It is vital to identify factors that affect the overwintering of waterbirds for conservation purposes. In this study, during the winter of 2018–2019, we documented 177,414 individuals of 74 species ...of waterbirds in the Jiangsu coastal area, an important but poorly known overwintering location. Of the species observed, 12 were listed as threatened. We found that natural wetlands loss is a significant contributor to population declines among overwintering waterbird species in the Jiangsu coastal area, greater than anthropogenic disturbance. This loss has forced waterbirds to choose artificial wetlands, where a total of 47 species were detected. Sorted by key zones for overwintering waterbirds, 16 surveying zones were identified in the area, and most are not fully protected. Thus, conservation efforts aimed at waterbirds should focus on at least 12 conservation gaps in diversity hotspots, emphasizing the management of artificial wetlands in the Jiangsu coastal area.
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•We documented 177,414 individuals of 74 species of overwintering waterbirds in the less studied Jiangsu coastal area.•Natural wetlands loss is a significant contributor to population declines.•Waterbirds chose artificial wetlands and need management.•16 unprotected zones were identified in the area for conservation efforts.•Conservation strategies were identified to protect the sensitive coastal zone.
Dongting Lake is the second largest freshwater lake in China and is one of the globally important wintering sites for migratory waterbirds in the East Asian–Australasian Flyway. Crucial sites and ...environmental variables for wintering migratory waterbirds are of great concern in the Dongting Lake wetlands. In this research, based on annual (2003/2004–2016/2017) waterbird and habitat census data, we recognized the crucial sites for waterbirds during wintering seasons by comparing the difference of waterbird populations at the community, foraging guild and species levels in different natural wetlands within East Dongting Lake, and then identified the crucial environmental variables affecting waterbird distributions by analyzing the relationship between waterbird populations and the environmental variables, including vegetation area, mudflat area, water area with the depth of 0–20 cm, water area with the depth of 20–50 cm, water area with the depth of 50–100 cm, water area with the depth >100 cm, growth status of vegetation (Min, Mean and Max NDVI), and the human disturbance. Results indicated that five natural wetlands, i.e., Daxiaoxi, Chunfeng, Baihu lakes, Dingzi dyke and Tanjiaweizi, were recognized as the crucial wintering sites for migratory waterbirds in the East Dongting Lake. Among the ten selected environmental variables, water areas with the depth of 0–20 cm, 20–50 cm and >100 cm, human disturbance, Min and Mean NDVIs were identified as the crucial environmental variables overall. Waterbirds at different levels exhibited significant linear relationship with certain environmental variables, with the exception of Bean goose and Lesser White-fronted goose at the species level, which showed Gaussian distribution with changes in mean NDVI. The crucial environmental variables appeared to be foraging guild- and species-specific. These findings provide significant information for managers to understand the differences of wetlands and waterbird populations within East Dongting Lake, and to make more targeted conservation efforts.
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•Waterbird populations were analyzed at community, foraging guild and species levels.•Five crucial wintering sites were verified in East Dongting Lake.•Six crucial environmental variables were identified in East Dongting Lake.•Crucial sites and environmental variables were foraging guild-specific.•Crucial sites and environmental variables were species-specific.
Human activities in Jakarta City, Indonesia, produce huge quantities of litter, much of which is dumped in mangrove habitats along the coast of Jakarta Bay. We identified three mangrove sites that ...contained no litter to varying amounts of litter and assessed its effect on the bird communities that are associate with those mangroves. We conducted this survey to determine how many birds are living with litter, and what sort of litter it is, and its impact on bird species during October–November 2020. The study sites were Arboretum Muara Angke (AMA), Angke-Kapuk Protection Forest, (Hutan Lindung Angke-Kapuk, HLAK), and Angke-Kapuk Nature Recreation Park (Taman Wisata Alam Angke-Kapuk, TWAAK). We also calculated the Index of Waterbird Community Integrity (IWCI) at each site and determined its relationship to litter. This index has been used previously to study the impact of anthropogenic disturbances. Litter identified in the study areas mostly consisted of plastic, followed by processed wood and rubber. Most of the litter was stranded suggesting that the mangrove roots retain litter. Of the 28 species co-occurring with litter, 10 were waterbirds. Only two species, Oriental darter (A. melanogaster) and Milky stork (M. cinerea), were never present where there was litter, showing a significant negative correlation with litter. The IWCI was highest in AMA, followed by TWAAK and HLAK. Litter also has no correlation with the IWCI, but the IWCI tended to be lower wherever litter was found in higher quantities. When monitor regularly, the decreasing values of IWCI would be useful as an alarm for an improvement in the litter management by considering the different types of mangroves based on hydrological conditions. At the end, the management activities of mangrove as part of Ramsar and litter management should be integrated.
The diversity and richness of the waterbird community is the main criterion used to classify wetlands as Ramsar and/or IBA sites. This study was carried out in the Soumar wetland (Setif province — ...northeastукт Algeria) from September 2019 to September 2020. Our aim was to study the ecological values of this wetland and the status of waterbirds. We recorded a total of 23 species belonging to 11 families. June was the most diverse month of the year (Shannon–Weaver and Simpson indices reached the maximum). October was the most equitable month (equitability reached maximum). We noted four key species according to IUCN status: Ferruginous Duck, Aythya nyroca (Near Threatened), Common, Pochard Aythya ferina (Vulnerable), White-headed, Duck Oxyura leucocephala (Endangered) and Northern Lapwing, Vanellus vanellus (Near Threatened). The main phenological status of waterbirds in Soumar was breeding or sedentary (26 % and 21 % respectively). The geographical location of the Soumar wetland and its diversity profile require a local management plan (depending on the waterbirds and their conservation), allowing the Soumar wetland to join the Ramsar network.
The conservation level of rare waterbirds reflects the quality of the regional ecological environment and wetlands, and suitable habitat patches and good environmental conditions are bases to support ...the activities of rare species in habitats. Establishing these conditions is also an important goal of habitat landscape and functional restoration. However, lack of these conditions limits population protection and habitat restoration of rare species. Based on the random forest (RF) algorithm and threshold indicator taxa analysis (TITAN), this paper performed habitat suitability assessment and environmental variable threshold analysis of rare waterbird species in Yancheng coastal wetlands. The results showed that the suitable area proportion of three waterbird species at different habitat sites was less than 20%. The unsuitable area proportions of red-crowned cranes and oriental storks at the CA habitat site were the highest, reaching 86.73% and 85.17%, respectively. In addition, analysis of the importance of environmental variables showed that the main influencing variables affecting the suitable habitat distribution of the three rare waterbirds were habitat type (T_hab), habitat area (A_hab), vegetation coverage (P_fvc), distance to farmland (D_far), distance to reeds (D_ree), ponds density (Ponds), distance to water surface (D_wat) and distance to main roads or seawalls (D_swa). These variables covered the type, area, coverage and distance indicators. With the exception of D_far, Ponds and D_swa, rare waterbirds had response thresholds to each environmental indicator, and these results supported the restoration of landscape structure and function of each habitat site. This study emphasized the importance of foods, water resources and hidden conditions for habitat selection in rare waterbirds. Finally, we proposed the maintenance and restoration patterns of the landscape structure and function of rare waterbird habitats, which are available for other coastal tidal wetlands.
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•The spatial distributions of suitable habitats of waterbird were different.•Response thresholds of main environmental variables were calculated.•Response thresholds reflected differences in habitat requirements among waterbird species.•This study guided landscape structure and function restoration of rare waterbird habitats.
Introducción: Las colonias de aves zancudas alcanzan miles de nidos densamente agrupados, que influyen marcadamente sobre las características del suelo o el agua que las rodea por un efecto de ...hiperfertilización. Esto provoca la acumulación nociva de compuestos nitrogenados, alterando la química del sustrato y produciendo defoliación y muerte de la vegetación. El impacto de estas colonias en los manglares de Cuba no se ha evaluado, por las dificultades logísticas que implica y la complejidad de sus procesos. Objetivo: En el presente trabajo se realizó la estimación de las cantidades de biomasa, energía y nutrientes movilizados en una colonia de Bubulcus ibis, durante una etapa de cría, a través de un modelo bioenergético de dinámica de sistemas. Métodos: Se emplearon 29 variables primarias, 3 ecuaciones bioenergéticas y la ecuación de crecimiento postnatal de esta especie, implementadas en el programa STELLA 9.1.3. De la interacción de estas variables se obtuvieron: la energía requerida por ciclo de reproducción, la biomasa consumida y los nutrientes depositados en la colonia. Se realizó un análisis de sensibilidad y un análisis de incertidumbre para explorar las variables que más influencia tienen sobre los resultados. El modelo fue validado mediante la consistencia en las unidades, la prueba de valores extremos y la comparación con valores registrados en la literatura. Finalmente, se simularon escenarios de disturbios que pueden afectar a una colonia real. Resultados: Según el modelo, para el crecimiento cada pichón requiere de 10 219.2 kcal totales. La colonia debe invertir en total 6.71 x 10.sup.6 kcal, lo que representa un consumo cercano a 2.2 toneladas de presas en una etapa de cría. Debido a este consumo, los nutrientes depositados en la colonia mediante las excretas estuvieron compuestos de 49 kg de nitrógeno, 7 kg de fósforo y 56 kg de calcio. Según el análisis de sensibilidad, las variables que producen cambios más fuertes en el resultado son el número de adultos de la colonia y el tamaño medio de puesta. El análisis de incertidumbre mostró poca influencia de las variables seleccionadas sobre las variables respuesta. Los disturbios simulados más dañinos para la colonia fueron las afectaciones al reclutamiento y el aumento de la mortalidad de los pichones. Palabras clave: guanotrofia; bioenergética; aves acuáticas; humedales. Modeling the effect of colonial breeding in Bubulcus ibis (Aves: Ardeidae) on biomass and energy flows of coastal mangrove. Introduction: The colonies of wading birds reach thousands of highly grouped nests, which have a marked influence on the characteristics of the soil or the water that surrounds them due to a hyperfertilization effect. This causes the harmful accumulation of nitrogen compounds altering the chemistry of the substrate and causing defoliation and death of vegetation. The impact of these colonies on the mangroves in Cuba has not been evaluated, due to the logistical difficulties involved and the complexity of their processes. Objective: Mathematical modeling is a useful tool in these situations, so in this work the estimation of the quantities of biomass, energy and nutrients mobilized in a colony of herons was carried out, through a bioenergetic model of system dynamics. Methods: We used 29 primary variables, 3 bioenergetic equations and the postnatal growth equation of this species, implemented in the STELLA 9.1.3 program. From the interaction of these variables, the energy required by the reproduction cycle, the biomass consumed and the nutrients deposited in the colony were obtained. A sensitivity analysis and an uncertainty analysis were carried out to explore the variables that have the most influence on the results. The model was validated by the consistency in the units, the test of extreme values and the comparison with values recorded in the literature. Finally, disturbances scenarios that can affect a real colony were simulated. Results: According to the model, each nestling require 10 219.2 kcal to growth. The colony must totally invest 6.71x10.sup.6 kcal, which represents consumption close to 2.2 tons of dams. Due to this consumption, the nutrients deposited in the colony by the excreta were 49 kg of nitrogen, 7 kg of phosphorus and 56 kg of calcium. According to the sensitivity analysis, the variables that produce the strongest changes in the result are the number of adults in the colony and the average clutch size. The uncertainty analysis showed little influence of the variables selected on the response variables. The most harmful simulated disturbances for the colony were the affectations to the recruitment and the increase of the mortality of the nestlings. Key words: guanotrophy; bioenergetic modelling; waterbirds; wetlands.
Between 2017 and 2019, 42 species of wintering waterbirds were recorded in the wetland complex of the Oued Righ valley in the Algerian Sahara. The intersite amplitudes of salinity explained the ...variations in species richness and distribution of waterbirds in the various wetlands studied. Oligohaline (0.5-5 ‰) and mesohaline (5-18 ‰) environments, represented by Lake Ayata, Lake Sidi Khelil and Oued Kherouf, were the most favorable to Anatidae with the exception of the tadornes where their presence was noted in the euhaline (30-40 ‰) and hyperhaline stations (> 40 ‰). The presence of the greater flamingo Phoenicopterus roseus and the slender-billed gull Chroicocephalus genei stood out in the most holomorphic areas of the complex, such as Chott Merouane. Dataset published through GBIF (Doi: 10.15470/6fqd0h)
China's coastal wetlands are critically important to shorebirds. Substantial loss of tidal flats, shorebirds' primary foraging grounds, has occurred from land claim and other processes, and is ...driving population declines in multiple species. Smooth cordgrass Spartina alterniflora was intentionally introduced to the coast of China in 1979 to promote conversion of tidal flats into dry land and has since spread rapidly. The occurrence of S. alterniflora reduces the availability of foraging and roosting habitat for shorebirds, and may be particularly detrimental in places that have experienced other tidal flat loss. However, the extent to which S. alterniflora is encroaching upon important shorebird habitat throughout coastal mainland China, and its intersection with tidal flat loss, has not been quantified. Here, we i) estimate change in the spatial extent of tidal flats between 2000 and 2015 in coastal mainland China where internationally important numbers of shorebirds have been recorded; ii) map the extent of S. alterniflora coverage in 2015 at the same set of sites; and, iii) investigate where these two threats to important shorebird habitat intersect. Our analysis of remote sensing data indicated a 15% net loss in tidal flat area between 2000 and 2015 across all sites, including a net loss in tidal flat area in 39 of 53 individual sites (74%). Spartina alterniflora occurred at 28 of 53 sites (53%) in 2015, of which 22 sites (79%) also had a net loss in tidal flat area between 2000 and 2015. Combined pressures from tidal flat loss and S. alterniflora invasion were most severe in eastern coastal China. Species highly dependent on migrating through this region, which include the Critically Endangered Spoon-billed Sandpiper and Endangered Nordmann's Greenshank and Far Eastern Curlew, may be particularly impacted. Our results underscore the urgent need to arrest tidal flat declines and develop a comprehensive control program for S. alterniflora in coastal areas of mainland China that are important for shorebirds.
•Tidal flat loss and introduced Spartina alterniflora impact coastal ecosystems.•Many coastal shorebirds are threatened and declining from habitat loss.•Tidal flat loss occurred at ¾ of important coastal shorebird sites in mainland China (2000–2015).•Spartina has invaded > ½ of important coastal shorebird sites in mainland China.•Tidal flat protection and spartina control are needed to avert further shorebird declines.
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