Feeding activity of cattle egrets and intermediate egrets at different stages of rice culture in Korea

Choi, Yu Seong; Kim, Sun Sook; Yoo, Jeong Chil

doi:10.5141/jefb.2010.33.2.149

Cited by 11 publications

(3 citation statements)

References 24 publications

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“…Therefore, in double cultivation, the rice field does not function as a feeding ground for intermediate egrets in May before irrigation (Fasola et al, 2022;Forti et al, 2021). Intermediate egrets raise their offspring in May and their food demand increases rapidly (Choi et al, 2010). Therefore, rice fields used for double cultivation do not adequately serve as foraging grounds for intermediate japonensis, instead of natural wetlands that have been lost (Choi et al, 2021;Fujioka et al, 2010;Katayama et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, the area under rice cultivation affects the size of the breeding population of herons and egrets (Fasola et al, 2022; Tourenq et al, 2000). Other herons and egrets, such as great egrets and grey herons, move to other habitats like rivers and reservoirs when rice growth in fields is dense, while intermediate egrets continue to hunt for food in and around rice fields by altering the types of food they acquire rather than using other wetlands (Choi et al, 2010). These birds are sensitive to structural changes in rice fields (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Effect of climate change‐induced increases on the range of rice‐barley double cultivation on the intermediate egret

Choi,

Son,

et al. 2023

Journal of Applied Ecology

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Intensification of cultivation methods and land‐use types, particularly in the face of climate change, has steadily weakened the habitat function of rice fields for waterbirds. Intermediate egrets (Ardea intermedia) are highly dependent on rice field habitats. Here, we examine the effect of a shift from rice monoculture to rice–barley double cultivation on the use of rice fields by intermediate egrets in South Korea. Rice–barley double cultivation has been increasing steadily in the southern region of South Korea due to changes in the rice growth period under climate change and maximization of economic benefits. We studied rice fields to determine the effect of the rice–barley double cultivation area on the abundance of intermediate egrets on the regional scale and their potential distribution pattern in response to double cultivation in relation to climate change using national‐scale climate, altitude and land cover data from 1 May to 23 June 2018. Compared to the irrigation practices used for rice monoculture, irrigation was stopped for some time in rice–barley double cultivation prior to planting, compromising the role of rice fields as a food ground for intermediate egrets. The potential abundance of intermediate egrets rapidly decreased by half when the double cultivation area increased to >40% of the total rice‐field area, and was less than one individual if the area increased to >80%. Furthermore, according to climate change projections, by 2100, the double cultivation area would account for 75.74% of the predicted range of intermediate egret foraging ground. Synthesis and applications. Double cultivation areas should be <40% of existing rice fields to minimize the impact of the change in cultivation practices. This approach can also convert rice fields to other types of land use. Consequently, appropriate conservation and management measures may be developed to maintain suitable habitats despite rapidly changing cultivation practices resulting from climate change.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of climate change‐induced increases on the range of rice‐barley double cultivation on the intermediate egret

Choi,

Son,

et al. 2023

Journal of Applied Ecology

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“…Grey Herons, Little Egrets and Black-crowned Night Herons mainly foraged vertebrates such as fishes and frogs, but main diet of Intermediate Egrets was small invertebrates (Choi et al 2010;Shin 2009). Therefore, these different prey items might be associated with different accumulation trends of lead and cadmium.…”

Section: Leadmentioning

confidence: 99%

Tissue Distribution of Heavy Metals in Heron and Egret Chicks from Pyeongtaek, Korea

Kim

2014

Arch Environ Contam Toxicol

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Iron, zinc, manganese, lead and cadmium were measured in the liver, kidney and bone of Grey Heron (Ardea cinerea), Intermediate Egret (Egretta intermedia), Little Egret (Egretta garzetta) and Black-crowned Night Herons (Nycticorax nycticorax) from Korea. Iron, zinc, manganese, lead and cadmium concentrations had species- and tissue- specific accumulation. Lead concentrations in all tissues of Black-crowned Night Heron and cadmium in kidneys of Intermediate Egret chicks were relatively higher than in other species. Iron and manganese in the liver, zinc in the bone, and lead and cadmium in the kidney were relatively higher than other tissues and these results have been reported in other birds. Lead concentrations in all species were at a level associated with acute lead poisoning and cadmium concentrations except for Grey Heron chicks were at a level associated with chronic cadmium exposure. Lead concentrations in livers and bones of heron and egret chicks were within a range considered background level (<6.00 μg/g dw). But, lead concentrations in kidneys of 12 of 37 heron and egret chicks were at concentrations associated with lethal lead poisoning (6.00-18 μg/g dw) and 7 of 37 chicks were compatible with death (>18.0 μg/g dw). For cadmium, all liver and kidney concentrations were at a level considered background for birds (<3.00 μg/g dw). Essential elements such as iron, zinc and manganese concentrations were within the range observed in other birds.

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Effect of the environmental quality and food chain on trace element concentrations in Heron and Egret chicks at Pyeongtaek Colony, Korea

Kim

2014

Ecotoxicology

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Trace element concentrations in the diet can affect the levels in birds. Heron and egret chicks have been recommended as useful biological indicators for monitoring trace element contamination in the aquatic ecosystem. Iron, zinc, manganese, copper, lead and cadmium concentrations were measured in the livers and stomach contents of Grey Heron (Ardea cinerea), Intermediate Egret (Egretta intermedia), Little Egret (Egretta garzetta) and Black-crowned Night Heron (Nycticorax nycticorax) chicks from Pyeongtaek colony, Korea in 2008. Iron, zinc, manganese, copper and cadmium concentrations in livers differed among four heron and egret species. Stomach content concentrations of iron, zinc, copper, lead and cadmium concentrations differed among the four species. Essential elements such as iron, zinc, manganese and copper concentrations were within the range of other heron and egret studies and these levels may be regulated by a normal homeostatic mechanism. Two of 11 (18.2%) Grey Heron and two of 10 (20.0%) Black-crowned Night Heron chicks exceeded the background lead level (<6 µg/g dw) for birds and were at a level considered lead exposed (6-30 µg/g dw). Cadmium concentrations did not exceed the background levels for wild birds. In livers of combined heron and egret chicks, lead, but not cadmium concentrations were associated with concentrations in the stomach contents. These results suggest that lead concentrations in chicks can reflect qualities of feeding area such as streams, rivers and paddy fields and chicks represent a bioindicator to evaluate lead contamination in aquatic ecosystems.

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Feeding activity of cattle egrets and intermediate egrets at different stages of rice culture in Korea

Cited by 11 publications

References 24 publications

Effect of climate change‐induced increases on the range of rice‐barley double cultivation on the intermediate egret

Effect of climate change‐induced increases on the range of rice‐barley double cultivation on the intermediate egret

Tissue Distribution of Heavy Metals in Heron and Egret Chicks from Pyeongtaek, Korea

Effect of the environmental quality and food chain on trace element concentrations in Heron and Egret chicks at Pyeongtaek Colony, Korea

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