Physiomorphic transformation in extreme endurance migrants:Revisiting the case of Bar-tailed Godwits preparing for trans-Pacific flights

In a 1998 paper entitled “Guts don’t fly: small digestive organs in obese bar-tailed godwits,” Piersma and Gill (1998) showed that the digestive organs were tiny and the fat loads huge in individuals suspected of embarking on a non-stop flight from Alaska to New Zealand. It was suggested that prior to migratory departure, these godwits would shrink the digestive organs used during fuel deposition and boost the size and capacity of exercise organs to optimize flight performance. Here we document the verity of the proposed physiomorphic changes by comparing organ sizes and body composition of bar-tailed godwits Limosa lapponica baueri collected in modesty midway during their fueling period (mid-September; fueling, n = 7) with the previously published data for godwits that had just departed on their trans-Pacific flight (October 19; flying, n = 9). Mean total body masses for the two groups were nearly identical, but nearly half of the body mass of fueling godwits consisted of water, while fat constituted over half of total body mass of flying godwits. The two groups also differed in their fat-free mass components. The heart and flight muscles were heavier in fueling godwits, but these body components constituted a relatively greater fraction of the fat-free mass in flying godwits. In contrast, organs related to digestion and homeostasis were heavier in fueling godwits, and most of these organ groups were also relatively larger in fueling godwits compared to flying godwits. These results reflect the functional importance of organ and muscle groups related to energy acquisition in fueling godwits and the consequences of flight-related exertion in flying godwits. The extreme physiomorphic changes apparently occurred over a short time window (≤1 month). We conclude that the inferences made on the basis of the 1998 paper were correct. The cues and stimuli which moderate these changes remain to be studied

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

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

On the frozen edge:Environmental and physiological constraints in the life history of a northerly-wintering shorebird

De populatie Calidris p. ptilocnemis (hierna: ptilocnemis), een ondersoort van de Beringstrandlopers, telt ongeveer 20.000 individuen. Deze ondersoort overwintert in het noorden van Cook Inlet, Alaska (61°N, 151°W). Dit is voor zover bekend het meest noordelijk gelegen overwinteringsgebied voor steltlopers in de gehele Stille Oceaan en het is bovendien het koudste gebied dat regelmatig overwinterende wadvogels herbergt. De extreme condities in het noorden van Cook Inlet zorgen voor hoge verblijfskosten en de jaarlijkse aangroei van zee- en landijs veroorzaken onvoorspelbare en moeilijke foerageer-omstandigheden voor de strandlopers. Op een experimentele manier, door de strandlopers van Alaska naar Texel te brengen, hebben we de energiehuishouding en het foerageergedrag van ptilocnemis vergeleken met een andere ondersoort van de Beringstrandlopers C.p. tschuktschorum (hierna: tschuktschorum). Deze ondersoort heeft een meer zuidelijk gelegen overwinteringsgebied rond de Stille Oceaan, langs de noordwest kust van Noord Amerika, waar de omstandigheden aanzienlijk milder zijn. De twee ondersoorten vertoonde vergelijkbare toenames in energieverbruik met temperatuurverlagingen, maar in vergelijking met tschuktschorum vertoonde ptilocnemis belangrijke verschillen in foerageer-ecofysiologie die voor een hogere energie-opname en doorstroom van de in de maag gekraakte schelpresten zorgde. Dit is waarschijnlijk het resultaat van fysiologische verschillen tussen de twee ondersoorten in verteringstelsel en niet van verschillen in foeragee gedrag of de begaafdheid in het vinden van prooien. In het wild vergroot ptilocnemis de maag en lever om de stofwisseling sneller en efficiënter te laten verlopen. Tegelijkertijd worden vetreserves opgeslagen die gebruikt worden om perioden van kou en voedselschaarste te kunnen overbruggen. Daarbij maakt de aanwezigheid van buitengewoon hoogwaardig voedsel in de vorm van Nonnetjes Macoma balthica het de steltlopers mogelijk hun winter door brengen in het hoge noorden van Alaska. Samengevat zorgen de aanwezigheid van deze hoogwaardige voedselbron in combinatie met de bovengenoemde fysiologische- en gedragsaanpassingen er voor dat ptilocnemis ondanks de ogenschijnlijke erbarmelijke omstandigheden in staat is te overwinteren in het koude Alaska

APPARENT SURVIVAL OF BREEDING WESTERN SANDPIPERS ON THE YUKON-KUSKOKWIM RIVER DELTA, ALASKA

We used 8 years of live recapture data (1998–2005) to estimate apparent annual survival for male (n = 237) and female (n = 296) Western Sandpipers (Calidris mauri) breeding on a 36-ha plot on the Yukon-Kuskokwim River Delta, western Alaska. Apparent annual survival (Φ) is the product of true survival and site fidelity, and estimates of Φ were corrected for the probability of encounter. Overall return rates (individual returned to the study site in a subsequent season) were lower for females (40%) than males (65%), as was Φ (± SE, females = 0.65 ± 0.05, males = 0.78 ± 0.03), and encounter rate (females = 0.51 ± 0.07, males = 0.74 ± 0.04). Results differed from previous estimates of Φ for this species as our estimates of Φ were higher for both males and females compared to estimates from another breeding site and two nonbreeding locations. Disparity among Φ estimates from breeding and nonbreeding areas highlights the need to delineate site-specific factors throughout the annual cycle that influence population dynamics of the Western Sandpiper

APPARENT SURVIVAL OF BREEDING WESTERN SANDPIPERS ON THE YUKON-KUSKOKWIM RIVER DELTA, ALASKA

We used 8 years of live recapture data (1998–2005) to estimate apparent annual survival for male (n = 237) and female (n = 296) Western Sandpipers (Calidris mauri) breeding on a 36-ha plot on the Yukon-Kuskokwim River Delta, western Alaska. Apparent annual survival (Φ) is the product of true survival and site fidelity, and estimates of Φ were corrected for the probability of encounter. Overall return rates (individual returned to the study site in a subsequent season) were lower for females (40%) than males (65%), as was Φ (± SE, females = 0.65 ± 0.05, males = 0.78 ± 0.03), and encounter rate (females = 0.51 ± 0.07, males = 0.74 ± 0.04). Results differed from previous estimates of Φ for this species as our estimates of Φ were higher for both males and females compared to estimates from another breeding site and two nonbreeding locations. Disparity among Φ estimates from breeding and nonbreeding areas highlights the need to delineate site-specific factors throughout the annual cycle that influence population dynamics of the Western Sandpiper

Quantifying Intra- and Interlimb Use During Unimanual and Bimanual Tasks in Persons with Hemiparesis Post-Stroke

Background Individuals with hemiparesis post-stroke often have difficulty with tasks requiring upper extremity (UE) intra- and interlimb use, yet methods to quantify both are limited. Objective To develop a quantitative yet sensitive method to identify distinct features of UE intra- and interlimb use during task performance. Methods Twenty adults post-stroke and 20 controls wore five inertial sensors (wrists, upper arms, sternum) during 12 seated UE tasks. Three sensor modalities (acceleration, angular rate of change, orientation) were examined for three metrics (peak to peak amplitude, time, and frequency). To allow for comparison between sensor data, the resultant values were combined into one motion parameter, per sensor pair, using a novel algorithm. This motion parameter was compared in a group-by-task analysis of variance as a similarity score (0–1) between key sensor pairs: sternum to wrist, wrist to wrist, and wrist to upper arm. A use ratio (paretic/non-paretic arm) was calculated in persons post-stroke from wrist sensor data for each modality and compared to scores from the Adult Assisting Hand Assessment (Ad-AHA Stroke) and UE Fugl-Meyer (UEFM). Results A significant group × task interaction in the similarity score was found for all key sensor pairs. Post-hoc tests between task type revealed significant differences in similarity for sensor pairs in 8/9 comparisons for controls and 3/9 comparisons for persons post stroke. The use ratio was significantly predictive of the Ad-AHA Stroke and UEFM scores for each modality. Conclusions Our algorithm and sensor data analyses distinguished task type within and between groups and were predictive of clinical scores. Future work will assess reliability and validity of this novel metric to allow development of an easy-to-use app for clinicians

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

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