35 research outputs found
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Factors Affecting Incubation Patterns and Sex Roles of Black Oystercatchers in Alaska
Studies examining the effects of human disturbance on avian parental behavior and reproductive
success are fundamental to bird conservation. However, many such studies fail to also consider the influence of
natural threats, a variable environment, and parental roles. Our work examines interactive relationships of cyclical
(time of day, tide, temperature, seasonality) and stochastic (natural/human disturbance) processes with incubation
patterns (attendance, bout lengths, recess rates) of the Black Oystercatcher (Haematopus bachmani), a shorebird
of conservation concern. We used 24-hr-per-day video monitoring of 13 molecularly sexed breeding pairs to
systematically examine incubation, revealing previously undocumented information that may inform conservation
practices for the genus. Seven of 22 video-monitored nests failed, primarily from egg depredation by nocturnal
mammals. Analyses of 3177 hr of video footage indicated a near doubling of incubation-bout lengths at night,
corresponding to the increased risk of nighttime egg predation. Females had higher overall nest attendance (54%
vs. 42%) and longer mean incubation bouts than did males (88 min vs. 73 min). Uninterrupted incubation bouts
were over twice as long as bouts interrupted by disturbance. Incubating males departed nests substantially more
frequently because of nest-area disturbances than did females in one but not both years of our study. Our findings
suggest that the sexes incubate in different but complementary patterns, facilitating efficient egg care in a dynamic
environment with several nest threats. We emphasize the importance of considering natural influences when human
threats to shorebird reproductive behavior and success are evaluated.Keywords: Black Oystercatcher, Disturbance, Incubation behavior, Prince William Sound, sex roles, Video monitoring, Nest failure, Haematopu
Region-Wide Ecological Responses of Arid Wyoming Big Sagebrush Communities to Fuel Treatments
If arid sagebrush ecosystems lack resilience to disturbances or resistance to annual invasives, then alternative successional states dominated by annual invasives, especially cheatgrass (Bromus tectorum L.), are likely after fuel treatments. We identified six Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis Beetle & Young) locations (152–381 mm precipitation) that we believed had sufficient resilience and resistance for recovery. We examined impacts of woody fuel reduction (fire, mowing, the herbicide tebuthiuron, and untreated controls, all with and without the herbicide imazapic) on short-term dominance of plant groups and on important land health parameters with the use of analysis of variance (ANOVA). Fire and mowing reduced woody biomass at least 85% for 3 yr, but herbaceous fuels were reduced only by fire (72%) and only in the first year. Herbaceous fuels produced at least 36% more biomass with mowing than untreated areas during posttreatment years. Imazapic only reduced herbaceous biomass after fires (34%). Tebuthiuron never affected herbaceous biomass. Perennial tall grass cover was reduced by 59% relative to untreated controls in the first year after fire, but it recovered by the second year. Cover of all remaining herbaceous groups was not changed by woody fuel treatments. Only imazapic reduced significantly herbaceous cover. Cheatgrass cover was reduced at least 63% with imazapic for 3 yr. Imazapic reduced annual forb cover by at least 45%, and unexpectedly, perennial grass cover by 49% (combination of tall grasses and Sandberg bluegrass [Poa secunda J. Presl.]). Fire reduced density of Sandberg bluegrass between 40% and 58%, decreased lichen and moss cover between 69% and 80%, and consequently increased bare ground between 21% and 34% and proportion of gaps among perennial plants &spigt; 2 m (at least 28% during the 3 yr). Fire, mowing, and imazapic may be effective in reducing fuels for 3 yr, but each has potentially undesirable consequences on plant communities
Raptor Interactions with Wind Energy: Case Studies from Around the World
The global potential for wind power generation is vast, and the number of installations is
increasing rapidly. We review case studies from around the world of the effects on raptors of wind-energy
development. Collision mortality, displacement, and habitat loss have the potential to cause population-level effects, especially for species that are rare or endangered. The impact on raptors has much to do with their behavior, so careful siting of wind-energy developments to avoid areas suited to raptor breeding, foraging, or migration would reduce these effects. At established wind farms that already conflict with raptors, reduction of fatalities may be feasible by curtailment of turbines as raptors approach, and offset through mitigation of other human causes of mortality such as electrocution and poisoning, provided the relative effects can be quantified. Measurement of raptor mortality at wind farms is the subject of intense effort and study, especially where mitigation is required by law, with novel statistical approaches recently made available to improve the notoriously difficult-to-estimate mortality rates of rare and hard-to-detect species. Global standards for wind farm placement, monitoring, and effects mitigation would be a valuable contribution to raptor conservation worldwide.publishedVersio
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Management, Morphological, and Environmental Factors Influencing Douglas-Fir Bark Furrows in the Oregon Coast Range
Many land managers in the Pacific Northwest have the goal of increasing late-successional forest structures. Despite the documented importance of Douglas-fir tree bark structure in forested ecosystems, little is known about factors influencing bark development and how foresters can manage development. This study investigated the relative importance of tree size, growth, environmental factors, and thinning on Douglas-fir bark furrow characteristics in the Oregon Coast Range. Bark furrow depth, area, and bark roughness were measured for Douglas-fir trees in young heavily thinned and unthinned sites and compared to older reference sites. We tested models for relationships between bark furrow response and thinning, tree diameter, diameter growth, and environmental factors. Separately, we compared bark responses measured on trees used by bark-foraging birds with trees with no observed usage. Tree diameter and diameter growth were the most important variables in predicting bark characteristics in young trees. Measured environmental variables were not strongly related to bark characteristics. Bark furrow characteristics in old trees were influenced by tree diameter and surrounding tree densities. Young trees used by bark foragers did not have different bark characteristics than unused trees. Efforts to enhance Douglas-fir bark characteristics should emphasize retention of larger diameter trees’ growth enhancement.Keywords: Bark furrow depth, Model selection, Experimental thinning, Cavity-nester
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Region-Wide Ecological Responses of Arid Wyoming Big Sagebrush Communities to Fuel Treatments
If arid sagebrush ecosystems lack resilience to disturbances or resistance to annual invasives, then alternative successional states
dominated by annual invasives, especially cheatgrass (Bromus tectorum L.), are likely after fuel treatments. We identified six
Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis Beetle & Young) locations (152–381 mm precipitation) that
we believed had sufficient resilience and resistance for recovery. We examined impacts of woody fuel reduction (fire, mowing,
the herbicide tebuthiuron, and untreated controls, all with and without the herbicide imazapic) on short-term dominance of
plant groups and on important land health parameters with the use of analysis of variance (ANOVA). Fire and mowing reduced
woody biomass at least 85% for 3 yr, but herbaceous fuels were reduced only by fire (72%) and only in the first year.
Herbaceous fuels produced at least 36% more biomass with mowing than untreated areas during posttreatment years. Imazapic
only reduced herbaceous biomass after fires (34%). Tebuthiuron never affected herbaceous biomass. Perennial tall grass cover
was reduced by 59% relative to untreated controls in the first year after fire, but it recovered by the second year. Cover of all
remaining herbaceous groups was not changed by woody fuel treatments. Only imazapic reduced significantly herbaceous cover.
Cheatgrass cover was reduced at least 63% with imazapic for 3 yr. Imazapic reduced annual forb cover by at least 45%, and
unexpectedly, perennial grass cover by 49% (combination of tall grasses and Sandberg bluegrass [Poa secunda J. Presl.]). Fire
reduced density of Sandberg bluegrass between 40% and 58%, decreased lichen and moss cover between 69% and 80%, and
consequently increased bare ground between 21% and 34% and proportion of gaps among perennial plants >2 m (at least 28%
during the 3 yr). Fire, mowing, and imazapic may be effective in reducing fuels for 3 yr, but each has potentially undesirable
consequences on plant communities.Keywords: Imazapic, Bromus tectorum, Fire, Resistance and resilience, Mowing, Tebuthiuro
Estimating Numbers of Fatalities of Eagles and Other Large Raptors at Wind Energy Facilities or Along Power Lines
In this talk I will focus on estimating probability of detection of eagles and other large raptors under typical search protocols, and how detection probability forms the essential component to estimating mortality from observed carcass counts. I will briefly describe the applicability of a new R package, GenEst, designed to estimate detection probability and mortality from user supplied data. Mortality estimates are fundamental for evaluating the impacts of wind and solar power development on wildlife and for identifying solutions to minimize those impacts
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Win(d)-Win(d) Solutions for wind developers and bats
Bat Conservation International initiated a multi-year, pre-construction study in mid-summer 2009 to investigate patterns of bat activity and evaluate the use of acoustic monitoring to predict mortality of bats at the proposed Resolute Wind Energy Project (RWEP) in east-central Wyoming. The primary objectives of this study were to: (1) determine levels and patterns of activity for three phonic groups of bats (high-frequency emitting bats, low-frequency emitting bats, and hoary bats) using the proposed wind facility prior to construction of turbines; (2) determine if bat activity can be predicted based on weather patterns; correlate bat activity with weather variables; and (3) combine results from this study with those from similar efforts to determine if indices of pre-construction bat activity can be used to predict post-construction bat fatalities at proposed wind facilities. We report results from two years of pre-construction data collection
Win(d)-Win(d) Solutions for wind developers and bats
Bat Conservation International initiated a multi-year, pre-construction study in mid-summer 2009 to investigate patterns of bat activity and evaluate the use of acoustic monitoring to predict mortality of bats at the proposed Resolute Wind Energy Project (RWEP) in east-central Wyoming. The primary objectives of this study were to: (1) determine levels and patterns of activity for three phonic groups of bats (high-frequency emitting bats, low-frequency emitting bats, and hoary bats) using the proposed wind facility prior to construction of turbines; (2) determine if bat activity can be predicted based on weather patterns; correlate bat activity with weather variables; and (3) combine results from this study with those from similar efforts to determine if indices of pre-construction bat activity can be used to predict post-construction bat fatalities at proposed wind facilities. We report results from two years of pre-construction data collection
Wind Energy Development: Methods to Assess Bird and Bat Fatality Rates Post-Construction
Monitoring fatalities at wind energy facilities after they have been constructed can provide valuable information regarding impacts of wind power development on wildlife. The objective of this monitoring is to estimate abundance of a super-population of carcasses that entered the area within a designated period of time. By definition, the population is not closed and carcasses can enter as they are killed through collision with turbines, and leave as they are removed by scavengers or decompose to a point where they are not recognizable. In addition, the population is not inherently mobile, but can only change location through some external force. A focus on number of animal carcasses comprising the super-population, combined with peculiar traits that resist classic assumptions, distinguish fatality estimation at wind-power facilities from more classic abundance estimates that can be addressed through mark-recapture techniques or other well-known abundance estimators. We review the available methods to estimate the super-population of carcasses at wind power facilities. We discuss the role of these estimates in determining appropriate levels of minimization and mitigation of impacts to individual species of concern. We discuss the potential to extrapolate these measurements to reflect the cumulative effect of the industry on individual species. Finally, we suggest avenues of research needed to strengthen our understanding of the effect wind power development has, and might have in the future, on wildlife on this continent and worldwide
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ZaldHaroldForestryClimaticLandformMicrotopographic.pdf
Tree invasions have been documented throughout Northern Hemisphere high elevation meadows, as well as globally in many grass and forb-dominated ecosystems. Tree invasions are often associated with large-scale changes in climate or disturbance regimes, but are fundamentally driven by regeneration processes influenced by interactions between climatic, topographic, and biotic factors at multiple spatial scales. The purpose of this research was to quantify spatiotemporal patterns of meadow invasion; and how climate, larger landforms, topography, and overstory trees have interactively influenced tree invasion. We combined airborne Light Detection and Ranging (LiDAR) characterizations of landforms, topography, and overstory vegetation with historical climate, field measurements of snow depth, tree abundance, and tree ages to reconstruct spatial and temporal patterns of tree invasion over five decades in a subalpine meadow complex in the Oregon Cascade Range, USA. Proportion of meadow occupied by trees increased from 8 % in 1950 to 35 % in 2007. Larger landforms, topography, and tree canopies interactively mediated regional climatic controls of tree invasion by modifying depth and persistence of snow pack, while tree canopies also influenced seed source availability. Landscape context played an important role mediating snow depth and tree invasion; on glacial landforms tree invasion was negatively associated with spring snowfall, but on debris flows tree invasion was not associated with snow fall. The importance of snow, uncertain climate change impacts on snow, and mediation of snow by interacting and context dependent factors in complex mountain terrain poses substantial hurdles for understanding how these ecotones may respond to future climate conditions