The 4th Pan European Duck Symposium was organized in Hanko, the southernmost city in Finland 7.–11.4.2015. The symposium covered subjects widely from duck population dynamics to habitat changes, hunting and management. The following is a short report of a few presentations from the first two days.
Game husbandry manager Jarkko Nurmi from the Finnish Wildlife Agency used his opening words to underline the need for flyway management in duck populations. As he showed, different scales for successful management of the game species exist; e.g. forest grouse can be managed very locally, while ducks need cooperation between countries located on their flyway. Finland is responsible for offering breeding habitats for ducks. A few years ago the Finnish Wildlife Agency set up a project called “The return of rural wetlands”, which was presented by special planner Mikko Alhainen. 44 model wetlands have been established during this EU-funded project, in addition to several others inspired by these models. The wetland construction has been cost-efficient with minimal bureaucracy, and has encouraged landowners to restore their wetlands or establish new ones. The project has been a success in every way and ducks have accepted the man-made wetlands very rapidly.
Associate Professor at Utah State University David Koons, the plenary speaker of the first day, introduced next-generation methods for studying waterfowl population dynamics. By combining bird and location data it may be possible to move smoothly from site-level studies to the flyway and continental levels. Also combining several types of population data it may be possible to reduce analyses bias. As a case study, he showed that splitting scaup data into yearly processes explained by population parameters allows researchers to comprehend that the cause behind population declines is in the disappearing recovery years, while individual parameters haven’t changed as much.
The plenary speaker of the second day, Adjunct Professor in Biology at the University of Saskatchewan Rober Clark, presented the effects of climate change on duck populations. Snow cover in Canada has decreased more than expected by prediction models. Dry seasons will become more common and severe, thus affecting the availability of wetlands, the food webs therein and various competitive interactions. Clark also underlined that wetland dynamics will change in boreal areas due to land use. It seems that late-nesting duck species such as scaups and scoters are most vulnerable to climate change, while early breeders such as common goldeneyes are more tolerant. These patterns are pronounced both in Europe and North America.
Michael Johnson gave an introduction to duck management in North America, especially in the U.S. prairie pothole region. Large changes have occurred, of which some have even accidentally supported duck populations. The increase of grassland cover, wet years and changes in predator communities have raised duck populations to remarkably high levels. However, the grassland area has been disappearing rapidly, which will be reflected in duck populations according to Johnson. He underlined that much of the grasslands and wetlands are unprotected. The numbers of hunters are declining, and thus conservation funding might be difficult to find.
Michel Gendron gave an overview of duck hunting in Canada, where hunter numbers have also decreased. The duck harvest in Canada has recently stabilized after a drop from the 1970s to 2005. Goose hunting has concurrently steadily increased due to the growth of goose populations and liberalization of hunting regulations. The annual National Harvest Surveys in Canada are conducted by 1) questionnaires to find out the hunting activity and harvest of species, and 2) with wing and tail collection to generate information on the age- and sex ratios of the species hunted.
In Russia, the yearly hunting quarry is studied by identifying species and sexes from photographs hunters are asked to send to researchers, as presented by Alexander Solokha. All the species are studied during the autumn hunt, while the mallard bag is also observed during the spring hunt.
The North Atlantic Oscillation (NAO) was addressed in several presentations as an explanation for duck population dynamics. Aleksi Lehikoinen presented the effects of winter and summer NAO on the variation of duck population dynamics in 14 waterbird species. Jukka Rintala showed that the NAO explained a total of 20% of the environmental variance in a group of 11 duck species. The umbrella species, varying with other species, were the garganey and common pochard. Sari Holopainen found that the brood production of the common teal in Finland is varying with the winter NAO index and exceptionally good brood production demands two highly positive NAO winters. The mechanism behind this is believed to be that during high winter NAO index years Finland receives more snow and thus more seasonal ponds are available for the ducks during the breeding season. Wintering numbers of the species were more stochastic, but some carry-over effects can be found. Anthony Fox suggested that wigeon reproduction to also be influenced by the NAO index, but the summer one in this case. Density-dependent processes were additionally found from the wigeon reproduction numbers.
Climate change has affected the migration phenology of common teals in France since the 1950s, as presented by Matthieu Guillemain. Birds arrive earlier and their movements during the winter have been diluted. In addition, the body condition of the wintering ducks has improved. Teals that have once wintered in Camargue seem to be returning the next year. However, as underlined by Guillemain, the hunting mortality in Camargue is high. As the duck turn-over rate is high, the stability of the wintering population is uncertain.
Several duck species have declined in Finland. Especially pronounced is the decline of species living in eutrophic lakes. It might be that vegetation overgrowth is causing the problem. Kim Jaatinen presented the cost efficient analysis of different management actions when working with overgrown wetlands. According to his analyses, cattle grazing is the best tool concerning bird diversity, and because it is also cheap, it was shown to be the most cost-efficient. Cutting and harrowing were also good alternatives, but because they do not produce dung, they are not as beneficial to some bird species as cattle grazing. Dredging was found to be the most expensive tool to control overgrowth. Ilkka Sammalkorpi presented that biomanipulation by removing fish could also be done in wetlands important for ducks.
In addition to freshwater ducks, some sea ducks have also been declining in Finland. Lasse Kurvinen showed dramatic trends of several common eider populations from the Finnish archipelago. Especially large colonies have disappeared. It seems that the colony-specific dynamics are mainly predation driven.
Opposite to Europe, Sidi Imad Cherkaoui told that the wintering numbers and distribution of several species in Morocco have increased during last decade. This is despite wetlands in the country meeting severe problems, such as drainage and urbanization. The ruddy shelduck is one of the species increasing its numbers in Morocco, and also in Netherlands as presented by Sjoerd Dirksen. His studies showed that the moulting populations of the species might be higher in some Central European countries than previously though.
Ducks offer ecosystem services, for instance by supporting connectivity for plants and invertebrates in isolated wetlands. The subject is now much studied, but was presented by Erik Kleyheeg in the symposium. Seeds carried on the bodies of ducks can end up far away from their origin, even hundreds of kilometers during the migration.
The Hanko bird observatory bird station produces a lot of information about migrating ducks. Just 70 kilometers south of the Hanko bird observatory station lays the Estonian bird observatory station Põõsaspea. Margus Ellermaa showed that even with this short distance between the observatories it is enough to create a huge difference between the numbers of migratory ducks due to differing migration paths.
Mallard farming is a big business in Europe and every year 3 million farmed mallards are released into the wild. Considering that the population estimate for mallards in Europe is 7,5 million, the farmed ones compose a huge proportion. Most of the farmed individuals are hunted, and as shown by Jocelyn Champagnon, their survival during the first half a year is low, about half of the wild ones. Still, genetic mixing to the wild population has happened, as presented by Gunnar Gunnarsson. Present day mallards in Europe have wider, shorter and higher bills than the species had prior to large-scale farming. Mallards also show to have “alien genes”: their occurrence is especially pronounced in mallards in the core farming areas in Western Europe, while the trait is rarer in mallards of the remote areas without farming.
Taej Mundkur from Wetlands International presented a study concerning critical habitats for waterbirds in the Arctic region. Based on species-specific habitat requirements the study aims to find the critical habitats of different stages of the species’ life cycles. The long-tailed duck and Steller’s Eider have been used as pilot species. The project should help find new conservation areas and critical areas that are currently under threat.