scholarly journals Changes in hunting season regulations (1870s–2019) reduce harvest exposure on greater and Gunnison sage-grouse

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0253635
Author(s):  
Jonathan B. Dinkins ◽  
Courtney J. Duchardt ◽  
Jacob D. Hennig ◽  
Jeffrey L. Beck
Keyword(s):  
Disease Outbreaks ◽  
Weighted Average ◽  
Population Declines ◽  
Sage Grouse ◽  
Hunting Season ◽  
Start Date ◽  
Potential Factor ◽  
Canadian Provinces ◽  
Hunting Regulations ◽  
Reduction In Area

Hunter harvest is a potential factor contributing to population declines of sage-grouse (Centrocercus spp.). As a result, wildlife agencies throughout western North America have set increasingly more conservative harvest regulations over the past 25 years to reduce or eliminate hunter success and concomitant numbers of harvested greater (C. urophasianus) and Gunnison (C. minimus) sage-grouse. Sage-grouse hunting has varied widely over time and space, which has made a comprehensive summary of hunting management challenging. We compiled data on harvest regulations among 11 western U.S. states and 2 Canadian provinces from 1870–2019 to create a timeline representative of hunting regulations. We compared annual harvest boundaries and area-weighted average hunting regulations, 1995–2018, relative to administrative boundaries and areas of high probability of sage-grouse occupation. We also summarized estimated numbers of birds harvested and hunters afield, 1995–2018, across both species’ ranges. From 1995–2018, there was a 30% reduction in administrative harvest boundaries across the greater sage-grouse range compared to a 16.6% reduction in area open to harvest within 8 km from active leks. Temporary closures occurred in response to wildfires, disease outbreaks, low population numbers, and two research projects; whereas, permanent closures primarily occurred in small populations and areas on the periphery of the species distribution. Similarly, area-weighted possession limits and season length for greater sage-grouse decreased 52.6% and 61.0%, respectively, while season start date stayed relatively stable (mean start date ~259 [mid-September]). In contrast, hunting of the now federally-threatened Gunnison sage-grouse ended after 1999. While restrictions in harvest regulations were large in area, closures near areas of high greater sage-grouse occupancy were relatively smaller with the same trend for Gunnison sage-grouse until hunting ceased. For greater sage-grouse, most states reduced bag and possession limits and appeared to adhere to recommendations for later and shorter hunting seasons, reducing potential for additive mortality.

scholarly journals Influence of environmental change, harvest exposure, and human disturbance on population trends of greater sage-grouse

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0257198
Author(s):  
Jonathan B. Dinkins ◽  
Kirstie J. Lawson ◽  
Jeffrey L. Beck
Keyword(s):  
Environmental Change ◽  
Population Growth ◽  
Human Disturbance ◽  
Human Population ◽  
Oil And Gas ◽  
Instantaneous Growth Rate ◽  
Sage Grouse ◽  
Hunting Season ◽  
Gas Well ◽  
Hunting Regulations

Hunter harvest of greater sage-grouse (Centrocercus urophasianus; hereafter “sage-grouse”) has been regulated by wildlife agencies during most of the past century. Hunting season regulations were maintained with the intention of providing sustainable hunting opportunities. Sage-grouse populations oscillate over time, and population growth can be influenced by seasonal weather and habitat disturbance. From 1995–2013, we compared sage-grouse lek trends from 22 relatively distinct sage-grouse population segments in 9 western U.S. states and 2 Canadian provinces. We stratified these populations into 3 broad categories (non-hunted [n = 8], continuously hunted [n = 10], and hunting season discontinued between 1996–2003 [n = 4]) with 8 different regulation histories to evaluate the potential impact of harvest on sage-grouse populations. Concomitantly, we assessed the effects of proportion burned, forested and cropland habitat; winter, spring, and summer precipitation; and human population, road, and oil and gas well densities on initial and time-varying lek counts. Density-dependent models fit lek trend data best for all regulation histories. In general, higher proportions of burnt, forested, and cropland habitat; and greater human population and oil and gas well densities were associated with lower equilibrium abundance (K). We found mixed results regarding the effect of hunting regulations on instantaneous growth rate (r). The cessation of harvest from 1996–2001 in approximately half of the largest sage-grouse population in our analysis was associated with higher r. Continuously harvested sage-grouse populations with permit hunting seasons had higher r during years with higher proportion of area exposed to permitted hunting rather than general upland game seasons. However, more liberal hunting regulations were positively associated with higher r in populations continuously harvested under general upland game hunts. Our results suggest that discontinuing harvest in the largest population resulted in greater population growth rates; however, this was not consistently the case for smaller populations. To no surprise, not all sage-grouse populations were influenced by the same environmental change or human disturbance factors. Our results will assist managers to understand factors associated with K, which provides the best targets for conservation efforts.

scholarly journals Spatial Distribution of Greater Sage-Grouse Nests in Relatively Contiguous Sagebrush Habitats

The Condor ◽  
2005 ◽  
Vol 107 (4) ◽  
pp. 742-752 ◽  
Author(s):  
Matthew J. Holloran ◽  
Stanley H. Anderson
Keyword(s):  
Radio Telemetry ◽  
Centrocercus Urophasianus ◽  
Spatial Arrangement ◽  
Population Viability ◽  
Prey Detection ◽  
Population Declines ◽  
Sage Grouse ◽  
Nesting Habitat ◽  
Nesting Site ◽  
Low Probability

Abstract Degradation of nesting habitat has been proposed as a factor contributing to Greater Sage-Grouse (Centrocercus urophasianus) population declines throughout North America. Delineating suitable nesting habitat across landscapes with relatively contiguous sagebrush cover is difficult but important to identify areas for protection. We used radio-telemetry to locate Greater Sage-Grouse nests in relatively contiguous sagebrush habitats in Wyoming to investigate the spatial arrangement of nests relative to lek and other nest locations. Nest distributions were spatially related to lek location within 3 and 5 km of a lek, and a 5-km buffer included 64% of the nests. There was no relationship between lek size and lek-to-nest distance, suggesting that accurate population trend evaluation might require lek surveys in addition to lek counts. Closest known lek-to-nest distance was greater for successfully hatched compared to destroyed nests, and closely spaced nests tended to experience lower success and have higher probabilities of both nests experiencing the same fate compared to isolated nests, suggesting that a mechanism of enhanced prey detection occurred at higher nest densities. A low probability that a given individual's consecutive-year nest spacing occurred randomly suggested nesting site-area fidelity. Although a grouped pattern of nests occurred within 5 km of a lek, the proportion of nesting females located farther than 5 km could be important for population viability. Managers should limit strategies that negatively influence nesting habitat regardless of lek locations, and preserve adequate amounts of unaltered nesting habitat within treatment boundaries to maintain nest dispersion and provide sites for philopatric individuals.

scholarly journals Within-Colony Transmission of Microsporidian and Trypanosomatid Parasites in Honey Bee and Bumble Bee Colonies

2020 ◽  
Vol 49 (6) ◽  
pp. 1393-1401
Author(s):  
Mario S Pinilla-Gallego ◽  
Emma E Williams ◽  
Abby Davis ◽  
Jacquelyn L Fitzgerald ◽  
Scott H McArt ◽  
...  
Keyword(s):  
Honey Bees ◽  
Disease Outbreaks ◽  
Parasite Prevalence ◽  
Bumble Bees ◽  
Disease Spread ◽  
Population Declines ◽  
Intensity Of Infection ◽  
Wild Bees ◽  
Social Bees ◽  
Pollinator Community

Abstract Parasites are commonly cited as one of the causes of population declines for both managed and wild bees. Epidemiological models sometimes assume that increasing the proportion of infected individuals in a group should increase transmission. However, social insects exhibit behaviors and traits which can dampen the link between parasite pressure and disease spread. Understanding patterns of parasite transmission within colonies of social bees has important implications for how to control diseases within those colonies, and potentially the broader pollinator community. We used bumble bees (Bombus impatiens Cresson) (Hymenoptera: Apidae) and western honey bees (Apis mellifera L.) (Hymenoptera: Apidae) infected with the gut parasites Crithidia bombi (Lipa & Triggiani) (Trypanosomatida: Trypanosomatidae) and Nosema ceranae (Fries et al.) (Dissociodihaplophasida: Nosematidae), respectively, to understand how the initial proportion of infected individuals impacts within-colony spread and intensity of infection of the parasites. In bumble bees, we found that higher initial parasite prevalence increased both the final prevalence and intensity of infection of C. bombi. In honey bees, higher initial prevalence increased the intensity of infection in individual bees, but not the final prevalence of N. ceranae. Measures that reduce the probability of workers bringing parasites back to the nest may have implications for how to control transmission and/or severity of infection and disease outbreaks, which could also have important consequences for controlling disease spread back into the broader bee community.

scholarly journals Environmental reservoir dynamics predict global infection patterns and population impacts for the fungal disease white-nose syndrome

2020 ◽  
Vol 117 (13) ◽  
pp. 7255-7262 ◽  
Author(s):  
Joseph R. Hoyt ◽  
Kate E. Langwig ◽  
Keping Sun ◽  
Katy L. Parise ◽  
Aoqiang Li ◽  
...  
Keyword(s):  
Disease Outbreaks ◽  
Population Declines ◽  
Pseudogymnoascus Destructans ◽  
White Nose Syndrome ◽  
Infection Dynamics ◽  
Environmental Reservoir ◽  
Severe Infections ◽  
Seasonal Epidemics ◽  
Host Infection ◽  
The Impact

Disease outbreaks and pathogen introductions can have significant effects on host populations, and the ability of pathogens to persist in the environment can exacerbate disease impacts by fueling sustained transmission, seasonal epidemics, and repeated spillover events. While theory suggests that the presence of an environmental reservoir increases the risk of host declines and threat of extinction, the influence of reservoir dynamics on transmission and population impacts remains poorly described. Here we show that the extent of the environmental reservoir explains broad patterns of host infection and the severity of disease impacts of a virulent pathogen. We examined reservoir and host infection dynamics and the resulting impacts of Pseudogymnoascus destructans, the fungal pathogen that causes white-nose syndrome, in 39 species of bats at 101 sites across the globe. Lower levels of pathogen in the environment consistently corresponded to delayed infection of hosts, fewer and less severe infections, and reduced population impacts. In contrast, an extensive and persistent environmental reservoir led to early and widespread infections and severe population declines. These results suggest that continental differences in the persistence or decay of P. destructans in the environment altered infection patterns in bats and influenced whether host populations were stable or experienced severe declines from this disease. Quantifying the impact of the environmental reservoir on disease dynamics can provide specific targets for reducing pathogen levels in the environment to prevent or control future epidemics.

scholarly journals Single infection with Batrachochytrium dendrobatidis or Ranavirus does not increase probability of co-infection in a montane community of amphibians

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jaime Bosch ◽  
Camino Monsalve-Carcaño ◽  
Stephen J. Price ◽  
Jon Bielby
Keyword(s):  
Batrachochytrium Dendrobatidis ◽  
Disease Outbreaks ◽  
Single Infection ◽  
Chytrid Fungus ◽  
Population Declines ◽  
Emerging Pathogens ◽  
Amphibian Species ◽  
Management Interventions ◽  
Amphibian Chytrid Fungus ◽  
Common Situation

AbstractUnderstanding the occurrence and consequence of co-infections can be useful in designing disease management interventions. Amphibians are the most highly threatened vertebrates, and emerging pathogens are a serious threat to their conservation. The amphibian chytrid fungus and the viruses of the Ranavirus genus are already widely distributed, causing disease outbreaks and population declines worldwide. However, we lack information about the occurrence and consequences of coinfection with these pathogens across age-classes of amphibian hosts. Here, we analyze the occurrence of infection of the amphibian chytrid fungus and ranaviruses during one season in two susceptible amphibian species at two different locations at which outbreaks have occurred. We found that the co-occurrence of both pathogens in a particular host is not common except in highly susceptible life-stages, and that single infections are the most common situation. Moreover, we found that the occurrence of one pathogen in a particular host did not predict the occurrence of the other. We attribute these results to the niches in which both pathogens proliferate in amphibian hosts.

scholarly journals Reciprocal abundance shifts of the intertidal sea stars, Evasterias troschelii and Pisaster ochraceus , following sea star wasting disease

2019 ◽  
Vol 286 (1901) ◽  
pp. 20182766 ◽  
Author(s):  
Sharon W. C. Kay ◽  
Alyssa-Lois M. Gehman ◽  
Christopher D. G. Harley
Keyword(s):  
Indirect Effects ◽  
Interference Competition ◽  
Disease Outbreaks ◽  
Ecological Communities ◽  
Population Declines ◽  
Sea Star ◽  
Sea Stars ◽  
Wasting Disease ◽  
Field Surveys ◽  
Pisaster Ochraceus

Disease emergence occurs within the context of ecological communities, and disease driven declines in host populations can lead to complex direct and indirect ecological effects. Varying effects of a single disease among multiple susceptible hosts could benefit relatively resistant species. Beginning in 2013, an outbreak of sea star wasting disease (SSWD) led to population declines of many sea star species along the west coast of North America. Through field surveys and laboratory experiments, we investigated how and why the relative abundances of two co-occurring sea star species, Evasterias troschelii and Pisaster ochraceus , shifted during the ongoing wasting epidemic in Burrard Inlet, British Columbia, Canada. We hypothesized that Evasterias is competitively inferior to Pisaster but more resistant to SSWD. Thus, we predicted that SSWD-induced declines of Pisaster could mitigate the negative effects of SSWD on Evasterias , as the latter would experience competitive release. We document shifts in sea star abundance from 2008–2017: Pisaster abundance and mean size declined during the outbreak, while Evasterias abundance increased from relatively rare to numerically dominant within the intertidal. When exposed to symptomatic sea stars, Pisaster and Evasterias both showed signs of SSWD, but transmission and susceptibility was lower in Evasterias. Despite diet overlap documented in our field surveys, Evasterias was not outcompeted by Pisaster in laboratory trails conducted with the relatively small Pisaster available after the outbreak. Interference competition with larger Pisaster , or prey exploitation by Pisaster during the summer when Evasterias is primarily subtidal, may explain the rarity of Evasterias prior to Pisaster declines. Our results suggest that indirect effects mediated by competition can mask some of the direct effects of disease outbreaks, and the combination of direct and indirect effects will determine the restructuring of a community after disturbance.

scholarly journals Comparison of Patterns of Genetic Variation and Demographic History in the Greater Sage-Grouse (Centrocercus urophasianus): Relevance for Conservation

2014 ◽  
Vol 7 (1) ◽  
pp. 19-29 ◽  
Author(s):  
Robert M. Zink
Keyword(s):  
Genetic Variation ◽  
Spatial Scales ◽  
Demographic History ◽  
Local Population ◽  
Centrocercus Urophasianus ◽  
Columbia Basin ◽  
Population Declines ◽  
Microsatellite Data ◽  
Sage Grouse ◽  
Declining Populations

The greater sage-grouse (Centrocercus urophasianus) was once widespread in western North America but its range has contracted by an uncertain degree owing to anthropogenic and natural causes. Concern over population declines has led to its proposed listing as threatened under the U.S. Endangered Species Act. Detailed genetic and demographic analyses of this species throughout its range are available but heretofore have not been compared. Reduced genetic variability is often taken as a proxy for declining populations, but rarely are there quantitative population estimates with which to compare. I compared published mitochondrial DNA (mtDNA) control region sequences, microsatellite allele frequencies at seven loci, and estimates of numbers of males per lek, number of active leks, percent decline in the best population models, and the probability (P) of Ne < 50 in 30 years and P(Ne < 500) in 100 years, at two spatial scales, 45 local population samples and 16 larger aggregates of samples. When excluding the populations from the Columbia Basin, which show little genetic diversity and are statistical outliers, there were no consistent relationships between estimates of genetic variation and demographic trends across the remainder of the range at either spatial scale. A measure of inbreeding derived from microsatellite data was also not related to population trends. Thus, despite habitat reduction and range fragmentation, the greater sage-grouse does not exhibit expected genetic signatures of declining populations. Possibly, the mtDNA and microsatellite data are insufficiently sensitive to detect population declines that have occurred over the span of a half century. Alternatively, only when populations are reduced to the levels seen in the Columbia Basin will genetic effects be seen, suggesting that the bulk of the range of the greater sage-grouse is not currently in genetic peril.

scholarly journals Duck Populations and Kill: an Evaluation of Some Waterfowl Regulations in Illinois

1944 ◽  
Vol 23 (1-5) ◽  
pp. 327-372 ◽  
Author(s):  
Frank C. Bellrose
Keyword(s):  
Hunting Season ◽  
Waterfowl Hunting ◽  
Ruddy Ducks ◽  
Hunting Regulations

This paper was conceived and written in an attempt to evaluate the effect of various hunting regulations on the kill of ducks in Illinois, and to ascertain the optimum dates for Illinois hunting seasons of various lengths.  Recent open seasons in Illinois' (1938-1942) have protected blue-winged teals more than any other species.  These open seasons have protected other species in the following descending order: shovelers, green-winged teals, pintails, widgeons, mallards and black ducks, ring-necked ducks, canvasbacks, lesser scaups, ruddy ducks and gadwalls. The dates for the waterfowl hunting season in Illinois should depend upon what species of ducks need the greatest protection, and whether the hunter or the waterfowl population should be favored. Open dates suggested by this study are as follows: For a 30-day season, November 1-30; for a 45-day season, October 22-December 5; for a 60-day season, October 10-December 8; for a 70-day season, October 1-December 9; for an 80-day season, September 26-December 14; for a 100-day season, September 20-December 28.

Disease outbreaks can threaten marine biodiversity

2020 ◽  
pp. 141-158
Author(s):  
C. Drew Harvell ◽  
Joleah B. Lamb
Keyword(s):  
Infectious Diseases ◽  
Disease Outbreaks ◽  
Community Change ◽  
Foundation Species ◽  
Marine Biodiversity ◽  
Marine Biota ◽  
Population Declines ◽  
Case Histories ◽  
Sea Stars ◽  
Marine Communities

Disease outbreaks have driven declines in some threatened species on land, including amphibians, bats, and birds. In the oceans, infectious diseases can also drive declines and are a potential agent of community change and threat to marine biodiversity. Recent disease-driven mass mortalities have affected a range of marine biota. This chapter outlines four case histories of disease outbreaks that affect marine communities and, in multiple cases, contribute to endangerment or listing as endangered species. The case histories include disease impacts to foundation species of corals and seagrasses, herbivores like abalone, and keystone predators like sea stars. Multi-host diseases in all these cases have contributed to extreme population declines. Infectious diseases pose the greatest threat to marine communities when they reduce foundation species like corals and seagrasses. In turn, disruption of marine communities may impact the services they provide to humans and other organisms through pathogen biofiltration. The authors suggest that marine disease impacts may be slowed by protecting the natural services provided by intact ecosystems.

scholarly journals Direct Identification of Northern Sage-grouse, Centrocercus urophasianus, Nest Predators Using Remote Sensing Cameras

2003 ◽  
Vol 117 (2) ◽  
pp. 308 ◽  
Author(s):  
Matthew J. Holloran ◽  
Stanley H. Anderson
Keyword(s):  
Centrocercus Urophasianus ◽  
Nesting Success ◽  
Ground Squirrels ◽  
Population Declines ◽  
Sage Grouse ◽  
Direct Identification ◽  
Taxidea Taxus ◽  
The Status ◽  
Visual Confirmation ◽  
Nest Predators

The status and apparent decline of Sage-grouse (Centrocercus spp.) has been of increasing concern and lower nesting success could be contributing to population declines. Our objective was to directly identify Sage-grouse nest predators. Following visual confirmation of radio-marked Sage-grouse nest establishment in 1997-1999, we installed automatic 35 mm cameras controlled by an active infrared monitor. Of 26 nests monitored by cameras, 22 successfully hatched and four were unsuccessful. American Elk (Cervus canadensis), Badger (Taxidea taxus), and Black-billed Magpie (Pica hudsonia) destroyed three of the four unsuccessful nests, and domestic cattle caused abandonment of the fourth. Richardson’s (Spermophilus richardsonii) and Thirteen-lined Ground Squirrels (S. tridecemlineatus) were recorded at nests, but were not detected in predation.

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