Projects per year
Alien predators are known to potentially strongly affect their prey populations. We studied the impact of Raccoon Dog (Nyctereutes procyonoides) on waterbird breeding success in semiurban wetlands in Finland. We had eight study wetlands. We manipulated Raccoon Dog density in two wetlands by removing Racoon Dogs (2002 protection year, 2003–2004 removal years). In addition, we performed nest predation experiments. We monitored Raccoon Dog density, estimated hunting bag and observed water bird breeding success. Our hypothesis predicts that the omnivorous Raccoon Dog plays a role in water bird breeding success by depredating nests. Our experiments showed that the Raccoon Dog hunting bag in eutrophic wetlands may be high as we removed 8.6–20.0 animals per km2. Both our nest predation experiment and field data indicated that Raccoon Dogs impact the breeding success of waterbirds. We found a significant relationship between Raccoon Dog density index and predation rate of the artificial nets, but not between Red Fox (Vulpes vulpes) density and predation on artificial nets. We did not find an association between the Raccoon Dog abundance and breeding success of Mallard (Anas platyrhynchos) and Great Crested Grebes (Podiceps cristatus). However, our study show that birds species with different breeding strategies – Great Crested Grebe, Mute Swan (Cygnus olor), Mallard, Eurasian Wigeon (Mareca penelope), Coot (Fulica atra), Lapwing (Vanellus vanellus) and Marsh Harrier (Circus aeruginosus) – when considered together showed higher breeding success both in 2003 and 2004 when compared to the breeding success before removal. There was, however, variation how strongly different species responded to raccoon dog removal Our results indicate that removal of alien Raccoon Dogs can be an important tool in wetland management.
Fields of Science
- 1181 Ecology, evolutionary biology