| Initial effects of prescribed fire on morphology, abundance, and phenology of forbs in big sagebrush communities in southeastern Oregon | Wrobleski, DW | 2003 |
KeywordsAntennaria dimorpha; Astragalus malachus; Astragalus purshii; Centrocercus urophasianus; Crepis modocensis; fire-enhanced flowering; Hart Mountain National Antelope Refuge; Lomatium canbyi; Lomatium nevadense; Lomatium watsonii; morphology; phenology; Phlox gracilis; Phlox longifolia; prescribed fire; restoration; Sage Grouse; sagebrush AbstractHistoric fire return intervals in Artemesia tridentata (big sagebrush) ecosystems have been altered by livestock grazing, fire suppression, and other land management techniques resulting in ecological changes in these areas. Increases in abundance of woody vegetation may be causing declines in native herbaceous understory species. We examined the effects of prescribed fire on the morphology, abundance, and phenology of nine abundant forb (herbaceous dicot) species used selectively by Centrocercus urophasianus (Sage Grouse). In September 1997 prescribed fire was applied to four of eight randomly assigned 400-ha A.t. wyomingensis (Wyoming big sagebrush) study plots at Hart Mountain National Antelope Refuge, Oregon. Livestock had not grazed experimental plots since 1991. Burning caused morphological changes such as significantly greater numbers of racemes and flowers per raceme in Astragalus malachus (shaggy milkvetch-Legumoideae) (9 in burn vs. 6 in control; 23 in burn vs. 21 in control, respectively). Also, prescribed burning caused greater numbers of flowers in Phlox gracilis (microsteris-Polemoniaceae) (57 vs. 13), greater numbers of umbels and umbelletts in Lomatium nevadense (Nevada desert parsley-Umbellifereae) (4 vs. 2 and 59 vs. 31, respectively), greater numbers of flower heads in Crepis modocensis (Modoc hawksbeard-Compositae) (32 vs. 21), and greater number of flowers/cm(3) in Phlox longifolia (longleaf phlox-Polemoniaceae) (0.11 vs. 0.06). Crown volume of Crepis modocensis (7,085 vs. 4,179 cm(3) ) and Astragalus malachus (2,854 vs. 1,761 cm(3) ) plants was greater in burned plots than control plots. However, burning resulted in a smaller crown area of Antennaria dimorpha (low pussytoes-Compositae) (20 vs. 37 cm(2) ). Phenology and time of flowering were also affected by fire. The period of active growth for each species was extended later into the summer in burned plots (p<0.01). In addition, Crepis modocensis and Lomatium nevadense flowered 12 to 14 days earlier in burned plots. Fire had no effect on frequency, density, and relative abundance of seven of the nine studied species. Fire reduced the frequency and relative abundance of A. dimorpha and Phlox longifolia and reduced the density of A. dimorpha . AuthorsWrobleski, DW; Kauffman, JB Year Published2003 PublicationRestoration Ecology LocationsDOI10.1046/j.1526-100X.2003.00084.x |
| Tactical allocation of effort among multiple signals in sage grouse: an experiment with a robotic female | Patricelli, Gail L. | 2010 |
Keywordsacoustic localization communication greater sage grouse multiple traits plasticity sexual selection trade-off AbstractMales in many species have complex, multicomponent sexual signals, and there may be trade-offs between different signal components. By adjusting their signaling behaviors, males may be able to produce more attractive courtship displays in the face of these trade-offs, but this possibility has rarely been tested. In this study, we examined adaptive adjustment of display behaviors during courtship in a lek-breeding bird, the greater sage grouse (Centrocercus urophasianus). We measured the potential trade-off between display quantity (display rate) and quality (a temporal feature of displays) in a wild population of sage grouse using controlled approaches of a robotic female to experimentally induce changes in male display rate. We found that males who are more successful in mating can increase quantity without a decline in quality, with only unsuccessful males expressing an apparent trade-off. Male mating success was also positively correlated with responsiveness to changes in receiver distance, suggesting that successful males may avoid a trade-off by tactically adjusting their display rate-saving energy by displaying at low levels when females are farther away and at higher levels as females approach. Alternative explanations for this differential response to female proximity are discussed. Our results suggest that to be successful, males may need both the ability to produce attractive signals and the ability to effectively allocate their display effort by responding to female behaviors. AuthorsPatricelli, Gail L.; Krakauer, Alan H. Year Published2010 PublicationBehavioral Ecology LocationsDOI10.1093/beheco/arp155 |
| Factors affecting nest-site selection and nest success of translocated greater sage grouse | Baxter, Rick J. | 2009 |
KeywordsNo keywords available AbstractTranslocations 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. AuthorsBaxter, Rick J.; Flinders, Jerran T.; Whiting, David G.; Mitchell, Dean L. Year Published2009 PublicationWildlife Research LocationsDOI10.1071/WR07185 |
| Determinants of threatened sage grouse in northeastern Nevada. | van Kooten, G. Cornelis | 2007 |
Keywordspopulation viability analysis, endangered species, sage grouse AbstractWe examined potential human determinants of observed declines in greater sage grouse (Centrocercus urophasianus) populations in Elko County, Nevada. Although monitoring of sage grouse has occurred for decades, monitoring levels have not been consistent. This article contributes to the literature by normalizing grouse counts by the annual effort to count them, performing regression analyses to explain the resulting normalized data, and correcting for sample selectivity bias that arises from years when counts were not taken. Our findings provide some evidence that cattle-grazing contributes to a reduction in sage grouse populations, but this result should be interpreted with caution because our data do not include indications about the timing and precise nature of grazing practices. Annual variations in weather appear to be a major determinant after statistically controlling for human interactions with the landscape, suggesting that climate change is a key potential long-run threat to this species. Authorsvan Kooten, G. Cornelis; Eagle, Alison J.; Eiswerth, Mark E. Year Published2007 PublicationHuman Dimensions of Wildlife LocationsDOI10.1080/10871200601107908 |
| How predation risk affects the temporal dynamics of avian leks: Greater sage grouse versus golden eagles | Boyko, AR | 2004 |
Keywordslek mating system, dynamic game theory, greater sage grouse, mating skew, density dependence, predation AbstractLeks often attract predators as well as mates, yet most evolutionary models have assumed that sexual selection, not predation, drives lekking behavior. We explored the influence of predation on lek dynamics using a stochastic dynamic game model based on the lek-breeding greater sage grouse (Centrocercus urophasianus) and its principal avian predator, the golden eagle (Aquila chrysaetos). The model predicts time-dependent male lek attendance as a function of factors affecting both mating success (female arrival rate, male numbers, and social status) and predation risk (eagle arrival rate and group size). Dominant males are predicted to arrive sooner and leave later than subordinates, especially if mating skew is high, predation risk is low, or the relationship between lek size and female arrival rate is weak. Both high mean levels of predation risk and small lek size should reduce lek attendance, but the relative tendency of predators to attack large versus small leks has little influence on predicted lekking behavior. Field observations confirmed the predicted effects of female arrival rate, lek size, male dominance, and weather-dependent predator arrival rates on lek departure times. Predicted effects of female arrival rates and male dominance on seasonal lek attendance were also supported. Our model provides an empirically supported adaptive explanation for short-term lek dynamics. It also suggests alternative interpretations for phenomena previously invoked to support the hotshot and skew models of lek formation. AuthorsBoyko, AR; Gibson, RM; Lucas, JR Year Published2004 PublicationAmerican Naturalist LocationsDOI10.1086/380419 |
|
The Adrenocortical Response of Greater Sage Grouse (
Centrocercus urophasianus
) to Capture, ACTH Injection, and Confinement, as Measured in Fecal Samples
| Jankowski, M. D. | 2009 |
KeywordsNo keywords available AbstractInvestigators of wildlife populations often utilize demographic indicators to understand the relationship between habitat characteristics and population viability. Assessments of corticosterone may enable earlier detection of populations at risk of decline because physiological adjustments to habitat disturbance occur before reproductive diminutions. Noninvasive methods to accomplish these assesments are important in species of concern, such as the greater sage grouse (GRSG). Therefore, we validated a radioimmunoassay that measures immunoreactive corticosterone metabolites (ICM) in fecal samples and used it to characterize the adrenocortical response of 15 GRSG exposed to capture, intravenous injection of 50 IU/kg adrenocorticotrophic hormone (ACTH) or saline, and 22 h of confinement. Those animals injected with ACTH exhibited a more sustained (P = 0.0139) and less variable (P = 0.0012) response than those injected with saline, indicating different levels of adrenocortical activity. We also found that potential field-collection protocols of fecal samples did not alter ICM concentrations: samples held at 4 degrees C for up to 16 h contained similar levels of ICM as those frozen (-20 degrees C) immediately. This study demonstrates a multiphasic adrenocortical response that varied with the level of stimulation and indicates that the assay used to measure this phenomenon is applicable for studies of wild GRSG. AuthorsJankowski, M. D.; Wittwer, D. J.; Heisey, D. M.; Franson, J. C.; Hofmeister, E. K. Year Published2009 PublicationPhysiological And Biochemical Zoology LocationsDOI10.1086/596513 |
| Mate choice in lekking sage grouse revisited: the roles of vocal display, female site fidelity, and copying | Gibson, Robert M. | 1991 |
KeywordsNo keywords available AbstractIn lekking sage grouse (Centrocercus urophasianus), females exhibit relatively unanimous mate choice for particular males, but a satisfactory explanation for this unanimity has been elusive. We present analyses of mating distributions from two leks over 4 years that provide evidence for female choice based on differences in vocal display performance of males, the locations at which hens mated in the previous year, and the choices of other females (copying). The unanimity of female choice varied markedly among leks and years in correlation with changes in the mean numbers of hens that mated at the same time and hence the opportunity to copy. The results confirm that hens assess phenotypic traits of males directly but also indicate that the secondary tactics of site fidelity and copying are often important components of female choice. The occurrence of these secondary tactics has three implications: the variance in mating success among lek males will be a poor predictor of the intensity of sexual selection on specific traits; female preferences may generate more clustered dispersions of displaying males than predicted by hotspot settlement models; and direct assessment of males by females may be difficult or costly, a conclusion that supports adaptive models of sexual selection over a nonadaptive Fisherian process. [Behav Ecol 1991;2:165-180] AuthorsGibson, Robert M.; Bradbury, Jack W.; Vehrencamp, Sandra L. Year Published1991 PublicationBehavioral Ecology LocationsDOI10.1093/beheco/2.2.165 |
| The secret sex lives of sage-grouse: multiple paternity and intraspecific nest parasitism revealed through genetic analysis | Bird, Krista L. | 2013 |
Keywordslek, multiple paternity, nest parasitism, paternity, polygyny, sage-grouse AbstractIn lek-based mating systems only a few males are expected to obtain the majority of matings in a single breeding season and multiple mating is believed to be rare. We used 13 microsatellites to genotype greater sage-grouse (Centrocercus urophasianus) samples from 604 adults and 1206 offspring from 191 clutches (1999-2006) from Alberta, Canada, to determine paternity and polygamy (males and females mating with multiple individuals). We found that most clutches had a single father and mother, but there was evidence of multiple paternity and intraspecific nest parasitism. Annually, most males fathered only one brood, very few males fathered multiple broods, and the proportion of all sampled males in the population fathering offspring averaged 45.9%, suggesting that more males breed in Alberta than previously reported for the species. Twenty-six eggs (2.2%) could be traced to intraspecific nest parasitism and 15 of 191 clutches (7.9%) had multiple fathers. These new insights have important implications on what we know about sexual selection and the mating structure of lekking species. AuthorsBird, Krista L.; Aldridge, Cameron L.; Carpenter, Jennifer E.; Paszkowski, Cynthia A.; Boyce, Mark S.; Coltman, David W. Year Published2013 PublicationBehavioral Ecology LocationsDOI10.1093/beheco/ars132 |
| Microsatellite DNA analysis shows that greater sage grouse leks are not kin groups | Gibson, RM | 2005 |
Keywordskinship; lek skew paradox; microsatellite analysis; sage grouse AbstractThe spectacular social courtship displays of lekking birds are thought to evolve via sexual selection, but this view does not easily explain the participation of many males that apparently fail to mate. One of several proposed solutions to this 'lek skew paradox' is that kin selection favours low-ranking males joining leks to increase the fitness of closely related breeders. We investigated the potential for kin selection to operate in leks of the greater sage grouse, Centrocercus urophasianus, by estimating relatedness between lekking males using microsatellite DNA markers. We also calibrated these estimates using data from known families. Mean relatedness within leks was statistically indistinguishable from zero. We also found no evidence for local clustering of kin during lek display, although males tended to range closer to kin when off the lek. These results make kin selection an unlikely solution to the lek skew paradox in sage grouse. Together with other recent studies, they also raise the question of why kin selection apparently promotes social courtship in some lekking species, but not in others. AuthorsGibson, RM; Pires, D; Delaney, KS; Wayne, RK Year Published2005 PublicationMolecular Ecology LocationsDOI10.1111/j.1365-294X.2005.02746.x |
| West Nile virus: pending crisis for greater sage-grouse | Naugle, DE | 2004 |
KeywordsCentrocercus urophasianus, emerging infectious disease, endangered species; greater sage-grouse; mosquito; population decline; survival; vector surveillance; West Nile virus AbstractScientists have feared that emerging infectious diseases could complicate efforts to conserve rare and endangered species, but quantifying impacts has proven difficult until now. We report unexpected impacts of West Nile virus (WNv) on radio-marked greater sage-grouse (Centrocercus urophasianus), a species that has declined 45-80% and is endangered in Canada and under current consideration for federal listing in the US. We show that WNv reduced late-summer survival an average of 25% in four radio-marked populations in the western US and Canada. Serum from 112 sage-grouse collected after the outbreak show that none had antibodies, suggesting that they lack resistance. The spread of WNv represents a significant new stressor on sage-grouse and probably other at-risk species. While managing habitat might lessen its impact on sage-grouse populations, WNv has left wildlife and public health officials scrambling to address surface water and vector control issues in western North America. AuthorsNaugle, DE; Aldridge, CL; Walker, BL; Cornish, TE; Moynahan, BJ; Holloran, MJ; Brown, K; Johnson, GD; Schmidtmann, ET; Mayer, RT; Kato, CY; Matchett, MR; Christiansen, TJ; Cook, WE; Creekmore, T; Falise, RD; Rinkes, ET; Boyce, MS Year Published2004 PublicationEcology Letters LocationsDOI10.1111/j.1461-0248.2004.00631.x |
