Migratory Shorebirds Research Articles

British Ornithologists’ Union

British Ornithologists’ Union

To migrate or not: drivers of over‐summering in a long‐distance migratory shorebird

The phenomenon of over‐summering in southern non‐breeding areas by boreal‐breeding birds is particularly prevalent among shorebirds. Despite its frequency, it is understudied compared with most other aspects of shorebird ecology. Our aim was to expand knowledge of this subject through a study of red knots Calidris canutus rufa over‐summering at a site in Argentina during the austral winter. We measured the proportion of one‐year‐old and adult over‐summerers and evaluated the roles of flight‐feather condition and physiological status (through leukocite profile, physiological stress index and presence of blood parasites) as triggers for over‐summering. We also explore sex‐ratio, the evolution of body mass and extent of breeding plumage within each age‐class. Over‐summerers were 57% yearlings and 43% adults, 46% females and 54% males. Almost all yearlings exhibited incomplete molt of primary feathers and some were in active primary molt. This suggests that the condition of flight‐feathers and the timing of molt are likely to be important factors selecting for deferred migration during the first year of life. Other factors, not associated with flight‐feather molt, seem to trigger over‐summering in adults, which had completed flight feather molt but had low fat loads and/or incomplete alternate plumage. We found no evidence of a weakened immune system, high loads of blood parasites or high stress levels that can explain this poor migratory conditioning and therefore over‐summering. Our data indicates that our adult age‐class comprises both young individuals postponing first breeding until they are at least two years old and sexually mature individuals with prior reproductive experience skipping a breeding opportunity. Breeding propensity and age at first breeding are both poorly known, but key demographic parameters that determine population growth. This study suggests that potentially they can be estimated from mark–recapture at non‐breeding areas and this warrants further study.

Collect, connect, upscale: Towards coordinated monitoring of migratory shorebirds in the Asia-Pacific

ABSTRACT Monitoring migratory species can be extremely challenging. For example, millions of migratory shorebirds migrate from breeding grounds in northern China, Mongolia and Russia to East Asia and Australasia each year, traversing more than 20 countries while on migration. Studies within individual nations have identified rapid declines in many species, yet progress toward a fully unified scheme for continuous tracking of population change at the scale of the entire East Asian-Australasian Flyway has been slow. To reflect on lessons learned and consider how further progress might be made, we review some of the factors that have limited the full emergence of shorebird monitoring in the East Asian-Australasian Flyway, including fragmentation among multiple databases, low data readiness, inadequate metadata and gaps in survey coverage. We conclude that while technical solutions for many of these issues do exist, the biggest challenge is to navigate the significant organisational, socio-cultural and resourcing contexts of those people doing the monitoring. Technical solutions alone will not create a cohesive network of people whose local efforts are pooled to create robust flyway-scale monitoring.

Notocotylus chionis (Trematoda: Notocotylidae) and Notocotylus sp. from shorebirds in southern Patagonian wetlands of Argentina: morphological and molecular studies

Southernmost South America provides significant wintering habitats for migrant shorebirds, most of which breed in the High Arctic tundra. Helminth species parasitizing these migratory birds have been well studied in North America; however, in South America they are poorly known. As part of an ongoing research on the helminth fauna from Patagonian birds in Argentina, we report Notocotylus chionis and Notocotylus sp. (Trematoda: Notocotylidae) parasitizing three shorebird species, the Nearctic migrants Calidris fuscicollis (WRSA) and Calidris bairdii (BASA) (Scolopacidae), and the Neotropical Charadrius falklandicus (TBPL) (Charadriidae). We provide a new morphological description of N. chionis considering that the previous one reported from the snowy sheathbill on Subantarctic islands are incomplete and based on few specimens. We also provided a morphometric characterization of Notocotylus sp. We obtained molecular data which confirmed the identification of specimens recovered from WRSA and TBPL as N. chionis. Phylogenetic analysis based on 28S ribosomal DNA sequences was performed. The results placed N. chionis close to other Patagonian species native to South America (i.e. N. primulus). Notocotylus chionis was found previously in the snowy sheathbill which inhabits in coasts of southern South America, Antarctic Peninsula and surrounding islands. Present finding in resident birds (TBPL) allows us to hypothesize that N. chionis is a Neotropical species whose life cycle is being completed in southern South America and Subantarctic islands and represents a valuable contribution to the knowledge of parasite diversity in the austral subpolar region of the western hemisphere.

Disentangling abiotic and biotic mechanisms behind the formation of heterospecific Nearctic-Neotropical shorebird flocks

Defense, vigilance, and optimal foraging are frequently related to the formation of flocks in birds. Few studies concerning long-distance migrant shorebirds analyzed whether phylogeny and ecological similarities of species are associated with the formation of heterospecific flocks. Here, we explore (1) the niche conservatism theory, (2) the competition-relatedness hypothesis, and (3) the niche construction hypothesis to explain the formation of wintering Nearctic-Neotropical heterospecific shorebird flocks in the southeastern coast of Brazil. In the first, closely-related species keep their ecological traits over time. In the last two hypotheses, ecological dissimilar and distant-related species may coexist due to strong biotic interactions. Our results discard the influence of relatedness between species and/or phylogenetic filtering signals that could act in the formation of heterospecific flocks. Co-participation of species in flocks is explained by similarities in body weight and tarsus length, which invokes the niche construction hypothesis. Probably, some similar-sized and niche-constructing species are relocating in space and changing the environment that they experience to optimize individual capacity to flee from predators. From an ecological perspective, numerous phenotypically similar species with redundant roles could lead to greater resilience of the community under anthropogenic disturbances. From an evolutionary perspective, different species with similar phenotypes may diminish costs of activity matching and augment individual fitness.

Influence of land use change on the waterbird community of Sihwa Lake, Republic of Korea

BackgroundLand use and development alter mudflat and wetland habitat availability, although mudflats and wetlands provide important stopover habitats for shorebirds during the spring and autumn migrations and support communities of ducks and geese during the winter months in the Republic of Korea. This study investigated land use changes around Sihwa Lake (Republic of Korea) and evaluated the effect of these changes on waterbird community characteristics.MethodsWe conducted a land-use-change analysis at the medium-resolution level using land cover maps for 2001, 2007, 2009, and 2014. Also, a tidal stream survey was conducted in Sihwa Lake and the surrounding reclaimed mudflats every season for 10 years (2003–2012) to identify the seasonal and interannual variations in waterbird species composition. To determine the total annual waterbird species and population counts, species diversity index, and interspecies variations, a TRIM (trends and indices for monitoring data) analysis was used.ResultsWetland area decreased more than 10% while agricultural land, barren land, and grassland area increased more than 10% due to continuous reclamation activities around Sihwa Lake. Barren land later turned into agricultural land or other land use. Sixty-three species and 566,623 individuals were recorded. The number of species, population size, and species diversity index by year and by species showed decreasing trends that were more marked in spring and summer. Furthermore, seasonal and annual variations in waterbird species composition showed decreasing trends in dabbling ducks, herons, grebes, and shorebirds but diving ducks displayed increasing trends. In particular, shorebirds were reduced to a greater extent than other waterbird species because of the reduction and simplification of the intertidal zone, and shallow waters caused by reclamation and road construction.ConclusionsIncreased development and construction around Sihwa Lake has altered migratory shorebird populations with a general decline in species diversity and population size. The greatest decline was observed in wading birds, while diving duck populations showed increasing trends.

Valuing Shorebirds: Bureaucracy, Natural History, and Expertise in North American Conservation.

This article follows shorebirds-migratory animals that have gone from game to nongame animals over the course of the past century in North America-as a way to track modern field biology, bureaucratic institutions, and the valuation of wildlife. Doing so allows me to make interrelated arguments about the history of wildlife management and science. The first is to note the endurance of observation-based natural history methods in field biology over the long twentieth century and the importance of these methods for the persistent contribution of amateurs. The second major line of argument advances the historical significance of scientific, government bureaucracies as sites of natural knowledge production. Historians of biology and ecology have tended to stress scientists with institutional homes in universities, museums, and at land-grant field stations-particularly as various forms of field biology became professionalized over the twentieth century. In contrast, migratory animals like shorebirds, whether under the auspices of the US Biological Survey or the contemporary Fish and Wildlife Service, were primarily studied and conserved by biologists in bureaucratic agencies. Mid- to low-level bureaucrats, along with avocational birders, have mainly been responsible for developing what we know about shorebird migration, behavior, and life history. And third, shorebirds foreground the importance of bureaucratic context for the valuation of nature, from their economic value to agriculture in the early twentieth century to their value as rare, endangered species in the twentyfirst.

Differences in Migration Timing along the Midcontinental Flyway in Sanderling (Calidris alba) from Three Gulf of Mexico Staging Areas

Although there is a clear link between early arrival on the breeding grounds and fitness in migratory birds, how winter and staging site use influence the timing of migration events prior to arrival at breeding areas is not well established. Therefore, there is a need to characterize the migration phenology of long-distance migratory birds. This study investigated the northbound migration timing of Sanderlings (Calidris alba) along the Central and Mississippi Flyways (i.e., the ‘Midcontinental Flyway’). Between 2015 and 2017, coded nanotags were attached to 120 Sanderlings in three staging areas in the USA portion of the Gulf of Mexico: North Padre and Bolivar Flats, Texas and sites in Louisiana. Individuals were then tracked northward using the Motus Wildlife Tracking System. Sanderling detections in more northern latitudes on northward migration were primarily in Saskatchewan (94%; n = 33), with only two individuals detected along the Atlantic coast. Sanderlings trapped in North Padre arrived later in Saskatchewan than individuals trapped in Bolivar Flats and Louisiana. Additionally, there was a negative association between Saskatchewan arrival timing and staging duration, such that later-arriving individuals from North Padre had significantly shorter staging durations and consequently departed from Saskatchewan at the same time as individuals originating from Bolivar Flats and Louisiana. These results provide new insight into the migration schedule of a declining long-distance migratory shorebird species and show how departure and arrival timing are linked across disparate staging sites.

Survival during the pre-fledging period rather than during post-fledging drives variation in local recruitment of an endangered migratory shorebird, the Southern Dunlin Calidris alpina schinzii

The declines in wet-grassland breeding shorebird populations are considered to mainly result from changes in reproduction. While there is plenty of information on nest survival, little reliable information exists on local recruitment due to confounding effects of permanent emigration. Furthermore, few studies have been able to study the roles of pre- and post-fledging survival on local recruitment. Therefore, it is unclear whether local recruitment of young reflects conditions at the breeding sites or at non-breeding sites. We studied an isolated population of the endangered Southern Dunlin (Calidris alpina schinzii) breeding on the west coast of Sweden to examine (1) brood survival (probability of at least one chick fledging) by following broods fates and (2) local recruitment (survival from hatching to 1 year old) using capture-recapture data. We then examined how much of the annual variation in juvenile survival was explained by variation in brood survival. Brood survival was on average 0.58 (annual range 0.08–1.00) and explained 64% of variation in annual local recruitment. Still local recruitment was rather high for a shorebird (0.17, SE = 0.023), which reflects the isolated nature of the study population. Our results suggest that local recruitment seems to be mainly constrained by chick survival during the pre-fledging period. Therefore, management of breeding sites leading to increased brood survival, e.g., reducing predation on chicks, should have strong impacts on local recruitment and local population growth.

Modelling the potential non-breeding distribution of Spoon-billed Sandpiper Calidris pygmaea

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.

Stakeholder engagement in the governance of marine migratory species: barriers and building blocks

Meaningful stakeholder engagement is important to collaborative decision-making and to effective polycentric governance, particularly when managing cross-scale environmental issues like those involving marine migratory species. In this paper, we explore the barriers to, and opportunities for, stakeholder involvement in the governance of threats to marine migratory species in eastern Australia, using semi-structured qualitative interviews and a focus group, as an example of the generic problem of managing migratory species within a large range state with multiple jurisdictions. Respondents identified several barriers to, and opportunities for, improved stakeholder involvement in the governance of marine migratory species, corresponding to 4 main themes: decision-making processes, information sharing, institutional structures, and participation processes. Respondents indicated that the governance system protecting marine turtles, dugongs, humpback whales, and non-threatened migratory shorebirds in eastern Australia would benefit from the introduction of new information pathways, reformed institutional structures (including environmental legislation), and improved participatory pathways for non-government stakeholders. Such changes could help harmonise the process of managing these species, leading to more effective conservation management throughout their range.

Defining separation zones for coastal birds at a wetland of global importance

Abstract ContextThe disruption of normal activities by humans (i.e. ‘anthropogenic disturbance’) can have important behavioural, physiological and population effects on coastal birds. These negative effects include increased vigilance, increased energy expenditure and reduced nesting success. To overcome this, separation distances (e.g. buffers and setbacks) are often used to separate threatening stimuli, such as humans, from wildlife. However, in most instances the determination of separation distances are based on little empirical information. This is particularly true for Africa, which supports huge populations of Palearctic migrant shorebirds. AimTo determine suitable separation distances that will reduce anthropogenic disturbance to the coastal bird community at West Coast National Park, South Africa. MethodsThe distance at which a behavioural response (i.e. flight initiation distance, FID) occurred among 15 common coastal bird species when presented with an approaching human was measured. Linear mixed-effects models were used to determine the relationship between FID and body size, migratory status, intraspecific flock size, flock species richness, foraging behaviour and several environmental covariates. Key resultsBody mass was significantly and positively correlated with FID, indicating that larger birds are more sensitive to the anthropogenic stimulus. Furthermore, it was shown that migratory birds had longer FIDs, suggesting that they are less risk tolerant compared with resident birds. The distance at which the approach was initiated (i.e. the start distance, SD) was also significantly and positively correlated with FID, supporting the hypothesis that birds will flush early to avoid the potential negative consequences of fleeing too late. Finally, there was a novel significant effect of increasing wind speed on increasing FID, suggesting a thermoregulatory trade-off. There was no effect of foraging behaviour, flock size or flock composition on FID. ConclusionBased on these data, buffer distances for tidal habitats at West Coast National Park should be set at ~170 m. ImplicationsImproved understanding of FID, and the morphological and behavioural predictors thereof, will enable West Coast National Park and other protected areas to designate separation distances or buffer zones that reduce the negative effects of anthropogenic disturbance on shorebird communities.

Water-level controlled reservoir as refugia for waterbirds in an urban landscape

Artificial wetlands can play an important role in waterbird conservation due to habitat loss and degradation of natural wetlands. Urban reservoirs can harbor waterbird communities, but they usually have lower biological diversity than natural wetlands. However, the value of reservoirs for waterbird conservation in urban areas needs further exploration. Here, we surveyed the waterbird community in a water-level controlled reservoir of an urban area in southeastern Brazil. We evaluate the seasonal variation in species composition, richness, and abundance. Monthly samplings were carried out between July 2017 and February 2018, through a boat line transect. A total of 7762 waterbirds were recorded, belonging to 32 species and 16 families. There were significant differences in species composition and abundance between dry and rainy seasons. The community was dominated by generalist and resident species, which Gallinula galeata and Jacana jacana were the most abundant species. We did not register migratory shorebirds during the surveys. Our results highlight the importance of reservoirs in urban areas, as they harbor feeding areas and breeding sites and may serve as refuges during dry seasons for resident waterbirds. We suggest management strategies to improve the importance of water-level controlled reservoirs as breeding areas for resident species and migratory stopover for shorebirds. Our results may also be considered for urban planning and waterbird conservation in urban areas.

Differences in dietary specialization, habitat use and susceptibility to human disturbance influence feeding rates and resource partitioning between two migratory Numenius curlew species

Migratory shorebirds select stopover sites to fuel their migration across heterogeneous coastal landscapes with abundant prey resources. Quantifying the degree of dietary specialization between closely-related species and how they partition resources across different coastal habitat types during both spring and autumn migration could identify some interesting possibilities for conservation management given the extent of anthropogenic habitat degradation at critical stopover sites. Here we used a comparative approach to examine diet specialization and feeding rates of two migratory Numenius curlew species, Far Eastern Curlew Numenius madagascariensis and Eurasian Curlew N. arquata populations, at an important stopover site in the Yellow Sea, China, and to assess the influence of habitat type, presence of human disturbance (activities related to aquaculture and oil production), and migratory season on their feeding behavior. Far Eastern Curlews were more dependent on tidal crabs and exhibited less dietary flexibility than its closely-related congener. Feeding rates on crabs by Far Eastern Curlews were not significantly different between mudflat and Suaeda salsa saltmarsh habitat but were negatively influenced by human disturbance and were higher during spring migration. In contrast, these effects were not apparent for Eurasian Curlew which fed predominantly on ragworms in saltmarsh habitat. The differences in prey type and feeding rates between adjacent habitats and migration seasons could explain how these two congeners fit syntopically along coastal wetland resource gradients. The extensive utilization of S. salsa habitat by both species suggests that saltmarshes represent an important feeding habitat for these species and that further conservation efforts aimed at reducing human disturbance would benefit both species and may lead to improved feeding rates for Far Eastern Curlews.

Salmonella enterica Serovar Hvittingfoss in Bar-Tailed Godwits (Limosa lapponica) from Roebuck Bay, Northwestern Australia.

Salmonella enterica serovar Hvittingfoss is an important foodborne serotype of Salmonella, being detected in many countries where surveillance is conducted. Outbreaks can occur, and there was a recent multistate foodborne outbreak in Australia. S Hvittingfoss can be found in animal populations, though a definitive animal host has not been established. Six species of birds were sampled at Roebuck Bay, a designated Ramsar site in northwestern Australia, resulting in 326 cloacal swabs for bacterial culture. Among a single flock of 63 bar-tailed godwits (Limosa lapponica menzbieri) caught at Wader Spit, Roebuck Bay, in 2018, 17 (27%) were culture positive for Salmonella All other birds were negative for Salmonella The isolates were identified as Salmonella enterica serovar Hvittingfoss. Phylogenetic analysis revealed a close relationship between isolates collected from godwits and the S Hvittingfoss strain responsible for a 2016 multistate foodborne outbreak originating from tainted cantaloupes (rock melons) in Australia. While it is not possible to determine how this strain of S Hvittingfoss was introduced into the bar-tailed godwits, these findings show that wild Australian birds are capable of carrying Salmonella strains of public health importance.IMPORTANCESalmonella is a zoonotic pathogen that causes gastroenteritis and other disease presentations in both humans and animals. Serovars of S. enterica commonly cause foodborne disease in Australia and globally. In 2016-2017, S Hvittingfoss was responsible for an outbreak that resulted in 110 clinically confirmed human cases throughout Australia. The origin of the contamination that led to the outbreak was never definitively established. Here, we identify a migratory shorebird, the bar-tailed godwit, as an animal reservoir of S Hvittingfoss. These birds were sampled in northwestern Australia during their nonbreeding period. The presence of a genetically similar S Hvittingfoss strain circulating in a wild bird population, 2 years after the 2016-2017 outbreak and ∼1,500 km from the suspected source of the outbreak, demonstrates a potentially unidentified environmental reservoir of S Hvittingfoss. While the birds cannot be implicated in the outbreak that occurred 2 years prior, this study does demonstrate the potential role for wild birds in the transmission of this important foodborne pathogen.

Building for Nature: Preserving Threatened Bird Habitat in Port Design

The fast economic development of the People’s Republic of China has created an increasing demand for usable land, resulting in large-scale land reclamations along the coastal zone. One of these regions is Tongzhou Bay (Jiangsu coast), a region characterized by large intertidal mudflats and deep tidal channels with potential for the development of agri-aquaculture and the construction of a deep-sea port. However, these intertidal mudflats also provide vital ecosystem services and support many wildlife species, including several endangered migratory shorebirds within the East Asian–Australasian Flyway. With increasing realization of the importance of maintaining such ecological values, a more integrated coastal development strategy is needed. This study aims to develop a sustainable integrated design for the Tongzhou Bay port, following a “Building with Nature” approach. We use a morphodynamic model to compute habitat suitability for two shorebird species (Great Knot Calidris tenuirostris and Bar-tailed Godwit Limosa lapponica). Several port configurations were developed on the basis of three design criteria: (1) create area for future port development, whilst (2) preserving existing high-value ecotopes for shorebirds and (3) enhance the natural accretion rate of such ecotopes. Simulation results showed a clear difference in siltation patterns, preservation and enhancement of preferred ecotopes. This work therefore demonstrates the potential and importance of morphological and habitat suitability modelling when designing large-scale reclamations and port constructions, especially in dynamic areas such as Tongzhou Bay.

Pro-inflammatory immune response is linked to wintering habitat in a migratory shorebird

AbstractMigratory shorebirds (Charadrii) show a strong dichotomy in their breeding and wintering strategies: Arctic-breeding species typically spend the wintering season in marine habitats, while more southerly breeding species tend to do so in freshwater habitats where pathogens and parasites, particularly vector-borne blood parasites, are generally more abundant. Thus, it has been hypothesized that the former group may reduce their investment in immunity, but experimental data supporting this hypothesis are lacking. Moreover, whether this contrasting habitat selection can shape investments in immunocompetence among populations within a species is uncertain. We experimentally tested the hypothesis that there is a significant association between habitat occupancy and the strength of a pro-inflammatory immune response in the Dunlin (Calidris alpina), a widely distributed long-distance migratory shorebird that breeds in (sub-)arctic areas and winters mainly, but not exclusively, in coastal habitats. Overwintering Dunlins occupying inland freshwater and marine habitats at a similar latitude were captured and acclimated under identical conditions in outdoor aviaries. After an acclimation period, they were challenged with phytohemagglutinin to assess the pro-inflammatory immune response and its associated energetic costs, measured by basal metabolic rate (BMR) and body mass changes. We found that freshwater Dunlins exhibited a higher (63%) pro-inflammatory immune response than marine Dunlins. Although this difference did not involve significant BMR changes, the time course of body mass response differed between freshwater and marine individuals. Our findings point to the existence of different pro-inflammatory immune responses and body mass adjustments associated with the wintering habitat. These intraspecific differences are likely due to population adaptation rather than phenotypic plasticity, where not only disease risk but also physiological adaptations to different salinity levels could play an important role.

Over-summering abundance, species composition, and habitat use patterns at a globally important site for migratory shorebirds

The Indian subcontinent is the primary wintering ground and stopover site for migratory shorebirds to refuel along the Central Asian and South Asian Flyways. Despite the conservation importance of this region for migratory shorebirds, we lack information on the distribution and abundance of over-summering shorebirds—migrants that remain on their wintering grounds during the breeding season—to evaluate the impacts of anthropogenic change on this poorly understood life history strategy. We conducted weekly surveys of over-summering shorebirds at mudflats, mangroves, and sand beaches at the Kadalundi-Vallikkunnu Community Reserve on the southwest coast of India, 2005–2018. We examined long-term patterns of over-summering shorebird abundance, species composition, and habitat use and estimated proportional changes in over-summering abundance of each shorebird species documented at this globally important site. Over the 14 yr study, we documented 7 over-summering species, including Lesser Sand Plover (Charadrius mongolus), Whimbrel (Numenius phaeopus), Greater Sand Plover (Charadrius leschenaultia), Kentish Plover (Charadrius alexandrinus), Common Sandpiper (Actitis hypoleucos), Ruddy Turnstone (Arenaria interpres), and Pacific Golden-Plover (Pluvialis fulva). Mean abundance and species richness were higher at mudflats than at mangroves and sand beaches, with fewer individuals and species observed over-summering after 2010. Mudflats also had the highest species diversity and evenness compared to mangroves and sand beaches. Management plans that aim to restore vulnerable mudflats and mangroves and to reduce anthropogenic threats such as sand mining and waste dumping are needed to prevent the loss of important over-summering, foraging habitat for migratory shorebirds in southern India and along the Central Asian and South Asian Flyways.

Oversummering in the southern hemisphere by long-distance migratory shorebirds calls for reappraisal of wetland conservation policies

In many migratory bird populations, individuals forgo migrating to the breeding grounds for one or more years and instead ‘oversummer’ in non-breeding areas. This behaviour occurs among long-distance migratory shorebirds, typically species exhibiting delayed maturity. As the oversummering areas remain poorly described, conservation strategies will be incomplete even in species experiencing ongoing global declines. Oversummering areas could be a weak link in the chain if they are spatially distinct from non-breeding grounds, and used during critical stages throughout individual’s lifetime. Here, we present a combining study based on (1) GPS-tracking adult Hudsonian godwits Limosa haemastica oversummering in inland South America, (2) two consecutive seasons of surveys to estimate minimum godwit abundance in that area, and (3) analyses of 13 years of shorebird counts based on the Neotropical Waterbird Census (NWC) in Argentina. Godwits arrived at pampa plain wetlands in early May and spent 5–6 months there. We observed godwits in six out of 44 wetlands surveyed, with a minimum of 366 and 746 godwits counted each survey. Based on frequency of occurrence in NWC, oversummering propensity in Argentina was high for three out of nine Nearctic shorebird species, all of which are of international conservation concern. Despite our limited survey effort, we found several hundred godwits that will likely represent only a small fraction of the population oversummering in this region. Given their delayed maturity, many other long-distance migratory shorebirds may spend large portions of their lives in previously undocumented wetlands while deferring migration. These unrecognized oversummering habitats fall outside the scope of today’s conservation efforts for Hudsonian godwits, because they are not spatially nested within the non-breeding grounds, an issue to be studied for other shorebirds. We therefore propose including specific criteria for oversummering areas when designating wetlands of international concern for the conservation of long-distance migratory shorebirds.

The mitochondrial genome of two long-distance migratory shorebirds: the Hudsonian godwit (Limosa haemastica) and the Red knot (Calidris canutus)

We report the mitochondrial genome sequences of two migratory shorebirds, the Hudsonian godwit (Limosa haemastica) and the Red knot (Calidris canutus) obtained through shotgun sequencing. The mitogenome is of 16.445 bp for the godwit and 15.609 bp for the knot containing thirteen protein-coding genes, two rRNAs, twenty-two tRNAs, and a control region. The ATP8 and tRNA-Glu were not found in the knot. Bayesian phylogenetic analysis supported the position of both species in the clade of the Scolopacidae Family.