Long-term fisheries datasets are particularly rare in Arctic environments and are essential to understanding the variability in harvest rates. We analyzed 30 years of harvest monitoring data and compared results to fish monitoring data from nearshore waters of Prudhoe Bay, Alaska, to determine the importance of age-0 recruitment and intra-annual factors on subsequent harvests of Arctic cisco in the Colville River delta (CRD), Alaska. While age-0 recruitment to Prudhoe Bay was positively associated with annual harvest success in the CRD, wind and salinity patterns and subsistence fishing location and timing also contributed significantly in explaining adult harvest variability. Harvest rates were highest closest to the river mouth and early in the season. Harvest rates increased with increasing salinity up to 25 ppt, then declined. As the climate changes in the region, we may see shifts in nearshore ocean and river conditions which will impact recruitment and fishing activity. These longterm monitoring efforts will continue to inform sustainable fisheries management in the face of a rapidly changing climate, and with ongoing infrastructure development in the region.

In the Pacific Arctic, the Chukchi Sea has been warming for decades, and exhibited an exceptionally warm period from 2015 to 2021. We examined changes in seabird distribution and abundance in the Chukchi Sea, and their relationships to environmental and prey conditions between 2 contrasting periods. We sampled systematically placed stations in late summer during 2 years before (2012, 2013) and 2 years during the warm period (2017, 2019; characterized by multiple marine heatwaves). Ship-based bird counts were used to model at-sea density of 5 seabird foraging guilds relative to oceanographic (water temperature, salinity, chlorophyll) and prey (large copepods, euphausiids, 3 forage fish taxa) variables. Relative to cool years, heatwave years were characterized by warmer, saltier waters, low abundance of large copepods and euphausiids, and elevated fish abundance, including an unprecedented abundance of age-0 walleye pollock Gadus chalcogrammus . Seabird species richness was higher during heatwave years but diversity was lower, driven by an influx of shearwaters. The best models for surface feeding and diving piscivores and diving planktivores included oceanographic and prey variables, plus a heatwave interaction term, indicating that responses to variables differed between cool and heatwave periods, with greatest disparity exhibited by diving planktivores. Models for surface planktivores were inconclusive, whereas shearwater distribution was associated with geographic variables (latitude, distance offshore), with relationships differing during cool and heatwave periods. We propose a conceptual model of how a prolonged period of marine heatwaves may affect the offshore seabird community via changes in prey species composition and distribution.

Oil and gas exploration and development is expanding across the Arctic Coastal Plain (ACP) of Alaska, USA. To examine the effects of industrial development on greater white-fronted geese (Anser albifrons), we monitored nests and nesting behavior within a 4-km2 study area within 4 km of gravel roads and pads during pre-development, construction, and operation activities at a new oil development in the National Petroleum Reserve-Alaska in 2013-2019. We examined distribution, incubation constancy, and nest survival in relation to distance to gravel roads or pads, year and status of development, presence of an ice road the previous winter, and land cover type. Nest density increased throughout the study period, which was consistent with surveys of this species in other regions of the ACP. There was no direct evidence that oil extraction infrastructure and the associated human activity adversely influenced the abundance, distribution, or daily nest survival of greater white-fronted goose nests. Geese avoided nesting in the alignments of ice roads from the previous winter, and land cover type influenced their nest distribution. Nest age and incubation constancy were important predictors of daily nest survival. The incubation constancy of successful nesters (98.5 +/- 0.1% [SE]) was significantly greater than for failed nesters (94.7 +/- 0.6%) for all years combined and tended to be greater during the pre-construction and construction years of 2014 and 2015, compared to when oilfield operations began in 2017 and 2019. Greater-white fronted geese appear to be tolerant of some levels of industrial activities and the presence of gravel roads did not have a significant effect on nest distribution, incubation constancy, or nest survival. We recommend, however, that indirect effects from ice roads should be explicitly considered in impact assessments because white-fronted geese avoid nesting in the footprints of the previous winter's ice roads and pads. We monitored nests and nesting behavior of greater white-fronted geese (Anser albifrons) within 4 km of gravel roads and pads during pre-development, construction, and operation activities at a new oil development in the National Petroleum Reserve-Alaska, 2013-2019, to examine the effects of industrial development. We found no evidence that oil extraction infrastructure and the associated human activity adversely influenced the abundance, distribution, or daily nest survival of greater white-fronted goose nests; however, we suggest that indirect effects from ice roads should be explicitly considered in impact assessments because white-fronted geese avoid nesting in the footprints of the previous winter's ice roads and pads. image

AbstractA fundamental assumption of many ecological studies is that researchers are studying a representative sample of the population of interest. However, fish and wildlife studies, including many telemetry studies, often rely upon data from marked individuals that are sampled opportunistically rather than randomly and may provide little information on unmarked individuals. Data that are unrepresentative at the time of marking may need to be censored until marked animal distributions are representative of the population. In the absence of additional data on unmarked individuals, evaluating the representativeness of newly marked individuals within a population of interest can be difficult. If previously marked individuals can be assumed to be spatially representative of the population, comparing the spatial distributions of different cohorts of marked individuals can provide an alternative means to assess the representativeness of newly marked animals. We used simulations to assess the effectiveness of a randomization test that compared the spatial distribution between newly marked and previously marked individuals as an alternative to recapture‐based methods for evaluating mixing of newly marked individuals with the population of interest and compared different metrics of spatial overlap. We then tested this randomization test on radio‐collared caribou (Rangifer tarandus) from 2 different herds with very different marking strategies. We found that, based on simulation results, kernel‐based metrics outperformed cluster analysis metrics and that Bhattacharyya's Affinity (BA) index of kernel overlap was a good metric to identify differences in spatial distribution between marked cohorts. The time it took for newly marked caribou to become mixed with previously marked animals was primarily related to the timing of marking in relation to seasonal movement patterns (periods of aggregation and dispersion, and seasonal differences in spatial fidelity) and the spatial distribution of marking relative to seasonal distribution. In some cases, mixing did not occur until calving aggregations formed in early June. We recommend that researchers evaluate the assumption that marked individuals are spatially representative of their study population and carefully assess sampling time and location of their marking program to increase the likelihood that marked individuals represent the population of interest.

The Coastal Plain of northern Alaska is an important nesting area for a variety of avian species, where the productivity of ground-nesting species can be strongly influenced by nest predators. Recently, the density of red foxes (Vulpes vulpes) has increased in many areas of the Arctic, likely because of climate warming as well as the availability of anthropogenic food sources during winter. In areas where they occur sympatrically, red foxes can outcompete and kill the smaller Arctic fox (Vulpes lagopus). There is considerable dietary overlap between the fox species, but if the red fox is a more successful nest predator, this ongoing shift in canid species could have important implications for ground-nesting species like the Yellow-billed Loon (Gavia adamsii). We examined time-lapse photographs from 186 nests of Yellow-billed Loons in northern Alaska during the years 2008 – 15 and 2019 for the presence of foxes and other nest predators and quantified nest predation by species. Although both Arctic and red foxes were photographed near nests, we found that all successful predation of Yellow-billed Loon nests by foxes was attributable to red foxes, which were the second most frequent predator of Yellow-billed Loon nests after Glaucous Gulls (Larus hyperboreus). Arctic foxes photographed at Yellow-billed Loon nests were unsuccessful at displacing incubating loons. Several data sources suggest that the prevalence of red foxes has increased in Arctic Alaska over the last three decades, a change that is likely to have negative impacts on the nesting success of Yellow-billed Loons and possibly other large waterbirds.

Reductions in nest attendance can increase predation risk and, therefore, reduce nesting success of ground-nesting birds. We recorded the incubation behavior, nest predators, and nesting success of yellow-billed loons (Gavia adamsii) at 2 adjacent study areas with differing amounts of industrial activity on the Arctic Coastal Plain of Alaska, USA, during 2008-2015 and 2019. Successful pairs had higher incubation constancies (97.3 +/- 1.7% [SE], n = 96 nests) than failed pairs (91.6 +/- 3.1%, n = 79 nests) and took fewer and shorter recesses than failed pairs. The intrusion of conspecifics into territories significantly lowered the daily incubation constancy of nesting pairs. Daily incubation constancy also declined as the daily maximum temperature increased, especially during periods with little wind. Both conditions contributed to nest failure. Predation was the primary cause of nest failure, with glaucous gulls (Larus hyperboreus) and parasitic jaegers (Stercorarius parasiticus) accounting for 41% of the nest failures. These avian predators took advantage of unattended nests, underscoring the consequence of disrupting incubation behavior. In both study areas, nest survival decreased as recess frequency increased. In the Colville Delta study area, loons with territories composed of separate nesting and brood-rearing lakes had lower nest survival than loons that used 1 lake for both activities. In the National Petroleum Reserve-Alaska study area (NPR-A), loons nesting on shorelines and peninsulas had lower nest survival than those nesting on islands and nest survival decreased as the proportion of days with intruders increased. The overall probability of a nest hatching >= 1 egg in the Colville Delta study area was 0.40 (95% CI = 0.26-0.54) and was 0.68 (95% CI = 0.40-0.91) in the NPR-A study area. Our results demonstrate the importance of nest attendance by yellow-billed loons in warding off nest predators on the Arctic Coastal Plain of Alaska and provide a mechanism that shows how a warming Arctic climate could negatively affect yellow-billed loons.

Caribou are the most abundant large terrestrial mammals in Arctic Alaska, providing important cultural and subsistence resource values for local communities. As oil and gas development expands across the Arctic Coastal Plain of northern Alaska, understanding the potential impacts on caribou and improving associated mitigation measures are a crucial focus of applied research. One consistently observed impact in northern Alaska is displacement of maternal caribou within 2 – 5 km of active oilfield roads and gravel pads for a period of 2 – 3 weeks during and immediately after calving. A potential mitigation measure to address calving displacement is convoying of traffic to reduce traffic frequency and vehicle-related disturbance on roads in calving areas. We conducted frequent road and aerial surveys of caribou near two oilfield roads, one with convoying and one without, over a 3-year period during the precalving, calving, and postcalving periods to evaluate the effectiveness of traffic convoying. Road surveys indicated that caribou closer to the roads and groups with calves exhibited more frequent and stronger behavioural reactions in response to traffic, and that moderate or strong reactions to traffic, such as standing up and walking or running away, were more frequent near the road with convoying than near the road with unlimited traffic. Aerial survey results indicated some avoidance of areas up to at least 2 km from the road with convoying and 4 km from the road without convoying by caribou groups with calves. This relationship was present even after adjusting for other factors affecting distribution. This avoidance of roads by maternal caribou was limited to the calving period and was not evident during the precalving or postcalving periods. In addition, an inactive elevated terrestrial drilling platform was present on the calving grounds during one year, but we found no evidence of caribou avoidance of that structure during calving at our scale of analysis.

We used data collected during a variety of research cruises in the northeastern Chukchi Sea and contributed to the Distributed Biological Observatory to explore the influence of the seasonal change in water masses on the development of the seabird community during the summer. Surveys that included seabird observations and hydrographic sampling were conducted from Alaska's northwestern coast to ~220 km offshore during 2008-2018. Species composition varied geographically, shifting from a nearshore community that included short-tailed shearwaters, loons, and seaducks to an offshore community dominated by crested auklets. Crested auklets were remarkably consistent in their occupation of Hanna Shoal among years and remained in the area throughout the summer. Short-tailed shearwaters exhibited the greatest seasonal and interannual variation in abundance and distribution of the 35 species recorded. They were concentrated south of 71°N and within 50 km of shore in August and tended to spread throughout the region in September. Surface-feeding species like gulls, fulmars, and phalaropes were 1-2 orders of magnitude less abundant and had wider distributions than birds that feed by diving. Including information about hydrography improved the fit of models of seabird density. Seabirds, especially those that breed in the Bering Sea, generally were more abundant in areas dominated by moderate-salinity Bering Sea Water than nearshore in low-salinity Alaska Coastal Water. The distribution of seabirds across the northeastern Chukchi Sea reflected the heterogeneity of oceanic habitats and prey availability over the shallow shelf. Our results will inform efforts to develop ecosystem models that incorporate oceanographic conditions to predict ongoing consequences of climate change.

Many animals migrate to take advantage of temporal and spatial variability in resources. These benefits are offset with costs like increased energetic expenditure and travel through unfamiliar areas. Differences in the cost-benefit ratio for individuals may lead to partial migration with one portion of a population migrating while another does not. We investigated migration dynamics and winter site fidelity for a long-distance partial migrant, barren ground caribou (Rangifer tarandus granti) of the Teshekpuk Caribou Herd in northern Alaska. We used GPS telemetry for 76 female caribou over 164 annual movement trajectories to identify timing and location of migration and winter use, proportion of migrants, and fidelity to different herd wintering areas. We found within-individual variation in movement behavior and wintering area use by the Teshekpuk Caribou Herd, adding caribou to the growing list of ungulates that can exhibit migratory plasticity. Using a first passage time-net squared displacement approach, we classified 78.7% of annual movement paths as migration, 11.6% as residency, and 9.8% as another strategy. Timing and distance of migration varied by season and wintering area. Duration of migration was longer for fall migration than for spring, which may relate to the latter featuring more directed movement. Caribou utilized four wintering areas, with multiple areas used each year. This variation occurred not just among different individuals, but state sequence analyses indicated low fidelity of individuals to wintering areas among years. Variability in movement behavior can have fitness consequences. As caribou face the pressures of a rapidly warming Arctic and ongoing human development and activities, further research is needed to investigate what factors influence this diversity of behaviors in Alaska and across the circumpolar Arctic.

Background Caribou and reindeer across the Arctic spend more than two thirds of their lives moving in snow. Yet snow-specific mechanisms driving their winter ecology and potentially influencing herd health and movement patterns are not well known. Integrative research coupling snow and wildlife sciences using observations, models, and wildlife tracking technologies can help fill this knowledge void. Methods Here, we quantified the effects of snow depth on caribou winter range selection and movement. We used location data of Central Arctic Herd (CAH) caribou in Arctic Alaska collected from 2014 to 2020 and spatially distributed and temporally evolving snow depth data produced by SnowModel. These landscape-scale (90 m), daily snow depth data reproduced the observed spatial snow-depth variability across typical areal extents occupied by a wintering caribou during a 24-h period. Results We found that fall snow depths encountered by the herd north of the Brooks Range exerted a strong influence on selection of two distinct winter range locations. In winters with relatively shallow fall snow depth (2016/17, 2018/19, and 2019/20), the majority of the CAH wintered on the tundra north of the Brooks Range mountains. In contrast, during the winters with relatively deep fall snow depth (2014/15, 2015/16, and 2017/18), the majority of the CAH caribou wintered in the mountainous boreal forest south of the Brooks Range. Long-term (19 winters; 2001–2020) monitoring of CAH caribou winter distributions confirmed this relationship. Additionally, snow depth affected movement and selection differently within these two habitats: in the mountainous boreal forest, caribou avoided areas with deeper snow, but when on the tundra, snow depth did not trigger significant deep-snow avoidance. In both wintering habitats, CAH caribou selected areas with higher lichen abundance, and they moved significantly slower when encountering deeper snow. Conclusions In general, our findings indicate that regional-scale selection of winter range is influenced by snow depth at or prior to fall migration. During winter, daily decision-making within the winter range is driven largely by snow depth. This integrative approach of coupling snow and wildlife observations with snow-evolution and caribou-movement modeling to quantify the multi-facetted effects of snow on wildlife ecology is applicable to caribou and reindeer herds throughout the Arctic.

ABSTRACT Barren ground caribou ( Rangifer tarandus granti ) are distributed in herds that seasonally use specific geographic regions within an annual range, with varying levels of fidelity during different periods (e.g., calving, insect relief, wintering). As a result, caribou management is generally tailored to individual herds that often range across administrative boundaries. Herd ranges can shift over time, seasonal ranges of adjacent herds often overlap, herds merge, and there is often little genetic differentiation among adjacent herds. If substantial herd interchange occurs, it would have important management implications by influencing estimates of herd size, herd composition, and harvest rates. We compiled satellite telemetry data from 2003–2015 for 4 large arctic caribou herds to quantify herd interchange rates. We calculated a metric of herd interchange based on the relationship of caribou locations to typical weekly herd ranges (all yrs combined) and the distance to other radio‐collared caribou from each of the 4 herds (yr specific). Although herd membership cannot always be clearly defined based on location, this metric provides an objective measure of the strength of evidence of herd membership that can be used to make comparisons among herds and time periods. We also calculated herd overlap and quantified how it varied throughout the year. Herd interchange was rare in the 2 larger herds, generally occurring when caribou overwintered with an adjacent herd, whereas herd interchange from the 2 smaller herds was more frequent and could last longer than a year. Although sample sizes were limited, there were no clear patterns in herd interchange with year or annual herd size. The 2 smaller herds had large seasonal overlap with adjacent herds, suggesting that herd interchange may be related to spatiotemporal herd overlap and relative herd size. Our results can help managers understand herd interchange and overlap to make management decisions, interpret research results, and develop more accurate population models. © 2020 The Authors. The Journal of Wildlife Management published by Wiley Periodicals LLC on behalf of The Wildlife Society.

ABSTRACTAs industrial development increases in the range of barren‐ground caribou (Rangifer tarandus granti) across the warming Arctic, the need to understand the responses of caribou to development and to assess the effectiveness of mitigation measures increase accordingly. The Central Arctic Herd (CAH) of caribou ranges across northern Alaska, USA, and the herd's summer range includes the Prudhoe Bay and Kuparuk oilfields, where the herd has been exposed to oil development for >4 decades. We used location data from global positioning system (GPS) radio‐collars deployed on female CAH caribou for 106 collar‐years, recording locations every 2 hours during 2008–2019, to examine caribou distribution and movements during 7 different seasons of the year in relation to infrastructure in the Kuparuk oilfield, which is characterized by more design improvements and mitigation measures than the older Prudhoe Bay oilfield. We examined movement metrics in terms of distance to gravel infrastructure (roads and pads) and time before and after movements across infrastructure (crossings). We also employed integrated step‐selection analysis to compare caribou movements with random movements. Caribou distribution was influenced by insect activity, distance to coast, landcover, and terrain ruggedness, and we found large seasonal differences in caribou responses to infrastructure. Consistent with previous research findings, avoidance of areas near roads and pads was strongest during the calving season and some caribou used roads and pads as insect‐relief habitat when oestrid flies (warble fly [Hypoderma tarandi] and nose bot fly [Cephenemyia trompe]) were active. Caribou moved through the Kuparuk oilfield repeatedly during summer, averaging >2 road or pad crossings a day when harassment by mosquitoes (Aedes [Ochlerotatus] spp.) and oestrid flies were the predominant factors influencing caribou movements. Caribou moved faster while crossing roads and pads but showed little pattern in speed or turn angle with distance to roads and pads. These results demonstrate that the effects of petroleum development on a caribou herd with long‐term exposure to industrial activity vary widely by season. Maternal caribou avoid active roads and pads during calving, but the incorporation of appropriate mitigation measures in oilfield design allows caribou to move through the Kuparuk oilfield during other snow‐free seasons. © 2020 The Authors. The Journal of Wildlife Management published by Wiley Periodicals LLC on behalf of The Wildlife Society.

ABSTRACT Less than 4,000 yellow‐billed loons ( Gavia adamsii ) breed in remote and disjunct locations in northern Alaska, USA. Over 75% of the United States population of yellow‐billed loons nests in the National Petroleum Reserve–Alaska (NPRA), where impending oil and gas development will intersect their breeding range. We investigated the relationship of recent oilfield development to occupancy of yellow‐billed loon territories by breeding pairs (indicated by active nests) and broods using 14 years of aerial surveys on the Colville River delta. We also evaluated the survey requirements prescribed by the Bureau of Land Management (BLM) for NPRA. We began aerial surveys for yellow‐billed loons in 1993, prior to construction of the Alpine oilfield in 1998, and followed territories through 2008, after construction of 2 additional satellite drill sites. We used records from 37 breeding territories on 36 lakes in model selection analyses to examine how habitat and disturbance factors (proximity to facilities and construction time period) influenced occupancy by breeding pairs and broods. Annually, 13 ± 2.5 (SE)% ( n = 14 yr) of broods ( n = 19) moved from nesting lakes to adjacent brood‐rearing lakes, and the remainder stayed in nesting lakes ( n = 128). Lakes used for nesting and brood‐rearing were almost 25 times larger ( = 95.9 ± 25 ha, n = 23 lakes) than nesting lakes from which broods left ( = 4.0 ± 1.1 ha, n = 7 lakes, P < 0.001). Thirty‐eight percent of territories ( n = 14 territories) were on lakes shared by >1 breeding pair. Lake type (deep open lakes with islands or polygonized margins, deep open lakes without islands or polygonized margins, and tapped lakes with high‐water connections) was the most influential covariate on occupancy by breeding pairs, and lake area was most influential on occupancy by broods. Time period and distance to facilities (as discrete zones at 1.6 km and 3.2 km and as linear distance) were factors in the highest‐ranked models for 5 of the 6 model sets that included disturbance parameters. Interaction terms for time period and distance to oilfield facilities were factors in 3 of 6 model sets. The pattern of occupancy of breeding territories, however, was not consistent with disturbance‐related effects. Occupancy of territories by breeding pairs was lower in the pre‐development period (lowest human activity) than in the latest development period (highest human activity) and higher in the zones near oilfield facilities than far from facilities. Occupancy of territories by broods was highest in the latest development period and similarly high in zones near and far from facilities. Application of BLM minimum survey requirements (3 yr with 2 surveys/yr) to the initial 3 years of surveys in this study resulted in detecting 81% of the known territories on the Colville River delta. The BLM restrictions on development were judged conservative in maintaining breeding territories around oilfield developments. Our results did not demonstrate displacement of nests or broods from long‐standing territories by oil development. Our findings suggest that territory occupancy by breeding pairs and broods of yellow‐billed loons on the Colville River delta was resilient to levels of human activity at recently constructed oilfield facilities. © 2018 The Authors. Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.

With industrial development expanding in the Arctic, there is increasing interest in quantifying the impacts of development projects on barren ground caribou (Rangifer tarandus granti). The primary data source to assess caribou distribution and predict impacts in remote areas of Alaska has shifted in recent decades from aerial survey data to telemetry data, but these techniques have different strengths and weaknesses. The ranges of two caribou herds, the Western Arctic Herd and the Teshekpuk Herd, overlap in northwest Alaska between Wainwright and Atqasuk, Alaska. Based on long-term telemetry data sets, this region was thought to be outside of the core calving ranges of both herds. Calving has long been reported to occur in this general area, but early reports assumed caribou were from the Western Arctic Herd and only one systematic aerial survey of caribou density and distribution during calving has been conducted in this area in recent decades. Following interest in industrial development in this area, we conducted aerial strip-transect surveys during early to mid-June 2013–2015 to directly assess the density and distribution of caribou in the area and we used existing telemetry data to compare our results to the seasonal distribution of both herds. Total caribou densities varied between 0.36 and 1.06 caribou/km² among years, and calf densities varied 0.04 and 0.25 calves/km² among years. Contrary to assumptions by early researchers in the area, telemetry data indicated that caribou in this area during early to mid-June were from the Teshekpuk Herd. The use of telemetry data alone underestimated the importance of this area for calving, but the combination of aerial surveys and telemetry data provided complementary information on caribou use of this area showing the importance of collecting the appropriate types of data for assessing potential impacts of development on caribou.

During migration, Common and King Eiders (Somateria mollissima and S. spectabilis) cross the Beaufort and Chukchi Seas of Arctic Alaska. Because they may become attracted to lights, eiders are susceptible to collision with structures, including offshore oil facilities. We used ornithological radar in 2001 – 04 to characterize the behavior of eiders migrating past Northstar Island, an oil-production island near Prudhoe Bay, Alaska, and to assess the effects of a hazing-light system on migrating eiders. “Eider” radar targets exhibited pulsed, irregular periods of movement; movement rates were higher when sea ice was present, without precipitation, and during tailwinds and crosswinds but were not affected by lights. Velocities (ground speeds) were higher when ice was present and with strong tailwinds. They were lower at night when the lights were on, but higher during the day when the lights were on. Radar targets exhibited little variation in flight behavior as they passed the island; the proportion of non-directional behavior was larger when ice was present, with tailwinds, with weak winds, and near the full moon when it was not visible. Lights had no effect on flight behavior. Birds tended to exhibit more course changes as they approached the island, greater angular changes when they changed course, and larger net increases in passing distance as a result of those course changes when the lights were on; however, none of these differences were statistically significant. Overall, the hazing lights at Northstar did not disrupt the birds’ migratory movements but resulted in increased avoidance of the island.

A small colony of nesting Lesser Snow Geese (Chen caerulescens caerulescens) was discovered on the Ikpikpuk River delta in 1992. The number of nesting pairs averaged 35 (Range = 0-60) from 1992 to 1998, then increased dramatically from 176 in 1999 to 12,373 in 2015, for a lambda of 1.40 (SE = 0.138). Concomitant with this dramatic population increase, the geographic extent of the colony expanded annually from three small islands in the northwestern portion of the delta during 1992-1999 to all vegetated deltaic islands in 2001 and farther inland on the mainland from 2006 onward. When colony growth was most rapid (2001-2008), nesting success averaged 79% (Range = 48-97%). Low nesting success during 2009-2014 (< 50% in all years except one), primarily caused by brown bears (Ursus arctos), was followed in 2015 by 96.6% success. In 2015, 22,009 adults (in both brood-rearing and adult-only flocks) were accompanied by more than 25,000 goslings in July and August. These numbers represent a remarkable increase in the abundance of Snow Geese west of the Colville River, where only 15 years previously fewer than 500 birds nested. Both immigration and high productivity probably have contributed to colony growth, although the relative importance of effects of the two factors in this growth has not been determined. Further analyses may provide insights into population relationships and the management implications of rapid local and regional growth of Snow Goose populations in northern Alaska.

We studied movement rates and the general flight behavior of bird flocks seen on radar and recorded visually at Northstar Island, Arctic Alaska, from 13 to 27 September 2002. Most of this period (13-19 and 21-27 September) had no gas-flaring events, but a major gas-flaring event occurred on the night of 20 September. Movement rates of targets on radar and of bird flocks recorded visually in the first similar to 50%-60% of the night were much lower during the non-flaring period than during the night of flaring, whereas rates in the last similar to 40%-50% of the night were similar in all periods. The general flight behavior of birds also differed significantly, with higher percentages of both radar targets and bird flocks exhibiting straight-line (directional) flight behaviors during the non-flaring periods and higher percentages of radar targets and bird flocks exhibiting non-straight-line (erratic and circling) flight behaviors during the gas-flaring period. During the night of gas flaring, the bright illumination appeared to have an effect only after sunset, when flocks of birds circled the island after being drawn in from what appeared to be a substantial distance from the island. On both radar and visual sampling, the number of bird flocks approaching the island declined over the evening, and the attractiveness of the light from flaring appeared to decline. The visibility of the moon appeared to have little effect on the behavior of birds. Because illumination from extensive gas-flaring is such a strong attractant to migrating birds and because most bird flocks fly at low altitudes over the water, flaring booms on coastal and offshore oil-production platforms in Arctic Alaska should be positioned higher than the mean flight altitudes of migrating birds to reduce the chances of incineration.

Wildlife Society BulletinVolume 38, Issue 1 p. fm ii-fm iii ContentsFree Access Online Contents: Volume 38, Number 1 First published: 22 March 2014 https://doi.org/10.1002/wsb.333AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume38, Issue1March 2014Pages fm ii-fm iii RelatedInformation

AbstractThere is a trade‐off between the frequency of telemetry locations (fix interval) and battery life when using Global Positioning System (GPS) collars. In general, decreasing the fix interval lowers the effective battery life of the collar. However, the strong relationship between fix interval and movement metrics is often underappreciated. Mean movement rates, maximum movement rates, total distance estimates, and some screening algorithms change dramatically with different fix intervals, particularly for highly mobile animals such as caribou (Rangifer tarandus), and must be interpreted in relation to the fix interval used to collect the data. We used a multi‐year, high‐resolution data set from GPS collars with 2‐hr fix intervals deployed on female caribou of the Teshekpuk Caribou Herd, Alaska, USA, 2006–2011, to examine the effect of fix interval on estimates of movement metrics. By calculating straight‐line distances between locations taken at different fix intervals, we examined the rate of change in various metrics of caribou movement as a function of fix interval. We also calculated correction factors for different fix intervals, and examined how they changed seasonally. We fit an equation to the maximum rate of movement of caribou as a function of fix interval and used this equation in a modification of one screening algorithm to assess how it is affected by fix interval. We demonstrate how the maximum speed equation could potentially be used to derive a modified filter for telemetry data from highly mobile animals. Our results highlight the importance of incorporating fix‐interval information into comparisons of movement metrics from different herds and time periods. © 2013 The Wildlife Society.

Radiotelemetry collars are frequently used to estimate demographic parameters of animals, such as annual survival and parturition rates. If animals are collared for multiple years and statistical adjustments are not made, these estimates can be biased by an unrepresentative age structure and individual variability of collared animals. To quantify the effects of different factors on the magnitude of these potential biases, we created a computer simulation of the female portion of a barren-ground caribou (Rangifer tarandus granti) herd and then randomly assigned collars to individuals within the simulated population. Under our default model, based on the Western Arctic Herd monitoring program, caribou were collared randomly from all females aged 2 years and over, and they remained collared for a mean of 7 years. Our simulations revealed that survival rates were underestimated by approximately 3.4% and parturition rates were overestimated by approximately 3.3%. The magnitude of these biases increased when individuals remained collared for longer periods. Increased individual variability in the population resulted in only small increases in survival and parturition rates. Because the magnitude of the bias increased steadily during the first years of the study, we found a substantial risk of incorrectly identifying a significant decline in survival in the first 7 years after marking. Including the number of years individual animals have been collared as a covariate in analyses can reduce the biases in demographic parameters and should be considered for inclusion in analyses when animal age is unknown. Actual survival rate estimates from telemetry data for the Western Arctic Herd were generally consistent with the results of these simulations. These potential biases should be considered when interpreting demographic parameters from multi-year collaring studies. (c) 2012 The Wildlife Society.