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At least 973 records · Page 54Linked to original sources

USGS2014

Prevalence, transmission, and genetic diversity of blood parasites infecting tundra-nesting geese in Alaska

A total of 842 blood samples collected from five species of tundra-nesting geese in Alaska was screened for haemosporidian parasites using molecular techniques. Parasites of the genera Leucocytozoon Danilewsky, 1890, Haemoproteus Kruse, 1890, and Plasmodium Marchiafava and Celli, 1885 were detected in 169 (20%), 3 (<1%), and 0 (0%) samples, respectively. Occupancy modeling was used to estimate prevalence of Leucocytozoon parasites and assess variation relative to species, age, sex, geographic area, year, and decade. Species, age, and decade were identified as important in explaining differences in prevalence of Leucocytozoon parasites. Leucocytozoon parasites were detected in goslings sampled along the Arctic Coastal Plain using both historic and contemporary samples, which provided support for transmission in the North American Arctic. In contrast, lack of detection of Haemoproteus and Plasmodium parasites in goslings ( n = 238) provided evidence to suggest that the transmission of parasites of these genera may not occur among waterfowl using tundra habitats in Alaska, or alternatively, may only occur at low levels. Five haemosporidian genetic lineages shared among different species of geese sampled from two geographic areas were indicative of interspecies parasite transmission and supported broad parasite or vector distributions. However, identical Leucocytozoon and Haemoproteus lineages on public databases were limited to waterfowl hosts suggesting constraints in the range of parasite hosts.

Alaska↗

USGS2023

Barrier islands and spits of northern Alaska: Decadal scale morphological change

Arctic barrier islands and spits are dynamic features influenced by a variety of oceanographic, geologic, and environmental factors. Many serve as habitat and protection for native species and shelter the coast from waves and storms that can flood and erode the adjacent mainland. This paper summarizes results of a study documenting changes to barrier morphology along the North Slope coast of Alaska between the United States-Canadian border and Cape Beaufort, from 1947 to 2020. Changes considered include number of barriers, area and perimeter, shoreline length, barrier sinuosity and width, presence and number of relict terminus features, presence and coverage of tundra vegetation, barrier orientation, termini migration rates, and elevation metrics. Wave conditions are also summarized and related to changes in barrier morphology. The results of this study help to better predict future barrier evolution and prevalence along Alaska’s coast by increasing our understanding of Arctic barrier development, migration, and degradation via the evaluation of historical morphometrics.

Alaska↗

USGS2011

Geology and petroleum potential of the east Barents Sea Basins and Admiralty Arch

The US Geological Survey (USGS) recently assessed the potential for undiscovered oil and gas resources of the East Barents Basins and Novaya Zemlya Basins and Admiralty Arch Provinces as part of the USGS Circum-Arctic Resource Appraisal. These two provinces are located NE of Scandinavia and the northwestern Russian Federation, on the Barents Sea Shelf between Novaya Zemlya to the east and the Barents Platform to the west. Three assessment units (AUs) were defined in the East Barents Basins for this study – Kolguyev Terrace Assessment Unit (AU), South Barents Basin and Ludlov Saddle AU, and North Barents Basin AU. A fourth, defined as Novaya Zemlya Basins and Admiralty Arch AU, is coincident with the Novaya Zemlya basins and Admiralty Arch Province. These AUs, all lying north of the Arctic Circle, were assessed for undiscovered, technically recoverable resources resulting in total estimated mean volumes of approximately 7.4 billion barrels of crude oil, 318 trillion cubic feet of natural gas and 1.4 billion barrels of natural gas liquids.

Geological Society Memoir↗

USGS2011

Geology and petroleum potential of the West Greenland-East Canada Province

The US Geological Survey (USGS) assessed the potential for undiscovered oil and gas resources of the West Greenland–East Canada Province as part of the USGS Circum-Arctic Resource Appraisal programme. The province lies in the offshore area between western Greenland and eastern Canada and includes Baffin Bay, Davis Strait, Lancaster Sound and Nares Strait west of and including part of Kane Basin. A series of major tectonic events led to the formation of several distinct structural domains that are the geological basis for defining five assessment units (AU) in the province, all of which are within the Mesozoic–Cenozoic Composite Petroleum System. Potential petroleum source rocks include strata of Ordovician, Lower and Upper Cretaceous, and Palaeogene ages. The five AUs defined for this study – the Eurekan Structures AU, NW Greenland Rifted Margin AU, NE Canada Rifted Margin AU, Baffin Bay Basin AU and the Greater Ungava Fault Zone AU – encompass the entire province and were assessed for undiscovered technically recoverable resources. The mean volumes of undiscovered resources for the West Greenland–East Canada Province are 10.7×10 9 barrels of oil, 75×10 12 cubic feet of gas, and 1.7×10 9 barrels of natural gas liquids. For the part of the province that is north of the Arctic Circle, the estimated mean volumes of these undiscovered resources are 7.3×10 9 barrels of oil, 52×10 12 cubic feet of natural gas, and 1.1×10 9 barrels of natural gas liquids.

Geological Society Memoir↗

USGS2022

Ordovician geology of Alaska

Ordovician rocks, found in northern, east-central, interior and southern Alaska, formed in a variety of depositional and palaeogeographic settings. Shallow- and deep-water strata deposited along the northwestern Laurentian margin occur in east-central Alaska (Yukon River area) and probably correlative rocks crop out to the north in the Porcupine River area. Ordovician strata elsewhere in Alaska are parts of continental or island arc fragments that, as indicated by faunal and detrital zircon data, have been variously displaced. In northern Alaska, Ordovician rocks are included in the Arctic Alaska–Chukotka Microplate (AACM), a composite tectonic entity with a complex history. Some Ordovician strata in the AACM (parts of the North Slope subterrane) represent displaced fragments of the northern Laurentian margin. Coeval strata in southwestern parts of the AACM (York and Seward terranes, Hammond subterrane) share distinctive lithologic and biotic features with Ordovician rocks in interior Alaska (Farewell and related terranes). Ordovician strata in southeastern Alaska (Alexander terrane) also likely compose a composite crustal fragment that accumulated in a complex arc system. Shared features between many of these units suggest similar origins as part of one or more crustal fragments situated in the palaeo-Arctic between Laurentia, Baltica and Siberia during early Paleozoic time.

Alaska↗

USGS2020

Dynamics, variability, and change in seasonal precipitation reconstructions for North America

Cool and warm season precipitation totals have been reconstructed on a gridded basis for North America using 439 tree-ring chronologies correlated with December-April totals and 547 different chronologies correlated with May-July totals. These discrete seasonal predictor chronologies are not significantly correlated with the alternate season and the reconstructions calibrate at least 40% of the variance in both December-April and May-July precipitation totals over a large portion of North America for up to 2,000-years. Validation statistics computed on independent instrumental precipitation data from 1901-1927 indicate that the December-April reconstructions are reliable over most of the western and southern United States and northcentral Mexico, and the May-July estimates are valid over most of the United States, southwest Canada, and northeast Mexico. The strong continent wide El Niño/Southern Oscillation (ENSO) signal embedded in the cool season reconstructions, and the Arctic Oscillation signal registered by the warm season estimates, both faithfully reproduce the sign, intensity, and spatial patterns of these ocean-atmospheric influences on North American precipitation as recorded with instrumental data. The reconstructions are included in the North American Seasonal Precipitation Atlas (NASPA) and provide new insight into decadal droughts and pluvials. They indicate that the 16th century megadrought, the most severe and sustained North American drought of the past 500-years, was the combined result of three distinct seasonal droughts each bearing unique spatial patterns potentially associated with seasonal forcing from ENSO, the Arctic Oscillation, and the Atlantic Multidecadal Oscillation. Significant 200- to 500-year long trends toward increased precipitation have been detected in the cool and warm season reconstructions for eastern North America. These seasonal precipitation changes appear to be part of the positive moisture trend measured in other paleoclimate proxies for the East that began due to natural forcing before the industrial revolution and may have recently been enhanced by anthropogenic climate change.

Journal of Climate↗

USGS2020

The clock keeps ticking: Circadian rhythms of free-ranging polar bears

Life in the Arctic presents organisms with multiple challenges, including extreme photic conditions, cold temperatures, and annual loss and daily movement of sea ice. Polar bears ( Ursus maritimus ) evolved under these unique conditions, where they rely on ice to hunt their main prey, seals. However, very little is known about the dynamics of their daily and seasonal activity patterns. For many organisms, activity is synchronized (entrained) to the earth’s day/night cycle, in part via an endogenous (circadian) timekeeping mechanism. The present study used collar-mounted accelerometer and global positioning system data from 122 female polar bears in the Chukchi and Southern Beaufort Seas collected over an 8-year period to characterize activity patterns over the calendar year and to determine if circadian rhythms are expressed under the constant conditions found in the Arctic. We reveal that the majority of polar bears (80%) exhibited rhythmic activity for the duration of their recordings. Collectively within the rhythmic bear cohort, circadian rhythms were detected during periods of constant daylight (June-August; 24.40 ± 1.39 h, mean ± SD) and constant darkness (23.89 ± 1.72 h). Exclusive of denning periods (November-April), the time of peak activity remained relatively stable (acrophases: ~1200-1400 h) for most of the year, suggesting either entrainment or masking. However, activity patterns shifted during the spring feeding and seal pupping season, as evidenced by an acrophase inversion to ~2400 h in April, followed by highly variable timing of activity across bears in May. Intriguingly, despite the dynamic environmental photoperiodic conditions, unpredictable daily timing of prey availability, and high between-animal variability, the average duration of activity (alpha) remained stable (11.2 ± 2.9 h) for most of the year. Together, these results reveal a high degree of behavioral plasticity in polar bears while also retaining circadian rhythmicity. Whether this degree of plasticity will benefit polar bears faced with a loss of sea ice remains to be determined.

Alaska↗

USGS2002

Energy resource potential of natural gas hydrates

The discovery of large gas hydrate accumulations in terrestrial permafrost regions of the Arctic and beneath the sea along the outer continental margins of the world's oceans has heightened interest in gas hydrates as a possible energy resource. However, significant to potentially insurmountable technical issues must be resolved be fore gas hydrates can be considered a viable option for affordable supplies of natural gas. The combined information from Arctic gas hydrate studies shows that, in permafrost regions, gas hydrates may exist at subsurface depths ranging from about 130 to 2000 m. The presence of gas hydrates in offshore continental margins has been inferred mainly from anomalous seismic reflectors, known as bottom-simulating reflectors, that have been mapped at depths below the sea floor ranging from about 100 to 1100 m. Current estimates of the amount of gas in the world's marine and permafrost gas hydrate accumulations are in rough accord at about 20,000 trillion m 3 . Disagreements over fundamental issues such as the volume of gas stored within delineated gas hydrate accumulations and the concentration of gas hydrates within hydrate-bearing strata have demonstrated that we know little about gas hydrates. Recently, however, several countries, including Japan, India, and the United States, have launched ambitious national projects to further examine the resource potential of gas hydrates. These projects may help answer key questions dealing with the properties of gas hydrate reservoirs, the design of production systems, and, most important, the costs and economics of gas hydrate production.

American Association of Petroleum Geologists Bulle↗

USGS2011

Movements of wolves at the northern extreme of the species' range, including during four months of darkness

Information about wolf ( Canis lupus ) movements anywhere near the northern extreme of the species' range in the High Arctic (>75°N latitude) are lacking. There, wolves prey primarily on muskoxen ( Ovibos moschatus ) and must survive 4 months of 24 hr/day winter darkness and temperatures reaching -53 C. The extent to which wolves remain active and prey on muskoxen during the dark period are unknown, for the closest area where information is available about winter wolf movements is >2,250 km south. We studied a pack of ≥20 wolves on Ellesmere Island, Nunavut, Canada (80°N latitude) from July 2009 through mid-April 2010 by collaring a lead wolf with a Global Positioning System (GPS)/Argos radio collar. The collar recorded the wolf's precise locations at 6:00 a.m. and 6:00 p.m. daily and transmitted the locations by satellite to our email. Straight-line distances between consecutive 12-hr locations varied between 0 and 76 km. Mean (SE) linear distance between consecutive locations (n = 554) was 11 (0.5) km. Total minimum distance traveled was 5,979 km, and total area covered was 6,640 km 2 , the largest wolf range reported. The wolf and presumably his pack once made a 263-km (straight-line distance) foray to the southeast during 19–28 January 2010, returning 29 January to 1 February at an average of 41 km/day straight-line distances between 12-hr locations. This study produced the first detailed movement information about any large mammal in the High Arctic, and the average movements during the dark period did not differ from those afterwards. Wolf movements during the dark period in the highest latitudes match those of the other seasons and generally those of wolves in lower latitudes, and, at least with the gross movements measurable by our methods, the 4-month period without direct sunlight produced little change in movements.

Ellesmere Island;Nunavut↗

USGS2018

International migration patterns of Red-throated Loons (Gavia stellata) from four breeding populations in Alaska

Identifying post-breeding migration and wintering distributions of migratory birds is important for understanding factors that may drive population dynamics. Red-throated Loons ( Gavia stellata ) are widely distributed across Alaska and currently have varying population trends, including some populations with recent periods of decline. To investigate population differentiation and the location of migration pathways and wintering areas, which may inform population trend patterns, we used satellite transmitters (n = 32) to describe migration patterns of four geographically separate breeding populations of Red-throated Loons in Alaska. On average (± SD) Red-throated Loons underwent long (6,288 ± 1,825 km) fall and spring migrations predominantly along coastlines. The most northern population (Arctic Coastal Plain) migrated westward to East Asia and traveled approximately 2,000 km farther to wintering sites than the three more southerly populations (Seward Peninsula, Yukon-Kuskokwim Delta, and Copper River Delta) which migrated south along the Pacific coast of North America. These migration paths are consistent with the hypothesis that Red-throated Loons from the Arctic Coastal Plain are exposed to contaminants in East Asia. The three more southerly breeding populations demonstrated a chain migration pattern in which the more northerly breeding populations generally wintered in more northerly latitudes. Collectively, the migration paths observed in this study demonstrate that some geographically distinct breeding populations overlap in wintering distribution while others use highly different wintering areas. Red-throated Loon population trends in Alaska may therefore be driven by a wide range of effects throughout the annual cycle.

Alaska↗

USGS2018

A multi-isotope (δ13C, δ15N, δ34S, δ2H) approach to establishing migratory connectivity in lesser snow geese: Tracking an overabundant species

Expanding populations of North American midcontinent lesser snow geese ( Anser caerulescens caerulescens ) have potential to alter ecosystems throughout the Arctic and subarctic where they breed. Efforts to understand origins of harvested lesser snow geese to better inform management decisions have traditionally required mark-recapture approaches, while aerial photographic surveys have typically been used to identify breeding distributions. As a potential alternative, isotopic patterns that are metabolically fixed within newly grown flight feathers following summer molting could provide inferences regarding geographic breeding origin of individuals, without the need for prior capture. Our objective was to assess potential to use four stable isotopes (δ 13 C, δ 15 N, δ 34 S, δ 2 H) from feather material to determine breeding origins. We obtained newly grown flight feathers from individuals during summer banding at three Arctic and two subarctic breeding colonies in 2014 ( n = 56) and 2016 ( n = 45). We used linear discriminant analyses to predict breeding origins from models using combinations of stable isotopes as predictors and evaluated model accuracy when predicting colony, subregion, or subpopulation levels. We found a strong inverse relationship between δ 2 H values and increasing latitude ( R 2 = 0.83), resulting in differences ( F 4, 51 = 90.41, P < 0.0001) among sampled colonies. No differences in δ 13 C or δ 15 N were detected among colonies, although δ 34 S in Akimiski Island, Baffin Island, and Karrak Lake were more enriched ( F 4, 51 = 11.25, P < 0.0001). Using δ 2 H values as a predictor, discriminant analyses improved accuracy in classification level as precision decreased [model accuracy = 67% (colony), 88% (subregion), 94% (subpopulation)]. Application of the isotopic methods we describe could be used to provide an alternative monitoring method of population metrics, such as overall breeding population distribution, region-specific productivity and migratory connectivity that are informative to management decision makers and provide insight into cross-seasonal effects that may influence migratory behavior.

Baffin Island, Southampton Island↗

USGS2020

Novel insights into serodiagnosis and epidemiology of Erysipelothrix rhusiopathiae, a newly recognized pathogen in muskoxen (Ovibos moschatus)

Muskoxen are a key species of Arctic ecosystems and are important for food security and socio-economic well-being of many Indigenous communities in the Arctic and Subarctic. Between 2009 and 2014, the bacterium Erysipelothrix rhusiopathiae was isolated for the first time in this species in association with multiple mortality events in Canada and Alaska, raising questions regarding the spatiotemporal occurrence of the pathogen and its potential impact on muskox populations.

Alaska, Yukon, Northwester Territories, Nunavut↗

USGS2021

Biogeography and ecology of Ostracoda in the U.S. northern Bering, Chukchi, and Beaufort Seas

Ostracoda (bivalved Crustacea) comprise a significant part of the benthic meiofauna in the Pacific-Arctic region, including more than 50 species, many with identifiable ecological tolerances. These species hold potential as useful indicators of past and future ecosystem changes. In this study, we examined benthic ostracodes from nearly 300 surface sediment samples, >34,000 specimens, from three regions—the northern Bering, Chukchi and Beaufort Seas—to establish species’ ecology and distribution. Samples were collected during various sampling programs from 1970 through 2018 on the continental shelves at 20 to ~100m water depth. Ordination analyses using species’ relative frequencies identified six species, Normanicythere leioderma , Sarsicytheridea bradii , Paracyprideis pseudopunctillata , Semicytherura complanata , Schizocythere ikeyai , and Munseyella mananensis , as having diagnostic habitat ranges in bottom water temperatures, salinities, sediment substrates and/or food sources. Species relative abundances and distributions can be used to infer past bottom environmental conditions in sediment archives for paleo-reconstructions and to characterize potential changes in Pacific-Arctic ecosystems in future sampling studies. Statistical analyses further showed ostracode assemblages grouped by the summer water masses influencing the area. Offshore-to-nearshore transects of samples across different water masses showed that complex water mass characteristics, such as bottom temperature, productivity, as well as sediment texture, influenced the relative frequencies of ostracode species over small spatial scales. On the larger biogeographic scale, synoptic ordination analyses showed dominant species— N . leioderma (Bering Sea), P . pseudopunctillata (offshore Chukchi and Beaufort Seas), and S . bradii (all regions)—remained fairly constant over recent decades. However, during 2013–2018, northern Pacific species M . mananensis and S . ikeyai increased in abundance by small but significant proportions in the Chukchi Sea region compared to earlier years. It is yet unclear if these assemblage changes signify a meiofaunal response to changing water mass properties and if this trend will continue in the future. Our new ecological data on ostracode species and biogeography suggest these hypotheses can be tested with future benthic monitoring efforts.

PLoS ONE↗

USGS2024

Increased pathogen exposure of a marine apex predator over three decades

Environmental changes associated with global warming create new opportunities for pathogen and parasite transmission in Arctic wildlife. As an apex predator ranging over large, remote areas, changes in pathogens and parasites in polar bears are a useful indicator of changing transmission dynamics in Arctic ecosystems. We examined prevalence and risk factors associated with exposure to parasites and viral and bacterial pathogens in Chukchi Sea polar bears. Serum antibodies to six pathogens were detected and prevalence increased between 1987–1994 and 2008–2017 for five: Toxoplasma gondii , Neospora caninum , Francisella tularensis , Brucella abortus/suis , and canine distemper virus. Although bears have increased summer land use, this behavior was not associated with increased exposure. Higher prevalence of F. tularensis , C. burnetii , and B. abortus/suis antibodies in females compared to males, however, could be associated with terrestrial denning. Exposure was related to diet for several pathogens indicating increased exposure in the food web. Elevated white blood cell counts suggest a possible immune response to some pathogens. Given that polar bears face multiple stressors in association with climate change and are a subsistence food, further work is warranted to screen for signs of disease.

Alaska↗

USGS2001

Evaluation of commercially prepared transport systems for nonlethal detection of Aeromonas salmonicida in salmonid fish

In vitro studies indicated that commercially prepared transport systems containing Amies, Stuart's, and Cary-Blair media worked equally well in sustaining the viability of the fish pathogen Aeromonas salmonicida, which causes furunculosis. The bacterium remained viable without significant increase or decrease in cell numbers for as long as 48 h of incubation at 18-20??C in Stuart's transport medium; consequently, obtaining mucus samples in such tubes were comparable to on-site detection of A. salmonicida by dilution plate counts on Coomassie Brilliant Blue agar. In three different assays of 100 samples of mucus from Atlantic salmon Salmo salar infected subclinically with A. salmonicida, dilution counts conducted on-site proved more reliable for detecting the pathogen than obtaining the samples in the transport system. In the on-site assays, dilution counts detected the pathogen in 34, 41, and 22 samples, whereas this was accomplished in only 15, 15, and 3 of the respective samples when the transport system was used. In an additional experiment, Arctic char Salvelinus alpinus sustaining a frank epizootic of furunculosis were sampled similarly. Here, too, dilution counts were more predictive of the prevalence of A. salmonicida and detected the pathogen in 46 mucus samples; in comparison, only 6 samples collected by using the transport system were positive. We also observed that the transport system supported the growth of the normal mucus bacterial flora. Particularly predominant among these were motile aeromonads and Pseudomonas fluorescens. In studies of mixed culture growth, two representatives of both of the latter genera of bacteria outgrew A. salmonicida - in some cases, to the total exclusion of the pathogen itself.

Journal of Aquatic Animal Health↗

USGS2007

Temperature-mediated differences in bacterial kidney disease expression and survival in Renibacterium salmoninarum-challenged bull trout and other salmonids

Resource managers considering restoration and reconnection of watersheds to protect and enhance threatened populations of bull trout Salvelinus confluentus have little information about the consequences of bacterial kidney disease (BKD) caused by Renibacterium salmoninarum. To better understand the response of bull trout to R. salmoninarum challenge, we conducted several laboratory experiments at two water temperatures. The extent, severity, and lethality of BKD in bull trout were compared with those of similarly challenged lake trout S. namaycush, Arctic char S. alpinus, Chinook salmon Oncorhynchus tshawytscha, and rainbow trout O. mykiss. The lethal dose of bacterial cells necessary to induce 50% mortality (LD50) was 10-fold lower at the 15??C challenge than at the 9??C challenge. Of the species tested, bull trout were relatively resistant to BKD, Arctic char were the most susceptible among Salvelinus species, and Chinook salmon were the most susceptible among Oncorhynchus species tested. Mean time to death was more rapid for all fish tested at 15??C than for fish challenged at 9??C. These results suggest that infection of bull trout with BKD likely poses a low risk to successful restoration of threatened populations. ?? Copyright by the American Fisheries Society 2007.

North American Journal of Fisheries Management↗

USGS2004

Lack of spatial genetic structure among nesting and wintering King Eiders

The King Eider (Somateria spectabilis) has been delineated into two broadly distributed breeding populations in North America (the western and eastern Arctic) on the basis of banding data and their use of widely separated Pacific and Atlantic wintering areas. Little is known about the level of gene flow between these two populations. Also unknown is whether behavioral patterns common among migratory waterfowl, such as site fidelity to wintering areas and pair formation at these sites, have existed for sufficient time to create a population structure defined by philopatry to wintering rather than to nesting locations. We used six nuclear microsatellite DNA loci and cytochrome b mitochondrial DNA sequence data to estimate the extent of spatial genetic differentiation among nesting and wintering areas of King Eiders across North America and adjacent regions. Estimates of interpopulation variance in microsatellite allele and mtDNA haplotype frequency were both low and nonsignificant based on samples from three wintering and four nesting areas. Results from nested clade analysis, mismatch distributions, and coalescent-based analyses suggest historical population growth and gene flow that collectively may have homogenized gene frequencies. The presence of several unique mtDNA haplotypes among birds wintering near Greenland suggests that gene flow may now be more limited between the western and eastern Arctic, which is consistent with banding data.

Condor↗

USGS2004

Temporal and geographic variation in survival of juvenile black brant

First-year survival has important implications for the structure and growth of populations. We examined variation in seasonal survival of first-year Pacific Black Brant ( Branta bernicla nigricans ) marked late in summer in Alaska at two brood-rearing areas on the Yukon-Kuskokwim Delta (Tutakoke and Kokechik) and one area on the Arctic Coastal Plain to provide insight into the magnitude and timing of mortality during fall migration. First-year survival was lower in early fall (15 July-1 October), when birds fledged from brood-rearing areas and migrated to their primary fall staging area at Izembek Lagoon, Alaska, than during late fall and early winter (1 October-15 February), when birds made a long-distance transoceanic flight (>5000 km) to wintering areas in Baja California, Mexico. When compared to other years, monthly survival during early fall was 20-24% lower in 1992, the year of latest hatch dates and slowest growth of goslings. There was strong evidence to indicate that survival varied geographically within the early fall period. Monthly survival estimates during early fall were lowest for birds from Tutakoke, highest for birds from the Arctic Coastal Plain, and intermediate at Kokechik. Our findings revealed that most juvenile mortality occurred during the first 2 months following banding, and variation in juvenile survival during this period was likely influenced significantly by environmental parameters and habitat conditions on the breeding grounds. Monthly survival estimates during the subsequent 4 months were similar across geographic areas, and long-distance migration was likely the most important contributor to juvenile mortality during this period.

Alaska↗