Ducks and geese can be seen in huge flocks and high densities in the temperate zone during the winter. Both are also heavily hunted in their wintering areas. But during the summer, many of the ducks and geese head far north, to the taiga and tundra, to breed in very low densities. They spread out into the millions of wetlands located at high latitudes. Ducklings are reared in barren wetlands, where food limits their survival.
Ducks that breed far, far away in north
Boreal wetlands are the main breeding areas for several European duck species. Without Russian breeders, over 90% of the common teals and common goldeneyes breed in boreal area covering Finland, Norway and Sweden. In addition, more than half of the European goosanders, red-breasted mergansers, pintails, wigeons and tufted ducks breed in these three countries.
Large share of the ducks hunted in western and southern Europe is thus originated from the boreal wetlands. Guillemain et al. (2014) conducted an isotope research of the teals hunted in France during the winter. These small ducks turned out to spend their summers mainly in the area reaching from Finland to Siberia. Teals are thus mainly produced in the boreal biome, but most of them are hunted in the temperate zone. Such source – harvest area – knowledge is not concerned in the European duck management, but in North America the process is better known, and work as a tool of the adaptive harvest management.
Changing boreal wetlands
It is expected that climate change will affect the wetlands, especially in the boreal biome, where the warming is rapid (IPCC). Alaskan wetlands are currently becoming smaller and their quality from the biodiversity and productivity perspective is declining. Some areas in Russia are expected to suffer drought while some should get more precipitation. How these changes affect the biota of the wetlands, especially concerning seasonal wetlands, is poorly known. In addition to the direct changes in the wetland habitats, the changing phenology of the spring due to climate warming might cause a miss-match phenomenon with ducks and their invertebrate food. Invertebrate availability is especially important for the females before egg-laying and for the young ducklings. If the phenology of ducks and invertebrates differs, it might have a negative effect to the ducks breeding success. However, an increasing temperatures might compensate the lack of food to some extent.
The numbers of wintering ducks in the boreal are increasing due to a milder winter climate. Several species that were scarcely wintering in Finland some decades ago are now common and numerous. Correspondingly their numbers in their old wintering sites have decreased. Some migratory species might not reach their old wintering areas anymore; a phenomenon that has been observed for instance in the UK. This shift in wintering areas will affect the quarries of the species in question.