selection models using logistic regression on data from 4 years of research prior to mitigation and for 4 years following the implementation of extensive mitigation efforts (e.g., decreased activity, buried powerlines). The post-mitigation habitat selection models indicated less avoidance of wells (well density beta = 0.18 +/- 0.08) than the pre-mitigation models (well density beta = -0.09 +/- 0.11). However, birds still avoided areas of high well density and nests were not found in areas with greater than 4 wells per km(2) and the majority of nests (63%) were located in areas with <= 1 well per km(2). Several other model coefficients differed between the two time periods and indicated stronger selection for sagebrush (pre-mitigation beta = 0.30 +/- 0.09; postmitigation beta = 0.82 +/- 0.08) and less avoidance of rugged terrain (pre-mitigation beta = -0.35 +/- 0.12; post-mitigation beta = -0.05 +/- 0.09). Mitigation efforts implemented may be responsible for the measurable improvement in sage-grouse nesting habitats within the development area. However, we cannot reject alternative hypotheses concerning the influence of population density and intraspecific competition. Additionally, we were unable to assess the actual fitness consequences of mitigation or the source-sink dynamics of the habitats. We compared the pre-mitigation and post-mitigation models predicted as maps with habitats ranked from low to high relative probability of use (equal-area bins: 1 -5). We found more improvement in habitat rank between the two time periods around mitigated wells compared to non-mitigated wells. Informed mitigation within energy development fields could help improve habitats within the field. We recommend that any mitigation effort include well-informed plans to monitor the effectiveness of the implemented mitigation actions that assess both habitat use and relevant fitness parameters.Anadarko Petroleum Corporatio
Mitigation Effectiveness for Improving Nesting Success of Greater Sage-Grouse Influenced by Energy Development
Sagebrush Artemisia spp. habitats being developed for oil and gas reserves are inhabited by sagebrush obligate species--including the greater sage-grouse Centrocercus urophasianus (sage-grouse) that is currently being considered for protection under the U.S. Endangered Species Act. Numerous studies suggest increasing oil and gas development may exacerbate species extinction risks. Therefore, there is a great need for effective on-site mitigation to reduce impacts to co-occurring wildlife such as sage-grouse. Nesting success is a primary factor in avian productivity and declines in nesting success are also thought to be an important contributor to population declines in sage-grouse. From 2008 to 2011 we monitored 296 nests of radio-marked female sage-grouse in a natural gas (NG) field in the Powder River Basin, Wyoming, USA, and compared nest survival in mitigated and non-mitigated development areas and relatively unaltered areas to determine if specific mitigation practices were enhancing nest survival. Nest survival was highest in relatively unaltered habitats followed by mitigated, and then non-mitigated NG areas. Reservoirs used for holding NG discharge water had the greatest support as having a direct relationship to nest survival. Within a 5-km2 area surrounding a nest, the probability of nest failure increased by about 15% for every 1.5 km increase in reservoir water edge. Reducing reservoirs was a mitigation focus and sage-grouse nesting in mitigated areas were exposed to almost half of the amount of water edge compared to those in non-mitigated areas. Further, we found that an increase in sagebrush cover was positively related to nest survival. Consequently, mitigation efforts focused on reducing reservoir construction and reducing surface disturbance, especially when the surface disturbance results in sagebrush removal, are important to enhancing sage-grouse nesting success
Pre-Mitigation Nesting Habitat.
<p>Relative predicted probability surface for the pre-mitigation nesting habitat model divided into 5 equal-area bins for greater sage-grouse in the Powder River Basin, Wyoming, U.S.A. Nest locations used in model development were collected from 2004–2007 and are indicated by the blue circles. The colors range from dark green to yellow to represent the range of relative nesting probability from low to high. Well locations are indicated by black circles.</p
Spatial variables.
<p>Spatial variables considered in the development of resource selection function models for greater sage-grouse. The same variables were included in the pre-mitigation (2004 to 2007) and post-mitigation (2008 to 2011) habitat models. Range is presented for each variable summarized at 1 km<sup>2</sup> for both pre- and post-mitigation landscapes.</p><p>Spatial variables.</p
Coefficient estimates.
<p>Model estimated beta coefficients and associated standard errors for global Resource Selection Function models for greater sage-grouse nesting habitat in the Powder River Basin, Wyoming, U.S.A. Pre-mitigation models were developed using nesting data from 2004–2007. Post-mitigation models were developed using nesting data from 2008–2011. Scale presents the spatial area over which each variable was summarized. TWI: Mean Topographic Wetness Index. VRM: Mean Vector Roughness Measure.</p><p>Coefficient estimates.</p
Coefficient Estimates.
<p>Standardized Beta-coefficients and associated standard errors for all variables included in the global Resource Selection Function models for greater sage-grouse nesting habitat models in the Powder River Basin, Wyoming, U.S.A. The gray lines represent estimates from the pre-mitigation model developed using nesting data from 2004–2007. The black lines represent coefficient estimates from the post-mitigation model developed using nesting data from 2008–2011. TWI: Mean Topographic Wetness Index. VRM: Mean Vector Roughness Measure.</p
Change in Nesting Habitat.
<p>Change in relative predicted probability surface between the pre- and post-mitigation nesting habitat models for greater sage-grouse in the Powder River Basin, Wyoming, U.S.A. Values range from -3 (black) to +3 (dark green) and represent the change in bin classification between the two models from pre-mitigation nesting habitat to post-mitigation nesting habitat. Nest locations used in the pre-mitigation model development (2004–2007) are indicated by the blue circles and the nest locations used in the post-mitigation model development (2008–2011) are indicated by the yellow circles. Unmitigated well locations are indicated by black circles. Mitigated wells are indicated by purple circles.</p