Trends and population dynamics of a Velvet Scoter (Melanitta fusca) population: influence of density dependence and winter climate

Abstract

30 31As many seaduck populations around the world have been reported to decline 32 there is an increasing demand for knowledge about intrinsic and extrinsic 33 factors determining population dynamics of these species. 34In this study we analyzed long term dynamics of the summer population of 35 velvet scoters (Melanitta fusca) breeding in the Åland archipelago in the 36 Baltic Sea; in particular, we examined the influence of winter weather and 37 density dependence on population change. The studied population exhibited 38 substantial fluctuations but only a weak negative trend during the total period 39 of 58 years and no significant trend at all during the latter three 40 decades of the study . We tested for density dependence and 41 incorporated winter NAO-index into the model to test for effects of winter 42 conditions. Our final model explained 56.3% of the variance of population 43 growth of the studied population. Delayed density dependence explained 44 29.7%, pre-breeding climate 8.3% and post-breeding climate 18.3% of the 45 variance. That breeding success is density dependent in a delayed manner is 46 in accordance with the apprehension that velvet scoters breed at the age of 47 two years. We conclude that density dependence and winter conditions must 48 be taken into consideration when discussing population changes in seaducks 49 in general and velvet scoter in particular. 50 51 52

Population abundance and trends of Saltmarsh (Ammodramus caudacutus) and Nelson’s (A. nelsoni) Sparrows: influence of sea levels and precipitation

“…For this region, the climate is projected to become progressively warmer and wetter, but also more variable, with an increase in both warm and wet extremes over the next several decades (Thibeault and Seth 2014). Extreme or adverse weather has been shown to interrupt breeding (Mearns and Newton 1988;Olsen and Olsen 1989) and can regulate populations (Hartman et al 2013). Variation in precipitation can help explain changes in annual fecundity and can have significant effects on population growth (Johnson and Geupel 1996).…”

Trends and drivers of change in diving ducks

“…Data from the Åland Islands are not included here, the most recent estimates indicate no real trend (Hartman et al 2013). …”

Density dependence and marine bird populations: are wind farm assessments precautionary?

“…The amount of error was selected from a uniform distribution bounded between 0% and 25% and applied to the population size at the previous time step. The upper bound of the error distribution was the highest value reported by the metaanalysis studies (Hartman et al 2013). This was considerably larger than the error reported in other studies, e.g.…”

“…The upper bound of the error distribution was the highest value reported by the meta‐analysis studies (Hartman et al . ). This was considerably larger than the error reported in other studies, e.g.…”