Abstract
- 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.
- 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.
- 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.
- 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