Flushing Responses of Golden Eagles (\u3cem\u3eAquila chrysaetos\u3c/em\u3e) in Response to Recreation

Disturbance because of human activity, including recreation on wildlands, can affect bird behavior which in turn can reduce breeding success, an important consideration for species of management concern. We observed Golden Eagles (Aquila chysaetos) during the breeding season to determine whether the probability of flushing was affected by the type of recreationist, distance to encounter, eagle nest attendance, or date. We monitored eagles in 23 nesting territories from distant (600-1,200 m) observation points and recorded recreation activity within 1,200 m of eagles in the Owyhee Front of southwestern Idaho. In most (86%, n = 270) encounters, eagles did not flush in response to recreationists; however, whether an eagle flushed was affected by the type of recreationist and whether an eagle was at or away from the nest. Eagles were 60 times more likely to flush in response to recreationists that stopped a motor vehicle and transitioned to walking (11 of 17 passes) and 4.5 times more likely to flush in response to off-road vehicle (ORV) riders (17 of 121 passes) than during encounters with road vehicles (7 of 107 passes). Flushing was 12 times more likely for eagles away from nests (23 of 87 passes) than eagles at nests (13 of 183 passes). Eagles flushed at greater distances in response to recreationists that transitioned from motor vehicles to walking (lsmean = 620 m) than when responding to either ORV riders (lsmean = 525 m) or road vehicles (lsmean = 318 m). Flushing distances tended to decline throughout the breeding season to suggest seasonal changes in the costs and benefits of responding to disturbance. After flushing from nests, most eagles (77%) spentaway, but some (23%) spent \u3e90 mins away from nests. Limiting recreational activities within 650 m and 1,000 m of nest sites may decrease nest-site flushing events by 77% and 100%, respectively. Because eagles seem most sensitive to humans transitioning between motorized and non-motorized recreation, land managers may strike a balance between access needs of recreationists and buffering eagles from disturbance by using a mix of trail closures and no-stopping zones that prevent transitions from motorized to walking activities

Recreation Disturbance to a Shrub-Steppe Raptor: Biological Consequences, Behavioral Mechanisms, and Management Implications

With rapid increases in outdoor recreation, and mounting evidence of impacts to wildlife, public land managers and biologists need better information on the nature of this potential disturbance. Outdoor recreation may impact wildlife negatively via human disturbance or habitat degradation. Golden eagles (Aquila chrysaetos) in shrub-steppe habitats face several current and emerging threats, including increased non-motorized and motorized (off-highway vehicle, OHV) recreation. We tested the hypothesis that recreation affects eagle breeding biology by monitoring eagle behavior and reproduction in response to recreation volume and activity types, and landscape features associated with recreation. We also investigated the probability that an adult golden eagle would flush, examined flight initiation distance (FID), and documented total time off the nest following flushing events in response to motorized and non-motorized recreationists. Territories with higher seasonal-average OHV volumes were less likely to be occupied than territories with lower seasonal-average OHV volumes, despite uniformly low OHV volume across all territories during the pre-breeding period. For non-migratory species, like eagles in southern Idaho, decreased occupancy during the breeding season may be the result of carry-over effects of disturbance in the non-breeding season, degraded habitat, or both. At occupied territories, early season volumes of pedestrians and other non-motorized recreationists negatively influenced adult eagle nest attendance and the likelihood of egg-laying. Behavioral observations of breeding birds revealed that adult nest attendance, a strong predictor of success, was associated negatively with the volume of pedestrians, and most pedestrians observed near the nests reached the area via motorized vehicles. In addition, nest survival was affected negatively by interval-specific OHV volume recorded by trail cameras. In most (87.1%, n = 279) instances, adult eagles did not respond to recreationists passing within 1200 m. Flushing was more likely to occur if eagles were perched away from the nest than if eagles were at the nest. FID was greater in the earlier portion of the breeding season, suggesting seasonal changes in the costs and benefits of responding to disturbance. Type of recreation activity did not affect the probability of flushing or FID, but flushing occurred frequently (36%, n = 36) when motorized recreationists stopped and changed their behavior near eagles. Recreationists on foot frequently go off trail and follow less predictable movement patterns than motorized recreationists and might create greater perceived risk. Taken together, these results suggest that OHVs may facilitate disturbance events leading to nest failure by transporting motorized recreationists, who become pedestrians, to areas near eagle nests. We propose that landscape features suitable for eagle nesting, like steep canyons and rocky outcrops, also inspire recreationists to transition from predictable movements along a trail to less predictable stop-and-go hiking; less predictable recreation activities may increase perceived risk for eagles. Expanding existing trail management efforts to consider the effects of pedestrian and non-motorized recreation, especially during the early portion of the breeding season, could help improve eagle productivity. Limiting motorized and non-motorized recreation activities within 650 m and 1000 m of nest sites may decrease flushing events by 77% and 100%, respectively. Trail management efforts on public lands may strike a balance between the needs of recreationists and eagles by implementing “no-stopping” zones near known eagle nesting areas

Data Associated with \u27Forecasting Disturbance Effects on Wildlife: Tolerance Does Not Mitigate Effects of Increased Recreation on Wild Lands\u27

There is widespread evidence that human disturbance affects wildlife behavior, but long-term population effects can be difficult to quantify. Individual-based models (IBMs) offer a way to assess population-level, aggregate effects of disturbance on wildlife. We created Tolerance in Raptors and the Associated Impacts of Leisure Sports (TRAILS), an IBM that simulates interactions between recreationists and nesting raptors, to assess the effect of human disturbance on raptor populations and test if changes in tolerance to disturbance could mitigate negative consequences. We used behavioral and demographic data from golden eagles Aquila chrysaetos, and recreation activity data to parameterize TRAILS and simulate the effects of pedestrian and off-highway vehicle (OHV) recreation on the likelihood of territory occupancy, egg-laying and nest survival of eagles over 100 years. We modeled eagle populations in the absence of recreation, with stationary 2014 levels of recreation, and with annual increases in recreation. Furthermore, we simulated eagles that developed tolerance to disturbance randomly, through natural selection, habitat imprinting, or habituation. In the presence of recreation, simulated eagle populations had significantly lower and more variable growth rates, population sizes and territory occupancy. Annual increases in recreation of 1–2% greatly exacerbated population declines. Though both habituation and natural selection lead to more tolerant eagle populations, neither buffered eagle populations from detrimental effects of recreation. These results suggest that long-lived species that experience encroachment from human activities may not adapt to human disturbance at a rate that compensates for changes in disturbance. This project illustrates the usefulness of IBMs for evaluating non-lethal threats, forecasting population changes and testing theoretical feedbacks in system processes

TRAILS Model: Tolerance in Raptors and the Associated Impacts of Leisure Sports

There is widespread evidence that human disturbance affects wildlife behavior, but long-term population effects can be difficult to quantify. Individual-based models (IBMs) offer a way to assess population-level, aggregate effects of disturbance on wildlife. We created Tolerance in Raptors and the Associated Impacts of Leisure Sports (TRAILS), an IBM that simulates interactions between recreationists and nesting raptors, to assess the effect of human disturbance on raptor populations and test if changes in tolerance to disturbance could mitigate negative consequences. We used behavioral and demographic data from golden eagles Aquila chrysaetos, and recreation activity data to parameterize TRAILS and simulate the effects of pedestrian and off-highway vehicle (OHV) recreation on the likelihood of territory occupancy, egg-laying and nest survival of eagles over 100 years. We modeled eagle populations in the absence of recreation, with stationary 2014 levels of recreation, and with annual increases in recreation. Furthermore, we simulated eagles that developed tolerance to disturbance randomly, through natural selection, habitat imprinting, or habituation. In the presence of recreation, simulated eagle populations had significantly lower and more variable growth rates, population sizes and territory occupancy. Annual increases in recreation of 1–2% greatly exacerbated population declines. Though both habituation and natural selection lead to more tolerant eagle populations, neither buffered eagle populations from detrimental effects of recreation. These results suggest that long-lived species that experience encroachment from human activities may not adapt to human disturbance at a rate that compensates for changes in disturbance. This project illustrates the usefulness of IBMs for evaluating non-lethal threats, forecasting population changes and testing theoretical feedbacks in system processes

Simulating the Success of Trail Closure Strategies on Reducing Human Disturbance to Nesting Golden Eagles

As nature-based recreation grows in popularity, there is concern for reduced fitness of animals exposed to chronic disturbance by these activities. Golden Eagles (Aquila chrysaetos) and other raptors are sensitive to human recreation near their nests, and managers of these species need strategies to mitigate negative effects. We used simulation models to separate the effects of trail density and configuration, land cover configuration, and volume of human recreation on the effectiveness of 2 trail closure strategies to manage disturbance. We simulated a breeding pair of Golden Eagles at 3 territories with varying degrees of trail density under current and increased levels of human activity. We simulated a baseline scenario, a scenario with a 600 m restrictive buffer around the nest, and a scenario where we closed all but the most popular trails to human recreation. We also conducted a trail-swapping simulation with trail configurations of each territory placed into the land cover of the other territories under current and increased levels of human recreation. This allowed us to isolate the effects of trail density and configuration from land cover configuration on flushing frequency of eagles. We found that for current levels of human recreation, the restrictive buffer was best at reducing flushing of incubating eagles, while closing all but the popular trails was best for foraging eagles. However, management did not mitigate disturbance for trail-swapping simulations, indicating that trail density was the main factor influencing eagle flushing frequency when human recreation was increased. Our results suggest that managers should consider both trail density and the level of human recreation before deciding on mitigation strategies, as approaches that work at lower human activity levels may be ineffective when activity levels increase

Whole-body vibration and occupational physical performance: a review

© 2015 Springer-Verlag Berlin Heidelberg Introduction: In the occupational environment, there are a considerable number of stressors that can affect physical performance in job tasks. Whole-body vibration (WBV), which arises from vehicle transit, is one such stressor that has been demonstrated to alter human function in several ways. This study identifies the known physical changes to human function which result from WBV, to comment on changes which may translate to performance in physically demanding occupational tasks. Methods: A systematic review is performed on the literature relating to changes in the neuromuscular, physiological and biomechanical properties of the human body, when exposed to WBV. Selection criteria are constructed to synthesise articles which strictly relate to in-vehicle WBV and physical responses. Results: In total, 29 articles were identified which satisfied the criteria for inclusion. A range of physical responses produced from WBV are presented; however, little consistency exists in study design and the responses reported. Discussion: Given the inconsistency in the reported responses, the precise changes to human function remain unknown. However, there is sufficient evidence to warrant the design of studies which investigate occupationally relevant physical performance changes following WBV