The Korea Institute of Ornithology and Department of Biology, Kyung Hee University, Seoul 130-701, Republic of Korea.
National Institute of Biological Resources, Incheon 22689, Republic of Korea.
Zoolog Sci. 2021 Apr;38(2):162-169. doi: 10.2108/zs200079.
Pesticide use is known to have a negative impact on the habitat use of birds. The decomposition of residual pesticides causes a drastic decrease in the biomass of wildlife food sources, indirectly affecting the ecosystem. In this study, we investigated the effects of pesticide use on the distributions of grey herons () and great egrets () in rice fields in the Republic of Korea. From early May to mid-June in 2015 and 2016, we recorded the abundance of these birds and their prey (loaches, other fish, tadpoles, and benthic invertebrates) and investigated their dependence on rice agricultural practices (eco-friendly vs conventional) and field types (harrowed, plowed, or transplanted). We found that both grey herons and great egrets preferentially used transplanted fields. Grey herons were observed more in conventional rice fields, while great egrets were observed more in eco-friendly rice fields. This may be driven by the distribution of their preferred prey types; we observed a higher density of tadpoles (the prey type favored by grey herons) in conventional fields and a higher density of loaches (the preferred prey of great egrets) in eco-friendly fields. Pesticides drive these patterns both directly and indirectly; pesticide use in conventional rice fields directly suppresses the abundance of loaches, which frees the tadpole population from predation pressures and indirectly boosts their abundance in conventional rice fields. Our findings suggest that the distributions of grey herons and great egrets vary depending on food availability and are directly and indirectly influenced by pesticide use.
农药的使用已知会对鸟类的栖息地利用产生负面影响。残留农药的分解导致野生动物食物源的生物量急剧减少，间接影响了生态系统。在这项研究中，我们调查了农药使用对韩国稻田中苍鹭（）和大白鹭（）分布的影响。在 2015 年和 2016 年的 5 月初至 6 月中旬，我们记录了这些鸟类及其猎物（泥鳅、其他鱼类、蝌蚪和底栖无脊椎动物）的数量，并调查了它们对水稻农业实践（环保型与传统型）和田间类型（耙地、耕犁或移栽）的依赖程度。我们发现苍鹭和大白鹭都优先选择移栽田。苍鹭在传统稻田中更常见，而大白鹭在环保稻田中更常见。这可能是由它们偏好的猎物类型的分布驱动的；我们在传统田间观察到更多的蝌蚪（苍鹭的首选猎物），而在环保田间观察到更多的泥鳅（大白鹭的首选猎物）。农药直接和间接导致了这些模式；传统稻田中农药的使用直接抑制了泥鳅的数量，从而使蝌蚪种群免受捕食压力的影响，并间接地增加了它们在传统稻田中的数量。我们的研究结果表明，苍鹭和大白鹭的分布取决于食物的可获得性，并且受到农药使用的直接和间接影响。
