Spring Staging Research Articles

Environmental DNA reveals a presence of Anser fabalis (Bean Goose) and an absence of A. erythropus (Lesser White-fronted Goose) in Finnish Northern Lapland

Abstract Detecting rare and elusive species from vast wilderness areas poses significant challenges. The Fennoscandian population of Anser erythropus (Lesser White-fronted Goose) is among the most endangered bird populations in Europe, with only 25–30 breeding pairs remaining in Northern Norway. Historically, its former breeding range extended across the mountainous regions of Fennoscandia. Thanks to targeted conservation efforts during the 21st century, A. erythropus has started to recolonize some of its former breeding areas in Norway and possibly also in Finland. Anser serrirostris rossicus (Tundra Bean Goose) is classified as Endangered (EN) in Finland, with just a few breeding pairs in northernmost Finnish Lapland with a poorly known breeding range. It breeds in higher numbers in Finnmark Norway and is listed as Vulnerable (VU) in Norway. Anser fabalis fabalis (Taiga Bean Goose), classified as Endangered in Norway, can also breed in the same area in low numbers. To locate individuals of these elusive goose species during breeding seasons, we used environmental DNA (eDNA) extracted from filtered lake water from selected lakes in northern Finland. We amplified and sequenced a short region of the mitochondrial control region to identify the species. Additionally, for positive controls, we sampled eDNA from the water of a Finnish spring staging site and known Norwegian breeding sites of the A. erythropus, from which eDNA of the A. erythropus was identified. eDNA of the A. erythropus was not detected within the former Finnish breeding range. Based on this, the A. erythropus has either not recolonized its former breeding habitats in Finland, the correct lakes were not sampled, the eDNA concentration was below detection limits, or due to other methodological issues. Anser serrirostris rossicus was detected in 3 lakes and A. fabalis fabalis in 10 lakes, providing new information about the breeding distribution of Bean Geese in Finnish Lapland.

Comparative analysis of stripe rust resistance in seedling stage and Yr gene incidence in spring and winter wheat from Xinjiang, China.

Stripe rust, caused by the fungus Puccinia striiformis f.sp. tritici (Pst), poses a significant threat to global wheat production. This study aims to analyze the distribution of stripe rust resistance genes, characterize resistance phenotypes at the seedling stage of 137 spring and 149 winter wheat varieties in Xinjiang, China, and discern differences in resistance between spring and winter wheat varieties. We used various Pst races (CYR23, CYR29, CYR31, CYR32, CYR33, CYR34) to characterize seedling resistance of spring and winter wheat varieties and to correlate resistance to the presence of wheat resistance genes (Yr5, Yr9, Yr10, Yr15, Yr17, Yr18, Yr26, Yr41, Yr80, Yr81) using molecular markers. Among spring wheat varieties, 62, 60, 42, 26, 51, and 24 varieties exhibited resistance to CYR23, CYR29, CYR31, CYR32, CYR33, and CYR34, respectively, with four varieties resistant to all varieties. Among winter wheat varieties, 66, 32, 69, 26, 83, 40 varieties demonstrated resistance to CYR23, CYR29, CYR31, CYR32, CYR33, and CYR34, respectively, with four varieties resistant to all varieties. Molecular testing revealed that, in spring wheat, 2, 17, 21, 61, 10, 0, 10, 79, and 32 varieties carried Yr9, Yr10, Yr15, Yr17, Yr18, Yr26, Yr41, Yr80, and Yr81 genes, respectively. In winter wheat, 40, 20, 7, 143, 15, 1, 6, 38, and 54 varieties carried Yr9, Yr10, Yr15, Yr17, Yr18, Yr26, Yr41, Yr80, and Yr81 genes, respectively. Notably, winter wheat exhibited a significantly higher resistance frequency than spring wheat, particularly in the incidence of Yr9, Yr10, Yr17, Yr18, and multi-gene combinations. In summary, this study provides information on seedling stage resistance to stripe rust 286 Xinjiang wheat varieties, elucidates the distribution of resistance genes in this population, and offers a mechanistic basis for breeding durable resistance in wheat. varieties from Xinjiang.

Comparison of the Phenotypic Flexibility of Muscle and Body Condition of Migrant and Resident White-Crowned Sparrows.

AbstractSeasonally breeding birds express variations of traits (phenotypic flexibility) throughout their life history stages that represent adaptations to environmental conditions. Changes of body condition during migration have been well studied, whereas alterations of skeletal and cardiac muscles, body mass, and fat scores have yet to be characterized throughout the spring or fall migratory stages. Additionally, we examined flexible patterns of muscle, body mass, and fat score in migrant white-crowned sparrows (Zonotrichia leucophrys gambelii) in comparison with those in a resident subspecies (Zonotrichia leucophrys nuttalli) during the stages they share to evaluate the influence of different life histories. Migrants showed hypertrophy of the pectoralis muscle fiber area on the wintering grounds in late prealternate molt, yet increased pectoralis muscle mass was not detected until birds readied for spring departure. While pectoralis profile and fat scores enlarged at predeparture in spring and fall, pectoralis, cardiac, and body masses were greater only in spring stages, suggesting seasonal differences for migratory preparation. Gastrocnemius mass showed little change throughout all stages, whereas gastrocnemius fiber area declined steadily but rebounded in fall on the wintering grounds, where migrants become more sedentary. In general, residents are heavier birds with larger leg structures, while migrants sport longer wings and greater heart mass. Phenotypic flexibility was most prominent among residents with peaks of pectoralis, gastrocnemius, and body masses during the winter stage, when local weather is most severe. Thus, the subspecies express specific patterns of phenotypic flexibility with peaks coinciding with the stages of heightened energy demands: the winter stage for residents and the spring stages for migrants.

Numerical assessment of low-speed impacts on ballistic gelatin on a spring stage as a human bio-simulant

Numerical assessment of low-speed impacts on ballistic gelatin on a spring stage as a human bio-simulant

The influence of diet on gut microbiome and body mass dynamics in a capital-breeding migratory bird.

Gut-associated microbial communities are known to play a vital role in the health and fitness of their hosts. Though studies investigating the factors associated with among-individual variation in microbiome structure in wild animal species are increasing, knowledge of this variation at the individual level is scarce, despite the clear link between microbiome and nutritional status uncovered in humans and model organisms. Here, we combine detailed observational data on life history and foraging preference with 16S rRNA profiling of the faecal microbiome to investigate the relationship between diet, microbiome stability and rates of body mass gain in a migratory capital-breeding bird, the light-bellied Brent goose (Branta bernicla hrota). Our findings suggest that generalist feeders have microbiomes that are intermediate in diversity and composition between two foraging specialisms, and also show higher within-individual plasticity. We also suggest a link between foraging phenotype and the rates of mass gain during the spring staging of a capital breeder. This study offers rare insight into individual-level temporal dynamics of the gut microbiome of a wild host. Further work is needed to uncover the functional link between individual dietary choices, gut microbiome structure and stability, and the implications this has for the reproductive success of this capital breeder.

The Effects of Phased Warming during Late Winter and Early Spring on Grain Yield and Quality of Winter Wheat (Triticum aestivum L.)

Phased warming in late winter and early spring can increase winter wheat grain yield. However, the effects of different durations of warming during this period on winter wheat grain yield and quality are not yet clear. Therefore, this study conducted field warming experiments in a movable polyethylene greenhouse during the late winter and early spring stages of the three wheat growing seasons from 2019 to 2022. The results showed that the accumulated growing degree days (GDD) of the warming treatment during the warming period were increased by 87.3–215.7 °C d compared to the control (CK). The warming treatment advanced and prolonged the duration of vegetative growth and spike differentiation after regreening, promoted spike and flower development, and increased grain length, grain width, and grain area. During the three growing seasons, the longer the warming duration (WD) of the warming treatment, the more obvious were the observed promoting effects on the kernel number per spike and 1000-kernel weight. From 2019 to 2021, compared to the CK, the spike number per unit area and grain yield of the warming treatments increased with the prolongation of WD. However, in the 2022 growing season the spike number per unit area and grain yield of the warming treatment were increased with longer WD, reaching the maximum at WD of 56 days and then gradually decreasing with longer WD. Compared to CK, the grain protein content, wet gluten content, and sedimentation value of the warming treatment decreased with the prolongation of WD. The promotion effect of longer WD on grain starch content and protein yield was more significant. In summary, the accumulated GDD during the warming period compared to CK was 155.8–181.2 °C d, and at WD of 50–56 days a relatively higher grain yield and protein yield could be obtained.

Food on a plate: Wild geese maintain higher food intake rates on uniform winter cereals fields versus diverse grasslands

Spring staging Greater White-fronted Geese Anser albifrons have increasingly shifted from traditional diverse grassland fields to monocultures of winter cereals, causing conflict with farmers. To account for this transition, we tested two key predictions, controlling for goose age effects and sward height. Firstly, that cereal is better quality than grass (based on crude protein content). Secondly, that geese show higher peck rate and step rate on grassland than cereal, enabling them to compensate for lower, less selective intake rates there compared to the uniform, dense, high quality arable sward where all blades are equally of high profitability. Laboratory analyses showed that winter cereal had 27 % higher crude protein content than grass. Based on data extracted from video sequences of spring foraging geese in NE Poland, first-year birds (“immatures”) showed significantly higher peck rates and step rates than adults in all situations, likely reflecting their less efficient foraging abilities. Both age classes showed significantly higher peck rates on grass than winter cereal as predicted. Combining differential protein content and lamina length/dry weight relationships of grass versus cereal showed that geese obtained 17–33 % more protein from cereal lamina of the same length. At observed peck rates, this equated to a 6 % greater hourly crude protein intake rate on cereals compared to grass at lamina length 2.5 cm, increasing to 29 % difference at 12.5 cm. Hence, at longer swards, cereals become increasingly profitable for foraging geese over grass swards, despite the higher peck rates observed on grass which failed to compensate for lower lamina quality. We contend that these interactions explain the simultaneous attraction of cereal over grass swards in this study area and likely elsewhere and we discuss the management implications of these findings.

Hydrological Functioning and Water Availability in a Himalayan Karst Basin under Climate Change

Karst springs are important water sources for both human needs and environmental flows. The responses of karst springs to hydrometeorological factors vary depending on local conditions. In this study, we investigated Martandnag spring in the Liddar catchment in the Kashmir valley of northern India. We used statistical time series (autocorrelation and cross-correlation) and machine-learning (ML) techniques (random forest regression (RFR) and support vector regression (SVR)) to characterize how rainfall, temperature, and snow cover affect the karst spring flow and predict the future responses of the spring stage based on climate scenarios, in the Intergovernmental Panel on Climate Change Assessment Report 6. The statistical time series showed that the memory effect of Martandnag spring varies from 43 to 61 days, indicating moderate karstification and a relatively high storage capacity of the karst aquifer in the Liddar catchment. The delay between recharge and discharge varies from 13 to 44 days, and it is more strongly correlated to snow/ice melt than to rainfall. The ML analysis shows that SVR outperformed RFR in predicting spring flow. Under all climate scenarios, a trained SVR model showed that spring flow increased during the late winter to early spring, and decreased during the summer (except in August) and in autumn. Scenarios with increased greenhouse gas emissions further reduced flow in the summer and autumn. These predictions can be helpful for water-resource planning in similar watersheds in the Western Himalayas.

Analysis of short-term and local scale variations in fish community structure in Dachen Island waters

Understanding the changes in community structure of fishery resources in island reef waters is crucial for effective fishery resource management, as these waters constitute a critical link in maintaining the sustainable development of offshore fishery resources. The study analyzed the structure of the fish community in the waters surrounding Dachen Island by using data collected during four voyage surveys conducted between September 2020 and April 2021. The study utilized co-occurrence network analysis, multiple regression trees, and functional diversity analysis to investigate the short-term and local scale changes in fish community structure. The results showed that the fish community in the waters adjacent to Dachen Island can be categorized into two groups: annual and stage-use species. The stage-use species include Scoliodon laticaudus, Trichiurus lepturus, Tetraodontidae, and others, which are used during the summer and autumn stages of bait migration. Additionally, Dasyatidae and others, which used during the winter and spring stages of reproductive migration. Furthermore, the study found that the habitats dominated by nearshore rocky habitats and distant deep habitats formed the local scale variation in community structure in island waters. The integrated analysis of species α-diversity and functional diversity provided a basis for understanding the mechanisms of biodiversity action. Our study aims to provide a theoretical framework for the development of fishery resource management strategies based on the life cycle of fish, and to serve as a reference for the prioritization of key protection areas for fishery resources in island and reef environments. Overall, the study’s findings can promote the understanding of community structure dynamics in island waters. Additionally, these findings can offer valuable insights into the restoration of habitats and the implementation of marine ranching activities in Dachen Island. Moreover, the outcomes can serve as a theoretical foundation for the development of appropriate management and conservation strategies for fisheries resources.

Co-occurrence with Greylag Geese Anser anser and other factors affecting vigilance in White‑fronted Geese Anser albifrons during their spring staging in Central Europe

Vigilance, a crucial factor affecting the behaviour of birds, is key to the safety of migratory animal flocks against predators and other threats. We examined the vigilance of White-fronted Geese in the Biebrza Basin (NE Poland), one of their major stopover sites in Europe. The study took place during their spring staging, from the end of February until the beginning of April. We found that the vigilance of White-fronted Geese decreased in the centre of mixed flocks with Greylag Geese. This may be associated with the larger size and wider field of view of Greylag Geese, as well as their territorial behaviour, as some of them belong to the local breeding population. White-fronted Geese can benefit from the group-size effect when they form larger flocks. In the presence of a vigilance stimulus, the individuals in the centre of a flock raised their alertness levels. As the probability of detecting danger is higher in large groups, flock size negatively affected the birds’ vigilance. Owing to their different experience and roles (adults care for their broods by being vigilant), adult birds appeared to be vigilant on both grassland and arable land, whereas immatures were vigilant only on arable land, where exposure to predatory pressure was greater. We believe that the lower level of vigilance of White-fronted Geese in large and mixed flocks may give them more time for foraging and, therefore, improve their chances of survival and breeding success during the oncoming spring.

Tabusintac Bay (New Brunswick, Canada): an important spring migratory stopover for Atlantic Brant (<i>Branta bernicla hrota</i>)

Atlantic Brant (Branta bernicla hrota) is an Arctic-breeding migratory waterfowl that relies heavily on Common Eelgrass (Zostera marina) for food during migration and overwintering. Although the abundance of Atlantic Brant along the coasts of the Maritime provinces has declined drastically over the past decades, some flocks continue to migrate through the area in spring. Here, we present field observations of Atlantic Brant spring staging in the Tabusintac Bay, New Brunswick, Canada. We surveyed the Tabusintac Bay seven times between 26 May and 6 June 2018. We observed a maximum daily count of 1259 individuals, which is comparable to high counts from the 1970s. These spring surveys indicate the continuing importance of Tabusintac Bay to Atlantic Brant for spring staging. There is a pressing need to increase monitoring and research in the region and to preserve or enhance the quality of the area for spring staging brant.

Should I breed or should I go? Manipulating individual state during migration influences breeding decisions in a long‐lived bird species

Abstract Documentation of carry‐over effects (COEs), defined as effects resulting from events that occurred in a previous time period, has largely been observational and understanding of specific mechanisms underlying COEs is still lacking. To investigate this, we simulated an environmental perturbation during the spring migration of a long‐lived bird species and looked at the subsequent effects on various breeding parameters. We captured female greater snow geese Anser caerulescens atlanticus on their spring staging sites and maintained individuals in captivity for up to 4 days before releasing them. We re‐observed females 3000 km North, on their Arctic breeding grounds, to estimate their breeding propensity (i.e. probability of initiating a reproductive event for a given year), and measured their arrival date, laying date, clutch size and nesting success. Only proxies of breeding propensity were affected by our manipulation, which decreased as the time spent in captivity increased. However, females were able to overcome the effects of captivity in two out of the 3 years of experimentation with normal or good environmental conditions at the breeding site. When facing the additional challenge of poor environmental conditions, many individuals manipulated during migration apparently curtailed their reproductive effort by skipping breeding. This experiment is the first to show that breeding propensity is an important parameter affected by COEs resulting from stressful events prior to reproduction in long‐lived species. Read the free Plain Language Summary for this article on the Journal blog.

Methane migration, sea ice melting and spatial distribution of chlorophyll-a in the Barents Sea

The paper considers the theoretical and practical aspects of the relationship between the processes of sea ice melting and methane migration, and their influence on the distribution of chlorophyll-a concentration as an indicator of productivity and the level of quantitative development of the phytoplankton community at the spring stage of the succession cycle. In the spring of 2018 and 2019 the thermohaline characteristics of waters and the content of chlorophyll-a in the Barents Sea were studied. The area of work covered both areas with the most probable release of methane from near-bottom gas hydrates, as well as background areas, where the presence of methane hydrates is unlikely. In 2018, the phytoplankton community of the study area was in the spring flowering stage. In the area of the most probable influence of methane, the average concentrations of chlorophyll-a were approximately 2 times higher than in the background area. High concentrations of the pigment were associated with the thawed layer, which may indicate the release of methane from the ice. In 2019, low concentrations of chlorophyll-a in the edge zone excluded the stage of spring flowering of the phytoplankton community, which did not allow us to trace the possible effect of the release of methane hydrates on the concentration of chlorophyll-a.

Birds of The Shumagin Islands, Alaska

We studied birds in the Shumagin Islands in 18 of the 37 years from 1970 to 2006 and synthesized all available information on birds of this area. A total of 126 forms of 125 species, including hypothetical species, has been recorded in the Shumagins, of which aquatic birds constitute 67% and terrestrial birds 33%. Overall, 52% of all forms breed, probably breed, or formerly bred; of these, aquatic birds represent 57% and terrestrial birds 43%. The avifauna is heavily weighted toward Nearctic (39% of all forms) and Beringian (32%) forms, followed by Holarctic (21%), Palearctic (6%), and Oceanian (2%) forms; breeding taxa are even more heavily weighted toward Beringian (46%) and Nearctic (40%) forms. The Shumagins have few breeding waterfowl, other freshwater birds, and shorebirds and are not on important flyways for any of these groups, despite lying near important spring and fall staging areas on the nearby Alaska Peninsula. The seabird and terrestrial avifaunas are diverse and similar to those in nearby areas, especially the eastern Aleutians. Populations of several seabird species in the Shumagins have declined substantially over the last 40 years. Two terrestrial species, the Pacific Wren (Troglodytes pacificus) and Pine Grosbeak (Pinicola enucleator), have expanded their breeding ranges into this area, and breeding distributions of some terrestrial birds in the outer Shumagins appear to be changing. Changes in range or breeding status have been caused, at least in part, by predation by introduced foxes, overgrazing by introduced cattle degrading already limited habitat, and the introduction of ground squirrels.

Solanum elaeagnifolium Invasiveness under Semi-Arid Environmental Conditions in Tunisia

Solanum elaeagnifolium, one of the world’s most widespread invasive weeds, thrives in the regions of Tunisia with a semi-arid climate. An enhanced understanding of its biological traits could be useful for its management. For this purpose, S. elaeagnifolium vegetative propagation, flowering, fruiting, and spread patterns were assessed under semi-arid environmental conditions at Chott Mariem (Tunisia) over three years (2013–2015). Our results revealed that S. elaeagnifolium showed an active vegetative growth phase during the spring (March–May). Thereafter, the plant stopped its vegetative growth in June–August in favor of flowering and fruiting. The vegetative growth resumed during September–October and declined in November, announcing its dormant period. Thanks to its vigorous rhizomatous system, S. elaeagnifolium was able to emit offshoots within a radius of 1.5 m from parent shoots by 30 months after its establishment. These findings could inform and improve dedicated management control options for S. elaeagnifolium. Silverleaf nightshade should be controlled before the full-flowering stage in spring and following the first autumnal rainfall to prevent vegetative propagation and fruiting.

Factors that affect migratory Western Atlantic red knots (Calidris canutus rufa) and their prey during spring stagingon Virginia's barrier islands.

Understanding factors that influence a species' distribution and abundance across the annual cycle is required for range-wide conservation. Thousands of imperiled red knots (Calidris cantus rufa) stop on Virginia's barrier islands each year to replenish fat during spring migration. We investigated the variation in red knot presence and flock size, the effects of prey on this variation, and factors influencing prey abundance on Virginia's barrier islands. We counted red knots and collected potential prey samples at randomly selected sites from 2007-2018 during a two-week period during early and peak migration. Core samples contained crustaceans (Orders Amphipoda and Calanoida), blue mussels (Mytilus edulis), coquina clams (Donax variabilis), and miscellaneous prey (horseshoe crab eggs (Limulus polyphemus), angel wing clams (Cyrtopleura costata), and other organisms (e.g., insect larvae, snails, worms)). Estimated red knot peak counts in Virginia during 21-27 May were highest in 2012 (11,959) and lowest in 2014 (2,857; 12-year peak migration [Formula: see text] = 7,175, SD = 2,869). Red knot and prey numbers varied across sampling periods and substrates (i.e., peat and sand). Red knots generally used sites with more prey. Miscellaneous prey ([Formula: see text] = 2401.00/m2, SE = 169.16) influenced red knot presence at a site early in migration, when we only sampled on peat banks. Coquina clams ([Formula: see text] = 1383.54/m2, SE = 125.32) and blue mussels ([Formula: see text] = 777.91/m2, SE = 259.31) affected red knot presence at a site during peak migration, when we sampled both substrates. Few relationships between prey and red knot flock size existed, suggesting that other unmeasured factors determined red knot numbers at occupied sites. Tide and mean daily water temperature affected prey abundance. Maximizing the diversity, availability, and abundance of prey for red knots on barrier islands requires management that encourages the presence of both sand and peat bank intertidal habitats.

Research on soil physical characteristics and dynamic response of groundwater to irrigation in typical irrigation area of Huangshui River Basin

Under the influence of the natural and human factors, water table of irrigated area Changes frequently, but it is mainly affected by irrigation water infiltration replenishment. Basic physical properties of different soil layer of the typical field were determined and analyzed, and 5 groundwater observation wells were constructed to carry out the experiment of the response of groundwater to irrigation. The results showed that the upper vertical 0-40 cm is loose, the 40-60 cm layer is relatively tight, and the lower part 60-200 cm tend to loose again. Soil saturated water holding capacity, capillary water holding capacity and field capacity showed increased first and then decreased trend with the increase of soil depth. They almost showed the same nearly evenly spaced degressive trend. The groundwater stage dynamic change rule of spring and seedling irrigation stage in the typical plot was fit to the hydrological geology condition of grade-Iterrace of Huangshui river valley. Lateral canal water direction formed a line effect. The rangeability of water table of spring irrigation period was significantly higher than that of seedling irrigation period.

Changes in Behaviour and Proxies of Physiology Suggest Individual Variation in the Building of Migratory Phenotypes in Preparation for Long-Distance Flights

Long-distance migration in birds is a complex syndrome that involves high energy costs and, in some species, substantial physiological re-organisation. Such flexible migratory phenotypes are commonly associated with bird species flying non-stop across vast ecological barriers, where there are few opportunities to stop and refuelen route. Prior to making migratory flights, some species have been found to atrophy organs that are not required (e.g., digestive organs) and grow those associated with powering flight (pectora muscles and heart), presumably to optimise costs. However, most studies of this flexibility have required sacrificing study animals and this has limited our capacity to measure individual variation and its potential consequences. Here we investigate the behavioural and, indirectly, physiological adaptation of an arctic breeding long-distance migrant the light-bellied brent gooseBranta bernicla hrota, during spring staging in southwest Iceland. We use a sequential sampling approach to record behavioural observations and conduct stable isotope analysis of faecal samples from uniquely marked individuals to assess protein catabolism. Individuals showed a three-phase fuel deposition process, with initial slow intake rates followed by hyperphagia and then a period of inactivity immediately prior to migratory departure (despite multiple days with favourable wind conditions). The C:N ratio and δ15N values in faeces were significantly linked to fat deposition during the latter stages and suggests catabolism (reorganisation of proteins) occurring prior to departure. Our results suggest a strategic delay in migratory departure to enable reorganisation into a flying phenotype and that the extent of this varies among individuals.

Dynamics of pre-breeding nutrient reserves in subarctic staging Lesser Snow Geese (Anser caerulescens caerulescens) and Ross’s Geese (Anser rossii): implications for reproduction

Phenological mismatch occurs when the timing of reproductive events and seasonal availability of resources become decoupled, and is increasing in migratory birds in response to climate change. Arctic-nesting geese acquire important nutrient reserves at spring-staging areas, but advancing springs, combined with large population increases and long-term goose-mediated habitat alteration, could induce a mismatch between optimal timing of nesting and accumulation of required reserves. From 2012 to 2019, we randomly sampled Lesser Snow (<em>Anser caerulescens caerulescens</em>) and Ross’s Geese (<em>Anser rossii</em>) throughout their spring migration near Churchill, Manitoba, Canada. Our objectives were to evaluate patterns of protein and lipid accumulation, and draw comparisons to historical estimates obtained before widespread habitat changes. We found significantly reduced pre-breeding protein reserves in Lesser Snow Geese relative to their historical values, but average protein reserve size increased somewhat with declining population size during the years of our study. Lesser Snow Geese catabolized lipid reserves, and no longer increased protein reserves during spring staging. Protein reserves were on average 17–23% smaller in 2012–2019 than in the 1970s, the deficit being equivalent to the amount of protein found in two to three eggs. In contrast, Ross’s Geese maintained lipid reserves, and accumulated protein during the staging period, irrespective of annual Lesser Snow Geese abundance. Based on patterns in gizzard hypertrophy, they appeared to be using a more digestible food source than were Lesser Snow Geese. Declines in protein reserves may hinder the ability for Lesser Snow Geese to keep nutritional pace with increasingly early springs, and could be an important underlying mechanism driving mismatches between vegetation phenology and emergence of goslings. Differences in recruitment between Lesser Snow Geese and Ross’s Geese could be related to differences in nutrient-reserve dynamics during the final stages of spring migration, which can carry over to influence annual breeding probability, clutch size, nest success, and likelihood of mismatch at a population level.

The annual cycle for whimbrel populations using the Western Atlantic Flyway.

Many long-distance migratory birds use habitats that are scattered across continents and confront hazards throughout the annual cycle that may be population-limiting. Identifying where and when populations spend their time is fundamental to effective management. We tracked 34 adult whimbrels (Numenius phaeopus) from two breeding populations (Mackenzie Delta and Hudson Bay) with satellite transmitters to document the structure of their annual cycles. The two populations differed in their use of migratory pathways and their seasonal schedules. Mackenzie Delta whimbrels made long (22,800 km) loop migrations with different autumn and spring routes. Hudson Bay whimbrels made shorter (17,500 km) and more direct migrations along the same route during autumn and spring. The two populations overlap on the winter grounds and within one spring staging area. Mackenzie Delta whimbrels left the breeding ground, arrived on winter grounds, left winter grounds and arrived on spring staging areas earlier compared to whimbrels from Hudson Bay. For both populations, migration speed was significantly higher during spring compared to autumn migration. Faster migration was achieved by having fewer and shorter stopovers en route. We identified five migratory staging areas including four that were used during autumn and two that were used during spring. Whimbrels tracked for multiple years had high (98%) fidelity to staging areas. We documented dozens of locations where birds stopped for short periods along nearly all migration routes. The consistent use of very few staging areas suggests that these areas are integral to the annual cycle of both populations and have high conservation value.