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Michael A. Schroeder - One of the best experts on this subject based on the ideXlab platform.
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Greater Sage-Grouse
2017Co-Authors: Steve Knick, John W. Connelly, Michael A. Schroeder, Matthew Vander HaegenAbstract:We examined the relationship between the Conservation Reserve Program (CRP) lands and Greater Sage-Grouse (Centrocercus urophasianus) in Washington state including an assessment of population change, nest-site selection, and general habitat use. We monitored nest-site selection of 89 female sage-Grouse between 1992 and 1997 with the aid of radiotelemetry. The proportion of nests in CRP lands significantly increased from 31% in 1992–1994 to 50% in 1995–1997, although more nests were detected in shrub steppe (59% vs. 41% of 202 nests). The increase appeared to be associated with maturation of CRP fields, which were characterized by increased cover of perennial grass and big sagebrush (Artemisia tridentata). Nest success was similar (P 0.38) for nests placed in the two cover types (45% in CRP and 39% in shrub steppe). Counts of fecal pellets indicated that sage-Grouse selected areas with greater sagebrush cover, especially in relatively new CRP in a shrub steppe landscape. Analysis of male lek attendance prior to implementation of CRP (1970–1988) illustrated similar rates of declines in two separate populations of sage-Grouse in north-central and south-central Washington. Data from 1992 to 2007 following establishment of the CRP revealed a reversal of the population decline in north-central Washington while the south-central population continued a long-term decline ( 17% vs. 2% of the occupied areas were in the CRP, respectively). These results indicate that lands enrolled in the CRP can have a positive impact on Greater Sage-Grouse, especially if they include big sagebrush and are focused in landscapes with substantial extant shrub steppe. The CRP for sageGrouse and other sage-dependent species should be considered a long-term investment because of the time required for sagebrush plants to develop.
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Habitat selection and use by sympatric, translocated greater sage‐Grouse and Columbian sharp‐tailed Grouse
The Journal of Wildlife Management, 2015Co-Authors: Kourtney F. Stonehouse, Lisa A. Shipley, Jason Lowe, Michael T. Atamian, Mark E. Swanson, Michael A. SchroederAbstract:Greater sage-Grouse (Centrocercus urophasianus) and Columbian sharp-tailed Grouse (Tympanuchus phasianellus columbianus) have declined substantially in Washington, USA, primarily because native shrub-steppe has been converted to agriculture. In response, state and federal agencies have acquired and restored habitat, and augmented and reintroduced Grouse to suitable areas. We examined how sympatric, translocated sage-Grouse and sharp-tailed Grouse used space and selected habitats within their spring–summer home ranges and at nest sites within remnant shrub-steppe surrounded by a matrix of cropland in eastern Washington. Because their life-history requirements differ, we expected extensive habitat partitioning between species. Using radiolocations of ≥43 birds of each species, we found that sage-Grouse had larger spring–summer home ranges than sharp-tailed Grouse, and the composite of home ranges for sharp-tailed Grouse fell almost completely within the composite of home ranges for sage-Grouse. By creating resource utilization function models using radiolocations of ≥53 birds of each species, we found that areas of highest predicted intensity of use for both species overlapped by >50%, even at the top 5% quantile. Both species used restored fields and areas farther from trees and roads or distribution lines more intensely. Sage-Grouse used less rugged areas more intensely, and both species used 3 levels of shrub cover equally. To compare selection of nest sites relative to available sites for nesting in both species, we created resource selection function models for ≥30 birds of each species and found that sage-Grouse selected areas farther from distribution lines, whereas sharp-tailed Grouse selected restored fields. When we examined vegetation characteristics used by female sage-Grouse and sharp-tailed Grouse at nest sites using a case-control, use versus non-use design for ≥26 birds of each species, we found sage-Grouse used areas with greater shrub cover, lower annual forb cover, and taller perennial grasses, whereas sharp-tailed Grouse used areas with greater perennial grass cover and taller perennial grasses and forbs. When we compared habitat features measured at nest sites between species, we found sage-Grouse used areas with greater moderate and dense shrub cover, lower sparse shrub cover, less restored fields, higher patch diversity, and areas farther from distribution lines than sharp-tailed Grouse. These differences resulted in only 38% overlap of areas within the top quartile of relative selection values for nest sites by the 2 species, and
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Fall Population Structure of Sage-Grouse in Colorado and Oregon
2015Co-Authors: Clait E. Braun, David A. Budeau, Michael A. SchroederAbstract:We studied the population structure of sage-Grouse (Centrocercus spp.) based on collection and analysis of 67,679 wings from hunter-harvested birds in 10 areas in Colorado and 12 areas in Oregon during 1973-1998 and 1993-2013, respectively. The harvest age structure for greater sage-Grouse (C. urophasianus) varied from 42 to 63% juveniles in Colorado and 27 to 58% in Oregon. Approximately 59% of the Gunnison sage-Grouse (C. minimus) harvest was juvenile. The overall adult male:female sex ratio was 28:72 for greater sage-Grouse in Colorado, 41:59 (this includes an unknown proportion of yearlings) for greater sage-Grouse in Oregon, and 34:66 for Gunnison sage- Grouse in Colorado. Proportions of females increased in all fall populations from juvenile to yearling to adult age classes. Estimated breeding success was similar for greater sage- Grouse in Colorado (47%) and Oregon (49%), but Gunnison sage-Grouse appeared to have higher (60%) breeding success. The average number of juveniles in the harvest per breeding-age female varied from 1.2 to 2.4. There was high annual variation within and among areas. Composite estimated annual survival varied from 46 to 48% for adult males and 56 to 59% for adult females.
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Ecology and management of sage-Grouse and sage-Grouse habitat
Rangeland Ecology & Management, 2004Co-Authors: John A. Crawford, Michael A. Schroeder, Rich A. Olson, Neil E. West, Jeffrey C. Mosley, Tom D. Whitson, Richard F. Miller, Michael A. Gregg, Chad S. BoydAbstract:Abstract Sage-Grouse (Centrocercus urophasianus and C. minimus) historically inhabited much of the sagebrush-dominated habitat of North America. Today, sage-Grouse populations are declining throughout most of their range. Population dynamics of sage-Grouse are marked by strong cyclic behavior. Adult survival is high, but is offset by low juvenile survival, resulting in low productivity. Habitat for sage-Grouse varies strongly by life-history stage. Critical habitat components include adequate canopy cover of tall grasses (≥ 18 cm) and medium height shrubs (40–80 cm) for nesting, abundant forbs and insects for brood rearing, and availability of herbaceous riparian species for late-growing season foraging. Fire ecology of sage-Grouse habitat changed dramatically with European settlement. In high elevation sagebrush habitat, fire return intervals have increased (from 12–24 to > 50 years) resulting in invasion of conifers and a consequent loss of understory herbaceous and shrub canopy cover. In lower elevatio...
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Grouse OF THE LEWIS AND CLARK EXPEDITION, 1803 TO 1806
Northwestern Naturalist, 2003Co-Authors: Fred C. Zwickel, Michael A. SchroederAbstract:Members of the Lewis and Clark expedition produced written descriptions of many species of wildlife, including 6 species of Grouse. We reviewed the accounts of 83 Grouse observations, plus summary descriptions and indirect references to Grouse by Meriwether Lewis, William Clark, and 3 of their sergeants. We then assigned them to species based on described characteristics, known distributions, habitat, behavior, and/or other written clues. Fifty-nine (71%) observations were con- sidered relatively unambiguous as to identity because of a bird's morphology and appearanceJ a descriptive name, a non-overlapping range, and/or other clues. These included greaterprairie-chick- ens (Tympanuchus cupido), sharp-tailed Grouse (1: phasianellus), greater sage-Grouse (Centrocercus uro- phasianus), blue Grouse (Dendragrpus obscurus), spruce Grouse (Falcipennis canadensis), and ruffed Grouse (Bonasa umbellus). Other observations were assigned to 'possible' species based on available evidence. Our evaluation of Lewis's and Clark's written descriptions differed in some cases from earlier reviews. Most notable differences involved blue, spruce, and ruffed Grouse and we offer sug- gestions for changes. We also used journal records to compare pre-settlement (by Euro-Americans) distributions of Grouse as indicated by the journal records with those today and to speculate on changes in abundance. Greatest changes have occurred in distributions and abundances of the 3 prairie Grouse, species whose habitats have been most impacted by settlement. Other highlights of the expedition include the 1st written descriptions of blue Grouse and greater sage-Grouse and of undescribed subspecies of sharp-tailed, spruce, and ruffed Grouse.
Simon J. Thirgood - One of the best experts on this subject based on the ideXlab platform.
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Spatial synchrony in red Grouse population dynamics
Oikos, 2007Co-Authors: Douglas H. Kerlin, Adam Smith, Daniel T. Haydon, David S. Miller, Simon J. ThirgoodAbstract:Red Grouse Lagopus lagopus scoticus populations exhibit unstable dynamics that are often characterised by regular periodic fluctuations in abundance. Time-series' of Grouse harvesting records collected from 287 management units (moors) across Scotland, England and Wales were analysed to investigate the broad scale patterns of synchrony in these fluctuations. Estimation of the spatial autocorrelation of Grouse population dynamics across moors indicates relatively high levels of synchrony between populations on adjacent moors, but that this synchrony declines sharply with increasing inter-moor distance. At distances of greater than 100 km, Grouse population time-series exhibit only weakly positive cross-correlation coefficients. Twenty-eight geographical, environmental and other candidate variables were examined to construct a general linear model to explain variation in local synchrony. Grouse moor productivity (average size of shooting bag), distance from the Atlantic coast moving in a north-easterly direction, April and June temperatures, and June rainfall significantly increased the explanatory power of this model. An understanding of the processes underlying synchrony in red Grouse population dynamics is a prerequisite to anticipating the effects of large-scale environmental change on regional patterns of Grouse distribution and abundance.
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Habitat predicts losses of red Grouse to individual hen harriers
Journal of Applied Ecology, 2004Co-Authors: Arjun Amar, Stephen M Redpath, Beatriz Arroyo, Simon J. ThirgoodAbstract:Summary 1 Hen harriers Circus cyaneus prey on red Grouse Lagopus l. scoticus and high breeding densities of harriers can limit the number of Grouse available for shooting in the autumn. Ultimately, Grouse hunting contributes to the maintenance of heather moorland, an ecologically important habitat for biodiversity in general and hen harriers in particular. Predation rates vary widely among harrier individuals. Understanding which factors influence this variation would be useful to target management to mitigate the effect of harriers on Grouse, such as diversionary feeding. 2 We used a simple habitat-based approach to test whether we could identify harrier nests to which most Grouse were delivered. Using remote sensing habitat data, we tested whether delivery rates of dead Grouse to the nest by hen harriers were higher for those pairs nesting in sites with more heather Calluna vulgaris. A relationship between heather cover and Grouse delivery rates might have been expected as Grouse densities were correlated with heather cover. 3 After adjusting for annual variation in Grouse abundance, the rate at which Grouse were delivered to harrier nests was positively associated with the proportion of heather cover within 2 km of harrier nests. This was primarily due to the positive effect of heather cover on female delivery rates. 4 This result allowed us to use habitat data to predict the harrier nests to which most Grouse chicks would be delivered. Comparison of predictions of the model with observations of food delivery to nests indicated that, in terms of Grouse chick delivery, the model correctly predicted the top 50% of harrier nests in five of six years. 5 We undertook an experiment where carrion was provided to certain harriers at nest sites, in order to decrease their predation on Grouse. Data from this experiment showed that when harriers were given diversionary food, the relationship between Grouse predation rate and habitat was removed, with Grouse predation reduced to negligible levels in most cases. This demonstrated the increased benefit of feeding birds with the highest proportion of heather cover within 2 km of their nest sites, rather than feeding birds at random within the conflict population. 6 Synthesis and applications. The amount of heather cover around hen harrier nests can be used to predict which pairs will predate most Grouse within a population. This information should facilitate targeted management practices, which may accrue greater benefit for Grouse stocks and potentially reduce the conflict between Grouse shooting and conservation of biodiversity.
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Do habitat characteristics influence predation on red Grouse
Journal of Applied Ecology, 2002Co-Authors: Simon J. Thirgood, Stephen M Redpath, Steve Campbell, Adam SmithAbstract:Summary 1 Predation is not only an important ecological process in the population dynamics of red Grouse Lagopuslagopusscoticus, but also has conservation implications for their predators such as hen harrier Circus cyaneus and peregrine falcon Falcoperegrinus. It has been suggested that habitat management might reduce the susceptibility of Grouse to predation and thus reduce conflicts between Grouse management and raptor conservation. 2 We investigated whether habitat characteristics influenced predation on red Grouse on a managed moor near Langholm in southern Scotland during 1992–96. We combined demographic studies of the Grouse population with radio-telemetry of individual Grouse to assess the influence of habitat on mortality rates. Systematic observations of hen harriers were also used to assess the effect of habitat characteristics on their encounter rates and strike success with Grouse and other prey. 3 There was no evidence that habitat characteristics directly influenced Grouse mortality rates at the scale of the Grouse population. However, Grouse densities were higher and overwinter losses of Grouse were lower on areas with greater cover of heather Callunavulgaris. The most likely explanation for the observed pattern of winter loss was that Grouse dispersed into areas with more heather, to some extent locally compensating for losses to predators. 4 Individual radio-tagged Grouse that survived the winter had more blaeberry Vacciniummyrtillus in their home ranges than Grouse that were killed in winter by predators. There was, however, no effect of heather cover, vegetation height or vegetation density on the likelihood of individual Grouse survival. 5 Hen harriers were more likely to encounter Grouse broods in a mixture of heather and grass than expected from the observed distributions of Grouse broods on moorland. However, having encountered a Grouse brood, there was no effect of habitat type or vegetation height on the strike success of the harriers. 6 We conclude that the direct effects of habitat on the susceptibility of red Grouse to predation are limited under current predator control regimes on managed moorland. Habitat management aimed at mitigating conflicts between raptor conservation and Grouse management should focus on reducing the availability of passerine and small mammal prey for hen harriers and thus reducing harrier abundance on Grouse moors. Further research is required, however, to assess the consequences of such management for biodiversity.
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Nest site characteristics and nest success in red Grouse Lagopus lagopus scoticus
Wildlife Biology, 2002Co-Authors: Steven T Campbell, Stephen M Redpath, Adam Smith, Simon J. ThirgoodAbstract:We assessed the influence of habitat characteristics on nest site selection and nest success of red Grouse Lagopus lagopus scoticus in three populations on managed moorland in Scotland during 1998–1999. We measured habitat characteristics at the nests of 148 radio-tagged female Grouse and compared them with similar measurements taken at fixed and random points within their home range. Red Grouse nested in vegetation that was significantly taller and denser, and with greater canopy cover, than points adjacent to nests or to random points. They nested more in mature heather and less in grass-dominated vegetation than would be expected by chance. Red Grouse nest success was high with 77% initial success rising to a minimum of 80% success once re-nesting had occurred. Nest success was weakly related to vegetation height in 1998, but no similar relationship was found in 1999. We suggest that the high nest success of red Grouse and the relatively small influence of habitat characteristics on the outcome of nesting attempts is due to predator control on managed Grouse moors in Scotland.
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numerical and functional responses in generalist predators hen harriers and peregrines on scottish Grouse moors
Journal of Animal Ecology, 1999Co-Authors: Stephen M Redpath, Simon J. ThirgoodAbstract:Summary 1. The functional and numerical responses of two generalist raptors (hen harrier and peregrine) were studied on one moor for 6 years and on five other moors for 5 years. 2. Neither species showed numerical responses to Grouse abundance. Harrier densities were highest in areas and years where their small prey (meadow pipits and small mammals) were most abundant. Peregrine densities were highest on southern study moors, probably in association with high abundance of racing pigeons. 3. For harriers preying on Grouse chicks, the available data fitted a sigmoidal or type III functional response. Peregrines showed a type II response to adult Grouse densities around eyries. 4. The proportion of Grouse chicks taken by harriers was estimated to have been highest at densities of 67 chicks km–2 (equivalent to a mean of about 12 broods km–2). The proportion of adult Grouse taken by peregrines appeared to be inversely density dependent, such that an increasing proportion of Grouse was taken at Grouse densities below 20 km–2. 5. In the absence of persecution, the impact of harriers on Grouse populations is most likely to be greatest on moors where alternative prey and thus harriers are abundant. The question of whether harriers may dampen Grouse population cycles at low Grouse density is discussed.
Jeffrey L. Beck - One of the best experts on this subject based on the ideXlab platform.
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Does Wyoming’s Core Area Policy Protect Winter Habitats for Greater Sage-Grouse?
Environmental Management, 2016Co-Authors: Kurt T. Smith, Jeffrey L. Beck, Aaron C. PrattAbstract:Conservation reserves established to protect important habitat for wildlife species are used world-wide as a wildlife conservation measure. Effective reserves must adequately protect year-round habitats to maintain wildlife populations. Wyoming’s Sage-Grouse Core Area policy was established to protect breeding habitats for greater sage-Grouse ( Centrocercus urophasianus ). Protecting only one important seasonal habitat could result in loss or degradation of other important habitats and potential declines in local populations. The purpose of our study was to identify the timing of winter habitat use, the extent which individuals breeding in Core Areas used winter habitats, and develop resource selection functions to assess effectiveness of Core Areas in conserving sage-Grouse winter habitats in portions of 5 Core Areas in central and north-central Wyoming during winters 2011–2015. We found that use of winter habitats occured over a longer period than current Core Area winter timing stipulations and a substantial amount of winter habitat outside of Core Areas was used by individuals that bred in Core Areas, particularly in smaller Core Areas. Resource selection functions for each study area indicated that sage-Grouse were selecting habitats in response to landscapes dominated by big sagebrush and flatter topography similar to other research on sage-Grouse winter habitat selection. The substantial portion of sage-Grouse locations and predicted probability of selection during winter outside small Core Areas illustrate that winter requirements for sage-Grouse are not adequately met by existing Core Areas. Consequently, further considerations for identifying and managing important winter sage-Grouse habitats under Wyoming’s Core Area Policy are warranted.
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spatial heterogeneity in response of male greater sage Grouse lek attendance to energy development
PLOS ONE, 2014Co-Authors: Andrew J Gregory, Jeffrey L. BeckAbstract:Landscape modification due to rapidly expanding energy development, in particular oil and gas, in the westernUSA, have prompted concerns over how such developments may impact wildlife. One species of conservation concern across much of the Intermountain West is the greater sage-Grouse (Centrocercusurophasianus). Sage-Grouse have been petitioned for listing under provisions of the Endangered Species Act 7 times and the state of Wyoming alone represents 64% of the extant sage-Grouse population in the eastern portion of their range. Consequently, the relationship between sage-Grouse populations and oil and gas development in Wyoming is an important component to managing the long-term viability of this species. We used 814 leks from the Wyoming Game and Fish Department's lek survey database and well pad data from the Wyoming Oil and Gas Conservation Commission to evaluate changes in sage-Grouse lek counts as a function of oil and gas development since 1991.From 1991-2011 we found that oil and gas well-pad density increased 3.6-fold across the state and was associated with a 24% decline in the number of male sage-Grouse. Using a spatial and temporally structured analysis via Geographically Weighted Regression, we found a 1-to-4 year time lag between development density and lek decline. Sage-Grouse also responded to development densities at multiple spatial neighborhoods surrounding leks, including broad scales of 10 km. However, sage-Grouse lek counts do not always decline as a result of oil and gas development. We found similar development densities resulting in different sage-Grouse lek count responses, suggesting that development density alone is insufficient to predict the impacts that oil and gas development have on sage-Grouse. Finally, our analysis suggests a maximum development density of 1 well-pad within 2 km of leks to avoid measurable impacts within 1 year, and <6 well-pads within 10 km of leks to avoid delayed impacts.
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Changes in the distribution and status of sage-Grouse in Utah
Western North American Naturalist, 2003Co-Authors: Jeffrey L. Beck, Dean L. Mitchell, Brian D. MaxfieldAbstract:Sage-Grouse (Centrocercus spp.) were abundant in all of Utah's 29 counties at the time of European settlement wherever sagebrush (Artemisia spp.) occurred. Greater Sage-Grouse (C. urophasianus) inhabited areas north and west of the Colorado River, and Gunnison Sage-Grouse (C. minimus) occupied suitable habitat south and east of the Colorado River. The largest Greater Sage-Grouse populations in Utah are currently restricted to suitable habitats in Box Elder, Garfield, Rich, Uintah, and Wayne Counties. A remnant breeding population of Gunnison Sage-Grouse occurs in eastern San Juan County. We stratified Greater Sage-Grouse populations (1971-2000) by counties where the 1996 to 2000 moving average for estimated spring breeding populations was >500 (GT500) or
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Influences of livestock grazing on sage Grouse habitat.
Wildlife Society Bulletin, 2000Co-Authors: Jeffrey L. Beck, Dean L. MitchellAbstract:Livestock grazing has been identified as one factor associated with the widespread decline and degradation of sage Grouse (Centrocercus urophasianus) habitat. We identi- fied n= 17 positive and negative impacts of livestock on sage Grouse and habitat. Little information is currently available concerning the directs impacts of livestock grazing on sage Grouse habitat. Indirect impacts are better understood than direct impacts. Chemical and mechanical treatments intended to provide increased quantities of grass forage for livestock have indirectly reduced the acceptability of sagebrush (Artemisia spp.) range- lands for sage Grouse. Our paper examines: 1) potential mechanisms whereby livestock grazing in big sagebrush (A. tridentata) communities can modify sage Grouse habitat and 2) the indirect influences of livestock production on sage Grouse habitat. Overall, live- stock grazing appears to most affect productivity of sage Grouse populations. Residual grass cover following grazing is essential to conceal sage Grouse nests from predators. Future research needs are identified and management implications related to livestock grazing in sage Grouse habitats are included.
Stephen M Redpath - One of the best experts on this subject based on the ideXlab platform.
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Habitat predicts losses of red Grouse to individual hen harriers
Journal of Applied Ecology, 2004Co-Authors: Arjun Amar, Stephen M Redpath, Beatriz Arroyo, Simon J. ThirgoodAbstract:Summary 1 Hen harriers Circus cyaneus prey on red Grouse Lagopus l. scoticus and high breeding densities of harriers can limit the number of Grouse available for shooting in the autumn. Ultimately, Grouse hunting contributes to the maintenance of heather moorland, an ecologically important habitat for biodiversity in general and hen harriers in particular. Predation rates vary widely among harrier individuals. Understanding which factors influence this variation would be useful to target management to mitigate the effect of harriers on Grouse, such as diversionary feeding. 2 We used a simple habitat-based approach to test whether we could identify harrier nests to which most Grouse were delivered. Using remote sensing habitat data, we tested whether delivery rates of dead Grouse to the nest by hen harriers were higher for those pairs nesting in sites with more heather Calluna vulgaris. A relationship between heather cover and Grouse delivery rates might have been expected as Grouse densities were correlated with heather cover. 3 After adjusting for annual variation in Grouse abundance, the rate at which Grouse were delivered to harrier nests was positively associated with the proportion of heather cover within 2 km of harrier nests. This was primarily due to the positive effect of heather cover on female delivery rates. 4 This result allowed us to use habitat data to predict the harrier nests to which most Grouse chicks would be delivered. Comparison of predictions of the model with observations of food delivery to nests indicated that, in terms of Grouse chick delivery, the model correctly predicted the top 50% of harrier nests in five of six years. 5 We undertook an experiment where carrion was provided to certain harriers at nest sites, in order to decrease their predation on Grouse. Data from this experiment showed that when harriers were given diversionary food, the relationship between Grouse predation rate and habitat was removed, with Grouse predation reduced to negligible levels in most cases. This demonstrated the increased benefit of feeding birds with the highest proportion of heather cover within 2 km of their nest sites, rather than feeding birds at random within the conflict population. 6 Synthesis and applications. The amount of heather cover around hen harrier nests can be used to predict which pairs will predate most Grouse within a population. This information should facilitate targeted management practices, which may accrue greater benefit for Grouse stocks and potentially reduce the conflict between Grouse shooting and conservation of biodiversity.
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Do habitat characteristics influence predation on red Grouse
Journal of Applied Ecology, 2002Co-Authors: Simon J. Thirgood, Stephen M Redpath, Steve Campbell, Adam SmithAbstract:Summary 1 Predation is not only an important ecological process in the population dynamics of red Grouse Lagopuslagopusscoticus, but also has conservation implications for their predators such as hen harrier Circus cyaneus and peregrine falcon Falcoperegrinus. It has been suggested that habitat management might reduce the susceptibility of Grouse to predation and thus reduce conflicts between Grouse management and raptor conservation. 2 We investigated whether habitat characteristics influenced predation on red Grouse on a managed moor near Langholm in southern Scotland during 1992–96. We combined demographic studies of the Grouse population with radio-telemetry of individual Grouse to assess the influence of habitat on mortality rates. Systematic observations of hen harriers were also used to assess the effect of habitat characteristics on their encounter rates and strike success with Grouse and other prey. 3 There was no evidence that habitat characteristics directly influenced Grouse mortality rates at the scale of the Grouse population. However, Grouse densities were higher and overwinter losses of Grouse were lower on areas with greater cover of heather Callunavulgaris. The most likely explanation for the observed pattern of winter loss was that Grouse dispersed into areas with more heather, to some extent locally compensating for losses to predators. 4 Individual radio-tagged Grouse that survived the winter had more blaeberry Vacciniummyrtillus in their home ranges than Grouse that were killed in winter by predators. There was, however, no effect of heather cover, vegetation height or vegetation density on the likelihood of individual Grouse survival. 5 Hen harriers were more likely to encounter Grouse broods in a mixture of heather and grass than expected from the observed distributions of Grouse broods on moorland. However, having encountered a Grouse brood, there was no effect of habitat type or vegetation height on the strike success of the harriers. 6 We conclude that the direct effects of habitat on the susceptibility of red Grouse to predation are limited under current predator control regimes on managed moorland. Habitat management aimed at mitigating conflicts between raptor conservation and Grouse management should focus on reducing the availability of passerine and small mammal prey for hen harriers and thus reducing harrier abundance on Grouse moors. Further research is required, however, to assess the consequences of such management for biodiversity.
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Nest site characteristics and nest success in red Grouse Lagopus lagopus scoticus
Wildlife Biology, 2002Co-Authors: Steven T Campbell, Stephen M Redpath, Adam Smith, Simon J. ThirgoodAbstract:We assessed the influence of habitat characteristics on nest site selection and nest success of red Grouse Lagopus lagopus scoticus in three populations on managed moorland in Scotland during 1998–1999. We measured habitat characteristics at the nests of 148 radio-tagged female Grouse and compared them with similar measurements taken at fixed and random points within their home range. Red Grouse nested in vegetation that was significantly taller and denser, and with greater canopy cover, than points adjacent to nests or to random points. They nested more in mature heather and less in grass-dominated vegetation than would be expected by chance. Red Grouse nest success was high with 77% initial success rising to a minimum of 80% success once re-nesting had occurred. Nest success was weakly related to vegetation height in 1998, but no similar relationship was found in 1999. We suggest that the high nest success of red Grouse and the relatively small influence of habitat characteristics on the outcome of nesting attempts is due to predator control on managed Grouse moors in Scotland.
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Meadow pipits, red Grouse and the habitat characteristics of managed Grouse moors
Journal of Applied Ecology, 2001Co-Authors: Adam Smith, Stephen M Redpath, S.t. Campbell, Simon ThirgoodAbstract:Summary 1 The abundance of meadow pipits appears to be a good indicator of the breeding density of hen harriers on moorland managed for red Grouse in Scotland. High densities of hen harriers can limit Grouse populations at low density and reduce shooting bags, with repercussions for Grouse moor management and conservation. We therefore examined the habitat characteristics of managed Grouse moors, asking whether changes in vegetation could alter the ratio of pipits, and thus harriers, to Grouse. 2 We examined Grouse abundance and habitat on 69 sites of 1 km2 in upland Britain, of which pipit abundance was studied on 36. Similar data were collected on 73 sites of 25 ha within the Langholm estate in south-west Scotland, in order to make a within-estate and among-moor comparison. 3 The distribution of pipit abundance on the Langholm estate was similar to that seen in the extensive among-moor study. Pipit and Grouse abundance were related to habitat in similar ways in the two data sets. 4 Pipits were the most frequent passerine, but their abundance was not related to Grouse abundance. Pipit abundance declined with increasing muirburn and heather, but increased with grass cover. In a linear regression model Calluna, Sphagnum and muirburn cover accounted for 42% of the variation in pipit abundance across Britain. 5 Grouse abundance was influenced by the regional location of the Grouse moor and to a lesser extent by its altitude. There were more Grouse on English moors with less patchy habitats. Bird species declined with increasing Calluna and Sphagnum cover and habitat patchiness. Bird species diversity increased from west to east and on moors with more muirburn. 6 This study provides evidence that meadow pipits are influenced by habitat characteristics on moorland managed for Grouse. This work also illustrates how habitat management may be able to mitigate human–wildlife conflicts: long-term increases in heather cover and management of this habitat by muirburn on Grouse moors may reduce pipit numbers and thus reduce the ratio of hen harriers to Grouse. However, the effects of such vegetation change on other components of the upland bird assemblage requires further investigation.
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Raptor predation and population limitation in red Grouse
Journal of Animal Ecology, 2000Co-Authors: Simon Thirgood, Stephen M Redpath, Peter Rothery, Nicholas J AebischerAbstract:Summary 1. We assessed the impact of predation by hen harriers and peregrine falcons on a red Grouse population in southern Scotland during 1992–98. Grouse density in April, July and October declined during this time, coincident with an increase in the numbers of breeding harriers and peregrines. 2. Winter losses of Grouse between October and April averaged 33% and were density-dependent. Raptors were the cause of about 70% of winter mortality and they killed about 30% of the Grouse present in October. We were unable to determine whether winter mortality in raptors was additive to other losses. 3. Summer losses of adult Grouse between April and July averaged 30% and were density-dependent. Raptors were the cause of more than 90% of the early summer mortality of adult Grouse. Summer losses of Grouse chicks between May and July averaged 45% and were not density-dependent. Harriers killed about 28% of Grouse chicks by late July and about 37% by the end of August. Summer raptor predation on adult Grouse and chicks appeared to be largely additive to other losses and we estimated that it reduced autumn Grouse densities by about 50%. 4. A model combining the estimated reduction in autumn Grouse density caused by raptors with the observed density dependence in winter loss predicted that, in the absence of raptors for 2 years, Grouse density in spring would be 1·9 times greater, and Grouse density in autumn 3·9 times greater, than in the presence of raptors. The model suggested that raptor predation prevented the Grouse population from increasing and was thus a limiting factor.
Pekka Helle - One of the best experts on this subject based on the ideXlab platform.
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Intestinal parasites as potential factors in the dynamics of a fluctuating forest Grouse community
Annales Zoologici Fennici, 2017Co-Authors: Marja Isomursu, Pekka Helle, Osmo RättiAbstract:Finnish populations of the capercaillie Tetrao urogallus, black Grouse Lyrurus tetrix and hazel Grouse Tetrastes bonasia have been fluctuating in synchronous cycles. Mechanisms behind these fluctuations are not well known. Parasites may regulate their host population under certain conditions. The Finnish Grouse harbour several species of intestinal parasites which may affect the populations. We studied the possibility of parasitic regulation in Finnish forest Grouse using intestinal samples from hunted Grouse collected in 1995–2000 and annual counts of Grouse densities. We found that abundance and prevalence of the nematode Ascaridia compar affected negatively the Grouse-community growth rate (all three species combined) and annual survival of Grouse. In years of Grouse density decline, the prevalence and abundance of A. compar was considerably higher than in other years. On the species level, this dynamic was most clearly seen in the capercaillie. The findings suggest the possibility of parasitic regulat...
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Coupling in goshawk and Grouse population dynamics in Finland.
Oecologia, 2012Co-Authors: Risto Tornberg, Pekka Helle, Esa Ranta, Andreas Lindén, Patrik Byholm, Jari Valkama, Harto LindénAbstract:Different prey species can vary in their significance to a particular predator. In the simplest case, the total available density or biomass of a guild of several prey species might be most relevant to the predator, but behavioural and ecological traits of different prey species can alter the picture. We studied the population dynamics of a predator–prey setting in Finland by fitting first-order log-linear vector autoregressive models to long-term count data from active breeding sites of the northern goshawk (Accipiter gentilis; 1986–2009), and to three of its main prey species (1983–2010): hazel Grouse (Bonasa bonasia), black Grouse (Tetrao tetrix) and capercaillie (T. urogallus), which belong to the same forest Grouse guild and show synchronous fluctuations. Our focus was on modelling the relative significance of prey species and estimating the tightness of predator–prey coupling in order to explain the observed population dynamics, simultaneously accounting for effects of density dependence, winter severity and spatial correlation. We established nine competing candidate models, where different combinations of Grouse species affect goshawk dynamics with lags of 1–3 years. Effects of goshawk on Grouse were investigated using one model for each Grouse species. The most parsimonious model for goshawk indicated separate density effects of hazel Grouse and black Grouse, and different effects with lags of 1 and 3 years. Capercaillie showed no effects on goshawk populations, while the effect of goshawk on Grouse was clearly negative only in capercaillie. Winter severity had significant adverse effects on goshawk and hazel Grouse populations. In combination, large-scale goshawk–Grouse population dynamics are coupled, but there are no clear mutual effects for any of the individual guild members. In a broader context, our study suggests that pooling data on closely related, synchronously fluctuating prey species can result in the loss of relevant information, rather than increased model parsimony.
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Vulnerability of black Grouse hens to goshawk predation: result of food supply or predation facilitation?
Oecologia, 2011Co-Authors: Risto Tornberg, Pekka Helle, Erkki KorpimäkiAbstract:The plant cycle hypothesis says that poor-quality food affects both herbivorous voles (Microtinae spp.) and Grouse (Tetraonidae spp.) in vole decline years, leading to increased foraging effort in female Grouse and thus a higher risk of predation by the goshawk Accipiter gentilis . Poor-quality food (mainly the bilberry Vaccinium myrtillus ) for these herbivores is induced by seed masting failure in the previous year, when the bilberry is able to allocate resources for chemical defence (the mast depression hypothesis; MDH). The predation facilitation hypothesis (PFH) in turn states that increased searching activity of vole-eating predators during or after the decline year of voles disturbs incubating and brooding Grouse females. The behaviours used by Grouse to avoid these terrestrial predators make them more vulnerable to predation by goshawks. We tested the main predictions of the MDH and PFH by collecting long-term (21-year) data from black Grouse Tetrao tetrix hens and cocks killed by breeding goshawks supplemented with indices of bilberry crop, vole abundance and small carnivores in the vicinity of Oulu, northern Finland. We did not find obvious support for the prediction of the MDH that there is a negative correlation of bilberry crop in year t with vole abundance and with predation index of black Grouse hens in year t + 1. We did find obvious support for the prediction of the PFH that there is a positive correlation between predator abundance and predation index of Grouse hens, because the stoat Mustela erminea abundance index was positively related to the predation index of black Grouse hens. We suggest that changes in vulnerability of Grouse hens may mainly be caused by the guild of vole-eating predators, who shift to alternative prey in the decline phase of the vole cycle, and thus chase Grouse hens and chicks to the talons of goshawks and other avian predators.
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Grouse dynamics and harvesting in Kainuu, northeastern Finland
Oikos, 2011Co-Authors: Petri Lampila, Harto Lindén, Esa Ranta, Mikko Mönkkönen, Pekka HelleAbstract:We study the dynamics of the capercaillie, black Grouse, hazel Grouse and willow Grouse in Kainuu game management district in northeastern Finland in the years 1989 – 2004. It appears that the 6 – 7 year periodicity that prevailed in this region from 1960s up to 1980s has now vanished in all species. Th e Grouse data are modelled using a linear autoregressive model with lag terms for population dynamics including Grouse harvest as annual bag and an index of winter severity (winter-time area of Baltic Sea ice cover). We use the Akaike information criterion for selecting the best model for each species; fi rst order lag is forced to the models. It turns out that a term is needed for harvesting (with a negative coeffi cient) in models for all species. For the capercaillie and the hazel Grouse second order lag was included, for the black Grouse and the willow Grouse fi rst order lag suffi ces. Th e willow Grouse is the only species where the index of winter strength (with a negative coeffi cient) is needed in the model.
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Intestinal parasite infection exposes Grouse to canine predators
Acta Veterinaria Scandinavica, 2010Co-Authors: Marja Isomursu, Pekka Helle, Osmo Rätti, Tuula HollmenAbstract:Background Sublethal parasite infections may cause mortality indirectly by exposing the host to predation. The best known example of this among birds is red Grouse in which caecal nematode infection causes increased risk of predation and can even affect population dynamics [1]. Intestinal helminth parasites are common in forest Grouse, capercaillie Tetrao urogallus, black Grouse Tetrao tetrix and hazel Grouse Bonasa bonasia [2], and these Grouse are valuable prey for several species of predators. We evaluated the hypothesis that parasite infection makes the host more vulnerable to predation by comparing the intestinal parasite infection status of Grouse hunted with a trained dog to that of Grouse hunted without a dog. Hunting with a dog can be regarded as close simulation of natural predation because the dog presumably locates the prey by the same cues as wild canine predators.
