Browsing by Subject "EUROPEAN BIRDS"

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  • Meller, Kalle; Vahatalo, Anssi V.; Hokkanen, Tatu; Rintala, Jukka; Piha, Markus; Lehikoinen, Aleksi (2016)
    Partial migration - a part of a population migrates and another part stays resident year-round on the breeding site - is probably the most common type of migration in the animal kingdom, yet it has only lately garnered more attention. Theoretical studies indicate that in partially migratory populations, the proportion of resident individuals (PoR) should increase in high latitudes in response to the warming climate, but empirical evidence exists for few species. We provide the first comprehensive overview of the environmental factors affecting PoR and the long-term trends in PoR by studying 27 common partially migratory bird species in Finland. The annual PoR values were calculated by dividing the winter bird abundance by the preceding breeding abundance. First, we analysed whether early-winter temperature, winter temperature year before or the abundance of tree seeds just before overwintering explains the interannual variation in PoR. Secondly, we analysed the trends in PoR between 1987 and 2011. Early-winter temperature explained the interannual variation in PoR in the waterbirds (waterfowl and gulls), most likely because the temperature affects the ice conditions and thereby the feeding opportunities for the waterbirds. In terrestrial species, the abundance of seeds was the best explanatory variable. Previous winter's temperature did not explain PoR in any species, and thus, we conclude that the variation in food availability caused the interannual variation in PoR. During the study period, PoR increased in waterbirds, but did not change in terrestrial birds. Partially migratory species living in physically contrasting habitats can differ in their annual and long-term population-level behavioural responses to warming climate, possibly because warm winter temperatures reduce ice cover and improve the feeding possibilities of waterbirds but do not directly regulate the food availability for terrestrial birds.
  • Potvin, Dominique A.; Pavon-Jordan, Diego; Lehikoinen, Aleksi (2017)
    In recent years, ringing recovery records in Europe have been identified as a potential important source of data for assessing the impact of climate change and other long-term changes on wintering population distributions of migrating birds. As with any voluntarily-gathered data, however, there are clear sources of bias that might impact results if researchers are not selective. Conversely, methods that exclude data should not be universally applied without proper assessment of their impact on final results. We examine the specific and seemingly conventional method of excluding data collected from hunted or intentionally killed individuals in studies of winter distributions of migrating European birds, to evaluate whether the exclusion or inclusion of this data does indeed affect the outcome of the analysis. We find that the exclusion of these data is warranted for many species, however may impact the power of statistical analyses unjustifiably for others. Our findings showed that wintering range sizes of species are similar when using data of killed or non-killed birds, although there may be latitudinal differences. Furthermore, we did not find evidence that wintering ranges of investigated 37 species would have moved northwards in general as would have been expected due to climate change. We suggest that rather than a universally-applied method of exclusion, these contributed data should be analyzed in context of the hunting history of the species in question and the time frame being considered, and give guidelines on how to most efficiently utilize this important data resource.
  • Gamero, Anna; Brotons, Lluis; Brunner, Ariel; Foppen, Ruud; Fornasari, Lorenzo; Gregory, Richard D.; Herrando, Sergi; Horak, David; Jiguet, Frederic; Kmecl, Primoz; Lehikoinen, Aleksi; Lindstrom, Ake; Paquet, Jean-Yves; Reif, Jiri; Sirkiä, Päivi M.; Skorpilova, Jana; van Strien, Arco; Szep, Tibor; Telensky, Tomas; Teufelbauer, Norbert; Trautmann, Sven; van Turnhout, Chris A. M.; Vermouzek, Zdenek; Vikstrom, Thomas; Vorisek, Petr (2017)
    Maximizing the area under biodiversity-related conservation measures is a main target of the European Union (EU) Biodiversity Strategy to 2020. We analyzed whether agrienvironmental schemes (AES) within EU common agricultural policy, special protected areas for birds (SPAs), and Annex I designation within EU Birds Directive had an effect on bird population changes using monitoring data from 39 farmland bird species from 1981 to 2012 at EU scale. Populations of resident and short-distance migrants were larger with increasing SPAs and AES coverage, while Annex I species had higher population growth rates with increasing SPAs, indicating that SPAs may contribute to the protection of mainly target species and species spending most of their life cycle in the EU. Because farmland birds are in decline and the negative relationship of agricultural intensification with their population growth rates was evident during the implementation of AES and SPAs, EU policies seem to generally attenuate the declines of farmland bird populations, but not to reverse them.