Nest predation is one of the main factors shaping waterbird abundances, but the impact of different predator species varies considerably between habitats and sites. To identify nest predators and evaluate their spatio-temporal impact on waterbird broods, we carried out a study with artificial nests and camera traps placed in the reedbeds of two eutrophic lakes in northeastern Poland. We also analyzed the importance of two factors for nest survival—water depth at nest site and egg concealment. Artificial nest survival was very low, with only about 8% of the nests surviving more than 10 days. Among the four most frequently recorded nest predators that comprised 95% of all predators filmed, the raccoon dog Nyctereutes procyonoides dominated (51.7% of records), followed by the marsh harrier Circus aeruginosus (24.5%), hooded crow Corvus cornix (12.2%), and American mink Neogale vison (11.6%). The predation rate of the raccoon dog significantly increased over time, being highest in July, and was opposite to that of the marsh harrier, whose nest predation was highest in April and declined over the next months, while the predation rates of the hooded crow and mink were stable. The concealing of eggs did not significantly decrease the probability of depredating nests. Water depth also did not significantly affect nest survival, and only the raccoon dog’s predation rate was negatively related to water depth. Birds depredated nests during the day and mammals both during the day and night; however, activity patterns of four main predators highly overlapped.

巢穴捕食是影响水鸟丰度的主要因素之一，但不同捕食者物种的影响在栖息地和地点之间存在很大差异。为了识别巢穴捕食者并评估它们对水鸟巢穴的时空影响，我们进行了一项研究，在波兰东北部两个富营养化湖泊的芦苇床上放置了人工巢穴和相机陷阱。我们还分析了巢穴生存的两个因素的重要性——巢穴所在地的水深和蛋的隐藏程度。人工巢的存活率很低，只有约8%的巢存活超过10天。在四种最常记录的巢穴捕食者中，占所有拍摄捕食者的 95%，其中貉Nyctereutes procyonoides占主导地位（占记录的 51.7%），其次是沼泽鹞Circus aeruginosus（24.5%）和冠鸦Corvus cornix（12.2%） 、美国水貂Neogale vison (11.6%)。貉的捕食率随着时间的推移显着增加，在 7 月份最高，与沼泽鹞的捕食率相反，沼泽鹞的巢捕食率在 4 月份最高，并在接下来的几个月内下降，而冠鸦和水貂表现稳定。隐藏蛋并没有显着降低巢穴被掠夺的可能性。水深也没有显着影响巢穴的存活，只有貉的捕食率与水深呈负相关。鸟类在白天掠夺巢穴，哺乳动物则在白天和夜间掠食；然而，四种主要捕食者的活动模式高度重叠。