Migratory Shorebirds Research Articles

Physiological parameters of a plover during nonbreeding and breeding seasons in Patagonia, Argentina

Migratory shorebirds are the most threatened avian species due to the effects of human activities and climate change. Physiological parameters are useful to evaluate the health status of free-living animals. Here we investigated lymphocytes, heterophils, heterophils/lymphocytes, and glucose for female and male Two-banded Plovers (Charadrius falklandicus Latham, 1790) during nonbreeding (body moult) and breeding (incubation) seasons in coastal areas of northern Patagonia, Argentina. We also measured corticosterone for the first time for this species during the breeding season. Nonbreeding Two-banded Plovers were more likely to have higher physiological measurements that were not dependent on body moult nor body condition, being similar between sexes. Differences found in glucose are likely related to recent feeding in nonbreeding birds compared with fasting during incubation. The gregarious nonbreeding behaviour in comparison with the isolated breeding pairs would increase the risk of acquiring parasites and (or) pathogens inducing a response of the immune system reflected in higher values of lymphocytes. Baseline corticosterone during breeding was similar between sexes and were lower compared with other values reported for breeding plovers. Two-banded Plovers undergo energetically demanding physiological changes during the nonbreeding stage, strengthening the idea that conservation of the environmental resources at these locations may be more important than previously thought.

Spatial and temporal overlap between foraging shorebirds and spawning horseshoe crabs (Limulus polyphemus) in the Cape Romain-Santee Delta Region of the U.S. Atlantic coast

Shorebird use of horseshoe crab (Limulus polyphemus) eggs as food items has been well documented along the Atlantic coast of the United States at northeastern stopover sites such as the Delaware Bay. However, the relationship between migratory shorebirds and horseshoe crab eggs has not been well studied in the South Atlantic Bight. The objective of our study was to assess the spatial and temporal overlap between the density of horseshoe crab eggs and the relative abundance of foraging shorebirds during spring migration in the Cape Romain-Santee Delta Region (CRSD), South Carolina, USA. The CRSD is a site of international importance for shorebirds that supports ∼100,000 shorebirds annually. We also sought to determine if horseshoe crab eggs were present in the diets of shorebirds at these sites. We monitored study plots between March and June 2015–2016 at predicted horseshoe crab spawning sites on beaches throughout Cape Romain National Wildlife Refuge. We conducted weekly shorebird surveys and collected core samples of beach substrate twice per month to measure densities of horseshoe crab eggs. We found a positive correlation between number of foraging shorebirds and horseshoe crab eggs for both years. In a molecular analysis of shorebird fecal samples, 95% of the samples tested contained DNA from horseshoe crab eggs. The spatial and temporal overlap between shorebirds and horseshoe crab eggs, and the dietary analysis of fecal samples, suggest that there are areas of localized horseshoe crab spawning that shorebirds can utilize as a food source during spring in Cape Romain National Wildlife Refuge.

Avian assemblages associated with different grasslands managements in cattle production systems in the pampas of Argentina

Modifications in the structure of grasslands have been responsible for the decline of several avian species due to a reduced quality in available habitat. Currently, applications of the herbicide glyphosate have been introduced to promote winter forage production in the Flooding Pampas of Argentina. Rotational grazing has been another technique used to promote winter forage production. Here, we evaluated different grasslands managements in cattle production systems on species richness, composition, and abundance of bird assemblages in grasslands Pampas. We put emphasis on responses of two neartic migratory shorebirds, the Buff-breasted Sandpiper (Calidris subruficollis) and the American Golden Plover (Pluvialis dominica). The three treatments on natural grassland were: (1) paddocks of Ryegrass growth promotion through the application of herbicide glyphosate; (2) paddocks managed with Rotational grazing, and 3) paddocks managed with Continuous grazing. We considered three periods of the breeding cycle of the birds (early, late, post-breeding) for two years (2011/2012, 2012/2013). Vegetation cover lower than 10 cm was greater in both Rotational and Continuous grazing sites in comparison to the ryegrass promotion sites. A NMDS analysis revealed a clear separation in structure of bird communities among the three grazing treatments. The abundance of total birds and of short grassland birds was lower in grasslands with Ryegrass promotion. An indicator species analysis revealed the associations of shorebirds with Rotational and Continuous grazing sites. Grassland management with glyphosate application had an effect on the structure of assemblages of grassland birds in the Flooding Pampas, which was negative particularly with Nearctic migrants of conservation importance.

The costs of migration: Injuries in migratory waterbirds along the west coast of India.

The long distant, transcontinental migration of shorebirds entails many well identified costs in terms of time, energy, and direct mortality risk. Injuries from debris or from human structures and activities were observed as the major reasons for the direct mortality of shorebirds during migration worldwide. We recorded injured birds in major coastal wetlands of Kerala, for a period of 15 years from 2005 to 2019. The injured birds were observed in 9 different sites in various districts of Kerala. The highest instances of injuries were observed in Kadalundi-Vallikunnu Community Reserve, the major wintering and stop over site of migrant shorebirds in the west coast of India. During the study period, fifty-eight individuals of shorebirds belonging to four families were found to be injured. The highest proportion of injuries was recorded among the families Scolopacidae and Charadriidae comprising long distance migrant shorebird species and the lowest among Laridae and Ardeidae. We recommend that environmental authorities pay special attention to minimize anthropogenic debris along the flyways used by migratory birds thereby reducing the risk of injuries to some of these species. Proactive measures such as removal of discarded fishing gear or plastic debris from wintering areas as well as stopover areas could greatly reduce injuries in migratory birds arising from anthropogenic sources.

First records of prevalence and diversity of avian haemosporidia in snipe species (genus Gallinago) of Japan.

Migratory birds are important carriers of pathogens such as viruses, bacteria and protozoa. Avian haemosporidia have been detected from many wild birds of Japan, but the infection status of migratory birds and transmission area are still largely unknown. Gallinago snipes are long-distance migratory shorebirds, and five species migrate to or through Japan, including Latham's snipe which is near threatened. Haemosporidian parasites in four snipe species were investigated to understand the role of migratory birds in the transmission of avian haemosporidia. Namely, this study aimed: i) to investigate differences in parasite prevalence and related factors explaining infection likelihood among these migratory species, ii) to explore the diversity in haemosporidian lineages and possible transmission areas, and iii) to assess the possibility of morphological effects of infection. Blood samples were collected from snipes caught in central and southwest Japan during migration. Parasites cytb gene DNA were detected via PCR-based testing, and detected lineages were phylogenetically analyzed. Additionally, factors related to prevalence and morphological effects of infection were statistically tested. 383 birds from four Gallinago snipe species were caught, showing higher overall prevalence of avian haemosporidia (17.8 %) than reported in other wader species in previous studies. This high infection rate is presumably due to increased contact with vector insects, resultant of environmental preferences. The prevalence of Plasmodium spp. Was higher in Swinhoe's snipes, while Haemoproteus spp. Was higher in Latham's snipes. These differences are thought to be related to ecological factors including habitat use, distribution and migratory route. Six lineages detected from juveniles indicate transmission between the breeding and sampling area. Contrary to expectations, a direct link between morphological features and haemosporidian parasite infection were not detected. These findings provide valuable information for conservation of this endangered migratory bird group. Further studies linking biological and parasitological research are anticipated to contribute to conservational actions.

Species‐specific demographic and behavioral responses to food availability during migratory stopover

AbstractUnderstanding the effects of migratory stopover site conditions on both demographic rates and migratory behaviors is critical for interpreting changes in passage population sizes at stopover sites and predicting responses to future changes and conservation actions. We used a Bayesian formulation of the open robust design model to analyze mark‐resight observations of three migratory shorebird species using Delaware Bay, USA during spring stopover from 2005 to 2018. We tested for an effect of stopover food availability and weather conditions on survival probability and the probability of returning to this site in the next year and found species differences in these relationships. After years with greater food availability, red knot Calidris canutus rufa had higher survival probability but ruddy turnstone Arenaria interpres were more likely to return to the site. Estimates of within‐year probabilities of arrival and persistence at the stopover site showed relatively consistent migration schedules for ruddy turnstone, but more interannual variation for red knot and sanderling Calidris alba. Shorebird use of this site typically peaked during May 26–28, but the estimated proportion of the population present during this period varied dramatically among years for red knot (range: 0.07–0.59) but less so for ruddy turnstone and sanderling. This demonstrates that both the proportion of the flyway population using this stopover site and the proportion present during a given sampling period vary among years, and both should be considered in analyzing and interpreting monitoring data. Stopover conditions can influence both migratory behavior and demographics, underscoring the importance of flyway‐wide monitoring.

The value of coastal saltpans for migratory shorebirds: conservation insights from a stable isotope approach based on feeding guild and body size

AbstractMigratory shorebirds are among the most threatened groups of birds. They rely on natural intertidal habitats outside the breeding season, but, to some extent have adjusted to using man‐made habitats. Here, we assessed the importance of coastal saltpans – a type of anthropogenic wetland – for feeding in migratory shorebirds during their northward migration along the East Asian‐Australasian Flyway (EAAF). We combined low tide counts on intertidal flats and nearby saltpans at the Luannan coastal wetland complex (Bohai Bay, China) with Bayesian mixing model analyses (BMMs) based on stable isotopes to evaluate the relative importance of coastal saltpans versus natural intertidal habitats as foraging grounds for migrating species. We grouped shorebird species (n = 24) according to feeding guild and body size, and found that both predictors explained the broad‐scale patterns of foraging use of saltpans by shorebirds at low tide. The guild of water‐surface foraging species (e.g. stilts and avocets), independently of body size, mostly fed in saltpans, and the small‐medium visual (e.g. plovers) and tactile‐surface (e.g. sandpipers) foraging species consumed a significant portion of their diet in this habitat. In contrast, most large tactile‐surface foraging species barely foraged in saltpans at low tide. BMMs showed that shorebirds had a greater reliance on saltpans than did traditional counts of foraging birds in each habitat at low tide. Saltpan food is rich in essential fatty acids, so the contribution of saltpans to the diet of shorebirds should not be considered only in absolute values, but also in the quality of this contribution. Saltpans may therefore help conserve declining shorebirds if properly managed – for example by controlling water levels – to serve the specific feeding guilds that rely on them. While our focus is in the EAAF, the findings are relevant for other flyways and other non‐tidal anthropogenic wetlands.

Plasticity in the hippocampal formation of shorebirds during the wintering period: Stereological analysis of parvalbumin neurons in Actitis macularius.

The number of parvalbumin neurons can be modified by social, multisensory, and cognitive stimuli in both mammals and birds, but nothing is known about their plasticity in long-distance migratory shorebirds. Here, in the spotted sandpiper (Actitis macularius), we investigated the plasticity of parvalbumin neurons of two brain areas during this species' wintering period at a lower latitude. We compared individuals in a nonmigratory rest period (November-January) and premigration (May-July) period. We used parvalbumin as a marker for counting a subpopulation of inhibitory neurons in the hippocampal formation (HF), with the magnocellular nucleus of the tectal isthmus (IMC) as a control area. Because the HF is involved in learning and memory and social interaction and the IMC is essential for control of head, neck, and eye movements, we hypothesized that parvalbumin neurons would increase in the HF and remain unchanged in the IMC. We used an optical fractionator to estimate cell numbers. Compared with the nonmigratory rest birds, parvalbumin neuron count estimates in the premigration birds increased significantly in the HF but remained unchanged in IMC. We suggest that the greater number of parvalbuminergic neurons in the HF of A. macularius in the premigration period represents adaptive circuitry changes involved in the migration back to reproductive niches in the northern hemisphere.

Factors determine the population characteristics of migratory shorebirds and their prey species in the coastal saltpans

Naturally-occurring seasonal saltpans serve as a major foraging ground for migratory shorebirds. Nevertheless, little is known about the role of various environmental factors in determining the density, diversity and species richness of shorebirds and their prey in India. This study was designed to collect quantitative data for the first time on the role of season, salinity, water depth, and prey availability in influencing the density, diversity, and species richness of migratory shorebirds in the eastern coastal saltpans of Tamilnadu, India. Selected sites were classified as seasonal saltpans and hypersaline saltpans based on the concentration of salinity in water. Shorebirds were counted systematically from (August) 2012 to (May) 2015 using the total count method. The measurement of salinity level and water depths of each sighting was also collected. The density, diversity and species richness of shorebirds showed highest in the seasonal saltpans than the hypersaline saltpans. The monsoon season attracted more shorebird density, diversity species richness when compared to other seasons. Calidris alpine was only the migratory shorebird species recorded in both types of saltpans and across seasons. The micro and macro-invertebrate prey species showed the highest in the seasonal saltpans. The Chironomid larva showed the highest turnover than other species recorded in the studied saltpans. The multiple regression models showed that the year, season, salinity, and water depth influence the shorebird density, diversity, species richness, and prey species' density with a more significant percentage. The study results found that saltpans are also an ideal habitat for migratory shorebirds and their diverse prey species seasonally.

Genetic differentiation in an endangered and strongly philopatric, migrant shorebird

BackgroundPopulations living in fragmented habitats may suffer from loss of genetic variation and reduced between-patch dispersal, which are processes that can result in genetic differentiation. This occurs frequently in species with reduced mobility, whereas genetic differentiation is less common among mobile species such as migratory birds. The high dispersal capacity in the latter species usually allows for gene flow even in fragmented landscapes. However, strongly philopatric behaviour can reinforce relative isolation and the degree of genetic differentiation. The Southern Dunlin (Calidris alpina schinzii) is a philopatric, long-distance migratory shorebird and shows reduced dispersal between isolated breeding patches. The endangered population of the Southern Dunlin breeding at the Baltic Sea has suffered from habitat deterioration and fragmentation of coastal meadows. We sampled DNA across the entire population and used 12 polymorphic microsatellite loci to examine whether the environmental changes have resulted in genetic structuring and loss of variation.ResultsWe found a pattern of isolation-by-distance across the whole Baltic population and genetic differentiation between local populations, even within the southern Baltic. Observed heterozygosity was lower than expected throughout the range and internal relatedness values were positive indicating inbreeding.ConclusionsOur results provide long-term, empirical evidence for the theoretically expected links between habitat fragmentation, population subdivision, and gene flow. They also demonstrate a rare case of genetic differentiation between populations of a long-distance migratory species. The Baltic Southern Dunlin differs from many related shorebird species that show near panmixia, reflecting its philopatric life history and the reduced connectivity of its breeding patches. The results have important implications as they suggest that reduced connectivity of breeding habitats can threaten even long-distance migrants if they show strong philopatry during breeding. The Baltic Southern Dunlin warrants urgent conservation efforts that increase functional connectivity and gene flow between breeding areas.

Favourable inland wetland conditions increase apparent survival of migratory shorebirds in Australia

ABSTRACT Many migratory shorebird species using the East Asian–Australasian Flyway are declining rapidly. While the loss of staging habitats in East Asia is considered the primary cause, stressors to fitness often occur throughout the geographic range of declining species, and threats in the non-breeding grounds have been comparatively poorly studied. Three species of migratory shorebird, Curlew Sandpiper (Calidris ferruginea), Sharp-tailed Sandpiper (C. acuminata) and Red-necked Stint (C. ruficollis), use Australia’s dynamic temporary wetland systems opportunistically, yet these large wetland systems have become increasingly degraded, with reduced frequency and extent of flooding. Here, we test whether variables related to wetland availability in Australia’s interior can explain annual variation in apparent survival, abundance or immature to adult ratios at three well-monitored coastal shorebird areas in southern Australia (total area > 1315 km2). We show that coastal annual bird abundance and ratios of immatures at the coast were higher when inland Australia was relatively hot and dry. Also, a small but significant amount of variation in annual apparent survival can be explained by annual variation in inland conditions, with higher survival rates in years when inland conditions were relatively wet and cool. For the endangered Curlew Sandpiper, the impacts of Australian environmental conditions may be exacerbating the impacts of conditions experienced in other parts of its range on fitness and survival. While the effects we document here are relatively weak, they do suggest that management of inland wetlands for these shorebirds may positively affect survival rates of these sharply declining species.

Far eastern curlew and whimbrel prefer flying low - wind support and good visibility appear only secondary factors in determining migratory flight altitude

BackgroundIn-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.MethodsHere 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.ResultsOur 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.ConclusionsWe 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.

Temperature and density influence survival in a rapidly declining migratory shorebird

Migratory species face geographically dispersed pressures over the course of their annual cycles. Designing effective conservation strategies for these species requires a detailed understanding of how these different pressures affect demographic rates throughout the annual cycle. As a long-lived species, population trends in the rapidly declining Eurasian curlew Numenius arquata are likely to be highly sensitive to impacts on adult survival. We combine data from multiple sources to analyse survival rates of overlapping populations that breed and/or winter in the United Kingdom. Our analyses demonstrate that curlew survival rates are reduced by cold weather and at high density; however, overall survival rates are high and have increased in recent years. Current population declines are, therefore, likely to be driven by low productivity. As such, efforts to stabilise and reverse declines should focus on increasing breeding success from current estimated levels of 0.25 chicks nest−1 to 0.43 chicks nest−1. In addition to increasing productivity, effective conservation strategies will need to maintain high levels of survival, which requires an improved understanding of population connectivity and demographic variation throughout the annual cycle.

Contrasting long-term population trends of beach-nesting shorebirds under shared environmental pressures

Identifying the drivers of long-term population change is a key goal of ecological studies. It is complicated by extrinsic and intrinsic factors that may covary with time and/or operate on a time lag. For migratory shorebirds that breed on the barrier islands of eastern North America, populations may be limited by the anthropogenic, climatic, biological environments they encounter throughout the annual cycle. Using three-decades (1989–2017) of breeding monitoring data collected by the National Park Service at two national seashores in North Carolina (Hatteras and Lookout), we examined the potential drivers of nesting piping plover (Charadrius melodus) and American oystercatcher (Haematopus palliates) populations. Hatteras had five times more annual visitors than Lookout, and our modelling revealed a strong negative relationship between the population size of breeding plovers and human activity and a positive relationship with protection efforts aimed at reducing disturbance. Breeding and wintering climatic conditions, population productivity, and nesting habitat availability showed only weak effects. Thus, a decade-long decline in plover numbers at both seashores starting in the mid-90s reversed as the parks' visitor counts decreased and stricter protections from potential disturbance were implemented. However, the two sympatric populations of oystercatchers showed the opposite population trends from each other at the neighboring seashores, increasing only on Lookout after a hurricane improved habitat and subsequently the reproductive output. Our study suggests a strong relationship between the anthropogenic environment and the population trend of a threatened species and, simultaneously, the important role of stochastic events in shaping populations of long-lived shorebird species.

Development of methodology and reference intervals for the analysis of the free-ranging Atlantic horseshoe crab Limulus polyphemus hemolymph.

The Atlantic horseshoe crab, Limulus polyphemus, is valuable to fishing and biomedical industries, for education in public aquaria, and of ecological importance because the eggs provide a critical food source for migratory shorebirds. While hematologic and biochemical analyses are fundamental tools for health assessment, reports are limited for the four extant species of horseshoe crabs; Lpolyphemus (East Coast North America), Carcinoscorpius rotundicauda (mangrove horseshoe crab Southeast Asia), Tachypleus gigas, and Tachypleus tridentatus (Southeast and East Asia). This prospective study measured hemolymph values to determine RIs from free-ranging horseshoe crabs during the annual breeding aggregation in Delaware Bay, USA. Near-shore animals were briefly manually restrained for hemolymph collection from the cardiac sinus. Hematologic samples (25 males, 25 females) were collected for hemocytometer counts using the Natt and Herrick method. A second set of 50 animals (25 males, 25 females) was sampled for biochemistry measurands, including copper concentration by spectrophotometer, osmolality by vapor pressure osmometer, and protein electrophoresis. Total hemocyte counts varied widely (RI 6600-44300/µL). Electrolytes were consistent with osmoconformers living in seawater. There was a marked difference in sexes, with females showing much lower protein, glucose, and copper levels. Eleven females had multiple outliers, and all data were excluded from RI calculations. Further studies of this species outside of spawning season are needed. Expanding our knowledge of horseshoe crab health is important to decreasing morbidity and mortality in research applications and maximizing longevity and overall health in display settings.

Insights from long-term shorebird monitoring for tracking change in ecological character of Australasian Ramsar sites

The Ramsar Convention is the centrepiece of international efforts for wetland conservation, aiming to maintain the ecological character of wetlands through holistic ecosystem management. Here, we review studies on shorebird populations at individual Australasian Ramsar sites and compare these against original listings under Criterion 6 to determine if there have been potential changes in ecological character. One to 12 migratory shorebird species have declined at four New Zealand and 18 Australian Ramsar sites over a 12 to 36-year period, resulting in 22 species (at 13 sites) no longer reaching Criterion 6 thresholds for Ramsar designation. In addition, 10 species at six Australian sites had exceeded the Limits of Acceptable Change. Despite these concerning results, there were remarkably few published site-based determinations of listed shorebird species' trends (and even fewer that were ≤5 years old). This is especially surprising since shorebird populations are regularly monitored at 27 out of 35 Australasian Ramsar sites (listed on the basis of one or more shorebird species). Thus, despite the volume of data available for analysis, long-term shorebird monitoring provides only limited insights about Ramsar ecological character. The value of these data would be greatly enhanced through complementary monitoring of other ecological characters at sites, particularly where shorebird populations provide early warning signs of potential deterioration. The main impediment to achieving a good understanding of how Ramsar sites are changing in Australasia appears to be a lack of analysis and centralised system for data and analytics, rather than a lack of monitoring data.

Estimating the conservation cost of the projected new international Lisbon airport for migratory shorebirds of the Tagus estuary, Portugal

SummaryThe increasing pressure of anthropogenic development in areas with high natural value poses a huge challenge for wildlife conservation worldwide. The Tagus estuary in southern Portugal is among the most important wetlands for migratory shorebirds in the East Atlantic Flyway (EAF). However, in 2020 the Portuguese government approved the construction of the new Lisbon international airport at the heart of the Tagus estuary. Intense aircraft traffic, flying at low altitudes during both approach and take-off, is expected to cross the estuary, overlapping to a great extent the important intertidal foraging areas. Here, we aim to quantify the potential loss of conservation value of the intertidal areas of the Tagus estuary for shorebirds resulting from the disturbance (noise) caused by overflying aircraft. Using a comprehensive dataset of wintering shorebird abundance and distribution in the whole intertidal estuarine area we first identified priority areas for conservation using a spatial prioritization approach. We then performed a replacement cost analysis by excluding the areas likely to become unsuitable or severely underused by birds due to intense air traffic noise. Our results suggest that the implementation of the new Lisbon airport may lead to a loss of up to 30% of the conservation value of the Tagus estuary in terms of intertidal feeding areas of wintering birds alone. The global impact will likely be greater when effects on supratidal roosts, as well as on passage birds, are also considered. The Tagus estuary, which is internationally important for six of the 10 species included in our analysis, is just one of a network of already depleted sites along the EAF. Thus, negative impacts on bird populations on the Tagus estuary will have repercussions and undermine conservation efforts elsewhere. The plight of shorebirds at the Tagus estuary is thus a matter of international conservation concern.

Insights into migratory connectivity and conservation concerns of Red Knots Calidris canutus in the austral Pacific coast of the Americas

SummaryMigratory species rely on several distant sites during the annual cycle which makes their conservation more complex than that of non-migratory species. Even one of the most extensively studied migratory shorebirds - the Red Knot Calidris canutus - is currently ‘Near Threatened’ at the global level. Conflicting observations of migratory routes cast uncertainty on the subspecies classification and migratory connectivity of Red Knots in the Pacific coasts of the Americas. To fill essential information gaps, we present the first detailed population morphometrics of Red Knots during the non-breeding season in the southern Pacific coast, along with resightings of these birds throughout the Americas. We also estimated daily rate of weight gain during fuelling based on body mass at captures and known departure dates. Resightings demonstrate reliance on staging areas in both the Mid-continental and Atlantic flyways during the northward migration, and additionally in the Pacific Flyway during southward migration. In addition to the strong connection with several areas also used by C. c. rufa on the North American Atlantic coast, our results show morphometric differences within the ranges of both C. c. rufa and C. c. roselaari. Given the threats faced by Red Knots, the population in Chiloé Archipelago should be treated as a separate conservation unit within interhemispheric conservation programmes for endangered shorebirds within the Americas.

Gut microbiome of migratory shorebirds: Current status and future perspectives.

Migratory shorebirds have many unique life history characteristics, such as long‐distance travel between breeding sites, stopover sites, and wintering sites. The physiological challenges for migrant energy requirement and immunity may affect their gut microbiome community. Here, we reviewed the specific features (e.g., relatively high proportion of Corynebacterium and Fusobacterium) in the gut microbiome of 18 migratory shorebirds, and the factors (e.g., diet, migration, environment, and phylogeny) affecting the gut microbiome. We discussed possible future studies of the gut microbiome in migratory shorebirds, including the composition and function of the spatial‐temporal gut microbiome, and the potential contributions made by the gut microbiome to energy requirement during migration.

Foraging Ecology of Birds in Mudflat Area of Tanjung Laboh, Johor

Tanjung Laboh is located in one out of three Important Bird Areas (IBAs) in Johor called South West Johor Coast which is very crucial foraging ground for resident and migratory shorebirds. However, the airfield development plan located in the area have been an issue as it might disturbed the foraging ecology of the shorebirds. Therefore, it is necessary to analyse the food resources present and the foraging behaviour of the shorebirds in order to determine the effect of disturbance towards the shorebirds’ foraging behaviour. Thus, a study was conducted for a month (July to August 2018) in the mudflat area of Tanjung Laboh to identified the time spent of foraging, food selection and foraging technique of shorebirds by using direct observation method. A total of 212 observations were recorded during sampling period. No significant differences were found in time spent foraging between the bird species, (F = 0.18, p = 0.946). A Spearman Rank Correlation proved that there is no significant relationship between the time spent of foraging and the number of preys taken by each species (R = 0.436, p > 0.05). Based on observation, fish is the most preferred diet choice among bird species which counts a total of 57% followed by unknown (20%), worm (19%) and bivalve (4%). Significant correlation was found between the abundance of bird and the frequency of disturbances (humans, dogs and vehicles) (p < 0.05) while human contribute to a higher percentage in disruptions towards the species studied (57.7%). The responses of the birds towards the disturbances were varied in this study, however the birds tend to choose foraging ground far from disturbance area as the disturbances might chase birds’ prey away thus reduce their feeding rate. By understanding how the shorebirds response toward disturbance, the conservation action can be enforced in the future.