Shorebird Community Research Articles

Area- and latitude- shaped shorebird diversity patterns reveal constraints of migratory bottlenecks along the Yellow sea coast of China

Migratory stopping regions are regarded as geographic bottlenecks. However, knowledge about constraints on migratory communities remains limited. This study proposed hypothetical spatial constraints (SCs) and tested the predictions by examining the response of multifaceted shorebird diversity to the tidal flat area and latitude of the stopping sites along the Yellow Sea coast. We estimated species richness (SR), phylogenetic and functional diversity (PD and FD) by building a species-level phylogenetic tree and measuring five functional traits of all species, using data on the shorebird community at 11 internationally important stopping sites of 2020–2021. We used multiple linear regression models and null models to examine the relationships between diversity metrics and stopping site variables (area and latitude). Functional and phylogenetic rarity of non-least concern species was calculated to estimate their risk of disappearance. The three dimensions of biodiversity decreased with decreasing area despite different slopes (i.e., FD was less sensitive to area than SR, whereas PD was lost more rapidly in smaller areas). In addition, only FD increased at sites approaching the terminal stopping area, implying that SR and PD were restricted from growing by latitude. Inferred from the PD and FD patterns, competitive exclusion tends be the dominant mechanism structuring the community, and the FD-inferred process was intensified in smaller sites toward the northerly terminal site. The area- and latitude-shaped diversity patterns indicate SCs on the migratory community, while a more intensive process of competitive exclusion tends to take place in smaller and near-terminal stopping sites. Consequently, the threatened shorebirds with less competitive capacity may be more prone than others in the SCs. This study highlighting the significance of the multifaceted biodiversity in monitoring the impacts of SCs and facilitating the development of conservation strategies in internationally critical migration bottlenecks.

Associations with landscape and local‐scale wetland habitat conditions vary among migratory shorebird species during stopovers

Wetlands provide many ecosystem services and functions, including critical stopover habitat for numerous migratory bird species. Yet, loss and degradation of wetlands due to land use and land cover changes have greatly reduced wetland extent worldwide, leading to declines of many migratory shorebirds globally. In the Western Hemisphere, wetlands of the North American Great Plains provide important stopover habitat for shorebirds; however, much remains to be learned about shorebird habitat use during stopovers in this region, including species‐specific associations with landscape‐scale wetland availability and characteristics of individual wetlands. To improve understanding of shorebird habitat use during migration, we conducted shorebird surveys at > 14 000 wetlands throughout Oklahoma, USA, from 2007 to 2009. For 16 shorebird species, we analyzed associations between observed abundance and wetland variables, including within‐wetland characteristics and availability of wetlands at multiple spatial scales surrounding survey locations. We found that the scale at which observed abundance of shorebirds was associated with wetland extent varied among species; 10 species responded most strongly to wetland extent at the 500 m scale, but 5 species and 1 species responded most strongly at 1000 and 2000 m scales, respectively. Observed abundance for most species was generally associated with higher wetland density at broad scales, presence of extensive shallow water, more usable area, and limited vegetation within wetlands, yet there was considerable interspecific variation in the strength and in some cases direction of effects of these within‐wetland characteristics. This interspecies variability highlights the importance of conserving a variety of wetland types with differing characteristics that support the entire shorebird community during migration. By informing optimal habitat requirements for shorebirds during a critical stage of their annual cycle, knowledge gained about species‐specific habitat needs from studies like ours can assist with development of conservation and management strategies that contribute to halting and reversing global shorebird declines.

Shorebird Monitoring Using Spatially Explicit Occupancy and Abundance

Loss of habitat and human disturbance are major factors in the worldwide decline of shorebird populations, including that of the threatened migratory piping plover (Charadrius melodus). From 2013 to 2018, we conducted land-based surveys of the shorebird community every other week during the peak piping plover season (September to March). We assessed the ability of a thin plate spline occupancy model to identify hotspot locations on Whiskey Island, Louisiana, for the piping plover and four additional shorebird species (Wilson’s plover (Charadrius wilsonia), snowy plover (Charadrius nivosus), American oystercatcher (Haematopus palliatus), and red knot (Calidris canutus)). By fitting single-species occupancy models with geographic thin plate spline parameters, hotspot priority regions for conserving piping plovers and the multispecies shorebird assemblage were identified on the island. The occupancy environmental covariate, distance to the coastline, was weakly fitting, where the spatially explicit models were heavily dependent on the spatial spline parameter for distribution estimation. Additionally, the detectability parameters for Julian date and tide stage affected model estimations, resulting in seemingly inflated estimates compared to assuming perfect detection. The models predicted species distributions, biodiversity, high-use habitats for conservation, and multispecies conservation areas using a thin-plate spline for spatially explicit estimation without significant landscape variables, demonstrating the applicability of this modeling approach for defining areas on a landscape that are more heavily used by a species or multiple species.

Trophic ecology of a migratory shorebird community at a globally important non-breeding site: combining DNA metabarcoding and conventional techniques

Studies providing a detailed diet description of whole-bird communities are surprisingly scarce. Yet, these studies are pivotal to comprehend the mechanisms structuring communities and the persistence of each species in the ecosystem. We characterized the diet of a shorebird community in a key non-breeding area of the East Atlantic Flyway, the Bijagós Archipelago (West Africa), combining molecular and morphological prey identification based on 239 droppings from 15 species. Our results show that while relying upon a super-abundant prey (fiddler crab), shorebirds consumed a very high number of taxa. We stress the relevance of highly mobile prey (especially crustaceans but also fish), which typically appear to be of little importance in most shorebird studies. Our results suggest that by consuming a high diversity of prey, shorebirds may reduce competition. This may be critical in a site ranked as the second most important area in West Africa for migratory shorebirds but marked by low benthic invertebrate availability. We further compared the performance of DNA metabarcoding and morphological identification of prey. Overall, molecular and morphological methods combined delivered the most comprehensive results, although molecular methods largely surpassed morphological methods regarding taxonomic detail achieved and number of prey taxa found (4 times more). Taxonomic resolution in the identification of polychaetes and bivalves using the 16S primer was low (mostly to class), whereas this primer clearly performed better than mitochondrial cytochrome c oxidase in identifying more insects and fish. We emphasize the need to increase invertebrate representatives from West Africa in barcode databases, in order to enhance metabarcoding results.

Obligation to Enhance OBIS Data for Sea- and Shorebirds of the Americas

The distributions of many sea- and shorebird species span large geographic areas, making them ideal candidates as biomonitors of ecosystem perturbations and long-term environmental trends. The basic question examined in this study was: Does a major open-access data archive contain sufficient temporal- and spatial-scale data to support more detailed inquiry into multi-decadal-scale responses in geographic distributions of specific taxa? The global-scale open-access data platform, Ocean Biodiversity Information System (OBIS), was searched to compile data on bird distributions of the Americas, including the Caribbean Sea. More than 680,000 occurrence records of 210 species, collected between 1965 and 2018, were located and evaluated by marine ecoregion. The Puget Trough/Georgia Basin marine ecoregion, along the United States/Canadian border, and the Virginian marine ecoregion on the US east coast, dominated occurrences, each with more than 100,000 records, while the Gulf of Maine/Bay of Fundy had the most years of records (42). Most records from South America (~29,000) came from the Channels and Fjords of Southern Chile, collected across 16 different years. More than 90% of the recorded data were collected since 1983, and more than 95% of the records were from North American marine ecoregions. We urge additional observations to be shared via OBIS to allow comprehensive large-scale and detailed meta-analyses of spatial and temporal trends in marine and shore-bird communities and their biodiversity.

Effects of Macrobenthos Relative to Floating-Leaved Plants on the Wintering Shorebird Assemblages at Shengjin Lake, China

In shallow lakes, floating-leaved plants can produce dense lakebeds that dramatically alter freshwater ecosystems and impact macrobenthic communities. Shorebirds are morphologically diverse and utilize different foraging strategies; they can partition food resources to achieve coexistence due to differences in food availability. In this study, we defined shorebird foraging guilds using a principal component analysis and explained differences in shorebird composition in terms of food availability by comparing macrobenthic and shorebird communities in Euryale ferox artificial planting areas, Trapa spp. natural growth areas, and control areas. The Mantel test and a Spearman analysis were used to correlate macrobenthic taxa with shorebird foraging guilds. We recorded four different macrobenthic taxa in the three study areas, including insects, gastropods, oligochaetes, and bivalves. Fifteen species belonging to three shorebird families were recorded across the three study areas. Our results suggest that floating-leaved plants are an important cause of differences in macrobenthic communities, and epifaunal macrobenthos (insects and gastropods) and infaunal macrobenthos (oligochaetes and bivalves) take on different patterns of diversity composition in different habitats. The macrobenthic and shorebird communities were potentially coherent. Different shorebird foraging guilds were limited by food availability and thus correlated differently with different macrobenthos. Therefore, differences in macrobenthic communities relative to floating-leaved plants can affect shorebird assemblages by affecting the availability of food resources.

Effects of habitat loss on migratory shorebird community structure at stopover sites: A case study in the Yellow River Delta, China

Coastal wetlands in China provide important stopover sites for migratory shorebird species. The loss of natural wetlands caused by land reclamation over the past few decades poses a major threat to shorebird populations. Although habitat loss at key stopover sites has been shown to lead to reductions in shorebird populations, the effects of habitat loss at specific stopover sites on shorebird populations remain unclear. Here, we used shorebird diversity indices and landscape metrics to elucidate the long-term (19952020) effects of habitat change on shorebird community structure in the Yellow River Delta, which is an important stopover site for shorebirds along the Yellow Sea coast. The results showed that the habitat area, largest patch index, mean patch area, and the aggregation index decreased over 25 years. By contrast, the number of patches and patch density increased over the same period. The richness, Shannon-Wiener index, Pielou index, and Simpson index of the shorebird community increased from 1995 to 2020, while abundance of shorebird declined by 90.14%. Declines in the abundance of species were more pronounced in larger-bodied ones than in smaller-bodied species (T=1.156, df=42, p=0.02). On the other hand, there were no significant differences in the decline in the abundance of threatened species and non-threatened species (T=-0.483, df=42, p=0.632) and coastal specialist species and generalist/inland specialist species (T=-1.197, df=42, p=0.239). The decrease in mean patch area significantly contributed to the reduction in abundance of shorebirds (N=6, p=0.01), and its effects were more pronounced on larger-bodied ones than on smaller-bodied species (T=-2.113, df=42, p=0.04). These results suggest that habitat loss in the Yellow River Delta has contributed to declines in shorebird populations and that larger-bodied ones are more sensitive to habitat change than smaller-bodied species. Existing wetlands are in urgent need of conservation, and further land reclamation in this region should be avoided. In addition, the development of conservation plans for coastal wetlands requires consideration of variation in the responses of different functional groups to habitat change.

Shorebird community and diversity in Bagan Serdang Beach, North Sumatra

The occurrence of shorebirds is strongly influenced by environmental factors, especially food availability. Shorebirds are closely linked to their habitat conditions, so they seek out feeding sites according to their life cycle. Coastal conditions that have changed due to human activities may affect the assemblage of shorebird community. The aim of this study is to determine the diversity of shorebird species and the factors that influence them. Bird observations were made for three days using the point count method while the number of individuals was estimated by using “block method”. The results revealed 17 shorebird species from the families, Charadriidae, Scolopacidae and Sternidae. The dominant species were Charadrius mongolus, Pluvialis fulva and Sterna hirundo. The number of species in the morning observations was higher than in the afternoon. The diversity index for migratory birds ranges from 1.16 to 1.96, which is relatively low. This study showed that mudflats in Bagan Serdang Beach, Pantai Labu District is occupied by shorebirds in this region.

Impact of human disturbance on the abundance of non‐breeding shorebirds in a subtropical wetland

AbstractShorebird populations have declined due to several threats throughout their annual cycle. Anthropogenic disturbance is one of the most ubiquitous threats to shorebird conservation in North America. Here, we studied the influence of human disturbance on shorebird community dynamics during migration and winter in Ensenada de La Paz, a subtropical coastal wetland in Mexico. We used negative binomial generalized linear mixed models to investigate the associations between spatial, biological, and anthropogenic variation and local shorebird abundance that accounted for shorebird body size (small, medium, and large) and foraging strategy (visual and tactile) of 22 shorebird species. After controlling for these different correlates of abundance, human disturbance (people, vehicles, and dogs) was negatively associated with shorebird abundance. During winter, all shorebird species were negatively related to human disturbance but positively associated with presence of raptors. However, small, tactile foraging birds exhibited a proportionally larger negative response to human disturbance than other shorebird types, indicative of guild‐level sensitivities to human disturbance regimes. The positive association between shorebird abundance and disturbance from predators was unexpected. Shorebirds likely concentrate in large groups to reduce predation risk, resulting in higher densities of shorebirds occurring in areas with high predation risk. Understanding factors influencing the abundance and habitat use of shorebirds on their non‐breeding grounds is paramount to support management and conservation policies for shorebirds and their habitats.Abstract in Spanish is available with online material.

Benthic infaunal spatial biodiversity, coexistence, and availability for shorebird communities in the Jakarta Coastal Wetlands, Indonesia

Abstract. Wibowo AA, Basukriadi A, Nurdin E, Nasution NS. 2022. Benthic infaunal spatial biodiversity, coexistence, and availability for shorebird communities in the Jakarta Coastal Wetlands, Indonesia. Intl J Bonorowo Wetlands 12: 23-32. Wetlands on the Jakarta Coast, Indonesia, is one of the important habitats for shorebirds. In the wetland ecosystem, benthic infauna is an important food source for the shorebird community. This study aims to assess the benthic infaunal spatial biodiversity and its availability for the shorebird community in the wetlands covering an ecotourism area and the west and east parts of a protected mangrove forest. The bird diversity was assessed using visual encounter surveys and 10 x 10 m plots for mangroves. The K-means clustering method measured the benthic infaunal coexistence and availability for shorebirds. Based on the result, benthic infauna was available as a food resource for shorebirds in the following order: Oligochaeta > Polychaeta > Gastropod > Crustacea, with the density of oligochaetes reaching 376.66 inds/100 m2. The Shannon-Wiener biodiversity index (H’) ranges for benthic infauna were 1.306-1.573. Gastropods were available to Ciconiidae and Anhingidae; oligochaetes and polychaetes were available to Anatidae, Scolopacidae, and Phalacrocoracidae. In contrast, crustaceans were not available to any shorebird species. As confirmed in this study, shorebird species were associated with the presence of benthic infaunal communities and it recommends conserving the wetlands to ensure the availability of benthic infauna.

Trophic Interactions of Shorebirds in a Wintering Area of Southern Brazil: Foraging Strategies and Habitat Preferences

In wintering shorebird communities, interspecific niche segregation can occur by differences in diet, behavior, and morphology. The Lagoa do Peixe National Park (LPNP) is a coastal wetland complex with lagoons and sandy beaches in Southern Brazil, providing an environment with high prey availability where mixed-species foraging flocks of the Sanderling Calidris alba and the White-rumped Sandpiper Calidris fuscicollis occur. We counted all individuals in flocks and observed a higher proportion of Sanderlings than White-rumped Sandpipers foraging in the intertidal zone. To describe and evaluate patterns of trophic interactions between the two species, we built ethograms using video recordings and analyzed the foraging techniques and microhabitats used by individuals. The White-rumped Sandpiper (n = 45) was sighted foraging both in the supralittoral (n = 14) and intertidal zone (n = 31), whereas the Sanderling (n = 46) mostly foraged in the intertidal zone (n = 44). We estimated niche measures from foraging strategies and habitat preferences, which together can indicate dietary specialization. While niche width was similar for the two species, niche overlap was not significant, probably due to the different foraging microhabitats and techniques used by these two species. Therefore, the LPNP ecosystem offers diverse opportunities for wintering shorebirds, and is the southernmost area in which niche estimates of the Sanderling were assessed.

Wintering shorebird in sandy coasts of Catania’s gulf (Sicily, Italy): 2011-2020

Sandy coasts are specific habitats of high ecological significance for many species of shorebirds. The Gulf of Catania, in the Eastern coast of Sicily, is considered one of the most important sandy coastal areas of the region for the wintering of different species of Charadriidae and Scolopacidae, also due to the presence of River Simeto’s mouth and other freshwater streams. Since the area has been subject to many changes in the last few decades and recent data were not available, a ten-year monitoring of the wintering shorebird community has been carried out, from January 2011 to January 2020, to understand its current ecological role and to update the knowledge about numbers and trends of Sicilian wintering shorebirds along the coast. A total of 3,171 individuals and 16 different species were observed, including a considerable amount of individuals of Calidris alba and Charadrius alexandrinus, despite the latter showed an 80% decrease in number in the last 20 years in the area. For each species, maximum numbers observed per winter and related five-year averages, estimates, IKA (Index of Abundance per Kilometre) and percentages in relation to the national wintering population have been reported. Furthermore, data about species associations were collected and analysed. This survey shows how the ecological value of River Simeto’s mouth has decreased considerably in the last decades in favour of other locations, such as the mouth of Canale Arci, where almost 50% of the birds were observed.

Distribución y abundancia de las aves playeras en planos intermareales del Parque Nacional Natural Sanquianga y la bocana de Iscuandé, Nariño (Colombia), entre 2009 y 2020

11 % de las aves playeras del corredor migratorio del Pacífico americano están disminuyendo y otro 46 % no cuenta con información para estimar su estado poblacional. Para entender la magnitud y las causas de estos cambios, se requiere información de sitios de concentración como la bocana de Iscuandé (IS) y el Parque Nacional Natural Sanquianga (PNNS). Para caracterizar la composición de las comunidades de aves playeras en estos sitios, se analizaron diez años de conteo. A partir de la abundancia proporcional, la prevalencia y la densidad media de cada localidad, se evaluó si existían diferencias entre sitios con diferente influencia marina y del río Patía. IS aportó el 63 % de la abundancia promedio, siendo el 80 % aves playeras pequeñas. En PNNS, la abundancia se repartió 40-60 % entre aves grandes y pequeñas, y la contribución de cada bocana fue proporcional al área muestreada. Estos resultados muestran que los dos sitios tienen comunidades diferentes de aves playeras. Esta heterogeneidad espacial tiene importantes implicaciones ecológicas y de conservación. El recambio en la composición taxonómica y por grupos de tamaño de aves playeras sugiere diferencias en el hábitat intermareal y en los organismos que lo habitan, lo que ofrece alternativas para la conservación de diferentes especies.

Shorebird Reproductive Response to Exceptionally Early and Late Springs Varies Across Sites in Arctic Alaska

While increases in overall temperatures are widely reported in the Arctic, large inter-annual variation in spring weather, with extreme early and late conditions, is also occurring. Using data collected from three sites in Arctic Alaska, we explored how shorebird breeding density, nest initiation, nest synchrony, nest survival, and phenological mismatch varied between two exceptionally early (2015 and 2016) and late (2017 and 2018) springs. We assessed these differences in the context of long-term data from each site and whether species exhibited conservative or opportunistic reproductive strategies. Conservative shorebirds typically display nest-site fidelity and territoriality, consistent population densities, relatively even individual spacing, and monogamous mating systems with bi-parental incubation. In contrast, opportunistic shorebirds display the opposite traits, and a polygamous mating system with uniparental incubation. In this study, we evaluated 2,239 nests from 13 shorebird species, 2015–2018, and found that shorebirds of both strategies bred earlier and in higher numbers in early, warm springs relative to historic levels (based on 3,789 nests, 2005–2014); opposite trends were observed in late springs. In early springs, nests were initiated less synchronously than in late springs. Nest survival was unrelated to spring type, but was greater in earlier laid nests overall. Invertebrate food resources emerged earlier in early springs, resulting in a greater temporal asynchrony between invertebrate emergence and chick hatching in early than late springs. However, invertebrate abundance was quite variable among sites and years regardless of spring type. Overall, our results were generally consistent with predicted relationships between spring conditions and reproductive parameters. However, we detected differences among sites that could not be explained by other ecological factors (e.g., predators or alternative prey). Differences in shorebird community composition and other subtler methodological/ecological differences among sites highlight the difficulty of understanding the complex nature of these ecological systems and the importance of evaluating questions at multiple sites across multiple years. Our study demonstrates that shorebirds exhibit a high degree of behavioral flexibility in response to variable Arctic conditions, but whether this flexibility is enough to allow them to optimally track changing environmental conditions or if evolutionary adjustments will be necessary is unknown.

Humboldt Bay, California, USA hosts a globally important shorebird community year-round

Humboldt Bay, California, USA hosts a globally important shorebird community year-round

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.

Shorebird Community and Guild in Trisik Beach, Yogyakarta

Pantai Trisik merupakan area lahan basah yang terletak di bagian selatan Daerah Istimewa Yogyakarta. Kawasan Pantai Trisik berperan penting bagi kehidupan burung pantai. Tujuan penelitian yaitu menganalisis komunitas dan guild pakan komunitas burung di kawasan Pantai Trisik. Penelitian dilaksanakan pada Bulan Oktober 2018 – Januari 2019 dengan teknik point count. Komunitas burung pantai di kawasan Pantai Trisik terdiri dari 22 jenis yang terbagi menjadi burung pantai migran dan residen. Tipe guild komunitas burung pantai di kawasan ini terbagi menjadi tiga kelompok guild pakan yaitu mollucivore, insectivore dan omnivore. Berdasarkan cara mendapatkan makanan, tipe guild mollucivore dikembangkan menjadi tiga tipe subguild. Tipe guild insectivore terdiri dari satu tipe guild. Tipe guild omnivore dikembangkan menjadi sepuluh tipe. Tipe guild yang paling banyak ditemukan adalah tipe guild omnivore sebanyak 17 jenis (77%).
 
 Kata kunci: komunitas burung, guild, burung pantai, kekayaan jenis

Response of shorebird habitat selection to coastal reclamation and urbanization in an extensively developed delta: A case study in Macao, China

Land-claim and human disturbance are major threats to shorebird population declines along the East Asian–Australasian Flyway. When existing tidal flats undergo greater anthropogenic disturbance from intensive urbanization, newly-formed tidal flats may provide alternative habitats for shorebirds. Knowledge of the key habitat factor influencing shorebirds communities is essential for tidal flat restoration and management, especially on intensively urbanized coasts. We compared the differences between old and newly-formed tidal flats in terms of habitat characteristics and shorebird communities, analyzed the influence of habitat metrics on shorebird species abundance and feeding strategies in Macao, China, from 2006 to 2009. Habitat characteristics and shorebird communities were significantly different between old and newly-formed tidal flats which represented different urbanization level. The greatest difference of shorebird communities between two tideland types occurred in winter. Artificial shoreline rather than high rise buildings had direct and negative impact on shorebird communities. The habitat factors relieved shorebirds from surrounding urbanized environment were vegetation coverage within tidal flat and adjacent grassland areas. Under the pressure of rapid urbanization, the newly-formed tidal flat, which had more natural boundaries, adequate vegetation coverage and extensive adjacent undisturbed grassland, provided more suitable habitat than old tidal flats for shorebirds in Macao. Conservation efforts for shorebirds should primary focus on maintaining the extent of current tidal flats, with emphasized management on reducing anthropogenic disturbance around tidal flats.

Virome heterogeneity and connectivity in waterfowl and shorebird communities

Models of host-microbe dynamics typically assume a single-host population infected by a single pathogen. In reality, many hosts form multi-species aggregations and may be infected with an assemblage of pathogens. We used a meta-transcriptomic approach to characterize the viromes of nine avian species in the Anseriformes (ducks) and Charadriiformes (shorebirds). This revealed the presence of 27 viral species, of which 24 were novel, including double-stranded RNA viruses (Picobirnaviridae and Reoviridae), single-stranded RNA viruses (Astroviridae, Caliciviridae, Picornaviridae), a retro-transcribing DNA virus (Hepadnaviridae), and a single-stranded DNA virus (Parvoviridae). These viruses comprise multi-host generalist viruses and those that are host-specific, indicative of both virome connectivity (host sharing) and heterogeneity (host specificity). Virome connectivity was apparent in two well described multi-host virus species -avian coronavirus and influenza A virus- and a novel Rotavirus species that were shared among some Anseriform species, while virome heterogeneity was reflected in the absence of viruses shared between Anseriformes and Charadriiformes, as well as differences in viral abundance and alpha diversity among species. Overall, we demonstrate complex virome structures across host species that co-exist in multi-species aggregations.

Weak niche partitioning by migrating shorebirds in a single-food-type environment

This study examined foraging niche partitioning among coexisting species of shorebirds on a sandy beach dominated by a single food type, Horseshoe Crab ( Limulus polyphemus) eggs, where use of foraging microhabitats of limited variety is temporarily restricted due to tidal cycle. The major goal of the study was to examine whether co-occurring species differed in selection of foraging microhabitats and use of feeding techniques. Ruddy Turnstone ( Arenaria interpres), Red Knot ( Calidris canutus), and Sanderling ( Calidris alba) foraged significantly more on sand and gravel compared to pools and swash zone, Semipalmated Sandpiper ( Calidris pusilla) foraged significantly more on sand and gravel compared to swash zone, but not significantly more compared to pools, while differences in use of microhabitats by Dunlin ( Calidris alpina), and Short-billed Dowitcher ( Limnodromus griseus) were non-significant. Turnstones used digging and turning stones, and pecking significantly more than probing, Semipalmated Sandpipers used pecking significantly more than probing, while all other species used probing significantly more than pecking. Knots and Sanderlings had the highest level of overlap both in use of microhabitats and foraging techniques, while turnstones and dowitchers had the lowest. Ruddy Turnstones were the only birds that used digging and turning stones to obtain food and these two foraging methods seemed to be the most important variables discriminating turnstones from other co-occurring shorebirds. However, despite the slight differences in use of foraging methods and microhabitats by different species, this study documented weak partitioning among shorebirds, particularly between sandpipers and dowitchers. These results indicate that the short-term absence of clear niche partitioning on a local scale may occur in shorebird communities.