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- Nilsson, Leif, et al.
(författare)
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Satellite tracking of Bean Geese Anser fabalis fabalis and A. f. rossicus from spring staging areas in northern Sweden to breeding and moulting areas.
- 2010
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Ingår i: Ornis Svecica. - 1102-6812. ; 20, s. 184-189
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Tidskriftsartikel (refereegranskat)abstract
- In order to determine their breeding and moulting siteswe fitted eight Taiga Bean Geese Anser fabalis fabalisand two Tundra Bean Geese A. f. rossicus with satellitetransmitters in 2007–2009 at their spring roosting sitesat Umeå and Luleå, Sweden. Nine of these transmitterstransferred GPS positions for 1–4 months. All positionswere N–ENE of the catching sites. The Tundra BeanGeese migrated to Finnmark in Norway and neighbouringparts of Finland. The Taiga Bean Geese migratedto sites near Övre Soppero (Sweden) and Kautokeino(Norway) in the west, through northern Finland, to RussianKarelia. Three of five Taiga Bean Geese with activetransmitters flew to Novaya Zemlya to moult. Our resultsindicate that a significant proportion of the Taiga BeanGeese that migrate along the coast of northern Swedenin spring do not breed west of 20° E, and that many ofthem moult on Novaya Zemlya. The Tundra Bean Geesethat pass through northern Sweden in spring belong tothe Finnmark population that breeds slightly north of theTaiga Bean Geese.
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- Pöysä, Hannu, et al.
(författare)
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Habitat associations and habitat change : seeking explanation for population decline in breeding Eurasian wigeon Anas penelope
- 2017
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Ingår i: Hydrobiologia. - : Springer Netherlands. - 0018-8158 .- 1573-5117. ; 785:1, s. 207-217
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Tidskriftsartikel (refereegranskat)abstract
- We explored whether the recent large-scale population decline of Eurasian wigeon (Anas penelope) in Europe may be linked to long-term vegetation changes in their boreal breeding wetlands. First, we assessed the importance of Equisetum, Phragmites, and Carex stands in lake selection by pairs and in foraging habitat selection by broods. Second, in 2013–2014 we revisited 58 lakes in Sweden and Finland studied in 1990–1991, to examine if there had been any long-term change in the abundance of habitat types preferred by wigeon. Finally, using continuous long-term data on breeding numbers of wigeon in 18 of the lakes studied in 1990–1991, we examined if wigeon numbers had changed at lakes where the habitat also had changed. We found that lake occupation of nesting wigeon pairs and foraging habitat use of broods were associated with the extent of Equisetum stands. The presence and abundance of this preferred habitat declined dramatically from 1990–1991 to 2013–2014 in the lakes from which the presence–absence data of wigeon emanate. Breeding numbers of wigeon showed a long-term declining trend in lakes where Equisetum has decreased. Our results imply that the recent population decline of wigeon in Europe may be linked to decrease of Equisetum habitat.
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- Pöysä, Hannu, et al.
(författare)
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Recovering Whooper Swans do not cause a decline in Eurasian Wigeon via their grazing impact on habitat
- 2018
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Ingår i: Journal of Ornithology. - : Springer Nature. - 0021-8375 .- 1439-0361 .- 2193-7192 .- 2193-7206. ; 159:2, s. 447-455
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Tidskriftsartikel (refereegranskat)abstract
- The Whooper Swan (Cygnus cygnus) is a good example of successful conservation, with rapidly growing numbers in Fennoscandia in recent decades. To the contrary, Eurasian Wigeon (Mareca penelope) shows a strong negative trend in breeding numbers, which raises conservation concerns. Previous research suggests a causal link between recent population trajectories of the two species. Both preferentially breed on wetlands with abundant horsetail (Equisetum spp.), a plant providing food for Whooper Swan and crucial feeding microhabitat for Eurasian Wigeon broods. We here test predictions based on the hypothesis that grazing on Equisetum by Whooper Swan reduces breeding habitat or breeding habitat quality for Eurasian Wigeon. We use data from 60 lakes in which waterfowl were counted in 1990–1991 and 2016, and Equisetum was mapped in 1990–1991 and 2013–2014. Lakes colonized by Whooper Swan typically had more abundant Equisetum vegetation in the past than lakes not colonized. Lake-specific decrease of Equisetum was not associated with colonization by Whooper Swan. The number of lakes occupied by Eurasian Wigeon decreased, but the decrease was not stronger on lakes colonized by Whooper Swan than on those that were not. Contrary to our prediction, current Eurasian Wigeon abundance was positively associated with Whooper Swan abundance. Moreover, Eurasian Wigeon did not decrease more on lakes from which Equisetum disappeared than on lakes in which there was still Equisetum left. This study does not support the idea that Whooper Swan affects Eurasian Wigeon negatively by grazing on Equisetum.
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- Sjöberg, Kjell, 1942-
(författare)
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Temporal relationships between fish-eating birds and their prey in a north Swedish river
- 1987
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The seasonal and diel feeding habits of the goosander, Mergus merganser, the red-breasted merganser, M. serrator, gulls (Larus canus, L. argentatus and L. fuscusj and terns, Sterna hirundo/paradisaea were studied at 64V05'N. Birds' activity patterns were influenced by the nocturnal spawning of the river lamprey (Lampetra fluviatilis). Food selection and food consumption by hand-raised mergansers together with aquarium studies of the diel activity patterns of their most important prey supplemented the field data. River lamprey dominated the diet of the goosander by weight and the sculpin Cottus gobio by number. The fish consumption of the goosanders was found to be about 12% of the available river lamprey biomass and about 17% of the sculpin biomass during the breeding season.In experimental situations the river lamprey was a low- pritority species compared with salmon , Salmo salar, brown trout, 53. trutta, and minnow, Phoxinus phoxinus, when presented to satiated birds of both Mergus species. When hungry, however, the birds caught the available prey irrespective of species, but they selected larger prey when two size classes were present. Experimental results were compared with field data on availability, consumption and the escape behaviour of the various fish species.The rivers emptying in the Bothnian Bay are regarded as important feeding areas for birds breeding along the coast. In early spring they get access to abundant and reliable food resources, e.g the river lamprey. Later on the three-spined stickleback, Gasterosteus aculeatus, supply both Mergus species with food in the river and also along the coast. From the middle of June potential food supply available to birds decreases in the rivers and becomes more abundant in the coastal area.
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- Thurfjell, Henrik, et al.
(författare)
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Habitat use and spatial patterns of wild boar Sus scrofa (L.): agricultural fields and edges
- 2009
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Ingår i: European Journal of Wildlife Research. - : Springer Science and Business Media LLC. - 1612-4642 .- 1439-0574. ; 55, s. 517-523
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Tidskriftsartikel (refereegranskat)abstract
- Rapidly increasing populations of wild boar in Sweden and Europe cause much damage to crops, and there is a critical need for more knowledge about their habitat utilization, especially of agricultural fields. In our study, we first assess the spatial pattern of damage in relation to the edges of agricultural fields. Next, with the aid of global positioning system collars, we studied the pattern of movement of wild boar on agricultural fields. Finally, in order to understand the role of agricultural fields, we studied how habitat selection may vary throughout the year. We found edge effects on damage patterns in agricultural fields. During winter and spring, we found wild boar not only to follow edges, but also to move along narrow landscape elements within agricultural fields. In our habitat analysis, we found strong avoidance of exposed agricultural fields throughout the year, but significantly less when crops are ripe.
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