Large-scale changes in marine and terrestrial environments drive the population dynamics of long-tailed ducks breeding in Siberia

Abstract

Migratory animals experience very different environmental conditions at different times of the year, i.e., at the breeding grounds, during migration, and in winter. The long-tailed duck Clangula hyemalis breeds in the Arctic regions of the northern hemisphere and migrates to temperate climate zones, where it winters in marine environments. The breeding success of the long-tailed duck is affected by the abundances of predators and their main prey species, lemmings Lemmus sibiricus and Dicrostonyx torquatus, whose population fluctuation is subject to climate change. In the winter quarters, long-tailed ducks mainly eat the blue mussel Mytilus edulis. We examined how North-west Siberian lemming dynamics, assumed as a proxy for predation pressure, affect long-tailed duck breeding success and how nutrient availability in the Baltic Sea influences long-tailed duck population size via mussel biomass and quality. Evidence suggests that the long-tailed duck population dynamics was predator-driven on the breeding grounds and resource-driven on the wintering grounds. Nutrients from fertilizer runoff from farmland stimulate mussel stocks and quality, supporting high long-tailed duck population sizes. The applied hierarchical analysis combining several trophic levels can be used for evaluating large-scale environmental factors that affect the population dynamics and abundance of migrants from one environment to another.

Climate and de-eutrophication affect abundance of benthos-feeding waterbirds in the Wadden Sea during stop-over

“…We used indirect information of habitat quality, such as amount of nutrients, geomorphology and climate, which have effects on the amount of food, feeding conditions and reproduction of birds. In the marine environment, nutrients such as nitrogen and phosphorus stimulate growth of phytoplankton, zooplankton, macrozoobenthos, sh and birds (Nielsen and Richardson 1996;Stottrup et al 2017;Nixon and Buckley 2002;Rintala et al 2022). The amount of riverine nutrients in the marine environments increased in Western Europe during the 1960s and 1970s, but massive efforts to purify huge amounts of waste water from cities and regulate the use of fertilizer by farmers reduced nutrient loads discharged into the marine environment after the 1980s (Riemann et al 2016).…”

Delayed dichromatism in waterfowl as a convenient tool for assessing vital rates

“…It is also crucial for measuring the effectiveness of management actions that are taken to restore, control, or eradicate populations (Shea & NCEAS Working Group on Population Management, 1998). Among the approaches available to managers to achieve these goals, those that rely on monitoring the number of individuals (counts) are by far the most popular (Rintala et al, 2022). In many cases, these methods allow the investigation of environmental factors underlying changes in population size, and thus help in the implementation of mitigating actions (Faillettaz et al, 2019).…”

Age and sex ratios of wintering Long-tailed Ducks Clangula hyemalis can be determined by analysis of photos of flying flocks at sea: A method description

“…The observed population decline of the Long-tailed Duck may also be partly caused by environmental factors at the Arctic breeding grounds. Fading lemming cycles, increased predation pressure, and factors related to climate change have been reported to negatively affect the reproductive success of several Arctic breeding waterbirds (Hario et al 2009, Nolet et al 2013, Aharon-Rotman et al 2015, Rintala et al 2022. To be able to establish effective management actions to stop the decline of the West Siberian / North European population of Long-tailed Ducks more detailed information about demographic parameters is needed.…”