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In biparental Charadriinae plovers, male and female incubation duties often resemble daily routines, with males typically incubating at night and females incubating during the day. By analysing incubation behaviour in three Arctic populations of Common Ringed Plover Charadrius hiaticula, we show that these diel routines are lost in the 24-h sunlight of the Arctic. In contrast, a non-Arctic population in East Scotland exhibited significant daily routines, with males dominating incubation during the late afternoon and night, and females dominating incubation during the early morning and midday hours. These patterns suggest that clear light/dark cycles are necessary for daily incubation routines to form in the Common Ringed Plover, although further research is needed to understand the specific drivers of this behaviour.

The Prairie Pothole Region of central Canada supports a diverse community of breeding waterbirds, but many species have declining populations and the demographic mechanisms driving the declines remain unknown. We conducted a 7-year field study during 1995–2001 to investigate the demographic performance of Marbled Godwits (Limosa fedoa) and Willets (Tringa semipalmata) breeding in managed wetlands near Brooks, Alberta. Mark-recapture analyses based on Cormack–Jolly– Seber models revealed that the annual rates of apparent survival for Marbled Godwits = 0.953 ± 0.012SE) and Willets ( = 0.861 ± 0.015SE) are among the highest rates of survivorship reported for any breeding or nonbreeding population of large-bodied shorebirds. Our estimates of life expectancy for males were comparable to longevity records in godwits (17.3 years ±5.8SE vs. 25–29+ years) and willets (7.7 ± 1.5SE vs. 10+ years). The two species both showed strong breeding site fidelity but differed in rates of mate fidelity. Pairs that reunited and males that switched mates usually nested 1.1–1.5 km. Returning pairs usually reunited in godwits (85%) but not in willets (28%), possibly because of species differences in adult survival or patterns of migration. Baseline estimates of annual survival for banded-only birds will be useful for evaluating the potential effects of new tracking tags or the environmental changes that have occurred during the past 20 years. Conservation strategies for large-bodied shorebirds should be focused on reduction of exposure to anthropogenic mortality because low rates of natural mortality suggest that losses to collisions at breeding sites or harvest at nonbreeding areas are likely to cause additive mortality. apparent survival, biometrics, demography, longevity, mark recapture, mate fidelity, shorebird, wader Applied ecology, Conservation ecology, Demography, Life history ecology, Population ecology, Zoology

Wire cages (i.e., predator exclosures) are frequently used to protect shorebird nests from predation. While exclosed nests often have higher survival than unexclosed nests, concerns exist over whether the conspicuous structures might draw attention of predators, potentially increasing risks to adults and newly-hatched chicks. We present a new approach to investigating predator responses to exclosures and other stimuli at shorebird nests. We used location data from GPS-collared red foxes (Vulpes vulpes) to examine short-term spatial responses of foxes to exclosure setup and hatching at piping plover (Charadrius melodus) nests on Fire Island, New York. We compared mean distances between fox locations and piping plover nests, and the proportions of fox locations within a 100-m buffer of nests, before and after exclosure setup and before, during, and after hatching. Mean distances from fox locations to nests were similar before versus after exclosure setup (x = 641 m before, 675 m after; permutation test for matched pairs, [PTMP], T = 0.28, P = 0.56, n = 9 foxes), before versus during hatching (x = 417 m before, 340 m during; PTMP, T = -0.93, P = 0.18, n = 5 foxes) and during versus after hatching (x = 340 m during, 330 m after; PTMP, T = 1.00, P = 0.84, n = 5 foxes). The proportions of fox locations within 100-m buffers surrounding nests were similar before versus after exclosure setup (x = 0.01 before, 0.03 after; PTMP, T = 0.26, P = 0.53, n = 9 foxes), before versus during hatching (x = 0.04 before, 0.15 during; PTMP, T = -1.44, P = 0.09, n = 5 foxes), and during versus after hatching (x = 0.15 during, 0.14 after; PTMP, T = 0.84, P = 0.80, n = 5 foxes). In 10 of 19 of our individual-level comparisons, there were no significant differences in the distances from fox locations to nests between paired event periods. In the other 9 individual-level comparisons, we found evidence of shifts in fox space use between paired event periods, but no clear directional trend across individuals. We conclude that the foxes in our study did not appear to consistently key in on exclosure setup or hatching at piping plover nests at the spatial scales considered in our comparisons. We recommend that managers continually re-evaluate the effects of exclosures at their management sites, as changes in nest predation, abandonment rates, and adult plover survival may all influence the relative benefit of exclosures for population growth. Our study illustrates the potential for using spatial data to investigate predator responses to various management actions taken to protect nesting shorebirds and other prey species of conservation interest. U.S. Army Corps of Engineers; U.S. Fish and Wildlife Service; Virginia Polytechnic Institute and State University Published version U.S. Army Corps of Engineers; U.S. Fish and Wildlife Service; Virginia Polytechnic Institute and State University

Individual-based field observations of breeding snowy plovers

Although invasive non-native species can adversely affect biodiversity in many ways, predation of native species by non-native species on islands can be severely damaging. Results of numerous studies document non-native birds preying on birds on islands, but our understanding of the number and type of species affected has been limited by the lack of a global review of these impacts. I identified the non-native bird species that have been recorded preying on birds, the locations where this predation occurred, and the bird species affected. Because the impacts of non-native birds can be particularly severe on small islands, I then identified the islands

Average annual temperatures in the Arctic increased by 2–3 °C during the second half of the twentieth century. Because shorebirds initiate northward migration to Arctic nesting sites based on cues at distant wintering grounds, climate-driven changes in the phenology of Arctic invertebrates may lead to a mismatch between the nutritional demands of shorebirds and the invertebrate prey essential for egg formation and subsequent chick survival. To explore the environmental drivers affecting invertebrate availability, we modeled the biomass of invertebrates captured in modified Malaise-pitfall traps over three summers at eight Arctic Shorebird Demographics Network sites as a function of accumulated degree-days and other weather variables. To assess climate-driven changes in invertebrate phenology, we used data from the nearest long-term weather stations to hindcast invertebrate availability over 63 summers, 1950–2012. Our results confirmed the importance of both accumulated and daily temperatures as predictors of invertebrate availability while also showing that wind speed negatively affected invertebrate availability at the majority of sites. Additionally, our results suggest that seasonal prey availability for Arctic shorebirds is occurring earlier and that the potential for trophic mismatch is greatest at the northernmost sites, where hindcast invertebrate phenology advanced by approximately 1–2.5 days per decade. Phenological mismatch could have long-term population-level effects on shorebird species that are unable to adjust their breeding schedules to the increasingly earlier invertebrate phenologies.

n Focus: Reneerkens, J., Versluijs, T. S. L., Piersma, T., Alves, J. A., Boorman, M., Corse, C., ... Lok, T. (2020). Low fitness at low latitudes: wintering in the tropics in-creases migratory delays and mortality rates in an Arctic breeding shorebird. Journal of Animal Ecology, 89, 691–703. A central question in migratory ecology has been to understand the fitness consequences of individual variation in migration distance among different species and populations. Reneerkens et al. (2020) investigated the demographic consequences of long-distance migration for Sanderlings Calidris alba, an Arctic-breeding species of sandpiper. Their study population has a remark-able geographic distribution with a breeding range that is concentrated in north-east Greenland and Ellesmere Island, Canada but a nonbreeding range that extends across 85° of latitude from Scotland to Namibia. The authors report on unexpected patterns of latitudinal variation in three demographic parameters: timing of passage on northward migration, probability of juvenile migration and apparent survival of adults. Sanderlings travelling 1,800–2,800 km to settle at north temperate sites dur-ing the nonbreeding season had earlier passage dates, and also higher probabilities of migration and apparent survival. In contrast, birds travelling 6,000–7,800 km to equato-rial sites experienced later passage dates, delayed maturity and lower apparent survival. However, if Sanderlings migrated even farther and flew over 11,000 km to nonbreed-ing sites in Namibia, then their performance was restored to early passage dates and higher survival. Movement tracks from birds tagged with geolocators showed that birds wintering in Namibia make nonstop flights of 7,500 km that bypass West Africa during northward migration. Thus, all lines of evidence suggest that Sanderlings face adversity when spending the nonbreeding season at equatorial latitudes. Moreover, the central finding that components of fitness can have nonlinear relationships with migration dis-tance is a novel discovery that leads to many additional questions. The new findings have broader implications for theoretical models of migration, and for understanding how different patterns of movements may arise or be maintained in migratory species

Background Dispersal is a critical life history strategy that has important conservation implications, particularly for at-risk species with active recovery efforts and migratory species. Both natal and breeding dispersal are driven by numerous selection pressures, including conspecific competition, individual characteristics, reproductive success, and spatiotemporal variation in habitat. Most studies focus on dispersal probabilities, but the distance traveled can affect survival, fitness, and even metapopulation dynamics. Methods We examined sources of variation in dispersal distances with 275 natal dispersal and 1335 interannual breeding events for piping plovers (Charadrius melodus) breeding in the Northern Great Plains between 2014 and 2019. Results Natal dispersal was on average longer (mean: 81.0 km, median: 53 km) than adult breeding movements (mean: 23.7 km, median: 1 km). Individuals moved the shortest distances when hatched, previously nested, or settling on river habitats. When more habitat was available on their natal area than in the year prior, hatch-year birds moved shorter distances to their first breeding location. Similarly, adults also moved shorter distances when more habitat was available at the settling site and when in closer proximity to other known nesting areas. Additionally, adult movement distance was shorter when successfully hatching a nest the year prior, retaining a mate, or initiating a current nest earlier. Conclusion Habitat availability appears to be associated with dispersal distance for both hatch-year and adult piping plovers. Conservation efforts that integrate dispersal distances may benefit from maintaining nesting habitat within close proximity to other areas for adults and a network of clustered sites spread out across a larger landscape for natal dispersal.

Coastal wetlands form a transition zone between terrestrial and marine environments and provide important ecosystem services. Land-use change in the coastal zone has a substantial effect on habitat connectivity and biodiversity. However, few studies have characterized the effects of land-use change on coastal habitat connectivity. We conducted remote sensing analysis, modeling with the Integrated Valuation of Ecosystem Services and Trade-offs model, geospatial analysis, and habitat connectivity analysis to evaluate historical spatiotemporal changes in the habitat quality and habitat connectivity of migratory shorebirds in the Yellow River Delta, which is an important stopover site along the East Asian–Australasian Flyway migratory route. Several high- and medium-quality areas have been converted to industrial mining and mariculture sites because of land reclamation. The probability of connectivity decreased by −66.7% between 1975 and 2020. Approximately 71.0%, 11.6%, and 5.8% of patches with high importance have been converted to non-habitat patches, habitat patches with medium importance, and habitat patches with low importance, respectively; approximately 58.9% and 11.7% of the patches with medium importance have been converted to non-habitat patches and habitat patches with low importance, respectively. The total priority conservation area was 389.4 km2, and 125.0 km2 (32.1%) of this area remains unprotected; these unprotected areas are mainly distributed in the northwestern and eastern parts of the Yellow River Delta. We recommend that the boundary of the Yellow River Delta National Nature Reserve be expanded to incorporate these unprotected areas.

Background Despite an increasing number of surveys and a growing interest in birdwatching, the population and distribution of Asian Dowitcher (Limnodromus semipalmatus), a species endemic to the East Asian–Australasian and Central Asian Flyways, remains poorly understood, and published information about the species is largely outdated. In boreal spring 2019, over 22,432 Asian Dowitchers were recorded in a coastal wetland at Lianyungang, Jiangsu Province, China, constituting 97.5% of its estimated global population. Methods In 2019 and 2020, we conducted field surveys at Lianyungang to determine the numbers of Asian Dowitchers using the area during both southward and northward migrations. We also assessed the distribution and abundance of Asian Dowitchers elsewhere along the China coast by searching literature and consulting expert opinion. Results The coastal wetlands of Lianyungang are the most important stopover site for Asian Dowitchers during both northward and southward migrations; they supported over 90% of the estimated global population during northward migration in two consecutive years (May 2019 and 2020). This area also supported at least 15.83% and 28.42% (or 30.74% and 53.51% using modelled estimates) of the global population during southward migration in 2019 and 2020 respectively. Coastal wetlands in the west and north of Bohai Bay also have been important stopover sites for the species since the 1990s. Although comprehensive, long-term monitoring data are lacking, available evidence suggests that the population of the species may have declined. Conclusions The high concentration of Asian Dowitchers at Lianyungang during migration means the species is highly susceptible to human disturbances and natural stochastic events. The coastal wetlands of Lianyungang should be protected and potentially qualify for inclusion in China’s forthcoming nomination for World Heritage listing of Migratory Bird Sanctuaries along the Coast of Yellow Sea-Bohai Gulf of China (Phase II) in 2023. Additional research is needed to understand Asian Dowitchers’ distribution and ecology, as well as why such a high proportion of their population rely on the Lianyungang coast.

Drivers of environmental change are causing novel combinations of pressures on ecological systems. Prediction in ecology often uses understanding of past conditions to make predictions to the future, but such an approach can breakdown when future conditions have not previously been encountered. Individual-based models (IBMs) consider ecological systems as arising from the adaptive behaviour and fates of individuals, and have potential to provide more reliable predictions. To demonstrate potential, we review a lineage of related IBMs addressing the effects of environmental change on waterbirds, comprising 53 case studies of 28 species in 32 sites in 9 countries, using the Drivers-Pressures-State-Impact-Response (DPSIR) environmental management framework. Each case study comprises the predictions of an IBM on the effects of one or more drivers of environmental change on one or more bird species. Drivers exert a pressure on the environment which is represented in the IBMs as changes in either the area or time available for feeding, the quality of habitat, or the energetic cost of living within an environment. Birds in the IBMs adapt to increased pressure by altering their behavioural state, defined as their location, diet and the proportion of time spent feeding. If the birds are not able to compensate behaviourally, they suffer a physiological impact, determined by a decrease in body energy reserves, increased mortality or decreased ability to migrate. Each case study assesses the impact of alternative drivers and potentially ways to mitigate impacts to advise appropriate conservation management responses. We overview the lessons learned from the case studies and highlight the opportunities of using IBMs to inform conservation management for other species. Key findings indicate that understanding the behavioural and physiological processes that determine whether or not birds survive following a change in their environment is vital, so that mitigation measures can be better targeted. This is especially important where multiple hazards exist so that sensitivities and worse case scenarios can be better understood. Increasing the involvement of stakeholders to help inform and shape model development is encouraged, and can lead to better representation of the modelled system, and wider understanding and support for the final model.

Background In-flight conditions are hypothesized to influence the timing and success of long-distance migration. Wind assistance and thermal uplift are thought to reduce the energetic costs of flight, humidity, air pressure and temperature may affect the migrants’ water balance, and clouds may impede navigation. Recent advances in animal-borne long-distance tracking enable evaluating the importance of these factors in determining animals’ flight altitude. Methods Here we determine the effects of wind, humidity, temperature, cloud cover, and altitude (as proxy for climbing costs and air pressure) on flight altitude selection of two long-distance migratory shorebirds, far eastern curlew (Numenius madagascariensis) and whimbrel (Numenius phaeopus). To reveal the predominant drivers of flight altitude selection during migration we compared the atmospheric conditions at the altitude the birds were found flying with conditions elsewhere in the air column using conditional logistic mixed effect models. Results Our results demonstrate that despite occasional high-altitude migrations (up to 5550 m above ground level), our study species typically forego flying at high altitudes, limiting climbing costs and potentially alleviating water loss and facilitating navigation. While mainly preferring migrating at low altitude, notably in combination with low air temperature, the birds also preferred flying with wind support to likely reduce flight costs. They avoided clouds, perhaps to help navigation or to reduce the risks from adverse weather. Conclusions We conclude that the primary determinant of avian migrant’s flight altitude selection is a preference for low altitude, with wind support as an important secondary factor. Our approach and findings can assist in predicting climate change effects on migration and in mitigating bird strikes with air traffic, wind farms, power lines, and other human-made structures.

Mangroves provide an ecotourism-based destination that can support mangrove conservation and biodiversity management programs, as well as an important stopover for migrating shorebirds. The importance of mangrove forest habitat for aquatic life functions as an activator of mangrove forests, conservation efforts are needed. Pasir Jambak Beach does not have mangrove vegetation, but has a relatively wide sand substrate along the coastline. Environmental factors other than prey abundance affect species richness and abundance of shorebirds. The richness of shorebirds in the mangrove wetlands is significantly and positively correlated with the mud plain area. Obviously, the vast wetlands are important factors that affect the distribution of shorebirds.

Sea level rise (SLR) and disturbances from increased storm activity are expected to diminish coastal ecosystems available to nesting species by removing habitat and inundating nests during incubation. We updated the United States Geological Survey's (USGS) Coastal Vulnerability Index, which provides a qualitative and relative assessment of a coastal area's vulnerability to erosion and shoreline retreat as a function of SLR and other factors, for the South Atlantic Bight. We considered a eustatic SLR projection of 14 cm by 2030. We linked long-term survey data for 3 sea turtle species, 3 shorebird species, and 5 seabird species to future coastal erosion vulnerability to SLR to understand effects of future SLR on nesting habitats. Over 2,000 km (43%) of the South Atlantic Bight coastline is projected to have an increase in coastal erosion vulnerability by the 2030s, with respect to its present vulnerability. Future vulnerability of SLR-induced erosion along the South Atlantic Bight is spatially variable, and the 11 coastal study species also varied in their use of coastal habitats with high future coastal vulnerability to SLR. For example, only 23% of high-density nesting habitat for the brown pelican (Pelecanus occidentalis) is expected to be at increased vulnerability to SLR, whereas >70% of the high-nesting density habitat for 2 seabird species (gull-billed tern [Gelochelidon nilotica], sandwich tern [Thalasseus sandvicensis]) is predicted to have higher future coastal erosion vulnerability by 2030. We provide predictions for the level of susceptibility of the study species to erosion from future SLR, which is the first step in managing coastal species for the changing environmental conditions associated with climate change and SLR. (c) 2019 The Authors. Journal of Wildlife Management Published by Wiley Periodicals, Inc. on behalf of The Wildlife Society. USFWS; South Atlantic Landscape Conservation Cooperative The findings and conclusions in this article are those of the authors and do not necessarily represent the views of the U.S. Fish and Wildlife Service. Sea turtle data were provided by the Florida Fish and Wildlife Conservation Commission Statewide Nesting Beach Survey, Canaveral National Seashore, University of Central Florida Marine Turtle Research Group, Archie Carr National Wildlife Refuge survey, Georgia Department of Natural Resources Sea Turtle Conservation Program, South Carolina Department of Natural Resources Marine Turtle Conservation Program, and North Carolina Wildlife Resources Commission Sea Turtle Project. D. Griffin provided data and information for South Carolina sea turtles. Seabird and shorebird nesting and occupancy data were provided by the Florida Fish and Wildlife Conservation Commission, Georgia Department of Natural Resources, South Carolina Department of Natural Resources, and North Carolina Wildlife Resources Commission. J. Brush provided the Florida seabird and shorebird data and background information. We sincerely thank the individual permit holders and volunteers who collected the sea turtle data for Florida, Georgia, North Carolina, and South Carolina, and the Air Force, 45th Space Wing. We appreciate the contributions from S. Pierre and M. Auman in organizing the biological data. We also thank S. Maddock and W. Golder for wintering piping plover data. The authors thank S. Dellinger and J. Heisey for their contributions to the wave gauge data analyses. We thank S. Hagan and D. Passeri for their contribution to the shoreline change analysis. Funding for Florida's sea turtle monitoring program has been provided by grants to the Florida Wildlife Commission under Project E -7 from the USFWS and by proceeds from sales of the Florida marine turtle license plates. This work was funded by the South Atlantic Landscape Conservation Cooperative.

Background Anthropogenic disturbance can negatively affect an animal’s energy budget by evoking movement responses. Existing research focuses mainly on immediate displacement as a disturbance effect, since this can be easily observed in the field. However, effects on movement over longer timescales are poorly examined and it is largely unknown if and to what extent they reflect immediate responses. Longer-term responses could for example be larger than immediate responses if birds, after disturbance, return to the original location and thereby travel twice the immediate disturbed distance. Methods We combined GPS tracking data with observational data to quantify the effects of anthropogenic (air force and walkers) and non-anthropogenic disturbances on distances travelled by roosting Eurasian Oystercatchers (Haematopus ostralegus) during the non-breeding season. We compared immediate displacement after a disturbance with distance travelled during the entire high tide period (longer-term response), while accounting for environmental factors. Additionally, we calculated energy expenditure due to disturbance based on observed disturbance frequencies. Results Disturbance resulted in an immediate displacement response of ~ 200 m (median). Air force disturbances tended to yield larger immediate responses than walker and, especially, than non-anthropogenic disturbances. Longer-term responses and immediate responses were approximately similar, suggesting that, over longer timescales, spatial disturbance effects in the study area remain confined to immediate effects. However, disturbances were infrequent (0.17 disturbances per bird per hour) and most disturbances were of natural origin (62%). Consequently, anthropogenic disturbance of roosting oystercatchers in the study area on average costs 0.08% of the daily energy expenditure. Conclusions Our results suggest that immediate spatial responses to disturbance can be a useful proxy for spatial responses over longer timescales. Over the non-exhaustive range of conditions investigated, energetic consequences of spatial disturbance responses for an oystercatcher in the study area are marginal due to low disturbance levels.

These morphometric data are in two tables from surfbirds (adults and chicks) captured at two locations in southcentral Alaska, 1997-1999.

Acoustic analysis does not support the elevation of Central and Western Canary Islands subspecies of the Eurasian Stone-curlew Burhinus oedicnemus distinctus to full species. To verify whether the vocal repertoires of Eurasian Stone-curlew subspecies oedicnemus and distinctus show biologically significant quantitative and qualitative differences. We carried out an acoustic analysis of some of the most frequently used call types of Eurasian Stone-curlew, recorded in Italy and in the Canary Islands. Additionally, we used playback experiments to test the response of the two subspecies to calls of their own and the other subspecies. The vocal repertoires of the individuals belonging to the two subspecies were rather similar, but the quantitative analysis of acoustic parameters showed some differences between the populations. In particular, the three most used call types showed higher frequency and faster utterance rhythm for distinctus than oedicnemus. Playback experiments indicated that individuals from the nominate subspecies responded in the same way to the playback of calls of individuals belonging to both subspecies. Acoustic analysis supports the distinctiveness of Eurasian Stone-curlew populations from Central and Western Canary Islands, thus confirming the available morphological and genetic data. These results, however, do not suggest that distinctus should be elevated to a full species.

Factors affecting stopover duration in birds are still much discussed. Field studies report contradictory evidence regarding the effect of fuel reserves on bird decision to depart from a stopover site, while the majority of laboratory tests performed on passerines reported a positive relationship between body conditions and migratory restlessness. In recent years, a few studies integrating laboratory and field investigations suggested that the amount of migratory restlessness could be a proxy of the individual willingness to depart from a stopover site in night-migrating passerines, but similar studies are lacking for other groups of birds. In this paper the factors affecting stopover length in the Wood sandpiper Tringa glareola (Charadriiformes Scolopacidae) were studied by integrating field observations and laboratory tests during spring migration. Our aims were to investigate (1) the influence of body conditions on migratory restlessness and (2) the influence of body conditions and of the amount of migratory restlessness on stopover duration, after controlling for meteorological conditions. Contrary to our expectations, we did not find any relationship between body condition and migratory restlessness nor stopover duration, while for the 1st time in a non-passerine species, evidence was produced that the amount of migratory restlessness is significantly related to the likelihood of leaving the stopover area. Our results emphasize the relevance of the studies integrating field and laboratory tests to understand the physiological and ecological factors affecting migratory behaviour in different bird species. Body conditions seem to be unrelated both to migratory restlessness and stopover duration. Migratory restlessness predicts the likelihood of leaving the stopover site. The quantification of migratory restlessness seems to be a useful tool for studying the effect of intrinsic and extrinsic factors on stopover behaviour in shorebirds.

Understanding relationships between habitat and ecological processes often depends on the spatial scale at which the landscape is measured. A common objective in studies of avian nesting ecology is to link habitat characteristics with nest predation for generating potential conservation and management strategies aimed at increasing avian reproductive success. Yet scale dependence likely plays a considerable role in these assessments, particularly when multiple species of nest predators are present. We identified nest predators of snowy plovers, a ground‐nesting shorebird, and modeled predator‐specific hazard rates of nest mortality in relation to the landscape at multiple spatial scales (200 m, 500 m, 1 km, 2.5 km, and 5 km) and at the nest site. We used a Bayesian latent indicator approach for weighting the influence of habitat across spatial scales and to gain insight into the hierarchical nature of how specific predators responded to the landscape when preying upon plover nests. We did not identify a common spatial scale that best predicted nest predation by all predators, though our results indicated that unfragmented playa and marsh habitats at large spatial scales reduced nest predation by all nest predators. Land cover features including grass, shrubs, human development, and open water elicited variable responses depending on the predator group, and predator groups responded at different spatial scales. Further, the spatial configuration of nests (nest dispersion) influenced nest predation by common ravens Corvus corax and foxes (kit fox Vulpes macrotis and red fox Vulpes vulpes), suggesting that certain predators develop a search image for nests. Our results illustrate that clarifying complex relationships between nest predation and habitat characteristics requires the incorporation of predator identity and scale dependence. Thus, management and conservation plans aiming to increase avian productivity by altering or restoring habitats will likely benefit from consideration of predator‐specific patterns at multiple spatial scales.

SummaryThe Spoon-billed Sandpiper Calidris pygmaea is a ‘Critically Endangered’ migratory shorebird. The species faces an array of threats in its non-breeding range, making conservation intervention essential. However, conservation efforts are reliant on identifying the species’ key stopover and wintering sites. Using Maximum Entropy models, we predicted Spoon-billed Sandpiper distribution across the non-breeding range, using data from recent field surveys and satellite tracking. Model outputs suggest only a limited number of stopover sites are suitable for migrating birds, with sites in the Yellow Sea and on the Jiangsu coast in China highlighted as particularly important. All the previously known core wintering sites were identified by the model including the Ganges-Brahmaputra Delta, Nan Thar Island and the Gulf of Mottama. In addition, the model highlighted sites subsequently found to be occupied, and pinpointed potential new sites meriting investigation, notably on Borneo and Sulawesi, and in parts of India and the Philippines. A comparison between the areas identified as most likely to be occupied and protected areas showed that very few locations are covered by conservation designations. Known sites must be managed for conservation as a priority, and potential new sites should be surveyed as soon as is feasible to assess occupancy status. Site protection should take place in concert with conservation interventions including habitat management, discouraging hunting, and fostering alternative livelihoods.

Publisher's version (útgefin grein), For many migratory species, migration can represent a significant part of the annual cycle and the strategies used to move between the breeding and non-breeding areas vary considerably. Weather conditions are important during migration, particularly wind and temperature, and can play a crucial role in the timing of events during the annual cycle of migratory birds. When timing of specific events is important, for example spring arrival and laying dates, the effects of weather on the previous migration might lead to important fitness consequences, as it may alter migration speed. During spring, Icelandic whimbrels Numenius phaeopus islandicus display two main migratory behaviors: a direct flight from the wintering to the breeding sites (direct migration), or, more commonly, two flights with one stopover (stopover migration). We investigated how wind conditions, temperature and spring departure date may drive individuals to adopt either migratory behavior. Interestingly, we found no differences in wind support during migratory flights, in temperature closer to Iceland or on crosswinds experienced in the region before reaching the main stopover areas. However, when individuals undertook a direct flight, departure date from the wintering sites was on average later, but this was not explained by wind patterns over a period of 7 days prior to departure. In addition, we explored the variation at the individual level for three birds that changed migratory behavior between years. The differences in all variables for these individuals reflected the variation observed at the population level. Overall, in such long migrations, it seems advantageous to perform a shorter flight to a stopover area, from where the weather conditions in the breeding areas may be assessed and avoid the risk of facing stochastic inclement weather prior to breeding, while synchronizing time of arrival with conspecifics. In contrast, direct flights seem more common when individuals are time pressed., This work was funded by RANNIS (Grant Nos: 130412-052 and 152470-052), the University of Iceland Research Fund, FCT/MCTES through national funds to CESAM (UIDP/50017/2020 + UIDB/50017/2020), CC (PD/BD/113534/2015), and JA (SFRH/BPD/91527/2012) and ProPolar.

Punta Banda, located in Baja California, Mexico, is made up of a five-mile long sandbar that extends into Todos Santos Bay (Bahía de Todos Santos) and creates a protected estuary with salt marsh, mud flat, sand dune, and lagoon zones that provide habitat to a variety of species, including migratory and resident birds. Wetlands and birds can be useful topics for engaging the public in conservation efforts because they are culturally relevant, inspire wonder, encourage connections to the outdoors, and are important components of a healthy coastal and marine ecosystem. Through two interactive ArcGIS StoryMaps, this capstone project aims to share data on the wetlands, shorebirds, and seabirds of the Punta Banda estuary with the public in order to continue to generate support for conservation efforts among locals and visitors. Despite conservation efforts, there are still many anthropogenic threats to the estuary and the birds that use it to feed and nest. This document provides a report of activities conducted as part of a capstone project for the Scripps Institution of Oceanography Master's program in Marine Biodiversity and Conservation.A StoryMap associated with this publication is linked above.

Agarophyton vermiculophyllum (formally known as Gracilaria vermiculophylla) is an invasive, bloom-forming, marine macroalga originating from Japan. A. vermiculophyllum has invaded estuaries along both eastern and western coasts of North America, the Atlantic coast of Europe, and the northwest African coastline. A. vermiculophyllum can be found on intertidal mudflats, which are soft-sediment environments, usually without rooted vegetation. In many estuaries A. vermiculophyllum is now the dominant, or only macroalga on mudflats. This species affects mudflat ecosystems by increasing the abundance, and in some cases diversity of epifauna. Whether these community differences lead to ecosystem-scale effects in food webs, or biomass, has not been investigated. Additionally, the generality of epifaunal community changes across abiotic gradients is not well understood. The goal of this dissertation was to understand the drivers of A. vermiculophyllum spatial distribution and its effect on mudflat trophic structure across abiotic gradients. A > 900 km2 dynamic coastal seascape across which mudflats varied in elevation, topographic complexity, wave exposure, and water residence time was used for a study system. To understand the role of geomorphology for mudflat producers and consumers I developed a novel index variable describing topographic variability on mudflats. I investigated the effect of A. vermiculophyllum on primary producers, macroinvertebrates, and shorebirds across a gradient of topographic variability. Through behavioral observations, large-scale manipulations, surveys and models, I found community-level changes caused by A. vermiculophyllum were decoupled from ecosystem-scale biomass changes. Shorebird communities partitioned mudflats based on the distribution of A. vermiculophyllum, with species preferring or avoiding macroalgal habitat based on their foraging mode specialization. However, the biomass of benthic microalgae, macroinvertebrates, and shorebirds, as well as the individual body sizes of the macroinvertebrate and shorebird communities, did not change when mudflats were colonized with A. vermiculophyllum. Mudflat topography explained A. vermiculophyllum spatial distribution, and the abundance and body size distribution of macroinvertebrates and shorebirds. Once accounting for mudflat topography and sediment characteristics, effects of A. vermiculophyllum for mudflat consumer biomass were not evident. This may have been due to compensatory changes in community body size distribution of invertebrates and birds driven by topography and sediment characteristics. Highly invasive species do not always have ecosystem-level effects, and while monitoring and more experimentation are certainly required, it appears for now that Agarophyton vermiculophyllum may be one of these cases.

Coastal wetlands are heterogeneous systems with multiple inputs and complex interactions within local food webs. Interpreting such complexity is limited by incomplete knowledge of trophic interactions among organisms. Although widely recognized as secondary consumers and predators of intertidal macroinvertebrates, shorebirds can also consume lower-trophic-level food sources, and frequently forage in adjacent supratidal habitats. To ascertain potential trophic links between overwintering shorebirds and alternative non-standard food sources, we collected carbon and nitrogen stable isotope data of shorebirds and benthic organisms from 4 coastal wetlands along the Eastern Atlantic: Tejo Estuary, Portugal; Sidi-Moussa, Morocco; Banc d'Arguin, Mauritania; and Bijagós Archipelago, Guinea-Bissau. Using dual-isotope Bayesian mixing models, we evaluated the relative importance of intertidal benthic macroinvertebrates and 3 other potential food sources (biofilm and seagrass rhizomes from intertidal areas, and saltpan macroinvertebrates) in the diet of wintering shorebirds. Although intertidal macroinvertebrates form the main part of most shorebird species' diet, our data revealed that supratidal saltpans can contribute to >30% of the biomass ingested by several shorebird species. Seagrass rhizomes represented >10% of the diet of several species in Banc d'Arguin and in Sidi Moussa. Little stint Calidris minuta appears to consume biofilm on all 3 wetlands where they were sampled, which is the first time biofilm consumption by shorebirds has been detected along the East Atlantic Flyway. Empirical evidence for generalized consumption of alternative food sources by intertidal avian predators show the greater complexity and food web connectivity in and of intertidal habitats, and also with the surrounding habitats.

Variation in migratory behavior is the result of different individual strategies and fluctuations in individual performances. A first step toward understanding these differences in migratory behavior among individuals is, therefore, to assess the relative contributions of inter- and intra-individual differences to this variation. We did this using light-level geolocators deployed on the breeding grounds to follow continental black-tailed godwits (Limosa limosa limosa) throughout their south- and northward migrations over multiple years. Based on repeated tracks from 36 individuals, we found two general patterns in godwit migratory behavior: First, migratory timing in black-tailed godwits varies mostly because individual godwits migrate at different times of the year. Second, individuals also exhibit considerable variation in timing within their respective migratory windows. Although the absolute amount of inter-individual variation in timing decreased over the course of northward migration, individual godwits still arrived at their breeding grounds across a span of more than 5 weeks. These differences in migratory timing among individuals are larger than those currently observed in other migratory bird species and suggest that the selective forces that limit the variation in migratory timing in other species are relaxed or absent in godwits. Furthermore, we could not attribute these individual differences to the sex or wintering location of an individual. We suggest that different developmental trajectories enabled by developmental plasticity likely result in these generally consistent, life-long annual routines. To investigate this possibility and to gain an understanding of the different selection pressures that could be acting during migration and throughout a godwit's life, future studies should track juvenile godwits and other migratory birds from birth to adulthood while also manipulating their spatiotemporal environment during development.

Each May for over three decades, avian influenza A viruses (IAVs) have been isolated from shorebirds and gulls (order Charadriiformes) at Delaware Bay (DE Bay), USA, which is a critical stopover site for shorebirds on their spring migration to arctic breeding grounds. At DE Bay, most isolates have been recovered from ruddy turnstones (Arenaria interpres), but it is unknown if this species is involved in either the maintenance or movement of these viruses outside of this site. We collected and tested fecal samples from 2823 ruddy turnstones in Florida and Georgia in the southeastern United States during four winter/spring sample periods—2010, 2011, 2012, and 2013—and during the winters of 2014/2015 and 2015/2016. Twenty-five low pathogenicity IAVs were recovered representing five subtypes (H3N4, H3N8, H5N9, H6N1, and H12N2). Many of these subtypes matched those recovered at DE Bay during the previous year or that year’s migratory cycle, suggesting that IAVs present on these southern wintering areas represent a source of virus introduction to DE Bay via migrating ruddy turnstones. Analyses of all IAV gene segments of H5N9 and H6N1 viruses recovered from ruddy turnstones at DE Bay during May 2012 and from the southeast during the spring of 2012 revealed a high level of genetic relatedness at the nucleotide level, suggesting that migrating ruddy turnstones move IAVs from wintering grounds to the DE Bay ecosystem.

BackgroundDeparture decisions and behaviors of migratory birds at stopover sites are expected to maximize fitness by trade-offs among avoiding predators, optimizing refueling (energy) capacity, and matching other life-history events. We predict that species with different body sizes and migratory destinations will exhibit different behaviors when departing from the same stopover site. We also predict that with strong time constraint at the final pre-breeding stopover site, departure decisions may be less sensitive to exogenous factors, such as wind condition, compared to other stopover or nonbreeding sites.MethodsWe recorded migratory departures of four shorebird species, i.e. Eurasian Curlew (Numenius arquata), Bar-tailed Godwit (Limosa lapponica), Great Knot (Calidris tenuirostris), and Grey Plover (Pluvialis squatarola), at Yalujiang Estuary Wetlands in China, a final pre-breeding stopover site in the northern Yellow Sea, from 2011 to 2014. We compared flock sizes, departure time and departure directions between species, and investigated the effects of tide and weather conditions (rain and ground wind speed and direction) on the departure decision of shorebirds.ResultsWe found that larger species departed in smaller flocks and were more variable in daily departure time. Departure trajectory of all four species appeared to be influenced by coastal topography. With the east–west coastline and intertidal mudflat on the south, birds exhibited westward or eastward deflection from the shortest migratory routes. Bar-tailed Godwit was the only species that deviated to the southeast and did not climb over the land. Birds avoided departure during precipitation, while their departure was not related to ground wind benefit or tidal condition.ConclusionsBody size among species, which influences their vulnerability to predators, might be important in shaping shorebird departure strategies. Diverse departure directions could be the result of different wind use tactics in climbing stage. Narrow optimal time window of breeding might lead to reduced flexibility in departure date at a final pre-breeding site. Both endogenous and exogenous are important in shaping departure behaviors and decisions.

Over 50% of Western Hemisphere shorebird species are in decline due to ongoing habitat loss and degradation. Many shorebird species require flooded habitat to rest and feed during migratory movements spanning thousands of miles between breeding and wintering grounds every spring and fall. In particular, shorebirds require shallowly flooded habitat (water depth We analyzed water extent dynamics across the Sacramento Valley of California, a globally important shorebird stopover site, for a 1983-2015 Landsat time series, and evaluated the effect of climate on water extent. Satellite measurements of surface water offer promise for understanding wetland habitat availability at broad spatial and temporal scales. A range of methods can detect open water from imagery, including supervised classification approaches and thresholds for spectral bands and indices. Thresholds provide a time advantage; however, there is no universally superior index, nor single best threshold for all instances. We used random forest to model the presence or absence of water from >6,200 reference pixels, and derived an optimal water probability threshold for our study area using receiver operating characteristic curves. An optimized mid-infrared (1.5–1.7 µm) threshold identified open water in the Sacramento Valley of California at 30-m resolution with an average of 90% producer’s accuracy, comparable to approaches that require more intensive user input. SLC-off Landsat 7 imagery was integrated by applying a customized interpolation that mapped water in missing data gaps with 99% user’s accuracy. On average we detected open water on ~26,000 ha (~3% of the study area) in early April at the peak of shorebird migration, while water extent increased five-fold after the migration rush. Over the last three decades, late March water extent declined by ~1,300 ha per year, primarily due to changes in the extent and timing of agricultural flood-irrigation. Water within shorebird habitats was significantly associated with an index of water availability at the peak of migration. Our approach can be used to optimize thresholds for time series analysis and near-real-time mapping in other regions, and requires only marginally more time than generating a confusion matrix. Two dimensional representations of flooded habitat are insufficient to capture dynamic changes within the narrow water depth range that is effectively accessible to migratory shorebirds. We developed a method to quantify shallow water habitat distributions in inland non-tidal wetlands, and assessed how water management practices have affected the amount of shorebird habitat in Sacramento National Wildlife Refuge Complex (SNWRC), California. We produced water depth distributions and modeled optimal habitat (Attempting to model the response of a community of shorebird species to flooded habitat dynamics from local to landscape scale necessitates a rich dataset including field observations of shorebird habitat use as well as information regarding regional habitat conditions over multiple time periods. Bringing together these data sources results in several challenges for classical statistical approaches, including overdispersion, fixed and random effects due to repeated measures, irregular temporal intervals, and missing data. We investigated how spring migration habitat use by 19 shorebird species at 327 wetland survey locations across SNWRC responded to flooded habitat fluctuations at multiple spatial scales from 1997-2015 using a generalized joint attribute modelling approach. In this analysis, we integrated shorebird census records and habitat conditions documented in the field with a suite of landscape-level habitat measurements derived from satellite imagery, as well as water availability, water allocation and land use information. We found that abundance by species peaked in late March and early April at SNWRC. Shorebird abundance responded positively to the amount of flooded habitat at a given wetland survey location. The total amount of water detected was the most important landscape habitat measure; shorebirds were less likely to be observed at high abundance at SNWRC wetlands when greater flooded habitat extent was present on the surrounding landscape. We found that human land and water management were influential drivers of shorebird habitat use. Water allocation information and reservoir storage resulted in better model fit (i.e., lower DIC) than including measures of surface water availability or drought conditions. Furthermore, the amount of landscape flooded habitat on agricultural land produced a better fit than considering all flooded habitat, or flooded habitat detected in wetlands. We found that the most relevant scale for measuring landscape flooded habitat was within 2-10 km of wetland survey locations; this distance could be a useful guideline for monitoring habitat conditions and targeting creation of supplemental habitat to bolster the existing wetland network in the Sacramento Valley.

While the principal use of light-recording geolocators is to determine geographical locations of migratory birds, supplementary wetness data have been used to refine estimates of minimum flight duration, on the assumption that a wet logger indicates the bird is on the ground. We provide a test of this assumption, by comparing wetness values against directly observed migratory departures of logger-equipped Bar-tailed Godwits Limosa lapponica and Red Knots Calidris canutus from the Manawatu River Estuary, New Zealand. Loggers recorded wetness every 10 min (Biotrack MK4093 and MK5093) or every one or four hours (Migrate Technology C65K). We retrieved loggers from 41 godwits from 2008– 2014 and from seven Red Knots in 2013–2014 for which we had corresponding departure information; in total there were 51 departures of godwits and seven of knots that we could match to actual departure times (this included multiple years for some godwits). Overall, 10-min wetness data were very accurate for both godwits and knots (median estimated departure times were 14 min and one min later than true departure, respectively), as were the 60-min and 240-min loggers on godwits if corrected by the wet counts that are recorded within measurement intervals (medians of 16 min earlier and 8 min earlier, respectively). These longer-interval loggers were still reasonably accurate without this adjustment (medians of 37 min and 74 min later, respectively). There was substantial variation between individuals and logger types, with 10-min loggers going dry up to 148 min (godwit) or 55 min (knot) earlier than true departure, while the 60-min and 240-min loggers recorded wetness up to 142 min or 124 min later than true departure (or 195 min or 232 min later, if unadjusted). Some of this variation simply reflects the interval over which wetness is recorded, but bird behaviour and/or logger performance must play a role in some cases (e.g. the logger going dry before departure or remaining wet after departure). Given observed bird behaviour upon arrival after migration (feeding on wet tidal flats), the wetness recording of geolocators is likely to give an accurate estimate of migratory flight duration, at least for species that frequent wet, particularly marine, habitats.

Polygamous Kittlitz’s plovers travel further over larger areas and interact with more individuals than the monogamous white-fronted plover. Movement patterns and social interactions influence gene flow and thus impact on speciation, although evidence from the field is limited. Here, we show that 2 Malagasy plover species exhibit different spatial behavior and social structure, consistent with existing genetic data. These results have implications for the genetic, social, and spatial processes by which new species are formed., Mating strategy and social behavior influence gene flow and hence affect levels of genetic differentiation and potentially speciation. Previous genetic analyses of closely related plovers Charadrius spp. found strikingly different population genetic structure in Madagascar: Kittlitz’s plovers are spatially homogenous whereas white-fronted plovers have well segregated and geographically distinct populations. Here, we test the hypotheses that Kittlitz’s plovers are spatially interconnected and have extensive social interactions that facilitate gene flow, whereas white-fronted plovers are spatially discrete and have limited social interactions. By experimentally removing mates from breeding pairs and observing the movements of mate-searching plovers in both species, we compare the spatial behavior of Kittlitz’s and white-fronted plovers within a breeding season. The behavior of experimental birds was largely consistent with expectations: Kittlitz’s plovers travelled further, sought new mates in larger areas, and interacted with more individuals than white-fronted plovers, however there was no difference in breeding dispersal. These results suggest that mating strategies, through spatial behavior and social interactions, are predictors of gene flow and thus genetic differentiation and speciation. Our study highlights the importance of using social behavior to understand gene flow. However, further work is needed to investigate the relative importance of social structure, as well as intra- and inter-season dispersal, in influencing the genetic structures of populations.

We investigated habitat preference of Common Sandpipers as part of a monitoring program in the Őrség National Park, Hungary. Field observations were conducted during the summers between 2008 and 2012 along a 47-km long section of the River Rába. During the observations we recorded the number and location of birds on the river bank. We divided the studied area into 1 km long sections and measured the proportion of the visually distinguishable habitat types (water, low gravel and sand bank, vegetation and degraded area) from a digitalized map. Furthermore, we recorded the number of the low banks and the number of bends of the river within each section, as well as the sections’ distance from the closest hydroelectric power plants and human settlements. In 2012 we also performed a detailed habitat mapping, recording the proportion of the vegetation types along the river bank and the number of fishing spots, embankment strengthenings and gravel banks. We tested the correlations between these habitat variables and number of birds present in the river sections. Our results show that Common Sandpipers were observed more frequently in locations which have (1) larger number and area of low gravel and sand banks, (2) less dense vegetation, and (3) lower proportion of degraded habitats. These findings can be taken into account in the conservation management of River Rába

In expanding populations, individuals may increasingly be forced to use sites of relatively low quality. This process, named the "buffer effect," was previously described for the Black-tailed Godwit (Limosa limosa islandica) in its use of nonbreeding sites in Great Britain and of breeding areas in Iceland. On the basis of diet analyses from droppings and stable isotopes, we describe a new case for the expanding French wintering population of the Black-tailed Godwit, an expansion accompanied by a drastic change in feeding strategy. In the 1990s, Black-tailed Godwits started using intertidal mudflats at Ile de Re, where they eat the rhizomes of seagrass (Zostera noltii) rather than the customary shellfish (Macoma balthica) eaten at both the preferred (initial) site (Aiguillon Bay) and the area occupied last (Yves to Marennes-Oleron bays). Individually color-marked godwits appeared faithful to both diet type and site, suggesting a cost of a change of strategy. This represents a first case of rhizome-feeding in shorebirds, and it exemplifies a case of carnivorous birds occupying a new site shifting to herbivory.

The spatial distribution of foraging animals at a given time simultaneously depends on (1) exogenous environmental variables such as resource availability and abiotic habitat characteristics, and (2) the endogenous variable social aggregation made up of the opposing mechanisms of conspecific attraction and repulsion. We developed an exogenous environment-social aggregation model to analyse the spatial distributions of six abundant shorebird species in the Dutch Wadden Sea at resolutions of 150 x 150, 200 x 200 and 250 x 250 m. We used these resolutions to check the robustness of the estimates to the modifiable areal unit problem. We estimated the model parameters by spatial autoregression. This approach enables, among others, estimation of the direct and indirect effects of an exogenous environmental variable on animal density. The former is given by the regression coefficient and the latter, which is due to the amplification of the direct effect by social aggregation, by the spatial multiplier. At all resolution levels and for all species, the explanatory power of social aggregation, measured by Nagelkerke R-2, was larger than the combined contribution of the exogenous environmental variables food availability, silt content and mudflat elevation. Social aggregation was stronger for dunlin, Calidris alpina, red knot, Calidris canutus, and curlew, Numenius arquata, than for oystercatcher, Haematopus ostralegus, grey plover, Pluvialis squatarola, and bar-tailed godwit, Limosa lapponica. The total impacts (that is, direct effect plus all indirect impacts) of the exogenous environmental predictors tended to exceed substantially the direct effects (which tend to be the only ones examined in studies on foraging distributions). (C) 2012 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Sexual selection may act as a promotor of speciation since divergent mate choice and competition for mates can rapidly lead to reproductive isolation. Alternatively, sexual selection may also retard speciation since polygamous individuals can access additional mates by increased breeding dispersal. High breeding dispersal should hence increase gene flow and reduce diversification in polygamous species. Here, we test how polygamy predicts diversification in shorebirds using genetic differentiation and subspecies richness as proxies for population divergence. Examining microsatellite data from 79 populations in 10 plover species (Genus: Charadrius) we found that polygamous species display significantly less genetic structure and weaker isolation‐by‐distance effects than monogamous species. Consistent with this result, a comparative analysis including 136 shorebird species showed significantly fewer subspecies for polygamous than for monogamous species. By contrast, migratory behavior neither predicted genetic differentiation nor subspecies richness. Taken together, our results suggest that dispersal associated with polygamy may facilitate gene flow and limit population divergence. Therefore, intense sexual selection, as occurs in polygamous species, may act as a brake rather than an engine of speciation in shorebirds. We discuss alternative explanations for these results and call for further studies to understand the relationships between sexual selection, dispersal, and diversification.

The effect of habitat management is commonly evaluated by measuring population growth, which does not distinguish changes in reproductive success from changes in survival or the effects of immigration or emigration. Management has rarely been evaluated considering complete life cycle of the target organisms, including also possible negative impacts from management. We evaluated the effectiveness of cattle grazing in the restoration of coastal meadows as a breeding habitat for small and medium‐sized ground‐nesting birds by examining the size and demography of a southern dunlin (Calidris alpina schinzii) breeding population. Using a stochastic renesting model that includes within‐season variation in breeding parameters, we evaluated the effect of grazing time and stocking rates on reproduction. The census data indicated that the population was stable when nest trampling was prevented, but detailed demographic models showed that the population on managed meadows was a sink that persisted by attracting immigrants. Even small reductions in reproductive success caused by trampling were detrimental to long‐term viability. We suggest that the best management strategy is to postpone grazing to after the 19th of June, which is about three weeks later than what is optimal from the farmer's point of view. The differing results from the two evaluation approaches warn against planning and evaluating management only based on census population size and highlight the need to consider target‐specific life history characteristics and demography. Even though grazing management is crucial for creating and maintaining suitable habitats, we found that it was insufficient in maintaining a viable population without additional measures that increase nest success. In the presently studied case and in populations with similar breeding cycles, impacts from nest trampling can be avoided by starting grazing when about 70% of the breeding season has past.

International audience; Trace elements concentrations (Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, Zn) were investigated in the liver, kidneys, muscle and feathers of 31 black-tailed godwits (Limosa limosa) accidentally killed during catches by mist net in the Pertuis Charentais, Atlantic coast of France. Analyses of carbon and nitrogen stable isotope ratios were carried out in liver, muscle and feathers in order to elucidate dietary patterns and to determine whether differences in diet explained the variation in elemental uptake. This study also aimed to have a preliminary assessment of sub-lethal effects triggered by trace elements through the investigation of gene expressions by quantitative real-time PCR, antioxidant enzyme activities (catalase, superoxide dismutase, glutathione peroxidase), and metallothionein (MT) levels. The results showed that Cr and Ni concentrations in tissues of adults were lower than in juveniles in part because adults may have eliminated these trace elements through moulting. Except for Cd and Ni, trace element concentrations were negatively correlated to the body mass of godwits. Ag, As, Hg and Se concentrations were positively linked with the trophic position of birds. The diet could be considered as a fundamental route of exposure for these elements demonstrating therefore the qualitative linkage between dietary habits of godwits and their contaminant concentrations. Our results strongly suggest that even though trace elements concentrations were mostly below toxicity threshold level, the elevated concentrations of As, Ag, Cd, Cu, Fe and Se may however trigger sub-lethal effects. Trace elements appear to enhance expression of genes involved in oxidative stress defence, which indicates the production of reactive oxygen species. Moreover, birds with the highest concentrations appeared to have an increased mitochondrial metabolism suggesting that the fight against trace element toxicity requires additional energetic needs notably to produce detoxification mechanisms such as metallothioneins.

TOC Summary: A lineage unique to Australia has been identified., We investigated carriage of avian influenza viruses by wild birds in Australia, 2005–2008, to assess the risks to poultry industries and human health. We collected 21,858 (7,357 cloacal, 14,501 fecal) samples and detected 300 viruses, representing a detection rate of ≈1.4%. Rates were highest in autumn (March–May) and differed substantially between bird types, areas, and years. We typed 107 avian influenza viruses and identified 19 H5, 8 H7, and 16 H9 (40% of typed viruses). All were of low pathogenicity. These viruses formed clearly different phylogenetic clades to lineages from Eurasia or North America, suggesting the potential existence of Australian lineages. H7 viruses were similar to highly pathogenic H7 strains that caused outbreaks in poultry in Australia. Several periods of increased detection rates (numbers or subtypes of viruses) were identified. This study demonstrates the need for ongoing surveillance to detect emerging pathogenic strains and facilitate prevention of outbreaks.

Rice fields are an alternative habitat for waterbirds and provide food and shelter for many avian species, but there is a lack of information about how the use of rice fields translates into population level effects. The aim of this study was to test the rela- tionship between the use of rice fields by European waterbirds and trends in their popu- lations. We tested this relationship during the autumn migration season and during the breeding season. Based on counts conducted over the last 23 years in natural marshes and areas of rice fields in Don˜ ana (SW Spain), an index of rice field use was constructed for 76 bird species, which was then compared to these species’ European population trends obtained from the literature. A positive relationship was found between waterbird popu- lation trends and the use of rice fields during autumn migration season. Our study suggests that changes in the Common Agriculture Policy in Europe leading to reductions in areas of rice cultivation may have important effects on waterbirds. The restoration of former marsh areas and the maintenance of rice cultivation would seem to be more environmentally friendly approaches than the use of these areas to grow alternative crops or solar farms

In response to environmental change, species have been observed altering their migratory behaviours. Few studies, however, have been able to determine whether these alterations resulted from inherited, plastic or flexible changes. Here, we present a unique observation of a rapid population-level shift in migratory routes—over 300 km from Spain to Portugal—by continental black-tailed godwits Limosa limosa limosa . This shift did not result from adult godwits changing staging sites, as adult site use was highly consistent. Rather, the shift resulted from young godwits predominantly using Portugal over Spain. We found no differences in reproductive success or survival among individuals using either staging site, indicating that the shift resulted from developmental plasticity rather than natural selection. Our results therefore suggest that new migratory routes can develop within a generation and that young individuals may be the agents of such rapid changes.

Subspecies Calidris canutus islandica of the Red Knot breeds on the arctic tundra of northeastern Canada and northern Greenland and winters along the coasts of northwestern Europe. During northward migration, it stops over in either Iceland or northern Norway. It has been assumed that it does the same during southward migration. Using ratios of stable carbon isotopes (delta(13)C) in whole blood, blood cells, and plasma, we investigated evidence for a stopover in Iceland en route from the breeding grounds to the Dutch Wadden Sea. With the expected diet (shellfish) and stopover duration at Iceland (12-15 days, maximum 17 days) and the turnover rates of blood cells (15.1 days) and plasma (6.0 days), Red Knots that stopped in Iceland should arrive with a blood (cell) delta(13)C midway between a tundra (-24.7 parts per thousand) and a marine value (-14.0 parts per thousand) and a plasma delta(13)C approaching the marine value (-15.3 parts per thousand). However, many adults arriving at the Wadden Sea had delta(13)C ratios in blood (cells) and plasma below these levels, and some arrived with clear tundra signals in blood cells, suggesting that they skipped Iceland during southward migration. Surprisingly, available data suggest this also to be true for juveniles during their first southward migration. The delta(13)C signature of second-year birds confirmed that they oversummered in the Wadden Sea. Our findings contradict the largely untested idea that juvenile shorebirds make more stopovers than adults as well as the idea that the migration between the Nearctic and Europe is necessarily a two-leg process.

Every year, Brazil receives large flocks of nearly 40 migratory shorebirds species. The accumulation of body fat and nutrients during the summer is necessary for the long return flights of these birds and is fundamental for feather moulting and the change of their plumage. We present here an examination of the relationship between body mass and plumage change in Arenaria interpres (Linnaeus, 1758), one of those birds, over time during its wintering period on the Brazilian coast. We analyzed information collected at five traditional stopover sites along the Brazilian coast, between 1997 and 2007. During the month of September, individuals with intermediate or breeding plumage had smaller body masses as compared to other months. From October to December, adult individuals were only observed with eclipse plumage and had average body masses of approximately 100 g. In March, individuals with intermediate, eclipse and breeding plumages were recorded, but their average body mass remained at approximately 100 g. In April and May the numbers of individuals with breeding or intermediate plumage increased, and they showed significant increases in body mass at a rate of approximately 1.5 and 2.3 g per day, in the north-northeastern and south coast, respectively, leading to an average mass of 124 and 143g in these months. That is suggested to be the departure mass of A. interpres in the Brazilian north-northeastern and south coast, respectively, when starting the migration to the breeding sites.

Four Great Knots (Calidris tenuirostris) were kept for six years in a constant-temperature indoor aviary. For two of those six years, they were kept under photoperiodic conditions that mimicked natural changes in daylength for wild birds, followed by four years under a constant photoperiod (light:dark cycle 12:12 h). Under cyclical "natural" photoperiods, three of the four birds maintained cycles of body mass and contour and flight-feather molt somewhat comparable to that of free-living birds, though the multiple mass peaks characteristic of northward migration were replaced by a single period of high body mass; the mass peaks for southward migration appeared to be absent. Contour-feather molts between nonbreeding and breeding plumages were delayed, and the period of wing molt was longer than in free-living birds. Under constant photoperiods, clear circannual phenotype cycles were maintained. The length of the period with elevated body mass tripled but was partly compensated by a shortening of the duration of wing molt (which never coincided with high body masses). Nevertheless, total cycle lengths were > 13 months. Perhaps most interestingly, under constant photoperiod, there was evidence that two components of what is normally considered an integrated phenotypic event, the prebasic molts of contour and wing feathers, were desynchronized. This suggests that the underlying organizational structure of traits is modular to some extent. Such modularity would increase the flexibility and versatility of the cyclic phenotype in evolutionary contexts.

Birds living in seasonal environments change physiology and behavior in correspondence to temporally changing environmental supplies, demands and opportunities. We recently reported that the chemical composition of uropygial gland secretions of sandpipers (Scolopacidae, order Charadriformes) changes during the breeding season from mixtures of monoesters to diesters, which fulfill specific functions related to incubation. A proper temporal match between the expression of diester preen waxes and incubation requires a flexible organization of the trait. Here we analyze the possible degrees of flexibility with reference to the functionality of better-understood molt and body mass cycles of free-living and captive red knots (Calidris canutus). The relative flexibility of seasonal cycles in preen wax composition was examined by two experimental perturbations: (1) giving birds restricted access to food and (2) monitoring them long-term under a constant photoperiodic regime. We found that wax type cannot change instantaneously, but that changing the type of wax is under similar organizational time constraints as the replacement of feathers. Just as molt and mass cycles, the seasonal rhythm of diester secretion appeared to be under endogenous control: most birds placed in a constant photoperiod still maintained seasonally changing preen waxes. Diester preen wax secretion was synchronized with the peak in body mass in spring, but became less well expressed under constant photoperiodic conditions and when food availability was limited.

Understanding the relative contributions of intrinsic and extrinsic factors to population structure and genetic diversity is a central goal of conservation and evolutionary genetics. One way to achieve this is through comparative population genetic analysis of sympatric sister taxa, which allows evaluation of intrinsic factors such as population demography and life history while controlling for phylogenetic relatedness and geography. We used ten conserved microsatellites to explore the population structure and genetic diversity of three sympatric and closely related plover species in southwestern Madagascar: Kittlitz's plover (Charadrius pecuarius), white-fronted plover (C. marginatus), and Madagascar plover (C. thoracicus). Bayesian clustering revealed strong population structure in the rare and endemic Madagascar plover, intermediate population structure in the white-fronted plover, and no detectable population structure in the geographically widespread Kittlitz's plover. In contrast, allelic richness and heterozygosity were highest for the Kittlitz's plover, intermediate for the white-fronted plover and lowest for the Madagascar plover. No evidence was found in support of the “watershed mechanism” proposed to facilitate vicariant divergence of Madagascan lemurs and reptiles, which we attribute to the vagility of birds. However, we found a significant pattern of genetic isolation by distance among populations of the Madagascar plover, but not for the other two species. These findings suggest that interspecific variation in rarity, endemism, and dispersal propensity may influence genetic structure and diversity, even in highly vagile species.

Methylmercury is a toxic form of mercury which persists in food webs for long periods of time and biomagnifies up successive trophic levels. Shorebirds breeding in the Arctic are exposed to methylmercury, derived from both natural and anthropogenic sources, when they ingest their invertebrate prey. Populations of many shorebird species are believed to be declining and one hypothesis for these declines is that they are due to detrimental effects of contaminants, including methylmercury. To test this hypothesis, we assessed mercury contamination in eggs of four Canadian Arctic-breeding shorebird species: black-bellied plover (Pluvialis squatarola), ruddy turnstone (Arenaria interpres), semipalmated plover (Charadrius semipalmatus) and white-rumped sandpiper (Calidris fuscicollis). Black-bellied plovers and ruddy turnstones are declining in the western hemisphere, whereas white-rumped sandpipers and semipalmated plovers have stable or slightly increasing populations. We found no relationship between egg mercury concentration and population trend for these four shorebird species. Intraspecific variation in mercury concentration was high. Notably, the mercury concentrations were much higher than levels found in a previous study of eggs of the same shorebird species from this same site, suggesting that mercury contamination may be subject to substantial inter-annual variation in the Canadian Arctic food web.

Habitat use has important consequences for avian reproductive success and survival. In coastal areas with recreational activity, human disturbance may limit use of otherwise suitable habitat. Snowy plovers Charadrius nivosus have a patchy breeding distribution along the coastal areas on the Florida Panhandle, USA. Our goal was to determine the relative effects of seasonal human disturbance and habitat requirements on snowy plover habitat use. We surveyed 303 sites for snowy plovers, human disturbance, and habitat features between January and July 2009 and 2010. We made multiple visits during three different sampling periods that corresponded to snowy plover breeding: pre-breeding, incubation, and brood-rearing and used multi-season occupancy models to examine whether human disturbance, habitat features, or both influenced site occupancy, colonization (probability of transition from an unoccupied site to an occupied site), and extinction (probability of transition from an occupied site to an unoccupied site). Snowy plover site occupancy and colonization was negatively associated with human disturbance and site extinction was positively associated with human disturbance. Interdune vegetation had a negative effect on occupancy and colonization, indicating that plovers were less likely to use areas with uniform, dense vegetation among dunes. Also, dune shape, beach debris, and access to low-energy foraging areas influenced site occupancy, colonization, and extinction. Plovers used habitat based on beach characteristics that provided stage-specific resource needs; however, human disturbance was the strongest predictor of site occupancy. In addition, vegetation plantings used to enhance dune rehabilitation may negatively impact plover site occupancy. Management actions that decrease human disturbance, such as symbolic fencing and signage, may increase the amount of breeding habitat available to snowy plovers on the Florida Panhandle and in other areas with high human activity. The specific areas that require this protection may vary across snowy plover life history stages.

Please cite this paper as: Hall et al. (2012) Avian influenza in shorebirds: experimental infection of ruddy turnstones (Arenaria interpres) with avian influenza virus. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750‐2659.2012.00358.x. Background Low pathogenic avian influenza viruses (LPAIV) have been reported in shorebirds, especially at Delaware Bay, USA, during spring migration. However, data on patterns of virus excretion, minimal infectious doses, and clinical outcome are lacking. The ruddy turnstone (Arenaria interpres) is the shorebird species with the highest prevalence of influenza virus at Delaware Bay. Objectives The primary objective of this study was to experimentally assess the patterns of influenza virus excretion, minimal infectious doses, and clinical outcome in ruddy turnstones. Methods We experimentally challenged ruddy turnstones using a common LPAIV shorebird isolate, an LPAIV waterfowl isolate, or a highly pathogenic H5N1 avian influenza virus. Cloacal and oral swabs and sera were analyzed from each bird. Results Most ruddy turnstones had pre‐existing antibodies to avian influenza virus, and many were infected at the time of capture. The infectious doses for each challenge virus were similar (103·6–104·16 EID50), regardless of exposure history. All infected birds excreted similar amounts of virus and showed no clinical signs of disease or mortality. Influenza A‐specific antibodies remained detectable for at least 2 months after inoculation. Conclusions These results provide a reference for interpretation of surveillance data, modeling, and predicting the risks of avian influenza transmission and movement in these important hosts.

The mission of the U.S. Fish and Wildlife Service (USFWS) is working with others to conserve, protect, and enhance fish, wildlife, plants, and their habitats for the continuing benefit of the American people. Toward fulfillment of that mission, a priority of the USFWS is conservation and management of migratory birds. Effective conservation actions to ensure the continued existence of a species on the landscape cannot be designed without first understanding basic life history characteristics of a species. It is common in the case of migratory birds, that we lack understanding of some of their elemental biological traits. The Marbled Godwit, Limosa fedoa, is one such species where we lack information and understanding of the birds ecology. The Marbled Godwit has been identified as a species of high conservation concern by USFWS and its many partners. Concern is warranted as the estimated global population is relatively small (173,500) coupled with significant loss and degradation of its breeding and wintering habitats. However, in order to assess where to focus conservation action that would provide the most benefit to the overall population first we need to learn more about its population trends and ecology. In this study, USFWS, Utah State University and many other partners propose a multi-year, $150,000 project to characterize the biogeography of Marbled Godwit populations. Using the latest technology in miniature satellite transmitters, we will determine migration routes, timing, distances, speed and duration. We will also determine the connectivity or the links between the major breeding, staging, wintering and stopover areas. Unraveling this mystery will help us identify key habitats for protection and allow us to examine the risks or threats that each subpopulation is exposed to throughout the annual cycle. The connectivity among and between disparate breeding subpopulations of North American Marbled Godwit is also the initial step in designing future studies to further understand population dynamics of the species.

Please cite this paper as: Hall et al. (2011). Experimental challenge and pathology of highly pathogenic avian influenza virus H5N1 in dunlin (Calidris alpina), an intercontinental migrant shorebird species. Influenza and Other Respiratory Viruses 5(5), 365–372. Background Shorebirds (Charadriiformes) are considered one of the primary reservoirs of avian influenza. Because these species are highly migratory, there is concern that infected shorebirds may be a mechanism by which highly pathogenic avian influenza virus (HPAIV) H5N1 could be introduced into North America from Asia. Large numbers of dunlin (Calidris alpina) migrate from wintering areas in central and eastern Asia, where HPAIV H5N1 is endemic, across the Bering Sea to breeding areas in Alaska. Low pathogenic avian influenza virus has been previously detected in dunlin, and thus, dunlin represent a potential risk to transport HPAIV to North America. To date no experimental challenge studies have been performed in shorebirds. Methods Wild dunlin were inoculated intranasally and intrachoanally various doses of HPAIV H5N1. The birds were monitored daily for virus excretion, disease signs, morbidity, and mortality. Results The infectious dose of HPAIV H5N1 in dunlin was determined to be 101.7 EID50/100 μl and that the lethal dose was 101.83 EID50/100 μl. Clinical signs were consistent with neurotropic disease, and histochemical analyses revealed that infection was systemic with viral antigen and RNA most consistently found in brain tissues. Infected birds excreted relatively large amounts of virus orally (104 EID50) and smaller amounts cloacally. Conclusions Dunlin are highly susceptible to infection with HPAIV H5N1. They become infected after exposure to relatively small doses of the virus and if they become infected, they are most likely to suffer mortality within 3–5 days. These results have important implications regarding the risks of transport and transmission of HPAIV H5N1 to North America by this species and raises questions for further investigation.

The relative importance of environmental colour for extinction risk compared with other aspects of environmental noise (mean and interannual variability) is poorly understood. Such knowledge is currently relevant, as climate change can cause the mean, variability and temporal autocorrelation of environmental variables to change. Here, we predict that the extinction risk of a shorebird population increases with the colour of a key environmental variable: winter temperature. However, the effect is weak compared with the impact of changes in the mean and interannual variability of temperature. Extinction risk was largely insensitive to noise colour, because demographic rates are poor in tracking the colour of the environment. We show that three mechanisms—which probably act in many species—can cause poor environmental tracking: (i) demographic rates that depend nonlinearly on environmental variables filter the noise colour, (ii) demographic rates typically depend on several environmental signals that do not change colour synchronously, and (iii) demographic stochasticity whitens the colour of demographic rates at low population size. We argue that the common practice of assuming perfect environmental tracking may result in overemphasizing the importance of noise colour for extinction risk. Consequently, ignoring environmental autocorrelation in population viability analysis could be less problematic than generally thought.