Impacts of microhabitat changes on wintering waterbird populations

Abstract

Caisang Lake, a human-modified wetland, experienced dramatic habitat alterations from the planting of lotus and culturing of crab. Whether the Caisang Lake still maintains populations of wintering waterbirds is of great concern. Here, we compare the changes in waterbird populations before and after habitat alterations in Caisang Lake and assess the driving factors leading to the dramatic changes in waterbird populations. Results indicate that wintering waterbird populations were significantly impacted by altered forage availability, with species- and guild-specific responses. Dramatic habitat alterations from planting lotus caused significant declines in areas of native vegetation, mudflats, and water that may have caused associated declines in herbivores, insectivores, and fish-eating waterbirds, respectively. In contrast, the increased size of the lotus area appears to have led to an increase in omnivorous waterbirds. A food shortage, potentially caused by a large area of Caisang Lake being used for culturing crab, might be another cause of the observed decline in fish-eating waterbirds. This study demonstrates a powerful approach to systematically evaluate waterbird responses to wetland management policies. These findings are important as efforts are made to protect the wintering waterbirds from the effects of human intervention, particularly at other Ramsar wetlands.

Overwintering Cranes, Waders, and Shorebirds versus Ducks and Coots Showed Contrasting Long-Term Population Trends in Caohai Wetland in Guizhou Province, China

“…The drop in abundance is particularly notable among waterbirds that rely on plant material and macroinvertebrates for sustenance, such as ducks and Coots, reflecting inadequate food supply, a notion discussed in prior studies [13,29]. Conversely, there has been a remarkable surge in the abundance of shorebirds and waders, which might be explained by the presence of ample food resources created by extensive shallows facilitated by diminished winter rainfall [31,32]. Furthermore, the diversity indicators of waterbirds have displayed noteworthy temporal fluctuations on various scales, with a tendency toward homogeneity.…”

“…The study also unveiled a five-to-sevenfold increase in the populations of wading birds and shorebirds during the study. Prior research has suggested that diverse feeding requisites can have distinct effects on specific species or foraging guilds [31]. Owing to low winter rainfall [21], extensive zones of shallow marshes (<20 cm) take shape in Caohai, offering abundant nourishment for insectivores, piscivores, and certain omnivorous waterbirds.…”

Aves do Jardim Botânico da Universidade Federal de Juiz de Fora, Minas Gerais, Brasil

“…As espécies aquáticas, em especial, foram estudadas devido ao fato de que durante a implantação do Jardim Botânico o lago e as áreas alagadas foram drenados, ocasionando em uma perda da fauna e flora aquática, o que possibilitou a avaliação da dependência das espécies por essas áreas. Espécies piscívoras podem ter sofrido mais com o impacto da drenagem, pois a fauna de peixes foi removida junto com a água do local, de modo que essas espécies de aves podem não ser observadas por longo período ou sofrer extinção local, embora o manejo direcionado à biodiversidade e outras ações antrópicas possam acarretar consequências positivas e negativas sobre populações de espécies aquáticas herbívoras, insetívoras ou piscívoras (Taft et al, 2002;Zou et al, 2017). Além disso, Donacobius atricapilla (Linnaeus, 1766), um passeriforme insetívoro também associado a ambientes aquáticos, não foi mais observado na área após remoção do taboal que margeava o lago (Manhães, observação pessoal), demonstrando que mesmo intervenções aparentemente pequenas podem afetar a estrutura das comunidades locais.…”

Population Dynamics and Habitat Preferences of Waterbirds across Six Wetlands at Different Geographical Scales

“…These areas act as biological supermarkets, hosting diverse ora and fauna, especially waterbirds (Donatelli et al, 2017). Waterbirds face numerous threats from anthropogenic activities, including habitat loss and degradation due to water abstraction, land transformation for agriculture, human settlements, domestic and industrial pollution, illegal hunting, and climate change (Ma et al, 2009;Galewski and Devictor, 2016;Zou et al, 2017;Rosenberg et al, 2019;Zhang and Ouyang, 2019). As a result, the waterbird species becomes critically endangered (CE), endangered (E), threatened (T), nearly threatened (NT), and vulnerable (V) due to these detrimental factors (Chen et al, 2011;Khan and Arshad, 2014).…”