ABSTRACT Research on stoat diet composition in New Zealand has primarily focussed on consumption of indigenous fauna in largely unmodified landscapes. This study used stomach content and stable isotope (δ13C and δ15N) analysis to assess stoat diet in a highly modified agricultural landscape in Southland, New Zealand, focussing on stoat predation of the mallard duck. Stoats were captured in Lochiel, Southland during August–November 2016 and 2017. Stomach content analysis of 26 captured stoats revealed limited stoat predation of mallards (n = 1) and mallard eggs (n = 1). Using liver tissue, stable isotope mixing models suggested that bird eggs on average met between 73 and 85% of stoat metabolic requirements throughout the mallard breeding period. Furthermore, mixing model outputs suggested that bird eggs made up a substantial proportion (77–84%) of stoat assimilated diet early in the mallard breeding period, when mallard eggs are readily available. In contrast, isotope mixing models suggested that mallard ducks/ducklings did not make a large overall contribution to stoat diets (< 3%). This study shows that stoats are an egg predator in the Southland agricultural landscape and mallard eggs may contribute to stoat assimilated diet early in the mallard breeding season before alternative prey items become available.

中文翻译：

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在农业景观中，野鸭是否以白鼬为食？

摘要 新西兰对白鼬饮食成分的研究主要集中在大部分未经改造的景观中对本地动物群的消费。本研究使用胃内容物和稳定同位素（δ13C 和 δ15N）分析来评估新西兰南地高度改造的农业景观中的白鼬饮食，重点是野鸭的白鼬捕食。2016 年 8 月至 11 月和 2017 年 8 月至 11 月期间，在南地的 Lochiel 捕获了白鼬。对捕获的 26 只白鼬的胃含量分析显示，白鼬捕食野鸭（n = 1）和野鸭蛋（n = 1）的情况有限。使用肝脏组织，稳定同位素混合模型表明，在整个野鸭繁殖期间，鸟蛋平均满足了 73% 到 85% 的白鼬代谢需求。此外，混合模型输出表明，在野鸭繁殖早期，当野鸭蛋很容易获得时，鸟蛋占白鼬同化饮食的很大一部分（77-84%）。相比之下，同位素混合模型表明野鸭/小鸭对白鼬饮食的总体贡献不大（< 3%）。这项研究表明，白鼬是南部农业景观中的一种蛋捕食者，而野鸭蛋可能在野鸭繁殖季节早期，在替代猎物出现之前，就有助于白鼬同化饮食。