Cameron L. Aldridge

LINKING OCCURRENCE AND FITNESS TO PERSISTENCE: HABITAT‐BASED APPROACH FOR ENDANGERED GREATER SAGE‐GROUSE

Detailed empirical models predicting both species occurrence and fitness across a landscape are necessary to understand processes related to population persistence. Failure to consider both occurrence and fitness may result in incorrect assessments of habitat importance leading to inappropriate management strategies. We took a two-stage approach to identifying critical nesting and brood-rearing habitat for the endangered Greater Sage-Grouse (Centrocercus urophasianus) in Alberta at a landscape scale. First, we used logistic regression to develop spatial models predicting the relative probability of use (occurrence) for Sage-Grouse nests and broods. Secondly, we used Cox proportional hazards survival models to identify the most risky habitats across the landscape. We combined these two approaches to identify Sage-Grouse habitats that pose minimal risk of failure (source habitats) and attractive sink habitats that pose increased risk (ecological traps). Our models showed that Sage-Grouse select for heterogeneous patches of moderate sagebrush cover (quadratic relationship) and avoid anthropogenic edge habitat for nesting. Nests were more successful in heterogeneous habitats, but nest success was independent of anthropogenic features. Similarly, broods selected heterogeneous high-productivity habitats with sagebrush while avoiding human developments, cultivated cropland, and high densities of oil wells. Chick mortalities tended to occur in proximity to oil and gas developments and along riparian habitats. For nests and broods, respectively, approximately 10% and 5% of the study area was considered source habitat, whereas 19% and 15% of habitat was attractive sink habitat. Limited source habitats appear to be the main reason for poor nest success (39%) and low chick survival (12%). Our habitat models identify areas of protection priority and areas that require immediate management attention to enhance recruitment to secure the viability of this population. This novel approach to habitat-based population viability modeling has merit for many species of concern.

Sage-grouse nesting and brood habitat use in southern Canada

Greater sage-grouse (Centrocercus urophasianus) populations have declined from 66 to 92% during the last 30 years in Canada, where they are listed as endangered. We used radiotelemetry to examine greater sage-grouse nest and brood habitat use in Alberta and assess the relationship between habitat and the population decline. We also identified the patch size at which sage-grouse were selecting nest and brood-rearing sites. Nest areas were in silver sagebrush (Artemisia cana) stands that had greater amounts of tall cover (P ≤ 0.001) at a patch size of 7.5 to 15 m in radius. Within those sagebrush stands, nests were located beneath the densest sagebrush present. Areas used for brood rearing had greater amounts of taller sagebrush cover in an area >15 m in radius than at random locations. Brood locations were not selected based on forb content; mesic areas containing forbs (20-40% cover) as a food resource for chicks were limiting (only 12% cover available). Overall cover of sagebrush is considerably lower in Canada (5-11%) compared with sagebrush (Artemisia spp.) cover in other areas throughout the range of greater sage-grouse (15-25%). If management goals are to provide suitable nesting and brood-rearing habitat, efforts should be directed toward protecting and enhancing sagebrush stands ≥30 m 2 and increasing overall sagebrush cover. Management strategies also should focus on increasing the availability of mesic sites and increasing the abundance of sites with >10% forb cover, to enhance brood rearing habitat.

Sage-Grouse Habitat Selection During Winter in Alberta

Abstract Greater sage-grouse (Centrocercus urophasianus) are dependent on sagebrush (Artemisia spp.) for food and shelter during winter, yet few studies have assessed winter habitat selection, particularly at scales applicable to conservation planning. Small changes to availability of winter habitats have caused drastic reductions in some sage-grouse populations. We modeled winter habitat selection by sage-grouse in Alberta, Canada, by using a resource selection function. Our purpose was to 1) generate a robust winter habitat-selection model for Alberta sage-grouse; 2) spatially depict habitat suitability in a Geographic Information System to identify areas with a high probability of selection and thus, conservation importance; and 3) assess the relative influence of human development, including oil and gas wells, in landscape models of winter habitat selection. Terrain and vegetation characteristics, sagebrush cover, anthropogenic landscape features, and energy development were important in top Akaikes Information Criterion–selected models. During winter, sage-grouse selected dense sagebrush cover and homogenous less rugged areas, and avoided energy development and 2-track truck trails. Sage-grouse avoidance of energy development highlights the need for comprehensive management strategies that maintain suitable habitats across all seasons.

NESTING AND REPRODUCTIVE ACTIVITIES OF GREATER SAGE-GROUSE IN A DECLINING NORTHERN FRINGE POPULATION

Abstract In Canada, Greater Sage-Grouse (Centrocercus urophasianus) are at the northern edge of their range, occurring only in southeastern Alberta and southwestern Saskatchewan. The population in Canada has declined by 66% to 92% over the last 30 years. We used radio-telemetry to follow 20 female Greater Sage-Grouse and monitor productivity in southeastern Alberta, and to assess habitat use at nesting and brood-rearing locations. All females attempted to nest. Mean clutch size (7.8 eggs per nest) was at the high end of the normal range for sage-grouse (typically 6.6–8.2). Nest success (46%) and breeding success (55%) were within the range found for more southerly populations (15% to 86% and 15% to 70%, respectively). Thirty-six percent of unsuccessful females attempted to renest. Fledging success was slightly lower than reported in other studies. Thus, reproductive effort does not appear to be related to the population decline. However, chick survival to ≥50 days of age (mean = 18%) was only about half of that estimated (35%) for a stable or slightly declining population, suggesting that chick survival may be the most important factor reducing overall reproductive success and contributing to the decline of Greater Sage-Grouse in Canada. Actividades de Anidación y Reproducción de Centrocercus urophasianus en una Población del Extremo Norte en Declive Resumen. En Canadá, Centrocercus urophasianus está en el extremo norte de su distribución, encontrándose sólo en el sureste de Alberta y el suroeste de Saskatchewan. La población de Canadá ha disminuido entre el 66% y 92% durante los últimos 30 años. Utilizamos radio-telemetría para seguir a 20 hembras de C. urophasianus y monitorear su productividad en el sureste de Alberta y para evaluar el uso de hábitat en sitios de anidación y de cría de los pichones. Todas las hembras intentaron anidar. El tamaño promedio de la nidada (7.8 huevos por nido) estuvo en el extremo superior del rango normal de C. urophasianus (típicamente 6.6–8.2). El éxito de anidación (46%) y de reproducción (55%) estuvieron dentro de los rangos encontrados en poblaciones de más al sur (15% a 86% y 15% a 70%, respectivamente). El treinta y seis por ciento de las hembras que no tuvieron éxito intentaron volver a anidar. El éxito en la crianza de polluelos hasta la etapa de volantones fue ligeramente menor que el reportado en otros estudios. Por lo tanto, el esfuerzo reproductivo no parece estar relacionado con el declive poblacional. Sin embargo, la supervivencia de los polluelos hasta 50 días de edad o más (promedio = 18%) fue sólo aproximadamente la mitad de lo que se ha estimado para una población estable o en ligero declive (35%), lo que sugiere que la supervivencia de los pichones podría ser el factor más importante reduciendo el éxito reproductivo en general y contribuyendo al declive de C. urophasianus en Canadá.

A comparison of sample types varying in invasiveness for use in DNA sex determination in an endangered population of greater Sage-Grouse (Centrocercus uropihasianus)

Obtaining blood and muscle samples is often not feasible in genetic studies on endangered species, therefore researchers must adopt sampling techniques that are less invasive, but yield poorer quality DNA (Taberlet et al. 1999). Noninvasive sampling has increased in avian genetics over the last decade (Pearce et al. 1997; Segelbacher and Steinbru¨ck 2001; Segelbacher 2002), but there has been no thorough comparison of the quality and quantity of DNA produced among sample types. Use of moderately invasive samples, such as mouth swabs (Poschadel and Moïler 2004) and plucked feathers (Taberlet and Bouvet 1991), has also increased, but such samples have not been compared to other types. The purpose of our study was to determine (1) whether DNA could be successfully extracted and amplified from a variety of noninvasive and moderately invasive sample types and (2) which sample types yield the best quality DNA for use in avian DNA sexing based on amplification of the chromo helicase DNA-binding (CHD) gene (Z fragment=224 bp and W fragment=252 bp). We evaluated three under utilized sample types (avian saliva, chick down, and predated eggshell membranes) along with common sample types for use in sex determination. Greater Sage-Grouse (Centrocercus urophasi-anus) are endangered in Canada and the southern Alberta population has declined by 66–92% since the 1970s (Aldridge and Brigham 2003). We collected samples from the Alberta population from 1998–2004. Sample collection protocols and modifications to published DNA extraction protocols using Qiagen DNeasy Ò Tissue Kits and QIAamp Ò DNA Micro Kits (Qiagen, California, USA) are outlined in Table 1. Qiagen DNeasy Ò Tissue Kits were used for all samples with the exception of mouth swabs because low concentration DNA was produced. QIAamp Ò DNA Micro kits were used for mouth swabs and yielded high quality DNA (Table 1). Samples were DNA sexed using the 1237L/ 1272H primer set and PCR cycling conditions from Kahn et al. (1998). Fifteen microlitre PCRs are described in Table 1. PCR products were separated on 3% agarose gels stained with ethidium bromide and visually scored. Low voltage (100 mV) was used for maximum separation and definition of sex-specific bands. All samples were sexed three times to ensure consistent results. Three separate PCRs (modified multiple-tubes approach; Segelb-acher and Steinbru¨ck (2001)) opposed to eight separate PCRs (multiple tubes approach; Taberlet et al. (1999)) were performed for each sample to avoid false typing of individuals with low DNA concentrations. Samples that did not …

The importance of within-year repeated counts and the influence of scale on long-term monitoring of sage-grouse†

ABSTRACT Long-term population monitoring is the cornerstone of animal conservation and management. The accuracy and precision of models developed using monitoring data can be influenced by the protocols guiding data collection. The greater sage-grouse (Centrocercus urophasianus) is a species of concern that has been monitored over decades, primarily, by counting the number of males that attend lek (breeding) sites. These lek count data have been used to assess long-term population trends and for multiple mechanistic studies. However, some studies have questioned the efficacy of lek counts to accurately identify population trends. In response, monitoring protocols were changed to have a goal of counting lek sites multiple times within a season. We assessed the influence of this change in monitoring protocols on model accuracy and precision applying generalized additive models to describe trends over time. We found that at large spatial scales including >50 leks, the absence of repeated counts within a year did not significantly alter population trend estimates or interpretation. Increasing sample size decreased the model confidence intervals. We developed a population trend model for Wyoming greater sage-grouse from 1965 to 2008, identifying significant changes in the population indices and capturing the cyclic nature of this species. Most sage-grouse declines in Wyoming occurred between 1965 and the 1990s and lek count numbers generally increased from the mid-1990s to 2008. Our results validate the combination of monitoring data collected under different protocols in past and future studies—provided those studies are addressing large-scale questions. We suggest that a larger sample of individual leks is preferable to multiple counts of a smaller sample of leks.

ACCOUNTING FOR FITNESS: COMBINING SURVIVAL AND SELECTION WHEN ASSESSING WILDLIFE-HABITAT RELATIONSHIPS

Assessing the viability of a population requires understanding of the resources used by animals to determine how those resources affect long-term population persistence. To understand the true importance of resources, one must consider both selection (where a species occurs) and fitness (reproduction and survival) associated with the use of those resources. Failure to do so may result in incorrect assessments of habitat quality and inappropriate management activities. We illustrate the importance of considering both occurrence and fitness metrics when assessing habitat requirements for the endangered greater sage-grouse in Alberta, Canada. This population is experiencing low recruitment, so we assess resource use during the brood-rearing period to identify management priorities. First, we develop logistic regression occurrence models fitted with habitat covariates. Second, we use proportional hazard survival analysis to assess chick survival (fitness component) associated with habitat and climatic covaria...

Population structure and genetic diversity of greater sage-grouse ( Centrocercus urophasianus ) in fragmented landscapes at the northern edge of their range

Range-edge dynamics and anthropogenic fragmentation are expected to impact patterns of genetic diversity, and understanding the influence of both factors is important for effective conservation of threatened wildlife species. To examine these factors, we sampled greater sage-grouse (Centrocercus urophasianus) from a declining, fragmented region at the northern periphery of the species’ range and from a stable, contiguous core region. We genotyped 2,519 individuals at 13 microsatellite loci from 104 leks in Alberta, Saskatchewan, Montana, and Wyoming. Birds from northern Montana, Alberta, and Saskatchewan were identified as a single population that exhibited significant isolation by distance, with the Milk River demarcating two subpopulations. Both subpopulations exhibited high genetic diversity with no evidence that peripheral regions were genetically depauperate or highly structured. However, river valleys and a large agricultural region were significant barriers to dispersal. Leks were also composed primarily of non-kin, rejecting the idea that leks form because of male kin association. Northern Montana sage-grouse are maintaining genetic connectivity in fragmented and northern peripheral habitats via dispersal through and around various forms of fragmentation.

The effect of vegetation structure on predation of artificial Greater Sage-Grouse nests

In Canada, Greater Sage-Grouse (Centrocercus urophasianus) are considered an endangered species by the Committee On the Status of Endangered Wildlife In Canada (COSEWIC), due to declining population numbers and distribution. Encroachment of agriculture and subsequent destruction of suitable sagebrush (Artemisia spp.) habitat is thought to be responsible for historical population declines. However, subtle changes in habitat quality may also result in reduced escape and nesting cover, which may lead to increased levels of predation. We examined the influence of vegetation cover and height on the fate of artificial Greater Sage-Grouse nests. Because most natural sage-grouse nests are associated with sagebrush, we predicted that sagebrush height and cover would be crucial to the success of nests. Lateral cover is important in protecting nests from detection by predators, and thus we predicted that nests surrounded by shorter grass would suffer greater predation rates than nests with taller grass. To experimentally test this hypothesis, we trimmed grass surrounding some artificial nests. Richardson’s ground squirrels (Spermophilus richardsonii) were the primary predators of artificial nests, with some predation by corvids and badgers (Taxidea taxus). Successful nests tended to be surrounded by shorter sagebrush, taller grasses, and taller, denser forbs than predated nests. Trimming grass around nests did not affect nest fate. However, ground squirrels typically attacked nests with less forb cover and fewer sagebrush, and avian predators tended to destroy nests at inactive leks with greater lateral cover. Thus, lateral cover provided by forbs and sagebrush appeared to be important for protecting nests from mammalian predators. These results suggest implementing management strategies that improve sagebrush habitat by providing tall, dense forbs and sagebrush, which could increase Greater Sage-Grouse nest success and recruitment.

Adaptive management of prairie grouse: how do we get there?

Abstract Managing prairie grouse has been largely a reactive process without any “true” management experiments being implemented, thereby limiting our ability to learn from management and enhance conservation efforts for declining prairie grouse populations. In a few cases where the potential existed for a passive or active adaptive approach, monitoring was insufficient to detect effects of changes in management practices. Similar problems appear to occur at planning stages in attempts to implement adaptive management for prairie grouse populations, preventing proper consideration of sound adaptive experiments that advance learning. Successful adaptive management begins with stakeholder gatherings following a policy planning process, which includes many steps, beginning with goal identification and understanding of uncertainties and culminating in model simulations to understand potential management policies. By following this process, the opportunity to implement successful management experiments can be enhanced. We discuss the successes and failures of prairie grouse management using 2 case studies, 1 for prairie sharp-tailed grouse (Tympanuchus phasianellus) in Manitoba and 1 for greater sage-grouse (Centrocercus urophasianus) in southern Alberta. We describe ways in which active adaptive management could improve our understanding of prairie grouse population declines and outline a policy planning process that, if followed, will allow adaptive management to be successfully implemented, enhancing prairie grouse management and conservation.