Passerine bird reproduction does not decline in a highly-contaminated mercury mining district of China

• Published in: Environmental pollution (1987) 2021-10, Vol.286, p.117440-117440, Article 117440
• Main Authors: Su, Tongping, He, Chao, Jiang, Aiwu, Xu, Zhidong, Goodale, Eben, Qiu, Guangle
• Format: Article
• Language: English
• Subjects: Biomagnification; China; Heavy metals; Impacts of mining; Mercury toxicology
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2021.117440

Mercury (Hg) is a neurotoxic element with severe effects on humans and wildlife. Widely distributed by atmospheric deposition, it can also be localized near point sources such as mines. Mercury has been shown to reduce the reproduction of bird populations in field observations in North America and Europe, but studies are needed in Asia, where the majority of emissions now occur. We investigated the reproduction of two passerines, Japanese Tit (Parus minor) and Russet Sparrow (Passer rutilans), in a large-scale Hg mining district, and a non-mining district, both in Guizhou, southwest China. Concentrations of Hg were elevated in the mining district (blood levels of 2.54 ± 2.21 [SD] and 0.71 ± 0.40 μg/g, in adult tits and sparrows, respectively). However, we saw no evidence of decreased breeding there: metrics such as egg volume, nestling weight, hatching and fledgling success, were all similar between the different districts across two breeding seasons. Nor were there correlations at the mining district between Hg levels of adults or juveniles, and hatching or fledgling success, or nestling weight. Nest success was high even in the mining district (tit, 64.0%; sparrow: 83.1%). This lack of reproductive decline may be related to lower blood levels in nestlings (means  3.0 μg/g. Bird reproduction in a highly contaminated Hg mining district did not show a statistically significant reproductive decline across two years compared to a