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.
Cover letter
Dear Editors,
we submit the MS “Balancing between predation risk and food by boreal breeding ducks” for publication in the special issue of Ecology and Evolution “Ecological Insights from Camera Trapping”.
We studied the effects of wetland quality for boreal breeding ducks from the two important aspects: predation and food. We used wildlife cameras for reliable nest predator identification around different breeding habitats of ducks. Interestingly, we did find that duck food availability is low and nest predation pressure is high at permanent lakes, while ponds (seasonal, beaver, man-made) were shown to be food rich habitats with low nest predation pressure. However, ponds are commonly not protected and for example seasonal ponds are typically drained for farmland or to improve forest grow. Our results emphasize the benefits of different wetland types in the landscape for the breeding ducks. Even important bird lakes might have high predation pressure, which underlines the need of predator control, especially concerning alien species. We think that our manuscript is timely and offer much needed information about conservation of wetland ecosystems from aspects that are so far poorly covered. Wildlife cameras turned out really useful method for identifying different predator species, even they took the eggs without leaving any clues behind.
Sincerely, on behalf of the authors,
Sari Holopainen