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At least 577 records · Page 32Linked to original sources
USGS2018

Evaluating the waterfowl breeding population and habitat survey for scaup

Potential bias in breeding population estimates of certain duck species from the Waterfowl Breeding Population and Habitat Survey (WBPHS) has been a concern for decades. The WBPHS does not differentiate between lesser ( Aythya affinis ) and greater ( A . marila ) scaup, but lesser scaup comprise 89% of the combined scaup population and their population estimates are suspected to be biased. We marked female lesser scaup (i.e., marked scaup) in the Mississippi and Atlantic Flyways, Canada and United States, with implantable satellite transmitters to track their spring migration through the traditional and eastern survey areas of the WBPHS, 2005–2010. Our goal was to use data independent of the WBPHS to evaluate whether breeding population estimates for scaup were biased and identify variables that might be used in the future to refine population estimates. We found that the WBPHS estimates of breeding scaup are biased because, across years, only 30% of our marked scaup had settled for the breeding period when the strata in which they settled were surveyed, 43% were available to be counted in multiple survey strata as their migration continued during the WBPHS, 32% settled outside the WBPHS area, the number of times a marked scaup was available to be counted by survey crews varied positively with the latitude that a marked scaup settled on breeding areas, the probability of a marked scaup being in a stratum while it was surveyed varied among years, and these probabilities were positively correlated with the traditional and eastern breeding population estimates for scaup. Annual population estimates derived from banding data provide a less biased and preferable method of monitoring scaup population status and trend. Development of models that include metrics such as survey stratum latitude and annual spring environmental conditions might potentially be used to improve scaup breeding population estimates derived from the WBPHS, but independent estimates from banding data would be important to evaluate such models.

Journal of Wildlife Management↗
USGS2018

Genetic structure in Elk persists after translocation

Elk ( Cervus canadensis ) translocation success is thought to be facilitated by high post‐release herd cohesion and limited movements; both should ensure genetic mixing following release. Such mixing is important to reduce potential effects of inbreeding or genetic drift, which can be especially important in small founding populations. We had a natural experiment where we could evaluate genetic mixing of 2 distinct lineages of elk after translocation to the same area. Founding elk ultimately came from north and south of a road barrier at Elk Island National Park (EINPN or EINPS, respectively), Alberta, Canada and the 2 groups were genetically distinct. During 2000 to 2003, elk originating from Elk Island National Park were translocated to Cumberland Mountains, Tennessee (TNCM) and Great Smoky Mountains National Park, North Carolina (GSMNP), USA (some elk spent time at Land Between the Lakes Recreation Area, Kentucky, USA, before their final translocation). At TNCM, translocated elk were hard released, whereas at GSMNP elk were held in pens up to 60 days before release (i.e., soft release). We hypothesized that associations formed in the source population would affect genetic structure in the future population. We predicted that matrilineal groups would stay closer together and have similar movements after translocation. We used 16 microsatellite markers to analyze genetic composition and structure of translocated elk and their offspring in the years after release. Most source elk used for translocation strongly assigned to either EINPN or EINPS (93.2%, n = 204). Evaluating the genetic structure of offspring after translocation, we found the 2 genetic groups mostly persisted ≥11 years following release. We measured the Euclidean distance between all possible pairs of telemetered female elk during each season and year and calculated the maximum distance moved from the release sites for females surviving >1 year. Mean Euclidean distances between pairwise locations of female elk were similar for each genetic cluster for each area. The mean distances for all paired locations (genetic clusters combined) in TNCM were 14.67 km ( n = 4,576 ± 13.23 [SD]) and in GSMNP were 9.30 km ( n = 1,468 ± 9.75). However, when looking at only simultaneous locations <50 m apart, the frequency of occurrence was higher ( P < 0.001) for elk with the same genetic structure (71.1%) compared with those with different structure (28.9%). The maximum distance travelled from the release site was not different for the 2 genetic groups, but EINPN females tended to travel farther. Pairwise female distances were lower in GSMNP where we used a soft release. Release methodology and social structure appear to affect movements and possibly genetic mixing after translocation. Given that restoration success can depend on maintaining genetic diversity and number of founders, our analyses suggest that within‐cluster breeding bias can result in lower genetic variability and a smaller effective population size than previously assumed.

Kentucky, Tennessee↗
USGS2018

Modeling golden eagle‐vehicle collisions to design mitigation strategies

The incidental take of golden eagles ( Aquila chrysaetos ) as a result of wind energy development requires some form of compensatory mitigation. Although several options have been proposed, only one has been formerly accepted and implemented, and the lack of options can limit the permit process for wind facilities. We developed a model to estimate numbers of golden eagles that die when struck by vehicles when eagles scavenge road kill to evaluate removal of road‐killed carcasses as an additional mitigation option. Our model estimates vehicle collision rates as a function of eagle densities, road traffic volume, and animal carcass abundance at the scale of a Wyoming, USA, county during fall‐winter, and quantifies the effects of different mitigation strategies, including estimates of uncertainty. We evaluated the plausibility of our model estimates by predicting mortality rates for each county in Wyoming and comparing overall state mortality to current estimates of mortality using derived estimates from expert judgment. We also developed a context‐dependent analysis of potential mitigation credits controlling for carcass number, traffic volume, and background carcass removals. We found that mitigation credit should be highest in areas with greatest number of carcasses. Collision mitigation is a potentially useful addition to the mitigation toolbox for wind energy development or other activities that need to offset predicted golden eagle mortality and satisfy incidental take permit requirements.

Wyoming↗
USGS2018

Demographic consequences of conservation reserve program grasslands for lesser prairie‐chickens

Knowledge of landscape and regional circumstances where conservation programs are successful on working lands in agricultural production are needed. Converting marginal croplands to grasslands using conservation programs such as the United States Department of Agriculture Conservation Reserve Program (CRP) should be beneficial for many grassland‐obligate wildlife species; however, addition of CRP grasslands may result in different population effects based on regional climate, characteristics of the surrounding landscape, or species planted or established. Within landscapes occupied by lesser prairie‐chickens (Tympanuchus pallidicinctus), CRP may provide habitat only for specific life stages and habitat selection for CRP may vary between wet and dry years. Among all study sites, we captured and fitted 280 female lesser prairie‐chickens with very high frequency (VHF)‐ and global positioning system (GPS) transmitters during the spring lekking seasons of 2013–2015 to monitor habitat selection for CRP in regions of varying climate. We also estimated vital rates and habitat selection for 148 individuals, using sites in northwest Kansas, USA. The greatest ecological services of CRP became apparent when examining habitat selection and densities. Nest densities were approximately 3 times greater in CRP grasslands than native working grasslands (i.e., grazed), demonstrating a population‐level benefit (CRP = 6.0 nests/10 km2 ± 1.29 [SE], native working grassland = 1.7 nests/10 km2 ± 0.62). However, CRP supporting high nest density did not provide brood habitat; 85% of females with broods surviving to 7 days moved their young to other cover types. Regression analyses indicated lesser prairie‐chickens were approximately 8 times more likely to use CRP when 5,000‐ha landscapes were 70% rather than 20% grassland, indicating variation in the level of ecological services provided by CRP was dependent upon composition of the larger landscape. Further, CRP grasslands were 1.7 times more likely to be used by lesser prairie‐chickens in regions receiving 40 cm compared to 70 cm of average annual precipitation and during years of greater drought intensity. Demographic and resource selection analyses revealed that establishing CRP grasslands in northwest Kansas can increase the amount nesting habitat in a region where it may have previously been limited, thereby providing refugia to sustain populations through periods of extreme drought. Nest survival, adult survival during breeding, and nonbreeding season survival did not vary between lesser prairie‐chickens that used and did not use CRP grasslands. The finite rate of population growth was also similar for birds using CRP and using only native working grasslands, suggesting that CRP provides habitat similar to that of native working grassland in this region. Overall, lesser prairie‐chickens may thrive in landscapes that are a mosaic of native working grassland, CRP grassland, with a minimal amount of cropland, particularly when nesting and brood habitat are in close proximity.

Journal of Wildlife Management↗
USGS2018

Greater sage-grouse vital rates after wildfire

Greater sage-grouse ( Centrocercus urophasianus ) have been subject to long-term and continuing declines in population and habitat since European settlement of western North America. Increased wildfire activity constitutes a primary threat to the species in western portions of their range, with documented declines in wildfire-affected populations. Following a 187,000-ha wildfire in southeastern Oregon and northern Nevada, USA, we used global positioning system (GPS) telemetry to monitor nest initiation, nest survival, nesting habitat, and adult survival of female sage-grouse during 2013 and 2014. We used known-fate models in Program MARK to estimate daily nest survival and monthly adult survival in relation to temporal patterns, physiological characteristics of females, and habitat and land-cover characteristics. We assessed habitat characteristics using geographic information system (GIS)-derived measures of post-fire habitat condition and land cover. Nest initiation rate following the fire was comparable to that observed in unaltered habitat. We observed nesting rates of 90% and 100% during 2013 and 2014, respectively, and renesting rates of 23% and 57% during the same years. Daily nest survival was consistently low in comparison to rates observed in concurrent studies in the region, for first nests during both years, and for second nests during 2013, but survival markedly increased for second nests during 2014. Sage-grouse generally did not leave the fire perimeter to nest, with 64% and 73% of nests located in the fire boundary during 2013 and 2014, respectively. Approximately 27% of nests were located in burned habitat during 2013, and 20% of nests in 2014 were located in burned habitat. Adult survival varied by month, and although patterns of monthly survival were similar between years, monthly survival rates were significantly reduced from the beginning of the study through the end of the first post-fire growing season. Our results indicate that sage-grouse continue to use fire-affected habitat in the years immediately following wildfire and sage-grouse experienced lower nest survival and adult female survival than other populations during the same period.

Oregon↗
USGS2018

Survival and cause-specific mortality of desert bighorn sheep lambs

Juvenile recruitment in desert bighorn sheep (Ovis canadensis mexicana) is highly variable, yet the mechanisms driving neonate survival are not well understood for the species. Few studies have equipped desert bighorn sheep lambs with radiocollars. As a result, definitive data on cause-specific mortality and lamb survival estimates are lacking. Our objectives were to estimate lamb survival rates and determine cause-specific mortality for desert bighorn sheep lambs during a period of mountain lion (Puma concolor) and coyote (Canis latrans) removal in southwestern New Mexico. We captured pregnant adult females each fall and fitted them with a telemetry collar and a vaginal implant transmitter to aid with neonate captures. We captured and radiocollared 12 desert bighorn sheep lambs in 2012 and 14 in 2013 within 48 hrs of parturition in the Peloncillo Mountains, New Mexico. We used the nest survival model in program MARK to estimate lamb survival to 6 months of age. Across both years there were 14 mortalities, 12 (86%) of which were due to predation. Mountain lions killed 5 lambs (2 in 2012 and 3 in 2013), coyotes killed 4 lambs (all in 2013), a gray fox (Urocyon cinereoargenteus) killed 1 lamb in 2012; 2 lambs were killed by unknown predators in 2013. Staged-based survival estimates indicated the highest mortality rates occurred in the first week post birth; 33% to 36% of all lamb mortalities occurred before 7 days of age. Lamb survival was substantially lower in 2013 (0.20 ± 0.11 [SE]) than in 2012 (0.69 ± 0.16) with the differences in survival attributed to increased coyote predation in 2013. We did not detect differences in body mass, chest girth, or neck circumference between lambs that were killed by predators and those that survived. Coyotes, mountain lions and gray fox killed lambs <8 weeks of age, but only mountain lions killed lambs > 8 weeks old. Studies that fail to capture desert bighorn lambs near parturition will likely produce negatively biased survival estimates and inaccurate appraisals of primary causes of mortality due to early mortality of lambs.

New Mexico↗
USGS2018

The black brant population is declining based on mark recapture

Annual survival and recruitment in black brant ( Branta bernicla nigricans ) have declined since the 1990s, yet aerial surveys of the global population have been stable or even increasing over the past decade. We used a combination of a Lincoln estimator based on harvest information and band recoveries, and marked‐unmarked ratios in bag checks in 1 harvest area in Mexico to estimate the number of adults in the population during 1992–2015. We produced weighted means from the 2 kinds of estimates for years in which we had data for both, with weights equal to the inverse of the variance of the individual estimates. We treated the black brant population as consisting of 2 subpopulations. One population consisted of breeding black brant on the Yukon‐Kuskokwim Delta (YKD), Alaska, USA, and the other consisted of Arctic (northern Alaska, western Canada, and eastern Russia) breeders, and nonbreeders and failed breeders from the YKD that underwent molt migration to the Arctic. For the global population estimates, we assessed potential bias due to differential marking and harvest of the 2 subpopulations, which was approximately 1%, probably because band recovery rates were similar for the 2 subpopulations. Population estimates declined from 229,980 (average for 1999–2002) to 161,504 (average for 2012–2015). Population estimates based on estimated harvest were variable but more stable in the later years of the study, when larger numbers of brant hunters were included in the sample. We suggest that the combination of Lincoln estimates and bag check data provides a reasonable and cost effective approach to monitoring the population.

Journal of Wildlife Management↗
USGS2019

Multi‐scale habitat selection of elk in response to beetle‐killed forest

Forests of the Rocky Mountains (USA and Canada) have experienced a large‐scale bark‐beetle ( Dendoctronus ponderosae ) epidemic that has led to widespread mortality of pine trees, followed by structural and compositional changes to the forest. The millions of dead trees resulting from this event likely have an effect on ecosystem processes, but currently those effects are mostly unclear. Changes to forest canopy and understory structure are likely to affect behavior and space use of large ungulates as forage abundance, thermal cover, and locomotive costs are presumably altered. We developed and tested hypotheses for how resource selection in summer of female elk ( Cervus canadensis ; n = 47; 2012–2016), the primary large mammal in our study area, was influenced by changes in canopy, understory vegetation, and downed logs in bark‐beetle affected forest in south‐central Wyoming, USA. We employed global positioning system (GPS) technology, an imagery‐derived land cover classification specifically depicting beetle‐affected forest, and on‐the‐ground forest measurements to develop resource and step selection functions. At the study area scale, elk avoided beetle‐killed forest during nearly all parts of the day and selected for intact conifer forest during the day. At the micro‐habitat scale, as canopy cover decreased in beetle‐killed areas, there was a concomitant increase in grass biomass and downed logs. Nevertheless, while in the forest, elk did not alter resource selection relative to changes in understory vegetation or downed logs. The boost in forage abundance within beetle‐killed areas was insufficient to overcome the presumed increases in energy expenditures associated with locomotion and thermoregulation in beetle‐killed forests. The bark‐beetle epidemic has altered how elk use the landscape and has resulted in a potential loss of forest habitat that elk use during the day. Our results indicate that habitat treatments (i.e., fire or harvest) that remove standing dead trees and downed logs in beetle‐killed forest would further facilitate understory growth while reducing the locomotion costs associated with foraging in beetle‐killed forest.

Wyoming, Colorado↗
USGS2019

Elk forage and risk tradeoffs during the fall archery season

During late summer and fall, elk ( Cervus canadensis ) need access to adequate nutrition to support physiological requirements for reproduction and overwinter survival. The archery hunting season often occurs during this period and can affect distributions of elk as they seek areas that minimize perceived harvest risk. Areas that confer lower harvest risk may provide relatively low‐value nutrition, resulting in a potential tradeoff between minimizing risk and accessing adequate forage. We used radio‐collar data collected from female elk during late summer and fall (Aug–Oct) and estimated resource selection models to evaluate the extent of this potential risk‐nutrition tradeoff. To evaluate if elk exposed to a greater hunting risk altered selection for forage resources, we assessed the relationship between individuals’ selection coefficients for forage and the proportion of their late‐summer‐fall home range accessible to hunters (our metric of hunting risk). Our results indicate that during the archery season, elk with higher‐risk home ranges selected more strongly for areas farther from motorized routes than elk with lower‐risk home ranges. Regardless of the level of risk, however, elk maintained or increased selection for areas with higher forage quality, suggesting that elk did not compromise access to nutritional resources during the archery season. Elk with higher‐risk home ranges were also exposed to the poorest nutrition and increased their selection for areas with higher forage quality more strongly than elk with lower‐risk home ranges during the hunting season. Elk with lower‐risk home ranges had access to the highest nutrition, which may be due to the availability of concentrated sources of high‐quality forage from irrigated agricultural areas on private lands that restricted hunter access. Resource agencies interested in encouraging elk to remain on public lands during the hunting seasons might consider closing motorized travel during the archery season to increase security on public lands, limiting hunter pressure on public lands, improving forage quality on public lands, and working with private land owners to enhance hunter accessibility and restrict elk access to high‐quality forage resources.

Montana↗
USGS2019

Understanding conservation decisions of agriculture producers

Most land in the United States (US) is privately owned and used for agriculture. To address the effect of agriculture on wildlife, conservation professionals and organizations need to understand the land use decisions made by farmers and ranchers. We developed a tool for categorizing farmers and ranchers by their conservation land use values (LUVs) to understand how those values affect their land use motivations and resultant decisions. We defined land as the whole natural environment including soil, water, plants, fish, and wildlife. We used principal axis factoring and reliability analysis to identify statements representing human-centered values and nature-centered values of farmers and ranchers. We tested the validity of the combined statements with a survey of South Dakota’s private landowners (N = 4,000, [Jan through May 2016]) resulting in the LUV scale. Crossing the average scores on the human-centered and nature-centered statements identified 4 LUV types: humans first (20%), nature first (29%), interconnected (29%), and disconnected (22%). Analysis of variance and chi-square tests showed that, compared to the humans first and disconnected LUV types, the nature first and interconnected LUV types reported significantly greater importance of the following: most categories of types of wildlife in their land use decisions; conservation-related motivations for participating in a United States Farm Bill Conservation Program; conservation-related motivations for land use decisions; and participation in conservation-related behaviors. Conservation professionals and organizations may use the LUV scale to better understand landowners’ land use decisions to evaluate and inform conservation policy, programs, messaging, and improve conservation outcomes.

Journal of Wildlife Management↗
USGS2019

Survival and movements of head‐started Mojave desert tortoises

Head‐starting is a conservation strategy in which young animals are protected in captivity temporarily before their release into the wild at a larger size, when their survival is presumably increased. The Mojave desert tortoise ( Gopherus agassizii ) is in decline, and head‐starting has been identified as one of several conservation measures to assist in recovery. To evaluate the efficacy of indoor head‐starting, we released and radio‐tracked 68 juvenile tortoises from a 2015 cohort in the Mojave National Preserve, California, USA. We released 20 tortoises at hatching (control) in September 2015, and reared 28 indoors and 20 outdoors in predator‐proof enclosures for 7 months before releasing them in April 2016. We monitored tortoises at least weekly after release until 27 October 2016, and documented survivorship, movement, and surface activity. We estimated survivorship by treatment and evaluated effects of treatment, proximity to a raven ( Corvus corax ) nest (predator) coincidentally established after release, distance moved between monitoring events, surface activity, and release size on individual fate in a generalized linear model. Although indoor head‐start tortoises reached the size of 5–6‐year‐old wild tortoises by release at 7 months of age, survival did not differ significantly among the 3 treatment groups. Combined annual survival was 0.44 (95% CI = 0.34–0.58). Tortoises that were closer to an active raven nest were significantly more likely to die, as were those seen more often outside their burrows and active aboveground. Predicted estimates for short‐term probability of survival approached 1.0 as distance from a raven nest exceeded approximately 1.6 km. Rearing treatment, movement distance, and body size were not significant predictors of fate over the 1‐year monitoring period. Head‐started tortoises released ≥1.6 km from areas of raven activity will likely have higher short‐term survival. Population recovery through head‐starting alone is unlikely to be successful if systemic ecosystem‐level issues, such as habitat degradation and conditions that promote human‐subsidized predators, are not ameliorated. © 2019 The Wildlife Society.

California↗
USGS2019

Condition bias of decoy-harvested light geese during the conservation order

Evidence that decoy harvest techniques primarily remove individuals of poorer body condition is well established in short-lived duck species; however, there is limited support for condition bias in longer-lived waterfowl species, such as geese, where decoy harvest is considered primarily additive because of their high natural survival rates. We evaluated support for the harvest condition bias hypothesis of 2 long-lived waterfowl species, the lesser snow goose ( Anser caerulescens caerulescens ) and Ross's goose ( Anser rossii ). We used proximate analysis to quantify lipid and protein content of lesser snow and Ross's geese collected during the Light Goose Conservation Order (LGCO) in 2015 and 2016 during spring migration in Arkansas, Missouri, Nebraska, and South Dakota, USA. In each state, LGCO participants collected birds using traditional decoy techniques and we collected birds from the general population using jump-shooting tactics. Total body lipid content in both lesser snow and Ross's geese varied with age, region of harvest, and harvest type (decoy or jump-shooting). On average, adult lesser snow and Ross's geese harvested over decoys had 60 g and 41 g, respectively, fewer lipids than conspecifics collected using jump-shooting. We observed lower lipid reserves in decoy-shot geese in all 4 states sampled despite general gains in lipid reserves as migration chronology progressed. Our data support that the harvest condition bias extends to longer-lived waterfowl species and during a life-history event (spring migration) in which harvest is not normally observed. In the case of overabundant light geese, the disproportionate harvest of poorer-conditioned lesser snow and Ross's geese may serve as an additional challenge against any realized effects of harvest to reduce the population, in addition to extremely low harvest rates.

Arkansas, Missouri, Nebraska, South Dakota↗
USGS2019

Public access for pheasant hunters: Understanding an emerging need

Ring-necked pheasant ( Phasianus colchicus ; i.e., pheasant) hunting participation is declining across North America, reflecting a larger downward trend in American hunting participation and threatening benefits to grassland conservation and rural economies. To stabilize and expand the pheasant hunting population, we must first identify factors that influence pheasant hunter participation. We used an extensive in-person hunter survey to test the hypothesis that hunter demographics interact with social-ecological traits of hunting locations to affect hunter decisions, outcomes, and perceptions. We built a series of Bayesian mixed effects models to parse variation in demographics, perceptions, and hunt outcomes of pheasant hunters interviewed at public access hunting sites across 3 regions in Nebraska, USA, that varied in pheasant abundance and proximity to urban population centers. Among pheasant hunters in Nebraska, access to private lands was negatively related to the human population density of a pheasant hunter's home ZIP code and the distance a hunter had traveled to reach a hunting location. Pheasant hunters interviewed closer to metropolitan areas tended to be more urban and travel shorter distances, and their parties were more likely to include youth but less likely to include dogs. Hunter satisfaction was positively associated with seeing and harvesting pheasants and hunting with youth. Whereas youth participation and the number of pheasants seen varied by study region, hunter satisfaction did not differ across regions, suggesting that hunters may calibrate their expectations and build their parties based on where they plan to hunt. The variation in hunter demographics across hunting locations and disconnects between social and ecological correlates of hunter satisfaction suggests that diverse pheasant hunting constituencies will be best served by diverse pheasant hunting opportunities.

Nebraska↗
USGS2019

Seismic survey design and impacts to maternal polar bear dens

Large‐scale industrial activities can have negative effects on wildlife populations. Some of these effects, however, could be reduced with effective planning prior to development. The Coastal Plain of the Arctic National Wildlife Refuge, in northeastern Alaska, USA, is an important maternal denning area for polar bears ( Ursus maritimus ). Recent legislation has opened the area for potential oil and gas development. As a result, there is interest in conducting winter seismic surveys across the area that could disturb denning female polar bears and lead to decreased cub survival. We sought to demonstrate how different seismic survey designs, with and without aerial den detection surveys, could affect the level of potential effect on denning polar bears during spring (Feb–Apr). We developed 5 hypothetical seismic survey designs for a portion of the Coastal Plain ranging from no spatial or temporal restrictions on activities to explicit consideration of when and where operations can occur. We evaluated how many dens might be disturbed by seismic surveys and the average distance activity came within simulated polar bear dens. Survey design had a large effect on the estimated number of dens that could be disturbed; the scenario with the highest spatial and temporal specificity reduced the number of dens disturbed by >90% compared to the scenario with no restrictions on when and where activity could occur. The use of an aerial den detection survey prior to seismic activity further reduced the number of dens disturbed by 68% across all scenarios. The scenario with the highest spatial and temporal specificity always had the lowest level of disturbance for all scenarios with and without the aerial survey included. Our study suggests that large reductions in the probability of disturbance can occur through careful planning on the timing and distribution of proposed activities even when surveys are planned in areas with a high density of polar bear dens.

Alaska↗
USGS2019

Caribou use of habitat near energy development in Arctic Alaska

Increasing demands for energy have generated interest in expanding oil and gas production on the North Slope of Alaska, raising questions about the resilience of barren-ground caribou populations to new development. Although the amount of habitat lost directly to energy development in the Arctic will likely be relatively small, there are significant concerns about habitat that may be indirectly impacted due to caribou avoidance behaviors. Behavioral responses to energy development for wildlife have been well-documented, but such responses are often assumed to dissipate over time, despite scant information on the ability of animals to habituate. To understand the long-term effects of energy development on barren-ground caribou we investigated the behavior of the Central Arctic Herd in northern Alaska, which has been exposed to oil development on its summer range for approximately 40 years. Using recent (2015-2017) location data from GPS collared females, we conducted a zone of influence analysis to assess whether caribou reduced their use of habitat near energy development, and if so, the distance the effects attenuated. We conducted this analysis for the calving, post-calving and mosquito harassment periods when caribou exhibit distinct resource selection patterns, and contrasted our results to past research that investigated the responses of the Central Arctic Caribou Herd immediately following the construction of the oil fields. Despite the long-term presence of energy development within the Central Arctic Herd summer range, we found that female caribou exhibited avoidance responses to infrastructure during all time periods, although the effects waned across the summer. Caribou reduced their use of habitat within 5 km of development during the calving period, within 2 km during the post-calving period, and within 1 km during the mosquito harassment period, areas which were predicted to overlap 12%, 15% and 17% of important calving, post-calving, and mosquito habitat areas, respectively. During the calving period, the indirect effects we observed were similar to those observed in past research, whereas during the post-calving and mosquito periods, we detected avoidance responses which had not been previously reported. These findings corroborate a growing body of evidence suggesting that habituation to industrial development in Arctic caribou is likely to be weak or absent, and emphasizes the value of minimizing the footprint of infrastructure within important seasonal habitat areas to reduce behavioral impacts to barren-ground caribou.

Alaska↗
USGS2020

Transmitter effects on growth and survival of Forster’s tern chicks

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.

California↗
USGS2020

Erratum: Seismic survey design and effects on maternal polar bear dens

Since the publication of this manuscript, readers have noted two errors in our analysis. The first is that we inadvertently stated that the forward looking infrared (FLIR) survey simulations only represented a single FLIR survey. In reality, the analysis assumed two independent FLIR surveys occurred prior to simulated seismic activity occurring. To evaluate the results for a single FLIR survey, readers can simply modify line 41 of the R code ‘jwmg21800-sup-0006-missed.dens.funcAnalysis.R’ to read ‘p2=0’ and re-run the analysis. The second error relates to our calculation of the expected number of dens in the 1002 Area.

Journal of Wildlife Management↗