Sari Holopainen

and 4 more

1. Wetlands belong to the globally most threatened habitats, and organisms depending on them are of conservation concern. Wetland destruction and quality loss may affect negatively also boreal breeding ducks in which habitat selection often needs balancing between important determinants of habitat suitability. In Finland duck population trajectories are habitat-specific, while the reasons behind are not known. 2. In this research, the balance of nest predation risk and invertebrate food abundance in boreal breeding ducks was studied in Finland at 45 lakes and ponds in 2017 and 2018. Nest predation experiments were conducted with artificial nests followed by wildlife cameras during seven days. Invertebrates were sampled from the study water bodies using emergence and activity traps. Duck pairs and broods were also surveyed from these and 18 additional water bodies. 3. The wildlife camera results indicate that predation risk was higher in the water bodies surrounded by agricultural land than forestland. Ponds (seasonal, beaver and man-made) had lower nest predation risk and they were also more invertebrate-rich habitats than permanent lakes. In addition, artificial nests further away from water bodies had higher survival than shoreline nests. Habitat use of duck pairs (prior to nesting) was not associated with invertebrate food, but duck broods preferred habitats rich in food. 4. High nest predation pressure in shorelines of especially agricultural landscapes may contribute the declining population trends of ducks in Finland. Controlling predators would be an important conservation action to improve duck breeding success. This research underlines the benefits of the availability of different water body types for the breeding ducks. There is an urgent need to pay attention to protecting seasonal ponds, while the lack of flooded waters may be mitigated by favouring beavers or man-made ponds.