Abstract
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.