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- Frank, Jens, et al.
(author)
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Åtgärder – minska viltskadorna
- 2010
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In: Vilt, människa, samhälle. - 9789147094189 ; , s. 285-301
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Book chapter (pop. science, debate, etc.)
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| 4. |
- Gunnarsson, Bengt, 1954, et al.
(author)
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A functional relationship between species richness of spiders and lichens in spruce
- 2004
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In: Biodiversity and Conservation. - 0960-3115. ; 13:4, s. 685-693
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Journal article (peer-reviewed)abstract
- Modern forestry has created stands with even age distribution of trees and fragmentation of the habitat. In boreal forests, the effects on biodiversity within many taxa need to be examined. We tested the hypothesis that species richness of foliose and fruticose lichens and spiders is positively related in the lower canopy of spruce (Picea abies) in forests with, or without, management in central Sweden. High species richness of lichens may increase the structural complexity of the microhabitat on spruce branches, and bring a higher species richness also in the spider community. In six areas, spruce branches were sampled in old-growth and managed boreal forest stands, respectively. Forest management did not affect the species richness of spiders or lichens, but an effect due to sampling area was found in the latter taxon. There was a significant covariation between species richness of lichens and spiders, and the hypothesised positive correlation was confirmed by separate analyses for each area and combining the probabilities. Moreover, regression analysis on mean values from each site revealed a positive relationship. We conclude that species richness of lichens and spiders covary on spruce branches for functional reasons, i.e. more lichen species promotes a more diverse spider community by increasing the structural heterogeneity. Our results might provide a 'shortcut' for assessing biodiversity in boreal forests.
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| 12. |
- Helldin, Jan Olof, et al.
(author)
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Viltet i samhället
- 2010
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In: Vilt, människa, samhälle. - 9789147094189 ; , s. 135-168
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Book chapter (pop. science, debate, etc.)
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| 13. |
- Kalman, Janos L, et al.
(author)
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Investigating polygenic burden in age at disease onset in bipolar disorder: Findings from an international multicentric study.
- 2019
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In: Bipolar disorders. - : Wiley. - 1399-5618 .- 1398-5647. ; 21:1, s. 68-75
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Journal article (peer-reviewed)abstract
- Bipolar disorder (BD) with early disease onset is associated with an unfavorable clinical outcome and constitutes a clinically and biologically homogenous subgroup within the heterogeneous BD spectrum. Previous studies have found an accumulation of early age at onset (AAO) in BD families and have therefore hypothesized that there is a larger genetic contribution to the early-onset cases than to late onset BD. To investigate the genetic background of this subphenotype, we evaluated whether an increased polygenic burden of BD- and schizophrenia (SCZ)-associated risk variants is associated with an earlier AAO in BD patients.A total of 1995 BD type 1 patients from the Consortium of Lithium Genetics (ConLiGen), PsyCourse and Bonn-Mannheim samples were genotyped and their BD and SCZ polygenic risk scores (PRSs) were calculated using the summary statistics of the Psychiatric Genomics Consortium as a training data set. AAO was either separated into onset groups of clinical interest (childhood and adolescence [≤18years] vs adulthood [>18years]) or considered as a continuous measure. The associations between BD- and SCZ-PRSs and AAO were evaluated with regression models.BD- and SCZ-PRSs were not significantly associated with age at disease onset. Results remained the same when analyses were stratified by site of recruitment.The current study is the largest conducted so far to investigate the association between the cumulative BD and SCZ polygenic risk and AAO in BD patients. The reported negative results suggest that such a polygenic influence, if there is any, is not large, and highlight the importance of conducting further, larger scale studies to obtain more information on the genetic architecture of this clinically relevant phenotype.
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| 14. |
- Klaassen, Raymond, et al.
(author)
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Flexibility in daily travel routines causes regional variation in bird migration speed
- 2008
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In: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 1432-0762 .- 0340-5443. ; 62:9, s. 1427-1432
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Journal article (peer-reviewed)abstract
- We used novel Global Positioning System-based satellite telemetry to reconstruct daily time budgets on travelling days of a long-distance migrant, the Osprey Pandion haliaetus, to reveal how landscape affects migratory performance. We compared daily travel routines between the Ospreys' passage of Europe and the Sahara. In Europe, where feeding habitat is abundant, Ospreys fed both before-after flights and during interruptions, thus, combining migration with foraging. This resulted in a 2.7-h shorter daily flight period in Europe than in the Sahara. A calculated energy budget indicated that a 'fly-and-forage migration strategy' is favourable in Europe because associated benefits (energy intake) more than outweigh costs (reduced flight time). The much shorter flight time in Europe was the main explanation why Ospreys covered on average 78 km less distance on a travelling day in Europe than in the Sahara. In addition, there were regional differences in hourly flight speeds that are most probably the result of variation in thermal soaring conditions. We conclude that landscape properties have a profound effect on migration through regional variation in daily routines.
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| 15. |
- Klaassen, Raymond, et al.
(author)
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Geographical and temporal flexibility in the response to crosswinds by migrating raptors.
- 2011
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In: Proceedings of the Royal Society B: Biological Sciences. - : The Royal Society. - 1471-2954 .- 0962-8452. ; 278, s. 1339-1346
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Journal article (peer-reviewed)abstract
- Wind and ocean currents may potentially have important effects on travelling animals, as an animal which does not respond to lateral flow will be drifted from its intended direction of movement. By analysing daily movements of migrating ospreys Pandion haliaetus and marsh harriers Circus aeruginosus, as recorded by satellite telemetry, in relation to global wind data, we showed that these raptors allow on average 47 per cent drift. Furthermore, our analyses revealed significant geographical and temporal variation in the response to crosswinds. During some parts of the migration, the birds drifted and in other parts they compensated or even overcompensated. In some regions, the response of marsh harriers depended on the wind direction. They drifted when the wind came from one side and (over)compensated when the wind came from the opposite side, and this flexible response was different in different geographical regions. These results suggest that migrating raptors modulate their response to crosswinds at different places and times during their travels and show that individual birds use a much more varied repertoire of behavioural responses to wind than hitherto assumed. Our results may also explain why contrasting and variable results have been obtained in previous studies of the effect of wind on bird migration.
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| 16. |
- Klaassen, Raymond, et al.
(author)
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Loop migration in adult marsh harriers Circus aeruginosus, as revealed by satellite telemetry
- 2010
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In: Journal of Avian Biology. - 0908-8857 .- 1600-048X. ; 41:2, s. 200-207
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Journal article (peer-reviewed)abstract
- Loop migration among birds is characterized by the spring route lying consistently west or east of the autumn route. The existence of loops has been explained by general wind conditions or seasonal differences in habitat distribution. Loop migration has predominantly been studied at the population level, for example by analysing ring recoveries. Here we study loop migration of individual marsh harriers Circus aeruginosus tracked by satellite telemetry. We show that despite a generally narrow migration corridor the harriers travelled in a distinct clockwise loop through Africa and southern Europe, following more westerly routes in spring than in autumn. We used the Normalized Difference Vegetation Index (NDVI) to identify potential feeding habitat in Africa. Suitable habitat seemed always more abundant along the western route, both in spring and autumn, and no important stopover site was found along the eastern route. Observed routes did thus not coincide with seasonal variation in habitat availability. However, favourable habitat might be more important during spring migration, when the crossing of the Sahara seems more challenging, and thus habitat availability might play an indirect role in the harriers' route choice. Grid-based wind data were used to reconstruct general wind patterns, and in qualitative agreement with the observed loop marsh harriers predominantly encountered westerly winds in Europe and easterly winds in Africa, both in autumn and in spring. By correlating tail- and crosswinds with forward and perpendicular movement rates, respectively, we show that marsh harriers are partially drifted by wind. Thus, we tentatively conclude that wind rather than habitat seems to have an overriding effect on the shape of the migration routes of marsh harriers. General wind conditions seem to play an important role also in the evolution of narrow migratory loops as demonstrated for individual marsh harriers.
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| 17. |
- Klaassen, Raymond, et al.
(author)
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When and where does mortality occur in migratory birds? Direct evidence from long-term satellite tracking of raptors.
- 2014
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In: Journal of Animal Ecology. - : Wiley. - 1365-2656 .- 0021-8790. ; 83:1, s. 176-184
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Journal article (peer-reviewed)abstract
- Information about when and where animals die is important to understand population regulation. In migratory animals, mortality might occur not only during the stationary periods (e.g. breeding and wintering) but also during the migration seasons. However, the relative importance of population limiting factors during different periods of the year remains poorly understood, and previous studies mainly relied on indirect evidence. Here, we provide direct evidence about when and where migrants die by identifying cases of confirmed and probable deaths in three species of long-distance migratory raptors tracked by satellite telemetry. We show that mortality rate was about six times higher during migration seasons than during stationary periods. However, total mortality was surprisingly similar between periods, which can be explained by the fact that risky migration periods are shorter than safer stationary periods. Nevertheless, more than half of the annual mortality occurred during migration. We also found spatiotemporal patterns in mortality: spring mortality occurred mainly in Africa in association with the crossing of the Sahara desert, while most mortality during autumn took place in Europe. Our results strongly suggest that events during the migration seasons have an important impact on the population dynamics of long-distance migrants. We speculate that mortality during spring migration may account for short-term annual variation in survival and population sizes, while mortality during autumn migration may be more important for long-term population regulation (through density-dependent effects).
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| 22. |
- Månsson, Johan, et al.
(author)
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Territory size and habitat selection of breeding Common Cranes (Grus grus) in a boreal landscape
- 2013
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In: Ornis Fennica. - 0030-5685. ; 90, s. 65-72
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Journal article (peer-reviewed)abstract
- Information on how birds use different types of habitat and move within landscapes is crucial for avian ecology, conservation and management. The Common Crane Grus grus has the widest distribution of all crane species and covers both increasing and decreasing populations. Ecological knowledge is therefore necessary both for conservation and to mitigate bird-human conflicts. We studied territory size and habitat selection of breeding Common Cranes (n=11) at two spatial scales in south-central Sweden by using VHF and UPS transmitters. Breeding families of Cranes were strongly associated with farmlands and wetlands independent of spatial scale. However, 41% of positions were within forested habitats. According to a compositional analysis, moist and wet forests were selected more frequently than dry forests. Territory size was on average 250 ha +/- 47.8 SE. The territories showed little overlap between neighboring breeding pairs. Our study provides information necessary for estimating densities of breeding pairs, but also to indicate habitat types worth special attention by landscape managers and conservationists.
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| 23. |
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| 24. |
- Strandberg, Roine, et al.
(author)
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Complex timing of Marsh Harrier Circus aeruginosus migration due to pre- and post-migratory movements
- 2008
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In: Ardea. - 0373-2266. ; 96:2, s. 159-171
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Journal article (pop. science, debate, etc.)abstract
- We tracked three juvenile and 14 adult Marsh Harriers Circus aeruginosus from southern Sweden via satellite to investigate migration strategies. Four individuals were tracked for at least two years. All three juveniles and four of the adults made west-oriented pre-migratory movements well before the onset of autumn migration, and trans-Saharan migrants visited post-migratory stopover areas in tropical Africa. By these movements, the harriers presumably exploit short-term regional variation in food abundance. Autumn and spring migration occurred in a relatively narrow corridor, without distinct differences between sexes in timing, speed, distance, and duration of migration, except that females tended to migrate faster in spring than did males. Juveniles migrated shorter distances than adults, and migration speeds were lower. Spring migration was similar to autumn migration in terms of speed and duration. Juveniles did not cross the Sahara Desert and three birds, one female and two juveniles, wintered in Europe, which is in accordance with a recent increase in the number of (juvenile) Marsh Harriers wintering in northwestern Europe. All birds that crossed the Sahara wintered in tropical West Africa. Harriers showed site fidelity to breeding, wintering and stopover areas. The overall migration speed of Marsh Harriers was similar to that of Ospreys Pandion haliaetus and Honey Buzzards Pernis apivorus, two other trans-Saharan migrants. Ospreys use fly-and-forage migration to promote resulting speed, whereas Honey Buzzards are particularly apt to exploit thermal soaring. How Marsh Harriers balance foraging versus travelling to accomplish their rapid migration speeds remains to be resolved.
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| 25. |
- Strandberg, Roine, et al.
(author)
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Converging migration routes of Eurasian hobbies Falco subbuteo crossing the African equatorial rain forest.
- 2009
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In: Royal Society of London. Proceedings B. Biological Sciences. - : The Royal Society. - 1471-2954 .- 0962-8452. ; 276:1657, s. 727-733
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Journal article (peer-reviewed)abstract
- Autumn migration of adult Eurasian hobbies Falco subbuteo from Europe to southern Africa was recorded by satellite telemetry and observed routes were compared with randomly simulated routes. Two non-random features of observed routes were revealed: (i) shifts to more westerly longitudes than straight paths to destinations and (ii) strong route convergence towards a restricted area close to the equator (1 degrees S, 15 degrees E). The birds migrated south or southwest to approximately 10 degrees N, where they changed to south-easterly courses. The maximal spread between routes at 10 degrees N (2134km) rapidly decreased to a minimum (67km) close to the equator. We found a striking relationship between the route convergence and the distribution of continuous rainforest, suggesting that hobbies minimize flight distance across the forest, concentrating in a corridor where habitat may be more suitable for travelling and foraging. With rainforest forming a possible ecological barrier, many migrants may cross the equator either at 15 degrees E, similar to the hobbies, or at 30-40 degrees E, east of the rainforest where large-scale migration is well documented. Much remains to be understood about the role of the rainforest for the evolution and future of the trans-equatorial Palaearctic-African bird migration systems.
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