Dean L. Mitchell

Survival, Movements, and Reproduction of Translocated Greater Sage-Grouse in Strawberry Valley, Utah

Abstract Translocations of greater sage-grouse (Centrocercus urophasianus) have been attempted in 7 states and one Canadian province with very little success. To recover a small remnant population and test the efficacy of sage-grouse translocations, we captured and transported 137 adult female sage-grouse from 2 source populations to a release site in Strawberry Valley, Utah, USA, during March–April 2003–2005. The resident population of sage-grouse in Strawberry Valley was approximately 150 breeding birds prior to the release. We radiomarked each female and documented survival, movements, reproductive effort, flocking with resident grouse, and lek attendance. We used Program MARK to calculate annual survival of translocated females in the first year after release, which averaged 0.60 (95% CI = 0.515–0.681). Movements of translocated females were within current and historic sage-grouse habitat in Strawberry Valley, and we detected no grouse outside of the study area. Nesting propensity for first (newly translocated) and second (surviving) year females was 39% and 73%, respectively. Observed nest success of all translocated females during the study was 67%. By the end of their first year in Strawberry Valley, 100% of the living translocated sage-grouse were in flocks with resident sage-grouse. The translocated grouse attended the same lek as the birds with which they were grouped. In 2006, the peak male count for the only remaining active lek in Strawberry Valley was almost 4 times (135 M) the 6-year pretranslocation (1998–2003) average peak attendance of 36 males (range 24–50 M). Translocations can be an effective management tool to increase small populations of greater sage-grouse when conducted during the breeding season and before target populations have been extirpated.

Chukar Watering Patterns and Water Site Selection

Abstract We evaluated chukar (Alectoris chukar) watering patterns as well as habitat variables influencing water site selection in western Utah. Motion-sensing cameras and chukar dropping counts were primary techniques to evaluate watering patterns. We took vegetative and other habitat measurements at each water source (n = 43) to discriminate use from nonuse sites using logistic regression. Chukars watered during daylight hours with a modal hour from 1200 hours to 1300 hours daylight savings time. Annual patterns suggest limited use of water sources from November to May with first observed visits occurring in June and last observed visits in October. Shrub canopy cover was the only variable to discriminate between site types (P < 0.01). Cross validation showed a predictive success rate of 84%. Significant differences were found between use and nonuse sites in terms of security cover (P < 0.01), but not total cover (P > 0.05). Chukars seem to have a loose shrub canopy threshold near 11% that is likely due to predation risk. Water sources meeting this threshold received use, whereas those not meeting this threshold did not. Increasing shrub canopy cover above 11% did not translate into increased water source use. Managers might want to consider annual patterns when setting hunt season timing and structure as well as judging sites for new water developments based on shrub canopy cover. More generally, these results suggest a behavioral constraint on the use of water sources as a function of predation risk—we should expect other species to demonstrate similar behavioral constraints. These constraints must be considered in any effort to determine benefits or impacts of water developments.

Occupied and unoccupied sage grouse habitat in Strawberry Valley, Utah

This study evaluated multiple aspects of spring/summer sage grouse (Centrocercus urophasianus) habitat in Strawberry Valley, Utah by measuring vegetation associated with nest, brood and adult use sites. In addition, 3 types of random habitats were measured including available habitat within core use areas, random sagebrush (Artemisia spp.)/grass habitat outside core use areas, and random sagebrush/grass habitat sites that had been converted to an understory of smooth brome (Bromus inermis Leyss) by past range management practices. Logistic regression was used to identify those habitat variables that discriminated between site types. Variables that discriminated adult habitat from brood rearing habitat included: 1) sagebrush height (P ≤ 0.01) and 2) forb diversity (P = 0.12) with sagebrush height being greater at adult sites and forb diversity greater at brood sites Variables that significantly discriminated occupied adult habitat from random habitat outside of core use areas included: 1) percent grass cover (P ≤ 0.01) and 2) area of sagebrush canopy (P = 0.03) with both variables having grater values in adult habitat. Variables that significantly discriminated occupied adult habitat from random habitat with a smooth brome understory included: 1) percent forb cover (P ≤ 0.01), 2) shrub canopy cover (P = 0.02), and 3) area of sagebrush canopy (P = 0.08) with all variables being greater in adult habitat. In addition, this study identified sagebrush age, sagebrush canopy area, and forb diversity as potentially important aspects of sage grouse habitat that have not been previously reported.

Chukar Seasonal Survival and Probable Causes of Mortality

Abstract Chukars (Alectoris chukar) have been introduced throughout the world. Despite this widespread distribution, limited information regarding seasonal survival, probable causes of mortality, and other basic life history characteristics is available to manage this harvested species. We estimated the probable cause of mortality for chukars with radiotransmitters by examining evidence at kill sites. We used model selection to evaluate influences of seasonal effects (fall raptor migration, peak migration, and reproductive period), demographic effects (age and sex), radio weight, and year on survival of chukars in western Utah, USA, by using a known-fate model in Program MARK and 2 years of telemetry data. We captured and randomly fitted 125 individual chukars with 2 different-sized radiotransmitters (97 F, 20 M, 8 sex undetermined). Model selection results showed our top 3 models accounted for 99% of Akaikes Information Criterion weight, and each one had seasonal and year effects. Two-week survival estimates were lower during peak raptor migration in both years and significantly (P < 0.05) so in year 2 (2-week S = 0.87, 95% CI = 0.77–0.94) compared with other year 2 intervals (2-week S > 0.91). Annual survival was lower in 2005 (S = 0.03, 95% CI = 0.01–0.09) compared with 2006 (S = 0.19, 95% CI = 0.12–0.31). We documented 95 deaths and classified 56% unknown, 33% avian predation, 8% hunter harvest, and 3% mammalian predation. Our research suggests that predation on chukars is substantial during the peak fall raptor migratory period and that the hunting take under current regulations is relatively small and likely compensatory.

Factors affecting nest-site selection and nest success of translocated greater sage grouse

Translocations have been used for decades to restore or augment wildlife populations, yet more often than not, little to no data and/or arbitrary means are used for determining translocation success. The objectives of our study were to describe nesting habitat utilised by the greater sage grouse translocated into an extant population and to identify factors related to nest success, thereby demonstrating the adaptability of the birds to their new environment and producing one measure of long-term translocation success. We trapped female grouse individuals during the spring on and near leks of source populations, fitted them with radio-transmitters, and released them in the morning onto an active lek in an extant population in Strawberry Valley, Utah. We monitored translocated females for nesting activity and documented nesting attempts, nest success, clutch size and embryo viability. Data were recorded on habitat variables associated with nest sites and paired-random sites, including factors known to be important for resident females that nested successfully. We used logistic regression and an a priori information-theoretic approach for modelling nest v. paired-random sites and successful v. unsuccessful nest sites. Our analyses suggested that crown area of the nest shrub and percentage grass cover were the two variables that discriminated between nest and paired-random sites. Females that nested successfully selected sites with more total shrub canopy cover, intermediate size-shrub crown area, aspects other than NW and SE, and steeper slopes than for unsuccessful nests. After being translocated from distant sites with differing habitat characteristics, these birds were able to initiate a nest, nest successfully, and select micro-habitat features similar to those selected by resident sage grouse across the species range. Our results demonstrate the adaptability of the translocated female sage grouse individuals and produce one tangible measure of long-term translocation success.

Conservation risks of exotic chukars (Alectoris chukar) and their associated management: implications for a widely introduced phasianid

Chukars (Alectoris chukar) have been widely introduced throughout the world. Their introductions and associated management for sport hunting have the potential to affect native ecosystems in a variety of ways. Our specific objectives were: (1) to document species using water developments designed to benefit chukar populations to determine whether, and at what prevalence, exotic species appear to use, and presumably benefit from, additional watering points; (2) to describe chukar diet with specific reference to cheatgrass and other exotic plant seeds; and (3) to determine whether chukars are a likely vector for dispersal of cheatgrass and/or other plant seeds via passage through the gut. In total, 27 different wildlife species were photographed across all 36 sampled water developments. Three exotic species were photographed to include chukars, rock dove (Columba livia), and red fox (Vulpes vulpes), with the latter two species photographed at only two and one site respectively. Mean number of species photographed (5.69 ± 1.09) ranged from 1 to 13, but was estimated near 10 after accounting for sampling time. Cheatgrass seed was found in 76.3% of crops and constituted 45.2% of dry weight. Thirteen plants germinated from 503 chukar faecal droppings. We found no evidence of widespread use of water points designed for chukars by other exotic species or dispersal of cheatgrass seed via passage through the gut. Chukars appear (at least initially) benign and they are not likely to be major vectors in plant seed dispersal. Furthermore, chukars could foster localised plant diversity in that they consume large quantities of primarily exotic plant seed and do not show a propensity for dispersal of seeds through faecal droppings.