1,681 research outputs found

    Messages From Earth: Nature and the Human Prospect in Alaska, by Robert B. Weeden

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    Wayward Youth: Trans-Beringian Movement and Differential Southward Migration by Juvenile Sharp-tailed Sandpipers

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    The sharp-tailed sandpiper (Calidris acuminata) is a long-distance migrant that travels each year from breeding grounds in the Russian Arctic to nonbreeding areas in Australasia. Most adults migrate rapidly from breeding grounds along a largely inland route through Asia. Here we report on the highly unusual migratory strategy of this species in which some juveniles, but virtually no adults, take a pronounced detour to western Alaska before proceeding on southward migration. We analyzed data from our own studies in this region and published and unpublished observations and specimen records of sharptailed sandpipers from the entire Pacific Basin. Each autumn, sharp-tailed sandpipers began arriving on coastal graminoid meadows and intertidal habitats throughout western Alaska during the last half of August and the last sandpipers departed from southwestern Alaska during October and November. Body mass of birds banded or collected across multiple years and sites in western Alaska (n = 330) increased by an average of 0.57 ± 0.06 g per day between mid-August and late October. Records suggest a small, regular movement of juveniles (and a very few adults) along the Asiatic coast, but we estimate from surveys that a few tens of thousands of juveniles stage in western Alaska each autumn. The distribution of sight and specimen records from the Pacific Basin during autumn suggests strongly age-segregated migration routes, with the principal migration of juveniles crossing central and western Oceania in a possible nonstop trans-Pacific flight from Alaska. This is only the second well-documented case of differential migration among birds that involves different routes for adults and juveniles, and it raises intriguing questions about how and why this system has evolved.  Le bécasseau à queue pointue (Calidris acuminata) est un migrant de longue distance qui se déplace chaque année depuis les zones de reproduction de l’Arctique russe jusqu’aux zones de non-reproduction de l’Australasie. La plupart des adultes migrent rapidement à partir des zones de reproduction le long d’un corridor largement situé à l’intérieur qui traverse l’Asie. Ici, nous faisons état de la stratégie migratoire grandement inhabituelle de cette espèce dans le cadre de laquelle certains juvéniles, mais quasiment aucun adulte, font une déviation prononcée vers l’ouest de l’Alaska avant de migrer vers le Sud. Nous avons analysé les données dérivées de nos propres études dans la région de même que des observations publiées et inédites et des enregistrements de spécimens de bécasseaux à queue pointue de tout le bassin du Pacifique. Chaque automne, les bécasseaux à queue pointue commençaient à arriver sur les prés côtiers de graminoïdes et dans les habitats intertidaux de l’ouest de l’Alaska pendant la deuxième moitié du mois d’août. Les derniers bécasseaux quittaient le sud-ouest de l’Alaska aux mois d’octobre et de novembre. La masse corporelle des oiseaux en bandes ou recueillis au cours de plusieurs années et à plusieurs emplacements de l’ouest de l’Alaska (n = 330) a augmenté en moyenne de 0,57 ± 0,06 g par jour entre la mi-août et la fin octobre. Les données laissent voir la présence d’un petit mouvement régulier de juvéniles (et très peu d’adultes) le long de la côte asiatique, mais nous avons estimé d’après les dénombrements que quelques dizaines de milliers de juvéniles passent un certain temps dans l’ouest de l’Alaska chaque automne. La répartition d’enregistrements d’observations et de spécimens du bassin du Pacifique à l’automne laisse entrevoir des routes migratoires fortement ségrégées en fonction de l’âge et que la migration principale de juvéniles traversant le centre et l’ouest de l’Océanie dans le cadre d’un vol transpacifique est susceptible d’être sans escale depuis l’Alaska. Il s’agit seulement du deuxième cas bien répertorié de migration différentielle d’oiseaux dont les trajets diffèrent chez les adultes et les juvéniles, et cela soulève des questions à savoir comment et pourquoi ce système a évolué

    Use of Nearshore and Estuarine Areas of the Southeastern Bering Sea by Gray Whales (Eschrichtius robustus)

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    During spring aerial surveys of the coast of the southeastern Bering Sea significant numbers of gray whales were seen in nearshore waters along the north side of the Alaska Peninsula. Many (50-80%) of these animals were observed surfacing with mud trails or lying on their sides, characteristics both associated with feeding. A migration route close to shore (within 1-2 km) was used until whales neared Egegik Bay, where they began to head west 5-8 km offshore, across northern Bristol Bay. Smaller numbers of gray whales were present throughout summer in nearshore waters and estuaries along the north side of the Alaska Peninsula. At Nelson Lagoon gray whales normally used the lagoon in spring, were absent during early summer, returned in mid-summer, and then were present until late November when they departed for the wintering grounds. Gray whales were present in the lagoon most often during periods of peak tidal flow; those that appeared to be feeding were oriented into the current. Three behaviors that appeared to be associated with feeding were observed: side-feeding from a stationary position within shallow waters of lagoon channels, diving within the lagoon and in nearshore waters, and elliptical side-feeding in the surf zone along the outer coast. Large crustaceans of the genus Crangon were available to and probably eaten by gray whales at Nelson Lagoon.Key words: gray whale, Eschrichtius robustus, feeding, behavior, estuaries, Bering Sea, AlaskaMots clés: baleine grise de Californie, Eschrichtius robustus, alimentation, comportement, estuaires, mer de Béring, Alask

    Coping with the Cold: An Ecological Context for the Abundance and Distribution of Rock Sandpipers during Winter in Upper Cook Inlet, Alaska

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    Shorebirds are conspicuous and abundant at high northern latitudes during spring and summer, but as seasonal conditions deteriorate, few remain during winter. To the best of our knowledge, Cook Inlet, Alaska (60.6˚ N, 151.6˚ W), is the world’s coldest site that regularly supports wintering populations of shorebirds, and it is also the most northerly nonbreeding location for shorebirds in the Pacific Basin. During the winters of 1997–2012, we conducted aerial surveys of upper Cook Inlet to document the spatial and temporal distribution and number of Rock Sandpipers (Calidris ptilocnemis) using the inlet. The average survey total was 8191 ± 6143 SD birds, and the average of each winter season’s highest single-day count was 13 603 ± 4948 SD birds. We detected only Rock Sandpipers during our surveys, essentially all of which were individuals of the nominate subspecies (C. p. ptilocnemis). Survey totals in some winters closely matched the population estimate for this subspecies, demonstrating the region’s importance as a nonbreeding resource to the subspecies. Birds were most often found at only a handful of sites in upper Cook Inlet, but shifted their distribution to more southerly locations in the inlet during periods of extreme cold. Two environmental factors allow Rock Sandpipers to inhabit Cook Inlet during winter: 1) an abundant bivalve (Macoma balthica) food source and 2) current and tidal dynamics that keep foraging substrates accessible during all but extreme periods of cold and ice accretion. C. p. ptilocnemis is a subspecies of high conservation concern for which annual winter surveys may serve as a relatively inexpensive population-monitoring tool that will also provide insight into adaptations that allow these birds to exploit high-latitude environments in winter.Le printemps et l’été, les oiseaux de rivage abondent et sont bien en vue dans les latitudes de l’extrême nord, mais au fur et à mesure que les conditions saisonnières se détériorent, peu d’entre eux hivernent dans ces régions. Au meilleur de nos connaissances, l’anse Cook, en Alaska (60,6˚ N, 151,6˚ O), est l’endroit le plus froid du monde où l’on trouve régulièrement des populations d’oiseaux de rivage l’hiver. Il s’agit aussi de l’emplacement le plus nordique du bassin du Pacifique à ne pas être consacré à la reproduction des oiseaux de rivage. Au cours des hivers allant de 1997 à 2012, nous avons réalisé des levés aériens de la partie supérieure de l’anse Cook afin d’être en mesure de répertorier la répartition spatiale, la répartition temporelle et le nombre de bécasseaux des Aléoutiennes (Calidris ptilocnemis) dans l’anse. Le total moyen des levés a permis de repérer8 191 ± 6 143 (DS) oiseaux, tandis que la moyenne du dénombrement le plus élevé au cours d’une seule journée d’hiver était de 13 603 ± 4 948 (DS) oiseaux. Dans le cadre de nos levés, nous n’avons détecté que des bécasseaux des Aléoutiennes, dont tous étaient essentiellement des individus de la sous-espèce désignée (C. p. ptilocnemis). Au cours de certains hivers, les totaux des levés se rapprochaient beaucoup des estimations de population de cette sous-espèce, ce qui laisse entrevoir l’importance de cette région en tant que ressource de non-reproduction pour cette sous-espèce. La plupart du temps, ces oiseaux ne se retrouvaient qu’à quelques endroits de la partie supérieure de l’anse Cook, bien qu’ils se répartissaient plus au sud de l’anse pendant les périodes de froid extrême. Deux facteurs environnementaux permettent aux bécasseaux des Aléoutiennes d’évoluer dans l’anse Cook l’hiver : 1) une source abondante de nourriture acéphale (Macoma balthica) et 2) une dynamique de courants et de marées qui a constamment pour effet d’alimenter les oiseaux en substrat pendant toutes les périodes, sauf celles de froid extrême et d’accrétion de glace. C. p. ptilocnemis est une sous-espèce dont la conservation présente de grandes inquiétudes et pour laquelle les levés hivernaux annuels peuvent constituer un outil de surveillance de population relativement abordable qui permettra également d’en savoir plus sur les adaptations qui permettent à ces oiseaux d’exploiter les milieux de haute latitude l’hiver

    Birds of the Northcentral Alaska Peninsula, 1976-1980

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    Between spring 1976 and fall 1980 we studied the occurrence, abundance, and habitat use of birds over a 2000 square km segment of the northcentral Alaska Peninsula. During this period observers were present 473 days and obtained records for all seasons. A total of 125 species was recorded; 63% (79 of 125) were water-associated. The breeding avifauna was found to be a mixture of Panboreal (49%), North American (34%), and Aleutican (17%) species. The Aleutican group was dominant in terms of biomass and numbers of individuals during the nonbreeding period. Forty-two species were confirmed breeding in the area and another 19 were suspected of breeding. The majority of birds occurred as migrants; 14 species were considered permanent residents and an additional 20 were winter residents. ... The area is a principal late summer and fall molting and staging area for several species of arctic and subarctic nesting waders and seaducks and emperor geese .... From late September through mid-October the density of water birds over the entire littoral and nearshore area approached 1000 birds square km. This density was exceeded many fold for certain species on particular segments of habitats in the area.Key words: birds, Alaska Peninsula, abundance, migration, nesting, habitat, distribution, zoogeographyMots clés: oiseaux, péninsule d'Alaska, abondance, migration, saison des nids, habitat, distribution, zoogéographi

    Residency Times and Patterns of Movement of Postbreeding Dunlin on a Subarctic Staging Area in Alaska

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    Understanding how individuals use key resources is critical for effective conservation of a population. The Yukon-Kuskokwim Delta (YKD) in western Alaska is the most important postbreeding staging area for shorebirds in the subarctic North Pacific, yet little is known about movements of shorebirds there during the postbreeding period. To address this information gap, we studied residency times and patterns of movement of 17 adult and 17 juvenile radio-marked Dunlin (Calidris alpina) on the YKD between early August and early October 2005. Throughout this postbreeding period, during which Dunlin were molting, most birds were relocated within a 130 km radius of their capture site on the YKD, but three birds were relocated more than 600 km to the south at estuaries along the Alaska Peninsula. On average, juvenile Dunlin were relocated farther away from the banding site (median relocation distance = 36.3 km) than adult Dunlin (median relocation distance = 8.8 km). Post-capture, minimum lengths of stay by Dunlin on the YKD were not significantly different between juveniles (median = 19 days) and adults (median = 23 days), with some birds staging for more than 50 days. Body mass at time of capture was the best single variable explaining length of stay on the YKD, with average length of stay decreasing by 2.5 days per additional gram of body mass at time of capture. Conservation efforts for postbreeding shorebirds should consider patterns of resource use that may differ not only by age cohort but also by individual condition.Pour donner lieu à la conservation efficace d’une population, il est essentiel de comprendre comment les individus se servent des ressources importantes. Le delta Yukon-Kuskokwim, dans l’ouest de l’Alaska, est l’escale de post-reproduction la plus importante des oiseaux de rivage du Pacifique Nord subarctique. Pourtant, on en sait peu sur les déplacements des oiseaux de rivage à cet endroit pendant la période de post-reproduction. Afin de combler ce manque d’information, nous avons étudié les durées de résidence et les habitudes de déplacement de 17 bécasseaux variables (Calidris alpina) adultes et de 17 bécasseaux variables juvéniles radio-marqués dans le delta Yukon-Kuskokwim du début août au début octobre 2005. Pendant la période de post-reproduction pendant laquelle les bécasseaux variables muaient, la plupart des oiseaux ont été déplacés dans un rayon de 130 km de leur lieu de capture dans le delta Yukon-Kuskokwim, mais trois oiseaux ont été relocalisés à plus de 600 km vers le sud, aux estuaires le long de la péninsule de l’Alaska. En moyenne, les bécasseaux variables juvéniles ont été déplacés plus loin du lieu de baguage (distance de déplacement médiane = 36,3 km) que les bécasseaux variables adultes (distance de déplacement médiane = 8,8 km). Par bécasseau variable, les durées de séjour minimales après la capture au delta Yukon-Kuskokwim ne différaient pas considérablement entre les juvéniles (médiane = 19 jours) et les adultes (médiane = 23 jours), certains oiseaux faisant escale pendant plus de 50 jours. La masse corporelle au moment de la capture était la meilleure et la seule variable expliquant la durée du séjour au delta Yukon-Kuskokwim, la durée moyenne du séjour diminuant de 2,5 jours par gramme supplémentaire de masse corporelle au moment de la capture. Les efforts de conservation des oiseaux de rivage en période de post-reproduction devraient tenir compte des modèles d’utilisation des ressources qui risquent de différer non seulement en fonction de la cohorte d’âge, mais également en fonction de l’état de l’individu

    The Pacific as the world’s greatest theater of bird migration:Extreme flights spark questions about physiological capabilities, behavior, and the evolution of migratory pathways

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    The Pacific Basin, by virtue of its vastness and its complex aeroscape, provides unique opportunities to address questions about the behavioral and physiological capabilities and mechanisms through which birds can complete spectacular flights. No longer is the Pacific seen just as a formidable barrier between terrestrial habitats in the north and the south, but rather as a gateway for specialized species, such as shorebirds, to make a living on hemispherically distributed seasonal resources. This recent change in perspective is dramatic, and the research that underpins it has presented new opportunities to learn about phenomena that often challenge a sense of normal. Ancient Polynesians were aware of the seasonal passage of shorebirds and other landbirds over the Pacific Ocean, incorporating these observations into their navigational “tool kit” as they explored and colonized the Pacific. Some ten centuries later, systematic visual observations and tracking technology have revealed much about movement of these shorebirds, especially the enormity of their individual nonstop flights. This invites a broad suite of questions, often requiring comparative studies with bird migration across other ocean basins, or across continents. For example, how do birds manage many days of nonstop exercise apparently without sleep? What mechanisms explain birds acting as if they possess a Global Positioning System? How do such extreme migrations evolve? Through advances in both theory and tracking technology, biologists are poised to greatly expand the horizons of movement ecology as we know it. In this integrative review, we present a series of intriguing questions about trans-Pacific migrant shorebirds and summarize recent advances in knowledge about migratory behavior operating at temporal scales ranging from immediate decisions during a single flight, to adaptive learning throughout a lifetime, to evolutionary development of migratory pathways. Recent advances in this realm should stimulate future research across the globe and across a broad array of disciplines

    Comparing different definitions of prediabetes with subsequent risk of diabetes: an individual participant data meta-analysis involving 76 513 individuals and 8208 cases of incident diabetes

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    Objective: There are currently five widely used definition of prediabetes. We compared the ability of these to predict 5-year conversion to diabetes and investigated whether there were other cut-points identifying risk of progression to diabetes that may be more useful. Research design and methods: We conducted an individual participant meta-analysis using longitudinal data included in the Obesity, Diabetes and Cardiovascular Disease Collaboration. Cox regression models were used to obtain study-specific HRs for incident diabetes associated with each prediabetes definition. Harrell's C-statistics were used to estimate how well each prediabetes definition discriminated 5-year risk of diabetes. Spline and receiver operating characteristic curve (ROC) analyses were used to identify alternative cut-points. Results: Sixteen studies, with 76 513 participants and 8208 incident diabetes cases, were available. Compared with normoglycemia, current prediabetes definitions were associated with four to eight times higher diabetes risk (HRs (95% CIs): 3.78 (3.11 to 4.60) to 8.36 (4.88 to 14.33)) and all definitions discriminated 5-year diabetes risk with good accuracy (C-statistics 0.79-0.81). Cut-points identified through spline analysis were fasting plasma glucose (FPG) 5.1 mmol/L and glycated hemoglobin (HbA1c) 5.0% (31 mmol/mol) and cut-points identified through ROC analysis were FPG 5.6 mmol/L, 2-hour postload glucose 7.0 mmol/L and HbA1c 5.6% (38 mmol/mol). Conclusions: In terms of identifying individuals at greatest risk of developing diabetes within 5 years, using prediabetes definitions that have lower values produced non-significant gain. Therefore, deciding which definition to use will ultimately depend on the goal for identifying individuals at risk of diabetes.This work was supported by the National Health and Medical Research Council of Australia (grant number 1103242). The Atherosclerosis Risk in Communities study has been funded in whole or in part with Federal funds from the National Heart, Lung, and Blood Institute, National Institutes of Health, Department of Health and Human Services, under contract nos. HHSN268201700001I, HHSN268201700002I, HHSN268201700003I, HHSN268201700005I, HHSN268201700004I. ES was supported by NIH/NIDDK grant K24DK106414. The Coronary Artery Risk Development in Young Adults Study (CARDIA) is supported by contracts HHSN2682018000031, HHSN2682018000041, HHSN2682018000051, HHSN2682018000061 and HHSN2682018000071 from the National Heart, Lung, and Blood Institute (NHLBI). The Jackson Heart Study (JHS) is supported and conducted in collaboration with Jackson State University (HHSN268201800013I), Tougaloo College (HHSN268201800014I), the Mississippi State Department of Health (HHSN268201800015I) and the University of Mississippi Medical Center (HHSN268201800010I, HHSN268201800011I and HHSN268201800012I) contracts from the National Heart, Lung, and Blood Institute (NHLBI) and the National Institute for Minority Health and Health Disparities (NIMHD). The Melbourne Collaborative Cohort Study (MCCS) recruitment was funded by VicHealth and Cancer Council Victoria. The MCCS was further augmented by Australian National Health and Medical Research Council grants 209057, 396414 and 1074383 and by infrastructure provided by Cancer Council Victoria. Cases and their vital status were ascertained through the Victorian Cancer Registry and the Australian Institute of Health and Welfare, including the National Death Index and the Australian Cancer Database. The Multi-Ethnic Study of Atherosclerosis was supported by contracts HHSN268201500003I, N01-HC-95159, N01-HC-95160, N01-HC-95161, N01-HC-95162, N01-HC-95163, N01-HC-95164, N01-HC-95165, N01-HC-95166, N01-HC-95167, N01-HC-95168 and N01-HC-95169 from the National Heart, Lung, and Blood Institute and by grants UL1-TR-000040 and UL1-TR-001079 from NCRR. The Population Study of Women in Gothenburg (PSWG) was financed in part by grants from the Swedish state under the agreement between the Swedish government and the county councils, the ALF-agreement ALFGBG-720201. VIVA Study received grants 95/0029 and 06/90270 from the Instituto de Salud Carlos III, Spain.S

    Acute kidney disease and renal recovery : consensus report of the Acute Disease Quality Initiative (ADQI) 16 Workgroup

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    Consensus definitions have been reached for both acute kidney injury (AKI) and chronic kidney disease (CKD) and these definitions are now routinely used in research and clinical practice. The KDIGO guideline defines AKI as an abrupt decrease in kidney function occurring over 7 days or less, whereas CKD is defined by the persistence of kidney disease for a period of > 90 days. AKI and CKD are increasingly recognized as related entities and in some instances probably represent a continuum of the disease process. For patients in whom pathophysiologic processes are ongoing, the term acute kidney disease (AKD) has been proposed to define the course of disease after AKI; however, definitions of AKD and strategies for the management of patients with AKD are not currently available. In this consensus statement, the Acute Disease Quality Initiative (ADQI) proposes definitions, staging criteria for AKD, and strategies for the management of affected patients. We also make recommendations for areas of future research, which aim to improve understanding of the underlying processes and improve outcomes for patients with AKD
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