Effect of habitat and landscape structure on waterbird abundance in wetlands of central Argentina

Determining the response of birds to local habitat characteristics and landscape structure is essential to understanding habitat selection and its consequences for the distribution of species. This study identified the influence of environmental factors as determinants of the waterbird assemblage composition in 39 wetlands in the Pampas of central Argentina. Multivariate analysis allowed the identification of environmental factors affecting the use of habitat by waterbird species, whose variable numbers were explained by local and landscape environmental factors. Interspecific variation in responses to changes in environmental factors shows that habitat selection occurs at a species-specific level, although species with similar ecological requirements tend to respond similarly to environmental heterogeneity. Plovers and flamingos were mostly associated with high salinity and the presence of a muddy shoreline and temporary ponds; ducks, herons and ibises were associated with vegetation abundance and decrease in salinity; piscivores and carnivorous species were associated with water depth. The small degree of overlap of habitat requirements between some species suggests a high level of specialization within waterbird assemblages. This knowledge can be used for the design of appropriate conservation and management strategies in central Argentina, where the alarming loss of wetlands requires management strategies that ensure the permanence of the greatest diversity of waterbirds.     

Habitat Use by Waterbirds in Relation to Pond Size,Water Depth,and Isolation: Lessons from a Restoration in Southern Spain

Wetland restoration is increasingly important to reverse habitat degradation, recover ecosystem services, and maintain biodiversity. To aid project design, more information is required on the influence of wetland size, depth of water, and isolation on the waterbird communities that become established. During a restoration project in Doñana, one of the Europe's most important wetland complexes, an experimental network of 96 temporary ponds with standard shape but variable size, water depth, and isolation was created. We surveyed the waterbird community in spring from 2006 to 2008 and related species abundance and richness to abiotic pond characteristics. We also performed analyses pooling species by foraging guilds or body size. Waterbird abundance and species richness were highest in 2007, the wettest year when the ponds had longer hydroperiods. Larger ponds had consistently higher abundance and species richness for the entire community and for different guilds and body sizes. Moreover, the density of birds per hectare was higher in large ponds than in the smaller ones. Pond isolation and excavated depth did not affect overall abundance and richness, although opposing effects of depth were observed on some size classes, and ducks and large birds preferred isolated ponds. Some bird groups preferred ponds at a particular location. This is the first waterbird study to address the importance of pond size, depth, and isolation independently of confounding variables such as pond shape. It illustrates the varied responses from different bird groups and demonstrates the importance of varying depth, location, and isolation to enhance community abundance and diversity .     

崇明东滩抛荒鱼塘的自然演替过程对水鸟群落的影响

人工湿地抛荒的现象普遍存在,但针对抛荒后的自然演替过程对水鸟群落影响的研究较少.于2007、2008、2011年对崇明东滩自然抛荒的人工鱼塘水鸟群落展开调查,探究抛荒后的自然演替过程对水鸟群落结构及不同水鸟类群的影响.3a累计观察到水鸟59种12819只,隶属6目12科.其中抛荒前最多,共53种11001只;抛荒第1年22种1673只;抛荒第4年最少,9种145只.鱼塘抛荒后水鸟种类和数量下降剧烈,物种多样性先上升再下降,均匀度逐年上升,优势度先下降再上升.方差分析结果表明,5个群落特征都存在极显著年度差异(P1＜0.01;P2＜0.01;P3＜0.01;P4=0.003;P5＜0.01).非参数检验结果表明,不同类群水鸟的种类和数量逐年下降趋势明显,且年际差异极显著.即抛荒后的自然演替过程对水鸟群落产生了不利影响.建议采取人工管理措施防止旱化,增加环境异质性,恢复水鸟群落多样性.     

Breeding waterbirds in relation to artificial pond attributes: implications for the design of irrigation facilities

The growth of inter-basin water transfers and the development of new irrigation facilities in southeastern Spain are responsible for a variety of ecological impacts. In spite of this, the construction of artificial ponds to keep water for intensive agriculture may also provide new habitats for breeding waterbirds. We counted waterbirds during the breeding season in artificial ponds that had been built up using different materials and measured their abiotic and biotic attributes. We found that ponds were used as breeding and foraging habitat by 22 different waterbird species and breeding numbers of a few of them seemed to be larger in these artificial facilities than in nearby natural and semi-natural wetlands. Abundance and richness of breeding waterbirds was influenced by construction materials. Ponds constructed with low density polyethylene and covered with sand and stones held more species and their numbers were higher than those constructed with other plastic materials. The presence of emergent and submerged vegetation as well as abiotic attributes, such as pond size, accounted for most of the deviance when modelling richness and species abundance.     

Long-term trends,seasonal abundance and energy consumption of waterbirds at Rietvlei,Western Cape,South Africa, 1950–1997

Waterbird counts at Rietvlei, a freshwater wetland in the Western Cape, were analysed for four periods: 1950–56, 1961–67, 1980–85 and 1992–97. Ninety-eight species of waterbirds were recorded during these counts. Palaearctic migrants predominated during summer, with Curlew Sandpipers, Calidris ferruginea, being the mast abundant species in all years, except in the 1960s and 1950s when Red-knobbed Coots, Fulica cristata, and Ruffs, Philomachus pugnax, outnumbered them respectively. Red-knobbed Coots and Yellow-billed Ducks, Anas undulata, were the most numerous species during winter in all years. The numbers of waterbirds at Rietvlei have shown a progressive increase since the 1950s, reaching over 8300 birds in the mid-summer of 1997. The increase in abundance of several species is attributed to changes in the water regime and habitat availability at the wetland. In terms of waterbird abundance, Rietvlei is the most important temporary vlei in the Western Cape and it ranks 16th in terms of waterbird abundance compared with all South African coastal and inland wetlands for which counts are available. In the light of Rietvlei being proclaimed a nature reserve, a conservation management plan for the area is discussed.     

冬季水鸟对崇明东滩水产养殖塘的利用

自然湿地的丧失和退化给依赖湿地生存的水鸟带来了严重威胁,人工湿地作为水鸟栖息地的功能日益受到关注.水产养殖塘是人工湿地的重要类型之一.通过研究崇明东滩水产养殖塘冬季水鸟群落组成及其栖息地特征,发现大面积养殖塘比小面积养殖塘吸引更多种类和更高密度的水鸟.养殖塘在放水前水位较高时吸引更多游禽栖息,而在放水后水位较低时吸引更多涉禽;在放水过程中,养殖塘中水鸟的种类最多,密度最大.另外,在放水的不同时期,不同的环境因子对水鸟群落的影响不同:放水之前,养殖塘水面面积和平均水深是水鸟种类和数量的主要影响因子,其中游禽种类和数量受水面面积影响较大,涉禽种类和数量受平均水深影响较大;放水过程中,裸地面积、芦苇面积、干扰程度、平均水深和水深变异对水鸟、游禽和涉禽的种类和数量起主要作用;放水之后,水深变异对水鸟种类和数量的影响较大,而影响游禽种类和数量的主要因子是水面面积,影响涉禽种类和数量的主要因子是水深变异.研究表明,通过对影响水鸟栖息地利用的主要因子的有效管理,养殖塘在提供经济效益的同时也能为水鸟提供适宜的栖息地.     

城市化对杭州市湿地水鸟群落的影响研究

１９９７年１２月￣１９９８年１１月,对杭州市区６类湿地１７９个术方中水鸟的分布和数量进行了调查,同时选取１１个栖息地参数进行分析。以确定影响杭州市湿地水鸟群落的主要因子;并提出了城市化综合指数可作为衡量城市化的指标,进一步分析了城市化与杭州市湿地水鸟群落的关系。结果显示,除了食物、水质和水深等因素外,景观水平和干扰的因素（湿地的形状、周转建筑的比例、湿地的连通性、至市中心的距离、噪音、人的有形干扰     

Agricultural ponds as alternative habitat for waterbirds: spatial and temporal patterns of abundance and management strategies

The progressive lost of natural wetlands as a consequence of human activities has lead to the use of new habitats by the species linked to water presence. In Southeast Spain, thousands of irrigation ponds have been lately constructed to store water for agriculture and are used by waterbirds as an alternative habitat. For this study, breeding and wintering waterbirds were counted in a subset of irrigation ponds between 2002 and 2007. Breeding communities were more abundant than wintering communities, but they presented a similar richness and diversity. The ponds were selected by waterbirds according to their characteristics, and breeding communities were more selective than wintering communities. Our results enhance the importance of pond size (area), connectivity (distance to the nearest wetland) and habitat quality (resource offer and construction material) in the pond selection process. The presence and design of these impoundments could be playing a crucial role for some waterbirds species. Therefore, the long-term information provided here can be useful for establishing management strategies for these artificial wetlands.     

Effect of landscape configuration and habitat quality on the community structure of waterbirds using a man-made habitat

Species occurrence and community structure are strongly influenced by multiple factors like habitat selection, species movement capabilities, competition, or conspecific and heterospecific attractions. More specifically, in waterbird communities, previous studies have identified the importance of environmental and structural characteristics of wetlands for their occupation and use. However, the effect of the surrounding landscape configuration remains unknown. In this article, we use a large network of artificial irrigation ponds to evaluate the importance of pond features in comparison to the effect of landscape and spatial configuration on the community at three different spatial scales. Our results show that landscape configuration has relatively little influence on structure of the waterbird community. Pond features were by far the most important variables to describe waterbird abundance and richness. At the species level, we detected differences in habitat preferences relating to species-specific ecological requirements. Our results highlight the importance of using a multiscale approach to understand and predict richness and abundance in waterbird communities. Our findings emphasize the need to maintain high-quality ponds to enhance their suitability for use as breeding and foraging sites.     

Habitat structure determines spider diversity in highland ponds

Wetlands (e.g. ponds, meadows) can be found in many landscapes, playing an important role in maintaining regional biodiversity and supporting heterogeneous communities. Spiders are diversified predators that are highly influenced by changes in plant community structure, heterogeneous habitats sustain high spider diversity and abundance. We investigated the characteristics of spider biodiversity in ponds with different habitat structures, by examining patterns across habitats of ponds with different vegetation levels. Sampling took place in four occasions over a year. We compared spider abundance, species richness and composition among ponds including distinct vegetation variables, related to life form, type of leaves, coverage and height. Overall 1174 individuals (194 adults) of 11 families and 37 morphospecies were sampled. We found mostly expected differences in the manner that communities were structured between different habitats. Thus, higher variability of abundance was explained for higher habitat structure of ponds. We also found differences in species composition between ponds with low emergent vegetation and higher habitat structures. Additionaly, spiders were consistently structured more by turnover than nestedness components, with a greater beta diversity of web-builders. Our results suggest varying levels of habitat structures and species substitution shape pond spider communities, depending on habitat heterogeneity and spider guild. Those findings demonstrate the clear role of spatial habitat structure, with more spider species preferring to build webs or actively hunt at vegetated environments on ponds.     

杭州市湿地水鸟的分布与多样性研究

１９９７年１２月至１９９８年１１月,对杭州市区６类湿地中水鸟的分布,密度和多样性进行了调查,结果显示,全年共有水鸟３８种,群落的组成季节变化较大,且以迁徒种类为主;留鸟为少数城市适应种,而迁徒鸟主要分布在郊区和郊区,很少深入城区,整个杭州区全年水鸟的多样性波动不大,密在秋冬季较高,但各类湿地水鸟的密度和多样性季节变产大;水产养殖场是杭州水鸟最重要的栖息地类型,西湖和水荡对于维持杭州市水鸟的数量和多     

Importance of gravel pits for the conservation of waterbirds in the Garonne river floodplain (southwest France)

The loss of natural wetlands throughout the World has made created habitats such as gravel pits, reservoirs or rice fields potentially important for waterbird conservation. In southwest France, the increasing abundance of gravel pits has allowed several bird species to colonize the region. The avian community was studied from 1996 to 1998 in six gravel pits in the Garonne floodplain. A total of 39 species of waterbirds were recorded, with higher abundance during the winter and post-breeding periods. We analyzed habitat use to identify key environmental factors determining the temporal and spatial distribution of the avian community. The presence of submerged macrophytes was found to be the most important factor influencing the distribution of waterbirds. The presence of paths in the vicinity of the areas reduced both the total number of birds and species richness owing to human disturbance. Gravel pits have an increasingly important role in the conservation of bird biodiversity. By controlling disturbance and management of vegetation, managers can enhance this role.     

Waterbirds and substrate quality of the Pichavaram wetlands,southern India

The water and mud characteristics of the six types of wetlands in Pichavaram were compared in order to determine whether the habitat of waterbird species was characterized by them. Waterbird species richness was most influenced by mud phosphorus levels. Variation in water pH was the principal factor that determined waterbird diversity. The water level mainly determined the density of waterbirds. Levels of pH and nitrites in the water also appeared to influence significant variations in waterbird diversity and density, respectively. Bottom substrate variables, viz. pH and phosphorus levels, were also significantly correlated with the density and richness of waterbirds, respectively. Water quality factors, viz. pH and nitrite and mud pH and phosphorus, were correlated with the abundance, while water depth was correlated with the accessibility of prey to the birds.     

Wetland Waterbird Food Resources Increased by Harvesting Invasive Cattails

The conservation of many freshwater marsh waterbirds (i.e., waterfowl, shorebirds, wading birds, and secretive marshbirds) in the Laurentian Great Lakes requires managing invasive emergent macrophytes, which degrade waterbird habitat by creating dense, litter-clogged stands, and excluding plants that produce nutritionally balanced and high-energy food (seeds, tubers, and submerged aquatic vegetation). The most commonly used management approach in the United States Great Lakes region involves the application of herbicides, which can stimulate waterbird forage plants but does not address the accumulation of plant litter, the underlying cause of plant community diversity loss and habitat degradation. We experimentally evaluated the effects of an alternative approach, harvesting invasive plants and their litter followed by flooding, on plant communities, focusing on the effects of these treatments to increase the abundance of high-energy wetland plants. At the Shiawassee National Wildlife Refuge in Michigan, USA, we experimentally treated an invasive cattail (Typha × glauca)-dominated wetland in August and September of 2016, 2017, and 2018, using a randomized block design with 4 blocks and 3 treatments (sediment surface harvest, above ground harvest, and control). We monitored the effects of these treatments on the abundance and dominance of waterbird forage-producing plants, plant diversity, and plant communities prior to (Jul 2016) and during the summer following each treatment (late Jul or early Aug 2017, 2018, and 2019). Additionally, we used pre- and post-treatment waterbird use-day data collected at the unit scale and compared values with satellite imagery-derived land cover changes. Compared to control plots, 3 years of harvesting and flooding significantly increased plant species diversity, increased the abundance of waterbird seed- and tuber-producing plant species by 5 times, and increased annual plant dominance by more than 10 times, while substantially reducing all measures of cattail and its litter. Use-days increased for total waterbirds, including waterfowl and dabbling ducks, following treatment. Cattail cover decreased and open water and non-cattail emergent vegetation cover increased. Harvesting invasive plant biomass coupled with flooding promoted a plant community composition and structure beneficial to waterbirds. © 2020 The Wildlife Society.     

Community structure and association of waterbirds with spatial heterogeneity in the Bahia Magdalena-Almejas wetland complex, Baja California Sur, Mexico

Community structure and association of waterbirds with spatial heterogeneity in the Bahia Magdalena-Almejas wetland complex, Baja California Sur, Mexico. To test the hypothesis that spatial heterogeneity determines waterbird diversity in a coastal wetland, we compared waterbird density, diversity, and species composition among various habitats and landscapes units in Bahia Magdalena-Almejas, Baja California Sur, Mexico. Based on diversity patterns and bird distribution, we assessed the effect of coastal development on the waterbird community structure. To gather information on habitat features and waterbird populations we conducted waterbird censuses in 329 habitat segments along the internal coastline of the study area, from February 2002 to February 2003. We performed non-parametric analyses to test the null hypothesis of no diference on waterbird density, and diversity among landscape units and seasons. The species composition was evaluated using ordination techniques. Waterbird density was higher in winter and autumn in the three lagoons of the study area, particularly in the insular coast, sandy beach and dunes; it was higher in the few segments of antropic sustrate. Diversity was significantly higher in mangrove habitat along the peninsular coast, and in mangrove-dunes association on the insular coast. Although modification of coastal natural habitat and boat transit disturbance had no influence on waterbird density or diversity, the highest richness of waterbirds occurred in well preserved areas. Species composition analysis showed differences between Santo Domingo Channel and Magdalena Bay. Pelagic and mangrove habitat had a species composition difference higher than those associations in other habitats. Such differences in species assemblages by habitat and landscape units suggest that communities are structured according to the range of available natural resources in structurally complex habitats, and that dominant piscivorous waterbird species were favored in this community.     

Promoting dragonfly diversity in cities: major determinants and implications for urban pond design

Urbanisation is increasing and it is essential to integrate biodiversity into the spatial planning of urban areas. This requires deeper understanding of biodiversity patterns in cities. We investigated which habitat variables are major determinants of dragonfly diversity and species assemblage structure in the municipal area of Dortmund (Germany). We sampled dragonfly larvae in 33 ponds situated in city parks, commercial, residential and agricultural areas. We recorded 30 autochthonous dragonfly species with species richness ranging from zero to 17. Additionally, we surveyed a set of environmental variables including habitat size, water level, pond structures and vegetation as well as surrounding landscape and potential disturbances like waterfowl and fish. Multivariate methods were used to identify the major determinants of dragonfly diversity, abundance and assemblage structure. Analysis indicated that diversity of aquatic and terrestrial vegetation affected dragonfly diversity positively. City park ponds had low diversity, but Ischnura elegans was obviously promoted by the specific park pond conditions, including high waterfowl density. We found five assemblages mostly determined by generalistic species which were related to different pond types. Moderately disturbed ruderal and pioneer ponds in residential and agricultural areas also contained increased numbers of rare species. Our results indicate that urban ponds may have a great value for maintaining biodiversity, but various disturbances have negative impact. To promote urban biodiversity we suggest a natural design of well-vegetated ponds as well as a high diversity of different pond types and particularly a more-natural redesign of city park ponds.     

Determinant landscape‐scale factors on pond odonate assemblages

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Impacts of colonial waterbirds on vegetation and potential restoration of island habitats

Colonial waterbirds have impacted forested island ecosystems throughout their breeding range, changing vegetation, and soil characteristics and bird communities. Our objectives were to (1) determine effects of three levels of colonial waterbird exclusion on overall vegetation diversity and growth, and survival of a candidate restoration species (black elderberry; Sambucus nigra canadensis); (2) investigate effects of different planting techniques on survival and growth of black elderberry; and (3) determine effects of waterbird colonization on soil chemistry. In 2012, we investigated effects of three levels of waterbird exclusion (none control plots [CON]; partial, which excluded waterbirds larger than gulls [PEX]; and full which excluded all waterbirds [FEX]) on bird use, existing vegetation growth and diversity, and survival of planted black elderberry on three islands in Door County, WI, Lake Michigan. In 2013, we evaluated survival of black elderberry established with four planting treatments within three waterbird exclusion treatments on two islands in 2013. We also compared soil chemistry characteristics between islands with and without nesting waterbirds for 2 years. Overall plant growth was greater in exclosures, but elderberry survival was similar among treatments. Soil replacement and weed suppression planting treatments did not affect survival, but generally increased overall elderberry biomass. Soil from nesting islands was more acidic and had greater nutrient concentrations than reference islands. Exclusion or removal of colonial nesting waterbirds from islands may improve overall vegetation growth, but successful restoration of woody vegetation may require significant soil manipulation and planting.     

Nestedness theory suggests wetland fragments with large areas and macrophyte diversity benefit waterbirds

Many artificial wetland constructions are currently underway worldwide to compensate for the degradation of natural wetland systems. Researchers face the responsibility of proposing wetland management and species protection strategies to ensure that constructed wetlands positively impact waterbird diversity. Nestedness is a commonly occurring pattern for biotas in fragmented habitats with important implications for conservation; however, only a few studies have focused on seasonal waterbird communities in current artificial wetlands. In this study, we used the nestedness theory for analyzing the annual and seasonal community structures of waterbirds in artificial wetlands at Lake Dianchi (China) to suggest artificial wetland management and waterbird conservation strategies. We carried out three waterbird surveys per month for one year to observe the annual, spring, summer, autumn, and winter waterbird assemblages in 27 lakeside artificial wetland fragments. We used the NeD program to quantify nestedness patterns of waterbirds at the annual and seasonal levels. We also determined Spearman partial correlations to examine the associations of nestedness rank and habitat variables to explore the factors underlying nestedness patterns. We found that annual and all four seasonal waterbird compositions were nested, and selective extinction and habitat nestedness were the main factors governing nestedness. Further, selective colonization was the key driver of nestedness in autumn and winter waterbirds. We suggest that the area of wetland fragments should be as large as possible and that habitat heterogeneity should be maximized to fulfill the conservation needs of different seasonal waterbirds. Furthermore, we suggest that future studies should focus on the least area criterion and that vegetation management of artificial wetland construction should be based on the notion of sustainable development for humans and wildlife.