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Raptor nests on human-built structures represent a significant source of conflict, as they can result in bird mortality, fires, or power outages due to falling nest materials or animals connecting with energized conductors. Power companies typically try to mitigate these conflicts to avoid service disruptions. Performing mitigation measures across all potentially problematic power infrastructure is generally not a practical solution given logistical, time, or budgetary constraints. Therefore, there is a need for quantitative, landscapescale tools to identify conflict risk and prioritize mitigation. We examined the influence of habitat and transmission infrastructure distribution on the potential risk of osprey (Pandion haliaetus) nesting-infrastructure conflict in the Tennessee Valley Authority (TVA) power service area within Tennessee, Alabama, Georgia, Kentucky, Mississippi, North Carolina, and Virginia, USA, using osprey nesting and conflict records from 1990-2020. We modeled risk using a 3-stage approach, which intersected a nesting habitat suitability model and density of infrastructure to evaluate the potential risk of conflict. Habitat suitability was greater on or near open water and closer to developed areas. Transmission line density was low (0.14 ± 0.29 lines/km²) and heterogenous across the service area with more lines within urban centers and near power facilities. Integrating habitat suitability and transmission infrastructure information revealed that very low and low-risk areas comprised 99% of the service area. Less than 1% comprised 1,113.7 km² of moderate and 82.2 km² of high or very high risk, mostly concentrated along major rivers and lakes, and around urban centers. Risk was more prevalent in the northeastern portion of the service area. This work presents a top-down approach to mitigating osprey--power infrastructure conflict, which allows for the prioritization of mitigation actions and can facilitate long-term coexistence with this protected species. [ABSTRACT FROM AUTHOR]

Effectively managing take of wildlife resulting from human activities poses a major challenge for applied conservation. Demographic data essential to decisions regarding take are often expensive to collect and are either not available or based on limited studies for many species. Therefore, modeling approaches that efficiently integrate available information are important to improving the scientific basis for sustainable take thresholds. We used the prescribed take level (PTL) framework to estimate allowable take for bald eagles (Haliaeetus leucocephalus) in the conterminous United States. We developed an integrated population model (IPM) that incorporates multiple sources of information and then use the model output as the scientific basis for components of the PTL framework. Our IPM is structured to identify key parameters needed for the PTL and to quantify uncertainties in those parameters at the scale at which the United States Fish and Wildlife Service manages take. Our IPM indicated that mean survival of birds >1 year old was high and precise (0.91, 95% CI = 0.90–0.92), whereas mean survival of first‐year eagles was lower and more variable (0.69, 95% CI = 0.62–0.78). We assumed that density dependence influenced recruitment by affecting the probability of breeding, which was highly imprecise and estimated to have declined from approximately 0.988 (95% CI = 0.985–0.993) to 0.66 (95% CI = 0.34–0.99) between 1994 and 2018. We sampled values from the posterior distributions of the IPM for use in the PTL and estimated that allowable take (e.g., permitted take for energy development, incidental collisions with human made structures, or removal of nests for development) ranged from approximately 12,000 to 20,000 individual eagles depending on risk tolerance and form of density dependence at the scale of the conterminous United States excluding the Southwest. Model‐based thresholds for allowable take can be inaccurate if the assumptions of the underlying framework are not met, if the influence of permitted take is under‐estimated, or if undetected population declines occur from other sources. Continued monitoring and use of the IPM and PTL frameworks to identify key uncertainties in bald eagle population dynamics and management of allowable take can mitigate this potential bias, especially where improved information could reduce the risk of permitting non‐sustainable take. [ABSTRACT FROM AUTHOR]

Infrastructure development can affect avian populations through direct collision mortality. Estimating the exposure of local bird populations to the risk of direct mortality from infrastructure development requires site‐ and species‐specific data, which managers may find difficult to obtain at the scale over which management decisions are made. We quantify the potential exposure of sandhill cranes (Antigone canadensis) to collision with horizontal structures (e.g., transmission lines) within vital wintering grounds of the Middle Rio Grande Valley (MRGV), New Mexico, USA, 2014–2020. Limited maneuverability and visual acuity make sandhill cranes vulnerable to collisions with infrastructure bisecting their flight paths. We used data from 81 global positioning system (GPS)‐tagged cranes to estimate the spatially explicit flight height distribution along the MRGV, the passage rate across hypothetical transmission lines, and the resulting exposure rate (exposed passes/crane/day). The exposure rate ranged from 0–0.28 exposed passes/crane/day (median = 0.015) assuming an exposure zone of 7–60 m above ground level, and identified hotspots of potential exposure within the MRGV. Mapped exposure rates can assist in the siting of proposed high‐voltage transmission lines, or other infrastructure, to limit effects on sandhill cranes and other avian species at risk of collision. Our approach can be replicated and applied in similar situations where birds are exposed to possible collision with power lines. © 2021 The Wildlife Society. [ABSTRACT FROM AUTHOR]

Radio‐telemetry is a commonly used scientific technique that allows researchers to collect detailed movement, habitat use, and survival data of animals; however, evidence indicates that using telemetry can affect behavior and survival. Using multiple breeding colonies and years, we investigated the effects of attached radio‐transmitters on growth and survival of Forster's tern (Sterna forsteri) chicks in San Francisco Bay, California, USA, 2010–2011. We tested these potential effects at isolated islands that allowed for high re‐capture rates (typically >85%) in radio‐marked and banded‐only chicks. Modeled Gompertz growth curves suggested that transmitters had a small negative effect on some of the asymptotic growth parameters of tern chicks; tarsus (−1.5 ± 0.7% [SE]), culmen (−1.7 ± 1.2%), and wing (−4.9 ± 2.0%) lengths were shorter for radio‐marked chicks compared to banded‐only chicks. In contrast, there was no difference in asymptotic mass between radio‐marked chicks and banded‐only chicks. Survival from hatching to fledging was lower for radio‐marked chicks than banded‐only chicks during 2010 (banded‐only = 0.313 ± 0.162 vs. radio‐marked = 0.250 ± 0.165) and 2011 (0.193 ± 0.030 vs. 0.123 ± 0.027). Most of the transmitter effect occurred within the first week after hatching, rather than in older chicks. Notably, the effect of transmitters on chick survival was primarily additive, indicating that the effect of transmitters on radio‐marked chicks was not influenced by other ecological covariates. Given the effect radio‐transmitters had on survival did not change across temporal or ecological gradients, transmitters can still be used to evaluate ecological factors affecting survival and timing of mortality and radio‐marked birds can be used to make inferences to the general population. Published 2020. This article is a U.S. Government work and is in the public domain in the USA. Radio‐transmitters affected the growth and survival of Forster's tern chicks. The transmitter effect on survival was additive, indicating that although estimates of survival of radio‐marked chicks may be lower relative to survival rates of banded‐only chicks, the relationships with ecological covariates still reflected the true relationships that would have been observed on banded‐only chicks. [ABSTRACT FROM AUTHOR]

As wind turbine‐caused mortality of birds and bats increases with increasing wind energy capacity, accurate fatality estimates are needed to assess effects, identify collision factors, and formulate mitigation. Finding a larger proportion of collision victims reduces the magnitude of adjustment for the proportion not found, thus reducing opportunities for bias. We tested detection dogs in trials of bat and small‐bird carcasses placed randomly in routine fatality monitoring at the Buena Vista and Golden Hills Wind Energy projects, California, USA, 2017. Of trial carcasses placed and confirmed available before next‐day fatality searches, dogs detected 96% of bats and 90% of small birds, whereas humans at a neighboring wind project detected 6% of bats and 30% of small birds. At Golden Hills dogs found 71 bat fatalities in 55 searches compared to 1 bat found by humans in 69 searches within the same search plots over the same season. Dog detection rates of trial carcasses remained unchanged with distance from turbine, and dogs found more fatalities than did humans at greater distances from turbines. Patterns of fatalities found by dogs within search plots indicated 20% of birds and 4–14% of bats remained undetected outside search plots at Buena Vista and Golden Hills. Dogs also increased estimates of carcass persistence by finding detection trial carcasses that the trial administrator had erroneously concluded were removed. Compared to human searches, dog searches resulted in fatality estimates up to 6.4 and 2.7 times higher for bats and small birds, respectively, along with higher relative precision and >90% lower cost per fatality detection. © 2020 The Authors. The Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society. Searching for fatalities at wind turbines, skilled scent‐detection dogs improved carcass detection rates over human searchers 17‐fold for bats and 3‐fold for birds, and in concurrent, overlapping fatality monitoring, human searchers found none of the 71 bat fatalities and 17% of the bird fatalities found by dogs. Findings of dogs increased fatality rate estimates over those of human searchers 6.4‐ and 2.7‐fold, respectively, along with higher relative precision and >90% lower cost per fatality detection. [ABSTRACT FROM AUTHOR]

ABSTRACT: The rock ptarmigan (Lagopus muta) is a popular game bird in Iceland, but the population has endured a long‐term decline. A hunting ban was enforced in 2003, but 2 years later hunting was allowed again with added restrictions. The aim of this study was to investigate the effects of a change in hunting regulations on the ptarmigan population in northeast Iceland, 1998–2013, using a population reconstruction model and to estimate the abundance of juveniles and adults, natural survival, and harvest mortality. The estimated abundance at the beginning of the hunting season ranged from 42,000 (95% CI = 36,000–49,000) birds in 2002 to 158,000 (95% CI = 105,000–250,000) in 1998. The natural survival of adult rock ptarmigan was density dependent and ranged from 36% to 65% (95% CI = 30–75%). Survival for juveniles was constant and was estimated to be 19% (95% CI = 18–20%). We included a change point in the model to account for a change in the harvest mortality that could have occurred with the changes in the hunting regulations. The results indicated that the change in hunting regulations did reduce ptarmigan harvest mortality and changed the harvest strategies of hunters. Inclusion of a change point in models is useful for managers to test if a change in regulations had an effect on the target population. © 2018 The Wildlife Society. [ABSTRACT FROM AUTHOR]

ABSTRACT Oil and gas development on the Arctic Coastal Plain (ACP) of Alaska, USA may have effects on Arctic-nesting birds. To estimate effects of industrial activity and investigator disturbance on avian productivity, we monitored nests of greater white-fronted geese ( Anser albifrons) with digital cameras and periodic nest visits during 2013-2014 at 2 sites on the ACP. A disturbed site was adjacent to human-made infrastructure and industrial clean-up activities initiated at the onset of the study and a control site was >2 km from sources of industrial disturbance. We assessed variation in estimates of incubation constancy, nest survival, and predator behavior relative to site, year, and distance from industrial activity using nest photographs obtained at 1-minute intervals. We compared analysis of hourly nest survival informed by intensive monitoring with cameras to analysis of daily nest survival informed by traditional nest visit data obtained at intervals of 5-7 days to assess how method and time scale of sampling affect ecological inference. Geese in both sites exhibited high levels of nest attendance and initiated incubation breaks less than once per day. Observer-caused incubation breaks associated with nest visits ( [ABSTRACT FROM AUTHOR]

ABSTRACT Free-roaming domestic cats are a major anthropogenic source of morbidity and mortality to wild birds and mammals in the United States. Permitted wildlife rehabilitators routinely treat cat-caused injuries. However, extent of these activities is under-reported in the scientific literature. To determine incidence, age class, mortality, diversity and frequency of species affected, nature of injuries, time in care, and temporal and geospatial trends associated with interactions between free-roaming cats and wildlife, we conducted a retrospective analysis on 20,921 records from small birds and mammals presented to the Wildlife Center of Virginia (WCV), USA between 2000 and 2010. Cat interaction was the second greatest cause of small-mammal admissions (14.8%), fourth greatest cause of mammal mortality (70.8%), fourth greatest cause of bird admissions (13.7%), and second greatest cause of avian mortality (80.8%). Eighty-three species were admitted following interactions with cats. Age of wildlife admitted following cat interaction varied by class; juvenile mammals were captured most frequently (40.5%), followed by neonates (34%), then adults (25.5%). However, adults were documented most frequently in birds (42.7%), followed by juveniles (37.2%), then nestlings (20.1%). Birds were more likely to have interactions with cats in rural areas, whereas degree of urbanization did not differ for mammals. Eighty-eight percent of cat interactions occurred between April and September, indicating a strong seasonal trend. Our findings indicate that free-roaming cats substantially contribute to admissions in a wildlife rehabilitation hospital and even with veterinary intervention, release potential is limited. Reducing the number of free-roaming cats will reduce interactions with wildlife and decrease the need for medical assistance. © 2016 The Wildlife Society. [ABSTRACT FROM AUTHOR]

ABSTRACT Livestock fences have been hypothesized to significantly contribute to mortality of lesser prairie-chickens ( Tympanuchus pallidicinctus); however, quantification of mortality due to fence collisions is lacking across their current distribution. Variation in fence density, landscape composition and configuration, and land use could influence collision risk of lesser prairie-chickens. We monitored fences within 3 km of known leks during spring and fall and surveyed for signs of collision occurrence within 20 m of fences in 6 study sites in Kansas and Colorado, USA during 2013 and 2014. We assessed mortality locations of radio-tagged birds ( n = 286) for evidence of fence collisions and compared distance to fence relative to random points. Additionally, we quantified locations, propensity, and frequency of fences crossed by lesser prairie-chickens. We tested for landscape and vegetative characteristics that influenced fence-cross propensity and frequency of global positioning system (GPS)-marked birds. A minimum of 12,706 fence crossings occurred by GPS-marked lesser prairie-chickens. We found 3 carcasses and 12 additional possible instances of evidence of collision during >2,800 km of surveyed fences. We found evidence for a single suspected collision based on carcass evidence for 148 mortalities of transmittered birds. Mortality locations of transmittered birds were located at distances from fences 15% farther than expected at random. Our data suggested minimal biological significance and indicated that propensity and frequency of fence crossings were random processes. Lesser prairie-chickens do not appear to be experiencing significant mortality risk due to fence collisions in Kansas and Colorado. Focusing resources on other limiting factors (i.e., habitat quality) has greater potential for impact on population demography than fence marking and removal. © 2016 The Wildlife Society. [ABSTRACT FROM AUTHOR]

ABSTRACT We compared the number of avian species detected and the sampling effort during fatality monitoring at 50 North American wind facilities. Facilities with short intervals between sampling events and high effort detected more species, but many facilities appeared undersampled. Species accumulation curves for 2 wind facilities studied for more than 1 year had yet to reach an asymptote. The monitoring effort that is typically invested is likely inadequate to identify all of the species killed by wind turbines. This may understate impacts for rare species of conservation concern that collide infrequently with turbines but suffer disproportionate consequences from those fatalities. Published 2015. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

ABSTRACT One of the most effective means of minimizing mortalities of large raptors from collisions with hazards is to locate hazards away from major activity centers. A reliable means of delineating bird activity centers on the landscape has been a significant impediment to progress in proactive infrastructure planning. We used Brownian bridge movement modeling to develop a population-wide, utilization probability surface for bald eagles ( Haliaeetus leucocephalus) within the upper Chesapeake Bay. We used locations ( n = 320,304) for individuals ( n = 63) tracked with global positioning system (GPS) satellite transmitters between 2007 and 2011 in the analysis. We intersected the electrical network on the probability surface within Aberdeen Proving Ground, a 350-km2 military installation to identify overlap between power lines and eagle activity centers. We also overlaid locations of eagle mortalities attributed to the lines ( n = 67) on the installation to assess the relationship between mortality rates and utilization probabilities. Areas of high bald eagle use were relatively rare on the landscape with only 0.1% and 5% of the area accounting for 10% and 30% of estimated utilization. Most electric lines were along roads and distributed away from eagle activity centers, with only 0.3% of lines located within areas with the highest estimated eagle use. Eagle mortalities were highly skewed to lines that overlapped with eagle activity centers. Eagle mortality rates (birds/100 km/yr) were 42 times higher along lines associated with the highest 10% of eagle use compared to lines associated with the lowest 10% use, suggesting that estimated utilization may be an effective proxy for mortality risk associated with electric line hazards. The majority (71.9%) of high-use bald eagle areas delineated within the study area have no existing electric lines. Utilization probabilities may be a potential tool for site-specific infrastructure planning. © 2015 The Wildlife Society. [ABSTRACT FROM AUTHOR]

ABSTRACT The peregrine falcon ( Falco peregrinus) population in eastern North America has grown significantly since the early 1980s, especially in urban areas, but few studies have assessed the factors that influence productivity. We reviewed all documented nesting attempts from southern Ontario, Quebec, Massachusetts, New Jersey, and Pennsylvania from 1980 through 2006 to evaluate these factors. Of 801 nesting attempts, 663 were successful, producing a total of 1,613 young. Mean productivity ranged from 1.7 young fledged per nesting attempt in New Jersey to 2.9 in Quebec. Peregrines nesting in quarries or on buildings had higher productivity than those using marsh towers or bridges, but productivity did not differ overall between urban and rural sites. Nests with overhead cover had higher productivity than those without, as did nests in trays or boxes compared to sites without any human-provided nesting aids. Peregrines favored nest sites facing east to south, but productivity did not vary significantly with direction. Several adults have contributed disproportionately to the growth of the eastern population, with just 5 females and males accounting for 8% and 9% of all young fledged, respectively. Of 160 documented mortalities, we identified cause of death for 118, with the most common being collisions with buildings (36%), vehicles (9%), aircraft (8%), and power lines (8%). In many urban areas, grounded fledglings are rescued and returned to higher perches. Of 85 individuals from southern Ontario that were rescued, at least 8 have subsequently bred, producing 65 known offspring. Although peregrines have been thriving in eastern cities, continued management effort may be required for them to maintain their level of success, with key measures including provision of appropriately located nest boxes and rescue of grounded fledglings. © 2014 The Wildlife Society. [ABSTRACT FROM AUTHOR]

ABSTRACT Quantifying sources and timing of variation in demographic rates is necessary to determine where and when constraints may exist within the annual cycle of organisms. Surf scoters ( Melanitta perspicillata) and white-winged scoters ( M. fusca) undergo simultaneous remigial molt during which they are flightless for >1 month. Molt could result in reduced survival due to increased predation risk or increased energetic demands associated with regrowing flight feathers. Waterfowl survival during remigial molt varies across species, and has rarely been assessed for sea ducks. To quantify survival during remigial molt, we deployed very high frequency (VHF) transmitters on surf scoters ( n = 108) and white-winged scoters ( n = 57) in southeast Alaska and the Salish Sea (British Columbia and Washington) in 2008 and 2009. After censoring mortalities potentially related to capture and handling effects, we detected no mortalities during remigial molt; thus, estimates of daily and period survival for both scoter species during molt were 1.00. We performed sensitivity analyses in which mortalities were added to the dataset to simulate potential mortality rates for the population and then estimated the probability of obtaining a dataset with 0 mortalities. We found that only at high survival rates was there a high probability of observing 0 mortalities. We conclude that remigial molt is normally a period of low mortality in the annual cycle of scoters. The molt period does not appear to be a constraint on scoter populations; therefore, other annual cycle stages should be targeted by research and management efforts to change population trajectories. Published 2014. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

ABSTRACT Roads have numerous direct and indirect ecological impacts on wildlife. Vehicle collisions are a top impact of roads on birds, with tens of millions of birds thought to be killed each year in the United States. However, currently available mortality estimates are extrapolated from a single study. We reviewed the literature and used 20 mortality rates extracted from 13 studies to systematically quantify data-driven estimates of annual U.S. mortality from bird-vehicle collisions. We generated 4 separate estimates along with uncertainty using different subsets of data deemed to be rigorous enough to contribute relatively little bias to estimates. All of our estimates of vehicle mortality are higher than previous U.S. figures. When averaging across model iterations, we estimated that between 89 and 340 million birds die annually from vehicle collisions on U.S. roads. Sensitivity analyses indicated that uncertainty about survey-related biases (scavenger removal and searcher detection of carcasses) contributes the greatest amount of uncertainty to our mortality estimates. Future studies should account for these biases to provide more accurate local estimates of mortality rates and to inform more precise national mortality estimates. We found relatively little information available to quantify regional, seasonal, and taxonomic patterns of vehicle collision risk, and substantial uncertainty remains about whether collisions contribute to large-scale impacts on bird populations. Nonetheless, the large magnitude of bird mortality caused by vehicle collisions combined with evidence that collisions can contribute to local population declines for some species highlights the need for implementation of conservation and management actions to reduce this mortality. Published 2014. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

ABSTRACT The post-fledging dependency period of birds is often characterized by high juvenile mortality, but fledglings in specific habitats may have increased survivorship. We describe habitat use by fledgling northern flickers ( Colaptes auratus) in relation to the availability of patchy forest and prairie habitat in central British Columbia, Canada. We used radiotelemetry to monitor survival of fledglings according to their use of habitats during the dependency period. The fledglings occupied habitats with a higher density of trees than either random locations or nest sites and they switched from forested areas to more open grasslands after 7-10 days post-fledging. Some moved >1 km from the nest within 4 days post-fledging. Fledglings from nests in small tree clusters with little forest cover within 250 m moved farther from their nest within the first 4 days post-fledging than fledglings from nests in larger forest patches. Fledgling survival was positively correlated with the amount of canopy cover and negatively correlated with the amount of forest cover at the larger landscape scale. Young flickers moved among habitat types, which may occur as a result of trade-offs between predation risk and food abundance between habitats. We conclude that fledgling flickers at younger ages used dense forested areas and grassland habitat and forest at older ages to maximize survival and to access food sources. Maintaining patches of dense cover and the amount of forest cover on less than 35% of the landscape may improve fledgling survival of flickers. © 2014 The Wildlife Society. [ABSTRACT FROM AUTHOR]

ABSTRACT We investigated the general patterns of movements in willow ptarmigan ( Lagopus lagopus) populations. We analyzed data from 300 radiocollared willow ptarmigan from 3 study areas in the Swedish mountain range, and from 2 previous studies of recoveries of wing-tagged chicks from 3 areas in southern Norway. We found that 80% of juvenile females dispersed more than 5 km from their natal area, whereas only 25% of juvenile males established a summer range more than 5 km from the area where they were caught as chicks. Mean dispersal distances of juvenile females were 3 times longer (10.4 km) than those of juvenile males (2.4 km). Movement differences within sexes were not associated with apparent female breeding success or ptarmigan density in the natal area, and adult females migrated between wintering areas used as juveniles and their first breeding site. We found no differences in dispersal distances between the Norwegian and Swedish populations. Movements of adult and juvenile females during spring were similar in all respects. At scales of more than 5 km, the movements of juveniles and adult females play a role in redistributing birds within landscape units, and represent important inter-population movements. The results of this study explain the apparent contradiction between non-compensatory mortality based on data from radio-marked ptarmigan, and the almost complete compensation based on annual counts. Estimating the extent of immigration into areas with high local mortality is difficult because of predation or harvest under conditions of high, fixed emigration and immigration dependent on local conditions. This represents a problem if dispersal distances include areas that are considerably larger than the size of the study area. © 2014 The Wildlife Society. [ABSTRACT FROM AUTHOR]

ABSTRACT The wetlands and grasslands of the Prairie Pothole Region (PPR) make it the most productive breeding habitat for North American ducks. The growth rate of mallard ( Anas platyrhynchos) populations is sensitive to changes in survival of adult females during the breeding season. Much of the PPR is suitable for large-scale wind-energy development and collisions of breeding females with wind turbines may be a novel source of mortality in this area. We assessed the effects of wind energy on breeding female mallard and blue-winged teal ( A. discors) survival by monitoring 77 radio-marked mallards and 88 blue-winged teal during the 2009 and 2010 breeding seasons at the Tatanka Wind Farm (TWF) near Kulm, North Dakota. During the same period, we monitored 70 female mallards and 75 blue-winged teal at an adjacent reference site without wind turbines (REF). We used an information-theoretic approach to investigate relationships between female survival and site (TWF vs. REF), year (2009 vs. 2010), and date. Collision mortalities were rare. Only 1 radio-marked female mallard and no blue-winged teal collided with wind turbines. Most mortalities were caused by predators (78.3%; 36/46), irrespective of species and site. For mallards, the best-approximating model indicated that breeding season survival was 1) lowest when a high proportion of radio-marked females were incubating, and 2) dependent on year and site such that expected survival ( [ABSTRACT FROM AUTHOR]

ABSTRACT Raptor electrocution mortality on power lines has been well documented over the past several decades, yet knowledge gaps, particularly regarding electrocution rates and estimates of losses, are still prevalent in the literature. Mortality estimates that do exist are often derived solely from utility outage records and exclude those not associated with a sustained outage. To address these shortcomings, we directly assessed raptor electrocution mortality beneath distribution power lines in east-central Alberta, Canada between June and August 2003. We also experimentally tested the effect of scavenger removal of carcasses. We observed the greatest rate of raptor mortality on transformer poles; 3-phase corner deadend poles were implicated in more incidents than expected based on proportional frequency, whereas tangent structures showed the opposite result. An estimated 94% of electrocution mortality was not associated with a power outage, indicating that utility outage data alone is insufficient to estimate incidence of electrocution. Scavenger removal rates were high, with >50% of the experimental carcasses removed within 7 days. Study results will assist utility companies and wildlife managers to better delineate structure retrofitting and new construction standards for structures that cause a disproportionately high number of raptor electrocutions, maximizing limited mitigation funds. © 2013 The Wildlife Society. [ABSTRACT FROM AUTHOR]

Management of migratory birds at the national level has historically relied on regulatory boundaries for definition of harvest restrictions and estimation of demographic parameters. Most species of migratory game birds are not expanding their ranges, so migratory corridors are approximately fixed. White-winged doves ( Zenaida asiatica), however, have undergone significant variation in population structure with marked range expansion occurring in Texas, and range contraction in Arizona, during the last 30 years. Because >85% of white-winged dove harvest in the United States (approx. 1.3 million annually) now occurs in Texas, information on vital rates of expanding white-winged dove populations is necessary for informed management. We used band recovery and mark-recapture data to investigate variation in survival and harvest across 3 geographic strata for white-winged doves banded in the pre-hunting season in Texas during 2007-2010. We banded 60,742 white-winged doves, recovered 2,458 bands via harvest reporting, and recaptured 455 known-age birds between 2007 and 2010. The best supporting model found some evidence for geographic differences in survival rates among strata (A-C) in both hatch-year (juvenile; A = 0.205 [SE = 0.0476], B = 0.213 [SE = 0.0278], C = 0.364 [SE = 0.0254]) and after-hatch year (adult; A = 0.483 [SE = 0.0775], B = 0.465 [SE = 0.0366], C = 0.538 [SE = 0.251]) birds. White-winged doves had a low probability of moving among strata (0.009) or being recaptured (0.002) across all strata. Harvest recovery rates were concordant with estimates for other dove species, but were variable across geographic strata. Based on our results, harvest management strategies for white-winged doves in Texas and elsewhere should consider differences in population vital rates among geographic strata. © 2012 The Wildlife Society. [ABSTRACT FROM AUTHOR]

Bird electrocution on power lines is an important conservation problem that affects many endangered species. We surveyed 3,869 pylons in the Barcelona Pre-littoral Mountains (Catalonia, NE Spain) and collected 141 carcasses of electrocuted birds, mainly raptors and corvids. Univariate analysis indicated that metal pylons with pin-type insulators or exposed jumpers, with connector wires, located on ridges, overhanging other landscape elements, and in open habitats with low vegetation cover were the most dangerous. A logistic regression model indicated that the probability of a pylon electrocuting a bird was mainly related to pylon conductivity, distribution of the conductive elements on the cross-arms, cross-arm configuration, habitat, topography, whether the pylon was overhanging other landscape elements, and presence of rabbits (Oryctolagus cuniculus). We validated the predictive power of this model by using a random sample of 20% of all pylons surveyed. We found that bird mortality was aggregated mainly on pylons assigned a high probability risk by the model. Pylons included in the very high electrocution risk category (9.2%) accounted for 53.2% of carcasses, whereas pylons classified in the low electrocution risk category (54.5%) only accounted for 3.5% of mortality. Power companies employed this classification to prioritize the correction of 222 pylons by installing alternate cross-arms and suspended jumpers and isolating wires and jumpers. We evaluated the effectiveness of this mitigation strategy. A significant fall in the mortality rate on corrected pylons combined with the lack of any reduction in the mortality rate in a sample of 350 noncorrected pylons indicated that the model selected adequately the most dangerous pylons and that the applied correction measures wereeffective. Consequently, our strategy may be a useful tool for optimizing efforts and resources invested in solving the problem of bird electrocution. [ABSTRACT FROM AUTHOR]

The possible role of tag color in mediating behaviors that could bias resighting rate has not been examined. In a study that began in 2007, we marked 725 ring-billed gulls (Larus delawarensis) with Bondcote royal blue, green, yellow, or orange patagial tags. Reports we gathered over 2 years indicated approximately a 3.4:1 bias in resighting rate toward yellow or orange tags. The observed bias is inconsistent with color-associated visibility bias or differential mortality among color-tagged breeding adults. Potential behavioral effects of tag color on individuals and conspecifics should be considered by biologists when planning marking studies. [ABSTRACT FROM AUTHOR]

We estimated electrocution rates for raptors and common ravens (Corvus corax) for the Moon Lake Electrical Association in northeastern Utah and northwestern Colorado, USA. From July 2001 to May 2003, we conducted mortality searches at randomly selected distribution line segments and poles within 3 regions, but rate estimates (0.0036-0.0112 deaths/pole/yr) may have been biased by the effects of scavengers and by long sampling intervals ( ≥3 months), which prevented us from determining the cause of death for most birds because of advanced decay. In 2002-2003, we conducted carcass removal experiments in the Rangely Oil Field (ROF) in northwestern Colorado to estimate scavenging effects, and in 2003-2004, we reduced sampling intervals to 1 month and searched for dead birds at all distribution poles in the ROF. The shorter sampling interval nearly tripled the number of birds suitable for necropsy, but we were still unable to establish cause of death for >40% of our sample. Instead of eliminating the unknowns from rate estimates, we estimated minimum annual electrocution rates using only confirmed electrocutions and maximum annual electrocution rates based on all available mortalities, including mortalities without known causes. Golden eagles (Aquila chrysaetos) accounted for 63% of dead birds found in 2003-2004, but they were removed by scavengers at rates well below hawks and owls (6.8% vs. 55.6%). We compared maximum rates for the ROF in 2003-2004 with the rates estimated from a survey conducted at the same poles in 1999 to assess the effects of retrofitting conducted by Moon Lake from 1999 to 2003. Electrocution rates in 2003-2004 were 47% lower than those in 1999. Raptor densities in the ROF did not change during our study, suggesting the reduction was not the result of changes in raptor populations. However, estimates of raptor densities in 1999 were not available, and we cannot be sure that numbers of birds using the oil field in 1999 were similar to those in 2003-2004. Our research emphasizes the difficulties of estimating electrocution rates precisely but suggests that utilities will have the greatest effect on mortality by monitoring power lines at large scales and focusing subsequent mitigation efforts in areas that pose the greatest risk to the greatest number of birds. [ABSTRACT FROM AUTHOR]

In a recent paper, Smallwood et al. (2010) conducted a study to compare their 'novel' approach to conducting carcass removal trials with what they term the 'conventional' approach and to evaluate the effects of the different methods on estimated avian fatality at a wind power facility in California. A quick glance at Table 3 that succinctly summarizes their results and provides estimated fatality rates and 80% confidence intervals calculated using the 2 methods reveals a surprising result. The confidence intervals of all of their estimates and most of the conventional estimates extend below 0. These results imply that wind turbines may have the capacity to create live birds. But a more likely interpretation is that a serious error occurred in the calculation of either the average fatality rate or its standard error or both. Further evaluation of their methods reveals that the scientific basis for concluding that 'many estimates of scavenger removal rates prior to [their] study were likely biased low due to scavenger swamping' and 'previously reported estimates of avian fatality rates ... should be adjusted upwards' was not evident in their analysis and results. Their comparison to conventional approaches was not applicable, their statistical models were questionable, and the conclusions they drew were unsupported. © 2013 The Wildlife Society. [ABSTRACT FROM AUTHOR]