Waterbird Abundance Research Articles

Seasonal changes in waterbird assemblages in Chambal River at Mukundra Hills National Park, Rajasthan, India

The seasonal pattern of species diversity and abundance of waterbirds of the Chambal River in the extent of Mukundra Hills National Park, Rajasthan, India was evaluated. The pre-monsoon (March–April 2021) and post-monsoon surveys (August–September 2021) were carried out using the direct count method with the help of a motorboat to monitor the population status of waterbirds. A total of 44 species of waterbirds belonging to 15 families and nine orders were identified, including 11 winter migratory species. Forty species of birds were recorded during pre-monsoon and 27 species during post-monsoon seasons. The species richness and relative abundance varied significantly between observed seasons (x2 = 532.77, df = 43, p <0.05). Breeding activities of three species were recorded, namely, Grey Heron, Black-crowned Night Heron, and the ‘Near Threatened’ Woolly-necked Stork. The present study reveals the status of waterbirds in the protected area of Mukundra Hills National Park.

Landscape context and wetland attributes influence wintering waterbirds in important bird and biodiversity areas: implications for conservation and management

ContextThe intensification and expansion of human activities have caused profound changes in global wetlands and their associated aquatic bird communities. Understanding the mechanisms that drive the spatial assemblages of wetland birds is important for the development of effective conservation and management strategies.ObjectivesThe overall objective was to evaluate the influence of wetland features such as size and distance to the nearest coastline, and landscape composition, configuration, and function in shaping waterbird richness and abundance in 43 Tunisian Important Bird and Biodiversity Areas (IBAs).MethodsSystematic waterbird surveys on species abundance and richness at each IBA were carried out between December and January in 2020/2021 and 2021/2022. Satellite remote sensing indices were used to map wetlands and characterize the vegetation condition in the landscape surrounding them. Landscape metrics were used to describe the habitat configuration around the wetlands.ResultsOur results show that landscape composition, configuration and function have significant effects on waterbirds (i.e., shorebirds, waterfowl, wading birds, and open-water birds). We found that wetland surface area and distance to the coast were important factors influencing the richness and abundance of waterbirds. Our results also indicate that landscape diversity is an important predictor of waterbird richness and abundance, and that there is a significant interaction between wetland surface area and distance to the nearest wetland in explaining the richness and abundance of waterbirds.ConclusionsThis study provides evidence that the richness and abundance of waterbirds are robustly dependent on the interaction between wetland surface area and distance to the nearest wetland. Furthermore, local wetland characteristics (wetland surface area and distance to the nearest coastline), landscape composition (forest area and urban area), landscape configuration (spatial heterogeneity), and landscape function (maximum and minimum NDVI), significantly affect wintering waterbird communities. This study also highlights the importance of large and connected wetlands in conserving various bird communities in Tunisian IBAs and provides recommendations for their conservation and sustainable management.

Threshold responses and relationships between waterbird distribution and habitat factors at Shengjin Lake, China

The wintering period is an essential part of the annual life history of waterbirds. The environmental conditions of habitats in winter directly affect the abundance and physical condition of waterbirds. Therefore, it is important to study the relationship between waterbird abundance and habitat factors. In this study, we conducted significance and threshold analyses between habitat factors and the waterbird community at Shengjin Lake, a Ramsar Site in China, using Redundancy Analysis (RDA), Spearman Correlation Analysis, and Threshold Indicator Taxa Analysis (TITAN). The results indicate that seven environmental variables significantly affected the abundance of waterbird communities, that is, fractional vegetation cover, degree of receding water, grassland area, mudflat area, shallow water area, deep water area, and distance to reeds. Waterbird communities exhibited significant threshold responses to all seven factors. The number of species significantly responding to different habitat factors varied among waterbird communities, with the highest number of species (15) responding to distance to reeds. Except for the deep water area and distance to reeds, waterbirds showed higher positive than negative thresholds for the remaining five factors. Different groups of waterbirds influenced the threshold responses of waterbird communities to habitat factors, and there were variations in how each waterbird group responded to these factors. The results of this study highlight the importance of habitat type, water recession degree, and shelter conditions in waterbird habitat selection. Minor differences in habitat structure can influence waterbird habitat preferences. Therefore, wetland management at Shengjin Lake should consider the specific habitat needs of different waterbird species.

Time of day, water coverage, and pond type impact waterbird abundance in aquaculture ponds in Taiwan

Time of day, water coverage, and pond type impact waterbird abundance in aquaculture ponds in Taiwan

Waterbird community changes in the Wilderness Lakes, South Africa (Part 1 of 3): Herbivores and omnivores

Global and regional degradation and loss of aquatic systems can negatively affect wetland-dependent waterbirds. The Wilderness Lakes Complex in South Africa, which incorporates the Wilderness Ramsar site, supports populations of 68 waterbird species including eight which periodically occur in globally significant (1% population) numbers. The study aimed to document long-term spatial and temporal (including seasonal) patterns of abundance of herbivorous waterbirds in the Wilderness Lakes Complex, and where possible identify potential causes for observed trends. The abundance of waterbirds on these wetlands was determined biannually from 1992 to 2019, with counts conducted from a boat following a standardised route. Historical abundance data from the 1980s was also used to describe long-term abundance changes. Observed seasonality of four herbivorous waterbirds differed from published accounts. Long-term abundance trends indicated a combination of declining, increasing and stable populations which, in several instances, differed from regional (southern African) assessments. Significant long-term decreases have occurred in five herbivorous species in the lakes complex (Common Moorhen Gallinula chloropus, Red-knobbed Coot Fulica cristata, Yellow-billed Duck Anas undulata, Cape Shoveler Anas smithii, Cape Teal Anas capensis), whereas increases have occurred in two species (Spur-winged Goose Plectropterus gambensis, Egyptian Goose Alopochen aegyptiaca). Similar types of change occurred across multiple waterbodies, and in different seasons. The similarity of trends in spatially separated wetlands suggested either high interconnectivity of populations between wetland systems and/or some drivers of change of mobile species being broad scaled and regional, rather than system specific. Local reasons for changes potentially include increasing extent of cultivated fields, a proliferation of emergent macrophytes and loss of open sandbanks, changing food availability, increasing disturbance, and disease.Conservation implications: The fundamental character of the Wilderness Ramsar site has changed, with reduced abundance of several previously abundant herbivorous waterbirds. Drivers of change in species abundances are multifaceted, complex, and frequently poorly understood. Recommended local corrective actions include the management of emergent macrophytes, avian diseases, disturbance, and water quality.

Waterbird community changes in the Wilderness Lakes, South Africa (Part 3 of 3): Diving piscivores and scavengers

Estuarine waterbodies typically support diverse and abundant waterbird communities. However, global environmental degradation as a result of anthropogenic activities is leading to species level changes in biodiversity, with top predators such as piscivorous waterbirds being particularly vulnerable to ecosystem changes. The study aimed to document long-term spatial and temporal patterns of abundance of piscivorous and scavenging waterbirds in the Wilderness Lakes Complex (WLC) in the Garden Route National Park, South Africa, and where possible identify potential causes for observed trends. The abundance of waterbirds on these wetlands was determined biannually from 1992 to 2019, with counts conducted from a boat following a standardised route. Historical waterbird abundance data from the 1980s were also used to describe long-term abundance changes. Eight of the species exhibited seasonal variability in abundance with most, excluding Common Tern Sterna hirundo, being more abundant in winter. Substantial changes occurred in the abundance of several species over the four-decade study period, notably increases in Cape Cormorant Phalacrocorax capensis and Great Crested Grebe Podiceps cristatus, and decreases in Common Tern and Black-necked Grebe Podiceps nigricollis. Long-term abundance trends indicate a combination of declining, increasing, and stable populations. Although some species have undergone contrasting abundance changes on different waterbodies in the WLC the dominant pattern was a similar direction of change on most or all waterbodies and in different seasons. Local reasons for changes probably include loss of sandbanks, changing prey availability, and the absence of recreational disturbance on some waterbodies.Conservation implications: Drivers of changes in the abundances of piscivores are likely to be multifaceted, functioning on multiple spatial and temporal scales, and affecting different species in different ways. Recommended local corrective actions include managing emergent macrophyte encroachment on sandbanks, reducing recreational disturbance, managing processes affecting indigenous fish stocks, and protecting nesting sites.

Waterbird community changes in the Wilderness Lakes, South Africa (Part 2 of 3): Shorebirds

Globally, many shorebirds, particularly the smaller migratory waders are declining, which can be attributed to multiple factors throughout their ranges. The Wilderness Lakes Complex in South Africa comprises two estuarine systems, that support diverse waterbird communities, including 17 abundant shorebirds. The study aimed to document long-term spatial and temporal patterns of abundance of shorebirds in the Wilderness Lakes Complex, and where possible identify potential causes for observed trends. The abundance of waterbirds on these wetlands was determined biannually from 1992 to 2019, with counts conducted from a boat following a standardised route. Historical abundance data from the 1980s were also used to describe long-term abundance changes. Ten shorebirds showed seasonal differences in abundances. Significant long-term decreases in abundance have occurred in seven shorebirds (Wood Sandpiper Tringa glareola, Marsh Sandpiper Tringa stagnatilis, Curlew Sandpiper Calidris ferruginea, Ruff Philomachus pugnax, Grey Heron Ardea cinerea, Greater Flamingo Phoenicopterus ruber, Black-winged Stilt Himantopus himantopus) and increases in three species (African Spoonbill Platalea alba, Little Egret Egretta garzetta, Glossy Ibis Plegadis falcinellus). Similar types of population changes occurred across multiple waterbodies and in different seasons. The similarity of shorebird abundance trends in spatially separated wetlands suggests either high interconnectivity of populations between wetlands systems and/or prominent drivers of change being broad scaled rather than system specific. Local reasons for changes potentially include the increasing spread of emergent macrophytes and resultant loss of open sandbanks, changing hydrodynamics, and alien fish proliferation, all likely changing food accessibility, as well as periodic high disturbance by waterbody users.Conservation implications: Changes in the abundances of several shorebirds, particularly small migratory waders, are substantial, with multiple likely local, regional and international drivers acting accumulatively. Recommended corrective actions include continuing involvement in the development and implementation of policies for waterbird conservation, and local management of emergent macrophytes, disturbance, and water level variability.

Roosting Behavior of Waterbirds at Ruhuna University Premises in Sri Lanka

Communal roosting is a habit of many waterbirds. Although it is a common behavioural pattern, only a few documentary records are available in Sri Lanka. Therefore, the present study aimed to investigate the roosting behaviour of waterbirds at Ruhuna University Premises, Sri Lanka. The study was conducted from November 2020 to February 2021 covering 20 field visits. During field visits, the abundance of waterbirds, their arrival time, intra-species, and inter-species interactions were observed. The responses of roosting waterbirds to human disturbances and occasional visitors to roosting sites were also recorded. The waterbirds roosted on a single Sonneratia caseolaris tree, located at the waterbody closer to the bank. Eleven species of waterbirds were identified, and the Cattle Egrets (Bubulcus ibis) were prominent (93%). The diversity and species abundance gradually increased during the study period. The highest species richness (11) and diversity (H- 0.8832) were recorded in February. The roosting behavior of birds has been altered by human disturbances. The waterbirds co-existed on the roosting site with inter- and intra-species associations while maintaining hierarchical levels (different height levels of the tree). Sixteen species of occasional visitors were recorded, and they left the site with the arrival of regular waterbirds.

When good turns to bad and alien predators appear: The dynamics of biodiversity change in boreal waterbird communities

Temporal patterns of biodiversity are often difficult to interpret because of our limited understanding of how communities vary through time and how processes drive this variation. A further challenge with dynamic systems is choosing an appropriate baseline against which biodiversity change is judged. We used abundance time series of breeding waterbirds in eutrophic lakes in Finland for 1946–2022 to study the dynamics of biodiversity change in local communities and the relative role of two presumed main drivers, i.e. eutrophication and alien predators, in contributing to historical and recent trends in local abundances and biodiversity. We set the cut-off for the historical and recent study periods in the mid-1980 s, because the systematic monitoring of breeding waterbirds in Finland started in 1986 and recent analyses of biodiversity change and population trends in European boreal waterbird communities are mainly based on time series and data gathered since 1986. Both species richness and the total abundance of waterbirds in local communities showed contrasting trends between historical (gathered before the mid-1980 s) and current (gathered after the mid-1980 s) community time series, with the current time series indicating a decline and the historical time series indicating an increase. The abundances of habitat specialists (species preferring eutrophic lakes) and habitat generalists (species using both eutrophic and oligotrophic lakes) showed a corresponding difference between the current and historical time series. The local extinction rates were higher among habitat specialists than among habitat generalists. The trend indices for wetland-nesting species (highly vulnerable to predation by two alien species (the raccoon dog, Nyctereutes procyonoides, and American mink, Neovison vison) in terms of nest site) abundances were more negative than the trend indices of species nesting further away from waterbodies (less vulnerable to predation by two alien species). In addition, bottom-feeding species (presumably more sensitive to negative impacts of eutrophication) did not show more negative population trends than surface-feeding species (presumably less sensitive to negative impacts of eutrophication). Regardless of equal sensitivity to negative impacts of eutrophication, two species highly vulnerable to two alien predators showed more negative population trends than a less vulnerable species. The results suggest that increased predation has been an important driver of the population and biodiversity declines in the studied waterbird communities. The mid-1980 s may not provide an ecologically appropriate baseline against which changes in the populations and biodiversity of boreal waterbird communities are judged.

Optimization of wetland water replenishment process based on the response of waterbirds in a semi-arid and cold region

Emergency ecological water replenishment(EEWR) has become a major strategy for recovering degraded wetland ecosystems worldwide. However, the actual replenishment process mainly depended on the tradeoff and experience between the managers of Taoer River and Xianghai Wetland, which is very random and lacks theoretical guidance. Thus, there is urge to assessing water replenishment effect on wetland and help to optimize the process. With contrasting results as different ecosystem elements respond differently, the optimization of water replenishment process should be based on the improvement of the ecosystem as whole rather than its separate elements. However, the dynamic monitoring of biotic and abiotic factors to reveal the complex relationships underlying their response can be challenging. Based on 6 years’ series data of migratory birds and environmental factors of Xianghai Wetland, which started emergency ecological water replenishment since 2004 and occurred frequently since 2011, the broader ecosystem response to water replenishment was analyzed using a multiple paths regression model and proposed an optimized scheme. The results showed that bird diversity was positively influenced by the increase in water area and vegetation was induced by ecological water replenishment. While the response of bird abundance to water replenishment varied with time, adequate open water in March was found to have a positive relationship with abundance by promoting vegetation germination and the reproduction of benthic organisms. High flow levels in the wet season (June–August) can negatively affect waterbird abundance by rapidly increasing water levels and inhibiting plant respiration, which leads to the reduction in feeding efficiency of waterbirds and biomass accumulation. Therefore, the existing ecological water replenishment time (May–September) is not suitable for bird abundance and should be advanced to spring (March–April). Given the antagonistic effect of flow on diversity and abundance, the total replenished water should be approximately 100 million m3. To avoid the negative influence of high water in the wet season, the allocation of water could be 0.3, 0.3, 0.2, and 0.2 million m3 in April, May, September, and October, respectively. These results scientifically support wetland protection and management.

Exploring NAO influence on waterbirds abundance through hydrological changes in a Mediterranean coastal wetland

Predicting how waterbird populations may respond to climate change is a major challenge for conservation, which could be addressed by understanding the effects of large-scale climate oscillations, such as the North Atlantic Oscillation (NAO), on breeding population size. Here, we explore the relationship between the NAO position and the abundance of waterbird breeding pairs in a protected Mediterranean coastal wetland (Mouth of the Guadalhorce River, Málaga, southern Iberian Peninsula). We found a significant and negative relationship between the winter NAO index and the abundance of grebes (r=-0.72, N=15, p<0.01), rails (r=-0.74, N=15, p<0.01), diving ducks (r=-0.56, N=15, p<0.05) and dabbling ducks (r=-0.54, N=15, p<0.05). Our results suggest that this relation is mediated by the NAO indirect effects on wetland flooded surface via changes in winter precipitation and Mediterranean sea level. These results should be considered to design appropriate environmental management strategies devoted to preventing or mitigating potential deleterious effects of the NAO variability on Mediterranean wetlands ecosystems and preserving their valuable waterbird communities.

Drought-induced changes in hydrological and phenological interactions modulate waterbird habitats dynamics

Floodplain wetlands are essential for the survival and reproduction of waterbirds, but droughts can negatively impact their food availability and habitat conditions, leading to a decline in waterbird abundance and diversity. To better understand the impact of hydrological and phenological variables on floodplain waterbird habitats during drought conditions, we employed hydrological modeling and remote sensing techniques to calculate fine-scale environmental variables. We constructed habitat suitability models using nine years of field surveys of waterbirds and identified the impact of the interaction effects between hydrological and phenological variables on waterbirds under drought and non-drought conditions. The results showed that hydrological and phenological variables can provide useful information for quantifying the habitat suitability of waterbirds. Drought-induced early water recession negatively impacted the quality of waterbird habitats, reducing their habitat suitability. Sedge eaters exhibited the most significant reduction of 34.47% in the total area of the lake, followed by seed eaters, fish eaters and invertebrate eaters. Tuber eaters had the largest increasing trend, with a significant increase area of 7.44% in total area. Our findings suggest that various feeding guilds exhibit distinct interactions in response to drought, which can be strengthened or weakened by alterations resulting from drought. For sedge eaters, seed eaters, and fish eaters, drought could result in a faster decline in habitat suitability by strengthening the interaction effects between variables. In contrast, for invertebrate eaters and tuber eaters, drought could weaken interaction effects between variables, resulting in a slower decline in habitat quality. The results provide valuable insights into the spatial distribution of overwintering waterbirds and can inform conservation efforts in wetlands.

Effects of Habitat Change on the Wintering Waterbird Community in China’s Largest Freshwater Lake

Poyang Lake wetland in the middle and lower Yangtze River floodplain provides important wintering sites for migratory waterbirds. Extreme climatic events and human activities have resulted in the degradation and redistribution of habitat over the last few decades. However, the effects of habitat changes on the abundance of waterbirds remain unclear. We used long-term waterbird monitoring data and Landsat remote-sensing data to characterize changes in abundance and the relationship between habitat variation and abundance. A total of 113 waterbird species were recorded in the wintering period between 1999 and 2021, including 23 globally threatened species. Greater White-fronted Goose (Anser albifrons), Swan Goose (Anser cygnoides), Bean Goose (Anser fabalis), and Tundra Swan (Cygnus columbianus) were the dominant species. A total of 46 species with more than 6 annual surveys and average abundance >100 were recorded between 1999 and 2021. For most species, the mean abundance across all sub-lakes was higher in the first year than in the last year, and no obvious changes were observed over the last 20 years. The mean abundances of the vulnerable species Hooded Crane (Grus monacha) and White-naped Crane (Grus vipio) significantly declined between 1999 and 2021. No significant changes in the mean abundance of all foraging groups were observed. The area of water bodies increased, and the area of mudflats decreased. For most species with significant changes in abundance, habitat change did not greatly contribute to variation in mean abundance. The reduction in the area of mudflats greatly contributed to declines in the mean abundance of the gray heron (Ardea cinerea) and gadwall (Anas strepera).

Species composition and diversity of waterbird communities in Important Bird and Biodiversity Area (IBA) of South West Johor Coast, Malaysia

Abstract. Fauzi NA, Munian K, Shah AKMK, Norazlimi NA. 2023. Species composition and diversity of waterbird communities in Important Bird and Biodiversity Area (IBA) of South West Johor Coast, Malaysia. Biodiversitas 24: 3471-3480. Mangroves play a crucial role in supporting intertidal flats and providing habitats that enrich benthic communities, which in turn serve as feeding grounds for coastal waterbirds. However, the degradation of mangrove habitats caused by coastal reclamation activities indirectly impacts prey availability and, consequently, the populations of waterbirds. The coastline habitat along the Important Bird and Biodiversity Area (IBA) of the South West Johor Coast is currently under threat due to new and ongoing development projects involving large-scale reclamation activities. Therefore, this research was conducted to study the diversity and abundance of waterbirds and their relationship with prey availability. The study was conducted in three coastal mudflat sites along the South West Johor Coast, namely Tanjung Piai, Pontian Kechil, and Muar, from November 2020 to May 2021. The direct observation technique was used to determine the abundance of waterbirds, while the benthic core sampling method was employed to assess prey availability in all study sites. In total, 3,717 individual waterbirds, comprising 17 species, were counted across the three study sites. The study confirmed a significant positive relationship between the abundance of waterbirds and prey availability (R2=0.501). The results of this study serve as important baseline data and references for the conservation of waterbirds along the South West Johor Coast. Through the study, we believe that the relevant authorities are able to formulate sound conservation strategies to preserve the habitat for a vast diversity of waterbirds.

Waterbird–habitat relationships in South Carolina: implications for protection, restoration, and management of coastal and inland wetlands

South Carolina coastal and inland wetlands are continentally important to resident, migrating, and wintering dabbling ducks (Anatini), diving and sea ducks (Aythini, Mergini, Oxyurini), pelagic waterbirds (Anhingidae, Laridae, Pelicanidae, and Phalcrocoracidae), and wading birds (Ardeidaie, Ciconiidae, Threskiornithidae). Our goal was to model wetland selection of these waterbird guilds in South Carolina during autumn–winter to determine habitat preferences and guide wetland conservation and restoration amid sea‐level rise and other coastal pressures. We conducted aerial surveys and recorded waterbird occurrence and relative abundance in winters 2017–2019. We modeled waterbird–habitat relationships relative to managed and unmanaged coastal and inland wetlands, legally protected conservation lands (e.g. federal, state, and private easements), and habitat diversity. Waterbirds selected a variety of wetlands emphasizing the importance of wetland diversity within habitat complexes. However, only managed tidal impoundments (MTIs) and protected conservation lands were selected across all waterbird guilds. Results suggest these are contemporary keystone habitats for promoting wintering waterbird abundance and diversity in South Carolina and other South Atlantic coastal regions. To compensate for future coastal wetland loss while facilitating the current and future needs of migrating and wintering waterbirds, we recommend: (1) identification and continued management of MTIs resilient to sea‐level rise; (2) strategic planning and partnerships for land acquisition and legal protections inland; and (3) land protection networks between extant coastal and inland sites designated for future construction and emigration of decommissioned MTIs. Stakeholder and partner engagement is paramount to prioritize resource allocation for the restoration, construction, and decommissioning of coastal and inland wetlands.

Abundance and diversity of waterbirds around the Begnas Lake of Pokhara Valley, Nepal

We studied the seasonal abundance and diversity of waterbirds around the Begnas lake of Pokhara Valley. The status of waterbirds in Begnas wetland is not documented so; we monitored the waterbirds using the point count method in 12 different plots around the lake and compared the seasonal abundance and diversity during the 2019 Summer and 2020 winter with 24 hours of observation in each plot. A total of 585 individuals of 25 waterbird species from 10 families were recorded during the study period. Among the recorded species two species were globally threatened and the remaining were the least concerned categories. The greater abundance of waterbirds was recorded during winter (t = -5.98, p < 0.001). The abundance of all feeding guilds was found higher during winter. Cattle egret was recorded with the greatest abundance (N = 85) and Relative abundance (RA = 14.52), it was followed by great cormorant (N = 57, RA = 9.74) and common pochard was the least abundant (N = 2, RA = 0.34). There was no seasonal variation in the Shannon Wiener index (H’) and species evenness however, the species richness was higher during winter (W = 16.5, p < 0.01). Distance to the forest, road, and settlement did not affect the abundance and diversity of waterbirds however, the abundance of insectivore birds was increased with the decrease of distance to croplands (t = -3.13, p < 0.05). The Begnas wetland was found with a lower abundance and diversity of waterbirds in comparison to the Phewa and other wetlands of the Terai region of Nepal. The lake water pollution, infrastructural development, anthropogenic activities, recreational activities, and infestation of invasive plants like water hyacinth were the main threats to the waterbirds around Begnas lake. An awareness program about the conservation of waterbirds and regular monitoring of waterbirds in Begnas was recommended.

Conservation significance of Changaram wetlands - a key wintering site for migratory shorebirds and other waterbirds in the western coast of Kerala, India

Changaram wetland is an important stopover ground for migratory shorebirds, gulls, terns, and other waterbirds in the western coast of Kerala and it encompasses major habitats like exposed mudflats, mangrove fringes, and an agroecosystem. A total of 77 species of waterbirds (shorebirds, large wading birds, gulls, and terns) including long distance migrants, local migrants, and resident species were encountered in our survey carried out during 2018 and 2019. Ten out of these 77 species fall under threatened category in the IUCN Red List and hence the Changaram wetlands demand immediate attention from the conservation perspective. Considering tremendous anthropogenic pressures faced by these wetlands, and the decline in the abundance of waterbirds, a regular system for monitoring the bird population and the wetlands must be deployed for the conservation of the ecosystem and of the birds.

Effects of rainfall in the arid zone on waterbird abundance at a wastewater treatment plant in coastal South Australia

We investigated which species of waterbirds at Bolivar, a wastewater treatment plant in Metropolitan Adelaide, South Australia, are likely to have been immigrants from the ephemeral wetlands in the arid zone. To do this, we compared the abundance of waterbird species observed at Bolivar during the dry period in the eastern arid zone of late 2018 and 2019 with that during the subsequent wet period 2020–2022. Pink-eared Duck Malacorhynchus membranaceus, Grey Teal Anas gracilis, Australasian Shoveler Spatula rhynchotis, Hardhead Aythya australis and Blue-billed Duck Oxyura australis were all more abundant during the arid-zone dry period. By contrast, Australian Shelduck Tadorna tadornoides, Eurasian Coot Fulica atra and Black Swan Cygnus atratus showed increased abundance in spring and early summer in all years, with no marked differences between the dry and wet periods in the arid zone. Wader species that breed in the Northern Hemisphere – Sharp-tailed Sandpiper Calidris acuminata and Red-necked Stint C. ruficollis – also tended to be more abundant during the arid-zone dry year, as did Red-necked Avocet Recurvirostra novaehollandiae, whereas Pied Stilt Himantopus leucocephalus tended to be more abundant in the arid-zone wet years, with breeding by this species taking place in spring. These data suggest that Bolivar is a critically important conservation site for waterbirds and that various species use this location as a refuge during dry times in the arid zone of eastern Australia.

The impact of earlier flood recession on metacommunity diversity of wintering waterbirds at shallow lakes in the middle and lower Yangtze River floodplain

The hydrological regime in wetlands plays an important role in the process of wintering waterbird metacommunity assemblage. However, increasing frequency of extreme climate and the intensification of human activities, such as the construction of sluices and dams, have resulted in frequently abnormal hydrological regime in the middle and lower Yangtze River floodplain. In recent years, earlier flood recession has become one of the main hydrological problems faced in the shallow lakes, having a great impact on wetland biodiversity. It is necessary to understand the impact of earlier flood recession on waterbirds, an indicator of wetland biodiversity, and the metacommunity concept is helpful to elucidate the underlying mechanism involved in the processes of assemblage by waterbird communities. In this study, we surveyed the wintering waterbirds at three sub-lakes of Caizi Lakes during 2019–2020 and 2020–2021 and compared the richness, abundance, alpha and beta diversity of waterbirds in and among local metacommunities under earlier flood recession and normal hydrological regime . The results showed that the earlier flood recession reduced the species richness in the early stage and abundance in the late stage, it also reduced the Shannon–Wiener index in the early stage and increased the dissimilarity between and within waterbird metacommunities in the late stage. The partition of beta diversity showed that the turnover component played a major role in the process of waterbird metacommunity assemblage. It was found that the earlier flood recession reduced the richness, abundance in different stages of flood recession, which also increased the turnover of waterbirds. Metacommunities with high habitat heterogeneity had better resistance to abnormal hydrological regime, which resulted in high dissimilarity between and within metacommunities. The results of this study provide important information for waterbird conservation and water level management at shallow lakes in the middle and lower Yangtze River floodplain.

Resilience to hydrological droughts in the northern Murray-Darling Basin, Australia

We respond to the problem of declining streamflows in the northern Murray–Darling Basin, Australia, a region that suffers from hydrological droughts and a drying trend. We partitioned the effect of meteorological trends from anthropogenic drivers on annual streamflow, quantified the effect of annual streamflow decline on waterbird abundance, estimated the effects of streamflow change on a measure of ecosystem resilience, and calculated the net benefits of in-stream water reallocation. The anthropogenic drivers of hydrological droughts were assessed by comparing the Lower Darling (hereafter the Barka) River, which has large recorded water extractions, with the adjacent Paroo River, which has very little recorded water extractions. Findings include: (1) only about one-third of the recent reduced streamflow of the Barka River is due to a meteorological drying trend; (2) statistically significant declines in waterbird species richness and abundance have occurred on both rivers between 1983–2000 and 2001–2020; (3) declines in waterbird abundance have been much larger along the Barka River than the Paroo River; and (4) ecosystem resilience, as measured by waterbird abundance, wasgreater on the Paroo River. Our four-step framework is applicable in any catchment with adequate time-series data and supports adaptive responses to hydrological droughts. This article is part of the Royal Society Science+ meeting issue ‘Drought risk in the Anthropocene’.