Waterbird Species Research Articles

Quantifying the variation of Scaly-sided merganser’ population and their divergent response to changes in hydrological connectivity of rivers in a high-latitude water tower

The Scaly-sided Merganser (SSME) is a globally endangered waterbird species, primarily inhabiting rivers. In recognition of its precarious status, it was added to the International Union for Conservation of Nature’s (IUCN) Red List of Threatened Species in 2002. The SSME is highly sensitive to ecological environmental changes driven by changes in hydrological connectivity, particularly within riverine habitats. Changbai Mountain, a high-latitude water tower in the Northeast Asia, is considered one of the most optimal breeding grounds for the SSME worldwide. Its extensive water system and dense primary forest create an environment particularly well-suited for this species. Over the past 40 years, rivers within Changbai Mountain have experienced phases of hydropower development and ecological restoration. These activities have dramatically altered the hydrological connectivity of the area. However, the response of SSME to these changes in aquatic ecology, driven by shifts in hydrological connectivity, remains uncertain. We employed the AutoRegressive Integrated Moving Average (ARIMA) model to analyze changes in the population size of the SSME. Furthermore, the GeoDetector model was used to understand the impact of ecological changes on the maximum population size (MPS) and distribution of SSME in the context of alterations in hydrological connectivity. Our findings reveal that the restoration of hydrological connectivity, a method of ecological restoration, exerts a bidirectional influence on both the distribution and the MPS of SSME. Our findings can be summarized as follows. Firstly, there was a general trend of increase in both the distribution points and population size of the SSME. Secondly, the contribution of driving factors to the MPS of SSME was ranked in the following order: temperature > Connectivity Status Index (CSI) > river width > fish abundance > river depth > velocity > altitude > forest type. Thirdly, the impacts on the distribution and MPS of SSME were not due to a single factor, but rather a complex interplay of multiple factors. Finally, the construction of small hydropower stations significantly disrupted the hydrological connectivity of rivers, thereby altering the natural habitat of the SSME. The reduction in fish population, resulting from the loss of hydrological connectivity, adversely affected the MPS. Conversely, an increase in water temperature due to loss of hydrological connectivity positively impacted the MPS. However, these effects displayed heterogeneity across different rivers. Our study suggests that the construction of gravel dams may be a suitable approach in certain sections of the river, with a recommended height limit of 1.5 m. This research provides valuable insights for managers, offering a sustainable foundation for future energy planning and ecological restoration efforts.

Identifying priority wetlands for the conservation of waterbirds in Wuhan, China

Given the severe threats affecting waterbirds and the limited resources, it is crucial to identify priority wetlands to optimize conservation efforts for waterbirds. This study aims to prioritize wetlands in Wuhan City based on the diversity, rarity, and conservation costs of waterbirds. Firstly, 17 focal waterbird species were selected as conservation targets based on the data availability and species rarity. The MaxEnt model was used to simulate the potential spatial distributions of the focal waterbirds, and corresponding weights were assigned based on their conservation status. Secondly, the Human Footprint Index (HFI) was employed to represent conservation costs. Finally, the Zonation 5 spatial prioritization software was used to identify cost-effective priority wetlands for waterbird conservation. The results show: (1) The species distribution model indicated that the distance to the wetland, land cover, and distance to the road were the primary environmental variables influencing the potential spatial distribution of focal waterbirds. (2) The top 10 %, top 20 %, and top 30 % priority wetlands identified by Zonation 5 had average coverage rates of 15.2 %, 28.0 %, and 39.6 % for focal waterbirds, respectively. (3) We identified major wetland conservation gaps in Wuhan, primarily including Caohu Lake, Luhu Lake, Futo Lake, and parts of Liangzi Lake. (4) Additionally, we recommend enhancing waterbird management in existing wetland protected areas, such as the Hougong Wetland Park and Donghu Wetland Park, to improve the effectiveness of waterbird conservation efforts. Our research provides scientific evidence to support the conservation of wetlands in Wuhan and the promotion of waterbird diversity. It also emphasizes the importance of finding a balance between conservation effectiveness and cost.

Interactions between stoneworts (Charales) and waterbirds.

Stoneworts (Charales) are green algae that represent an important food resource for many waterbird species in Europe and elsewhere. Browsing avian herbivores (e.g. swan, goose, duck and coot species) consume Charales plant vegetative parts, by head-dipping, up-ending or diving. A lower fibre content and longer growing season may make Charales as attractive to such herbivores as sympatric submerged higher plant species in some circumstances. Charales respond to environmental stress (e.g. drought) by producing abundant diaspores, in the form of oospores (sexual) and bulbils (asexual), both rich in starch, generating abundant food for waterbirds at critical stages in their annual migratory cycles. Waterbirds feed on these by diving (e.g. common pochard Aythya ferina and red-crested pochard Netta rufina) or by filtering from the water column (e.g. dabbling duck species), ensuring dispersal of sexually produced and vegetative diaspores locally (because of predator swamping) and remotely (through endo- and ectozoochorous dispersal by long-distance migratory waterbirds). Greater invertebrate density and diversity associated with Charales canopies enhances their attractiveness over other submerged macrophyte beds to diving predators [e.g. tufted duck Aythya fuligula, common pochard and Eurasian coot Fulica atra (hereafter coot)]. Fish fry preying on these invertebrates use such vegetation as predator cover, in turn providing prey for avian piscivores such as grebes and cormorants. Abundant Charales contribute to maintaining a transparent water column due to canopy density, nutrient effects, dampening of sedimentation/remobilisation of suspended matter and nutrients and allelopathic effects on other plants (especially phytoplankton). Shallow, relatively eutrophic waters can flip between clear-water high-biodiversity (where Charales thrive) and turbid species-poor depauperate stable states (lacking Charales). Shifts between turbid conditions and rich submerged Charales beds have profound elevating effects on aquatic diversity, to which waterbirds show rapid aggregative responses, making them ideal indicator species of ecological change; in the case of Charales specialists (such as red-crested and common pochard), indicators of the presence and abundance of these plants. Large-bodied colonial nesting birds (e.g. cormorants, gulls, heron and egrets) aggregating along lake shores contribute high N and P loadings to water bodies sensitive to such external and internal inputs and can cause local eutrophication and potential loss of Charales. Despite variation from complete seasonal removal of Charales biomass to undetectable grazing effects by herbivorous birds, evidence suggests little effect of avian grazing on biomass accumulation or the stability of community composition (under otherwise stable conditions), but we urge more research on this under-researched topic. We also lack investigations of the relative foraging profitability of different Charales organs to waterbirds and the degree of viability of gyrogonites (fertilised and calcified oospores), vegetative bulbils and plant fragments after passage through the guts of waterbirds. We especially need to understand better how much the carbonate armour of these organs affects their viability/dispersal via waterbirds and urge more research on these neglected plants and their relationships and interactions with other organisms in the aquatic biota.

A preliminary investigation of zooplankton diapausing eggs from waterbird faecal droppings in New Zealand

ABSTRACT We analysed internal dispersal of zooplankton by waterbirds (endozoochory) in New Zealand, quantifying zooplankton eggs in faecal droppings collected at two lakes, Lake Rotoroa (Hamilton) and Lake Rotorua. Sixty-seven faecal droppings were collected from Mallard Ducks (20), Canada Geese (11), Greylag Geese (6), Black Swans (20) and Australian Coots (10). Fifty eggs were found, with a mean of 0.75 eggs per dropping, indicating that waterbirds consume zooplankton eggs, and that these pass through the digestive system. No significant difference was observed in the abundance of eggs among waterbird species, and no eggs hatched in the laboratory. Our results suggest that waterbird dispersal of zooplankton in New Zealand is occurring, but numbers being transported are low. Further, as non-native waterbirds such as mallard ducks and geese do not migrate in New Zealand to the extent they do elsewhere, they are likely not primary vectors for zooplankton dispersal.

Comparing different management strategies of river mouths for waterbird conservation: A case study along the Yellow Sea coast

Coastlines with extensive estuaries and broad tidal flats are acutely vulnerable to coastal development. The tidal wetlands of the Yellow Sea are globally important for waterbirds, yet river mouths have disproportionately been developed as industrial ports, fishing ports, or have become abandoned fishing ports, with the type of management strategies depending on biophysical attributes and regional economic drivers. However, river mouths also support extensive upper tidal flat ecosystems, in contrast to many open coastal regions of the Yellow Sea, where reclamation has excised many of the upper tidal flats and dramatically reduced the time that tidal flats are available for foraging and roosting waterbirds each day. However, the extent to which waterbirds disproportionately occurs in river mouths compared to the open coast in the region remains unclear. We used a paired survey design to quantify the waterbird communities and habitat attributes (i.e., areas of upper tidal flats, Spartina alterniflora, and human activity) of 15 river mouths and 15 otherwise similar adjacent open coasts areas along the Yellow Sea coast. Waterbird species richness and abundance were higher in river mouths than open coasts. Among river mouths, the most species rich waterbird communities occurred in fishing ports and the most species poor in industrial ports. Notably, upper tidal flats were absent in many of the open coast regions, which had been subject to reclamation. Our results suggest that river mouths, especially those river mouths currently used as fishing ports, are probably of crucial importance for waterbird conservation on the Jiangsu coast due to their larger areas of upper tidal flats. Our work highlights the need to ensure that the tidal flats in river mouth systems are effectively protected to promote the completion of the annual cycle of migratory waterbirds.

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).

Identifying the wetlands of international importance in Beibu Gulf along the East Asian – Australasian Flyway, based on multiple citizen science datasets

The Beibu Gulf (Gulf of Tonkin, Vinh Bac Bo in Vietnamese), located midway along the East Asian-Australasian Flyway (EAAF), is a critical stopover and wintering region for migratory waterbirds. This transboundary coastal region, spanning between China and Vietnam, harbors diverse wetland habitats that provide refuge to waterbird species, including highly threatened species such as the spoon-billed sandpiper (CR) and the black-faced spoonbill (EN). However, the scarcity of comprehensive assessments regarding waterbird abundances, distribution, key wetland habitats, and regional threats hinders our understanding of its conservation significance at the flyway level. Further research is needed to address these knowledge gaps and facilitate effective conservation efforts in the Beibu Gulf. By synthesizing accessible citizen science datasets and published records from wetland sites in south China and northeast Vietnam, we concluded that at least 97 waterbird species used the Gulf’s wetlands during their annual cycle. Among surveys conducted from 2014 to 2022, 5 and 11 waterbird species were considered as first and second class protected species under the National Key Protected Wild Animal List in China; 2 species were listed as Critically Endangered on the IUCN Red List, 4 as Endangered and 2 as Vulnerable, underlying the critical importance of the Beibu Gulf for the survival of these species. Our study identified 25 sites in the Beibu Gulf that met the criteria for designation as internationally important wetlands. Alarmingly, less than a quarter (n = 5, or 20%) of these sites benefit from national or international protection. Localized threats, including aquatic resource harvesting, hunting, and aquaculture/fisheries, were widespread in the region. This study provides a crucial scientific baseline for continued waterbird monitoring, site prioritization, and the development of effective habitat management plans to conserve vital coastal wetland habitats in the Beibu Gulf in China and Vietnam.

The use of drone to study the nesting behavior of milky stork: Some preliminary observations

Abstract. Mardiastuti A, Mulyani YA, Akbar A, Wicaksono B, Rahmawati T, Wulandari YP, Warsajaya. 2023. The use of drone to study the nesting behavior of milky stork: Some preliminary observations. Biodiversitas 24: 4549-4557. The use of a drone to census waterbirds has been increasingly popular. However, study on the waterbird’s behavioral response to the drone was still limited. The objective of this study is to reveal the response of the breeding milky stork Mycteria cinerea to the drone as a new and safer tool for collecting breeding behavior data. Factors that influence the success of the observation by using a drone were also identified and a set of recommendations was formulated. The research was conducted during the breeding season of the milky stork in Pulau Rambut, a small island in Jakarta Bay, between December 2022 and March 2023. Three types of drones were tested in the pilot study, and eventually, a small manually piloted drone (Syma X25 Pro) was found to be more appropriate for behavioral study. The bird response to the drone (no, neutral, temporary, negative response) was observed through a combination of various distances and angles of the drone to the nest trees. Despite the weather obstacles, this study suggested that the milky stork mostly (17 out of 20 trials) showed no response or neutral response to the drone. Some temporary responses were detected due to some accidental events, including a sudden launch of the drone. In conclusion, a small-size, easy-to-maneuver drone that produces low noise and mild wind can be used by using a manual pilot mode to study the breeding behavior of milky storks or other similar waterbird species.

Functional traits explain waterbirds' host status, subtype richness, and community-level infection risk for avian influenza.

Species functional traits can influence pathogen transmission processes, and consequently affect species' host status, pathogen diversity, and community-level infection risk. We here investigated, for 143 European waterbird species, effects of functional traits on host status and pathogen diversity (subtype richness) for avian influenza virus at species level. We then explored the association between functional diversity and HPAI H5Nx occurrence at the community level for 2016/17 and 2021/22 epidemics in Europe. We found that both host status and subtype richness were shaped by several traits, such as diet guild and dispersal ability, and that the community-weighted means of these traits were also correlated with community-level risk of H5Nx occurrence. Moreover, functional divergence was negatively associated with H5Nx occurrence, indicating that functional diversity can reduce infection risk. Our findings highlight the value of integrating trait-based ecology into the framework of diversity-disease relationship, and provide new insights for HPAI prediction and prevention.

Birds of SABAP2 pentad 2915_2555 on the Jagersfontein Road, south-west of Bloemfontein, Free State

This paper describes results of a bird survey done at Pentad 2915_2555 on the Jagersfontein road south-west of Bloemfontein between April 2008 and January 2023. A total of 197 species have been recorded from mainly 169 full-protocol SABAP2 cards (162 done by author) and more than 30 ad hoc lists. The seasonality of waterbird species is discussed based on responses and occurrences after the rainfall seasons. Higher reporting rates were obtained for species such as Yellow-billed Ducks (49.7%), Red-billed Teals (37.9%) and White-faced Whistling Ducks (32.0%) during the summer months, which were sometimes still present into the drier winter months. Spur-winged Goose (39.6%) and Egyptian Goose (69.2%) also have high reporting occurrences, although South African Shelducks showed a more seasonal occurrence with lower reporting rates (17.8%). The seasonality of winter visiting species such as Swallow-tailed Bee eater and Sickle-winged Chats is discussed. Sickle-winged Chats were mostly observed in the area between April–August preferring low shrubs in open patches in grassland and on gravel roads. Swallow-tailed Bee eater were observed in the Buddleja sp. bush areas on the slope of the hill at the Praalhoek farm between May and July. The seasonal occurrence of Melodeuis Larks, which starts singing after the first summer rains, is also discussed. The ongoing monitoring of bird populations through the SABAP2 project (and with other platforms such as the Virtual Museum digitization projects) is emphasized and therefore the importance of monitoring bird populations over time.

Water Birds of Subhas Sarobar and their Diversity Assessment: Capacity Building in Research Aptitude of Students of Rammohan College, Kolkata

Abstract: Birds perform numerous important ecological services and are sensitive indicators of biological diversity and environmental trends. Around the world, birds may be found in nearly every climate and at nearly every height. They are a natural method of eradicating pests from farms, gardens, and aquatic habitats. Numerous bird species react to even little alterations in the structure and make-up of their habitats, making them useful as environmental change indicators. The Subhas Sarobar is a sizable body of water close to the East Calcutta Wetland (220 43'6" N, 880 24'3" E), which is home to several water bird. The West Bengal Pollution Control Board, a division of the West Bengal Government, first reported the presence of an avifauna in this environment in the year 2000. The current authors looked into the avifauna's actual state in Subhas Sarobar (2019–2020). In contrast to the 7 species reported in 2000, 13 species of water birds belonging to 6 Orders and 6 Families were discovered during a field survey. The Shannon-Wiener index has been used to gauge their diversity. They have been discovered to be in homeostasis, despite anthropological disturbance.

Inventory of Migratory Water birds in the coastal areas of Purba Medinipur district, West Bengal, India.

The present study was done on migratory water birds in the coastal and surrounding areas of Purba Medinipur, West Bengal, India from July 2020 to June 2022. A total number of 51 migratory water bird species belonging to 7 orders and 10 families were recorded during this study. Among the recorded species 45 species were the Least Concern (LC) and 4 were Near Threatened (NT) and 1 species each were Vulnerable (VU) and Endangered (EN). Scolopacidae was represented as highest family of 16 species because aggregation of migratory waders birds during winter season. The overall Shannon Diversity Index (H’) was 0.892 and the Shannon Evenness (J’) value was 0.226. The Simpson’s Diversity Index (D) was 0.286. All the diversity Index were lowest because of dominating Lesser Whisting-duck Dendrocygna javanica (Horsfield, 1821) (9015) aggregate in the coastal wetlands and bheries during winter season. In future more focus will be on this areas as there are many places still not properly explored and several wetlands which need to be studied in a thorough manner for a better understanding about the migratory avian diversity of this area.

Attenuation of Responses of Waterbirds to Repeat Drone Surveys Involving a Sequence of Altitudes and Drone Types: A Case Study

Remotely piloted aircraft systems (RPAS, or ‘drones’ hereafter) have potential for surveying waterbird species and habitats, but there is a risk that the disturbance from drones could compromise count accuracy and bird welfare. We examined the response of 16 waterbird species to repeated up-and-back overhead drone flights (n = 50 flights) at multiple flight heights (80, 60, 40 and 20 m) using three common drone platforms (DJI Matrice 300, DJI Mavic 2 Enterprise Advanced and DJI Phantom 4). A ground observer scored the species’ responses to overhead drone flights, which ranged from no response (no change to initial behavior), vigilance (head turning and tracking), movement within the site (swimming, diving, flight into or on the water) and substantial flight resulting in departure from the pond (fleeing). A total of 280 waterbird encounters with overhead drones were observed. The most common response across all flights was no response (70.7%), followed by vigilance (27.5%), whereas more intense responses were comparatively rare (1.8%). The responses were of higher intensity during earlier overhead drone flights, before moderating substantially during later flights. Thus, our case study provides the first unambiguous evidence of the attenuation of responses of bird species to drones.

Spatial Distribution of Malaysian Storks Determined Based on Citizen Science (eBird) Data

Waterbird populations are rapidly declining worldwide, including in many countries in Southeast Asia. Massive land use changes in Peninsular Malaysia are a major threat to biodiversity due to habitat loss and alteration, affecting the populations of many waterbird species. This study was conducted to determine the spatial distribution of three stork species, the Asian Openbill Anastomus oscitans, Painted Stork Mycteria leucocephala and Milky Stork Mycteria cinerea, in Peninsular Malaysia using the citizen science database, eBird. About 86,881 occurrences of the Asian Openbill, 2,391 occurrences of the Painted Stork and 242 occurrences of the Milky Stork were identified in the eBird database throughout Peninsular Malaysia between 2019 and 2021, suggesting major differences in occurrence size between the three species. Map generated from ArcGIS and a statistically significant difference in the population distribution of the three stork species across Peninsular Malaysia indicate habitat segregation. The populations of these stork species should be carefully monitored and managed to avoid imbalance with other waterbird populations.

Drone‐induced flight initiation distances for shorebirds in mixed‐species flocks

Abstract Drone use has increased in the last decade prompting management efforts to regulate flights near vulnerable wildlife; however, these efforts are hindered by a lack of data characterising drone‐induced wildlife disturbance. Many shorebird populations are rapidly declining and efforts to survey them can be hampered by the inaccessibility of their habitat. Drone surveys might overcome this barrier, although there is a risk that increased drone use near shorebirds may cause disturbance and exacerbate declines. We characterise drone‐induced disturbance for mixed‐species shorebird flocks to inform the management of drones near shorebirds. We conducted 240 drone approaches of mixed‐species flocks containing roosting non‐breeding shorebirds in Moreton Bay, eastern Australia. We performed approaches horizontally at varying vertical distances and recorded metrics characterising the drone, flock and environment. This enabled us to estimate the factors influencing disturbance as well as the distance of an approaching drone at which the flock is likely to take flight. We determined the drone‐induced flight initiation distance for 12 species of waterbird, including seven shorebird species. We could not approach Eastern Curlew Numenius madagascariensis at any vertical distance below the recreational drone limit of 120 m without inducing flight; however, for all other species, there was less than 20% probability that they would take flight when approached by a drone at vertical distances above 60 m. We do not recommend approaches below 30 m. We also found that flight initiation of mixed‐species flocks is largely dictated by the most sensitive species present, and that disturbance generally increases with approach velocity, drone noise/size, decreasing distance, and if the drone is obscured by trees. Policy Implications. We conclude that (i) drone use needs to be carefully regulated to ensure roosting shorebird flocks are not approached within distances that will disturb the most sensitive species likely to be present, (ii) researchers contemplating drone surveys need to carefully evaluate the risk of disturbance, especially where there are mixed‐species flocks, and (iii) that alternatives to drone surveys should be sought wherever disturbance data for the species potentially encountered are unavailable.

Composition and feeding guilds bird community in tropical peatland of Orang Kayo Hitam Forest Park buffer area, Jambi, Indonesia

Abstract. Pangestu PG, Iswandaru D, Wulandari C, Novriyanti, Prasetia H. 2023. Composition and feeding guilds bird community in tropical peatland of Orang Kayo Hitam Forest Park buffer area, Jambi, Indonesia. Intl J Bonorowo Wetlands 13: 57-65. Tropical peat ecosystems are vulnerable to fire damage and conversion, including in the Orang Kayo Hitam (OKH) Forest Park buffer villages, Jambi Province, Indonesia. The peat ecosystem is a habitat for various birds. In the ecosystem, birds act as seed dispersers, pest controllers, and pollinators, so their presence can be used as bioindicators of environmental quality. This study aims to analyze the composition and feed guilds of the bird community. The line transect method is used to explore the path in bird watching. The data were then analyzed using descriptively and qualitatively. In total, 29 species from 18 families comprised five species of waterbirds and 25 species of land birds. The families with the highest number of species were Alcedinidae, with a percentage of 13.79% each (4 species). At the same time, the lowest were Apodidae, Bucerotidae, Hirundinidae, Laniidae, Meropidae, Psittacidae, Rallidae, Cisticolidae, Turnicidae, Ploceidae, and Passeridae, with only one species (3.45%) identified per family. Based on the feed guild, there were nine types of guilds, with the highest rate being granivore (24,14%), while the lowest was insectivore on the forest floor (3.45%). The presence of bird species based on the feed guild indicates that shrubs or weeds dominate the land cover of the buffer village around the OKH Forest Park.

Impact of coastal island restoration engineering and subsequent tourism on migratory waterbirds: a 3‐year case from Southern China

Coastal engineering poses a significant threat to the survival of migratory waterbirds worldwide. However, the mechanisms through which engineering affects waterbirds are still unclear. To gain a better understanding of this issue, we conducted a three‐year survey of waterbirds on Shanxinsha Island, which underwent restoration engineering, along the East Asian–Australasian Flyway. We compared the seasonal migratory change among different species groups through and after the island restoration engineering. We observed a total monthly maximum count of 118,506 individuals from 61 waterbird species over the span of 38 months, including eight globally threatened species and five species that exceeded 1% of the flyway population. Throughout the survey periods, the average number of total waterbirds and small shorebirds observed during the migrating season decreased by 52.7 and 48.6%, respectively. The massive loss of high‐tide roosting areas was the primary factor contributing to this decline. The combined effects of increased vegetation and deeper water levels resulted in a 38.8% reduction in exposed tidal flat area, as determined through land cover verification and fractional vegetation cover calculations. While tourism activities exhibited fewer negative consequences compared to island restoration engineering, they had a greater impact on small breeding shorebirds. Our study showed that small shorebirds were particularly susceptible to island restoration engineering, whereas large shorebirds and swimming birds were more flexible in their use of roosting or foraging sites. We suggest that the impact of future coastal engineering requires more detailed assessment and monitoring, especially for small migratory shorebirds.

Diet composition of White-tailed Eagles inhabiting two adjacent inland lakes in Northern Greece

Abstract In territorial raptors, breeding performance and foraging behaviour are affected by territory characteristics as the abundance and availability of different prey species varies between habitats. In this study, we examined the diet of two White-tailed Eagle pairs, occupying neighbouring territories in two adjacent inland lakes in Northern Greece. We assess the diet composition of the species in the southernmost part of its European range and evaluate any intraspecific differences in the diet that may reflect resource and/or niche partitioning between territories. We found that birds and specifically waterbirds comprise the largest and quantitatively most important part of the White-tailed Eagle´s diet, with fish being the second most important prey group that was only found in the nest remains from one territory. There was high diet overlap between the two territories and when considering only avian prey our results suggest that the species predates on heavier (and the most common) waterbird species. A main factor that could be driving differences in the abundance and availability of different prey species between territories could be lake physiography, as our results point to a segregation and a subsequent resource partitioning between territories, with each pair utilizing an adjacent lake and its associated habitats. Competition and territoriality therefore seem to be important intraspecific interactions that along with prey availability could promote changes in territory size and ultimately affect individual fitness.

Limnological factors that affect waterbird assemblages in semi-arid reservoirs of Tigray National Regional State, northern Ethiopia

Published accounts of the conservation of biodiversity indicate that understanding patterns of species distribution and richness is crucial. However, what drives patterns of species composition in a landscape remains debatable. I examined the relationship between limnological characteristics of reservoirs, morpho-edaphic variables, biological variables, and patterns of bird species richness and distribution. Six limnological, three morpho-edaphic variables, and biological variables were recorded for 35 reservoirs and analyzed by multivariate statistical techniques. To investigate the most important explanatory factors influencing avian species richness and their distribution, redundancy analysis (RDA) was used. A total of 85 bird species from 54 genera, with a mean species richness 14.23 ± 6.72 (mean ± standard deviation) per reservoir, were recorded. The RDA analysis identified two significant RDA axes, and 34.4% of the variation in species richness is explained by environmental variation (R2adj = 0.34375; P < 0.001). Bird species richness was positively correlated with the surface area of reservoirs. I showed here that reservoir size and environmental heterogeneity were the important features that affect bird species richness, thus providing an important insight into the ecological relationship between waterbird species richness and the limnological characteristics of reservoirs. The strong positive correlation between species richness and both size and environmental variables underscores the importance of these reservoir features in the management of wildlife conservation. Large, environmentally heterogeneous reservoirs can support more species than small, environmentally homogeneous reservoirs because large, environmentally heterogeneous limnetic ecosystems can provide different resources for nesting, foraging, and roosting habitats for a diversified bird species. The result here also plays a role towards strengthening our knowledge of aquatic bird ecology and the natural history of African-Eurasian Migratory waterbirds.

The Richness of Sarcocystis Species in the Common Gull (Larus canus) and Black-Headed Gull (Larus ridibundus) from Lithuania

The common gull (Larus canus) and the black-headed gull (Larus ridibundus) are common waterbird species in Lithuania. Until now, the composition of Sarcocystis species in these birds was unknown. The current study aimed to identify Sarcocystis spp. by the morphological examination of sarcocysts found in the muscle tissues and by DNA sequence analysis. Between 2011 and 2019, the leg muscles of 42 common gulls and 63 black-headed gulls were tested for Sarcocystis spp. Based on the methylene blue staining of squashed muscle samples, sarcocysts were detected in six common gulls (14.3%) and in six black-headed gulls (9.5%). Under a light microscope, one type of microcyst was observed. Sarcocysts were thread-like (2860–8250 × 40–180 μm) and had a smooth and thin (0.8–1.4 μm) cyst wall, while bradyzoites were banana-shaped and 5.0–9.2 × 1.3–2.4 μm in size. The sequencing of complete ITS1 showed the presence of S. columbae, S. halieti and S. wobeseri in the common gull and S. columbae and S. halieti in the black-headed gull. The highest intraspecific genetic variability was established for S. halieti, which is characterized by a wide host range. This species is considered to be pathogenic, therefore further histopathological examination of the various organs of gulls is needed.