| 1. |
- Dahle, B., et al.
(author)
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Predation on adult moose Alces alces by European brown bears Ursus arctos
- 2013
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In: Wildlife Biology. - : Wiley. - 0909-6396 .- 1903-220X. ; 19:2, s. 165-169
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Journal article (peer-reviewed)abstract
- Several North American studies have reported significant predation rates on moose Alces alces by brown bears Ursus arctos. We documented predation on moose by brown bears in south-central Sweden, where brown bears and moose occurred at estimated densities of 10-30 and 400-1,340/1,000 km(2), respectively. Bears killed 0.8% of radio-collared adult female moose (i.e. >= 1 year old) annually and no male moose (>= 1 year old). Bear predation was the least important mortality factor we documented. Based on tracking brown bears on snow during spring we recorded one successful hunt for every 372 km of tracks and documented attacks only by adult bears and successful attacks only by adult males. Autopsy of moose older than calves that were killed by brown bears revealed that yearlings were more prone to predation than older moose, and that older (i.e. >= 2 years) cows were more vulnerable to predation than older bulls. Our study suggests a lower tendency for Scandinavian brown bears to prey on moose compared to most of the North American studies.
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| 2. |
- Gatali, Callixte, et al.
(author)
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Bird diversity in the savanna habitats of Akagera National Park, Rwanda, in the post-war recovery period
- 2015
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In: Ostrich. - : National Inquiry Services Center (NISC). - 0030-6525 .- 1727-947X. ; 86:3, s. 267-276
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Journal article (peer-reviewed)abstract
- The biodiversity of Akagera National Park (ANP), Rwanda, has reportedly been declining since 1990 due to conflict and war in the country between 1990 and 1994. In this paper, we describe bird diversity in the post-war recovery period. We used systematic plots, point counts and presence-absence surveys to estimate bird species richness and diversity in acacia savanna habitats of the park between 2009 and 2011. We recorded a total number of 301 species, of which 75% were resident and 22% migrant, including a large number of Palearctic visitors and Afrotropical migrants. Particularly notable were four endemic species of the Lake Victoria region, four globally threatened and nine near-threatened species as well as species that had not previously been recorded in the park and those overlooked by past records. Estimated species richness and diversity at the landscape level were 346 and 0.98, respectively, mean estimates per plot were 42 and 0.86 for species richness and diversity, respectively. Our results highlight regional and international importance of ANP in protecting important bird diversity. We also emphasise that ANP is the only savanna habitat in Rwanda where typical savanna birds occur. Our findings provide new insights for further strengthening of efforts to conserve the park's biodiversity.
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| 3. |
- Gunnarsson, Bengt, 1954, et al.
(author)
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Variable female mating positions and offspring sex ratio in the spider Pityohyphantes phrygianus (Araneae : linyphiidae)
- 2004
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In: Journal of Insect Behavior. - 0892-7553. ; 17:1, s. 129-144
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Journal article (peer-reviewed)abstract
- Chromosomal sex determination and male heterogamety have been thought to seriously impede direct sex ratio control. However, in Pityohyphantes phrygianus, a solitary sheetweb spider with a skewed sex ratio, earlier experimental studies suggested that there are options for female control of offspring sex ratio, if females change their position during the normal mating sequence. Here we show that under natural conditions there is considerable between-female variation in positions, especially after termination of mating. Computer simulations of the orientation of female inner genitalia suggest that sperm are placed in different storage sites depending on the positions adopted. This means that a specific position after mating might potentially influence offspring sex ratio. The variance in offspring sex ratio among females in earlier experiments was binomially distributed, which leads us to conclude that females control the mean sex ratio but do not exercise direct control of the sex of individual offspring.
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| 4. |
- Neumann, Wiebke, et al.
(author)
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Divergence in parturition timing and vegetation onset in a large herbivore-differences along a latitudinal gradient
- 2020
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In: Biology Letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 16:6
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Journal article (peer-reviewed)abstract
- In northern environments, the period of access to high-quality forage is limited, exerting strong selective pressure to optimize the timing of parturition. We analysed timing and variation in moose (Alces alces) parturition dates of 555 females at 18 study sites across 12 degrees of latitude (56-68 degrees N, 1350 km) in Sweden. We found evidence for a spatial match of parturition timing to vegetation onset, but no evidence that moose adjust parturition to vegetation onset in a given year. We found a breakpoint at 64 degrees N. Despite adaptation across latitudes, temporal divergences occurred. Females below 64 degrees N calved after vegetation onset and females above 64 degrees N calved before. Here, parturition before vegetation onset might be a strategy to optimize forage utilization time with the very short growing season. Highly seasonal environments such as at higher latitudes may make it advantageous to adapt parturition towards long-term climatic patterns by matching the most favourable period. Given the direction of temporal divergence, our study suggests that climate change may have less of an impact on moose parturition at northern latitudes than southern latitudes.
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| 5. |
- Nordén, Björn, 1965, et al.
(author)
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Indicators of biodiversity, what do they indicate? Lessons for conservation of cryptogams in oak-rich forest
- 2007
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In: Biological Conservation. - : Elsevier BV. - 0006-3207. ; 135:3, s. 369-379
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Journal article (peer-reviewed)abstract
- In the Nordic countries, sets of Indicator (Signal) species, predominantly cryptogams, have been used as one measure to find forest stands which may harbour Red List species. Such data could potentially also be used to prioritise among stands for protection as nature reserves. We studied if the number of Signal species indicates the number of Red List species in oak-rich mixed forest in south Sweden. We also explored if species richness of the investigated groups is correlated with the number of Red List or Signal species. In 25 stands, we surveyed epiphytic and epixylic bryophytes and lichens, ground-floor bryophytes, and wood-living fungi. We studied correlations for two datasets; (1) all forest species and (2) deciduous forest specialists. When relating the number of Signal species to the number of Red List species for each taxon and in total, a significant correlation was found for temperate deciduous forest lichens. The number of Signal species was further significantly correlated to total species richness for lichens (all forest species) and for wood-living fungi (both datasets). The number of Red List lichens was correlated to total lichen richness (deciduous forest species). Signal species seem not to be unequivocal in prioritising potential reserves among valuable oak-rich woodlands and surveys by Red List species experts may be needed. Signal species may be more useful for finding relatively valuable sites in a matrix of production forest. Moreover, Signal species seem to be useful surrogates for total cryptogam species richness.
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| 6. |
- Nyberg, Jenny, 1976, et al.
(author)
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Cardiovascular and cognitive fitness at age 18 and risk of early-onset dementia.
- 2014
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In: Brain : a journal of neurology. - : Oxford University Press (OUP). - 1460-2156. ; 137:Pt 5, s. 1514-23
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Journal article (peer-reviewed)abstract
- Patients with early-onset dementia are a significantly under-recognized subgroup of patients with an increasing prevalence. Epidemiological studies are limited and studies of modifiable risk factors, such as physical fitness, are lacking. We aimed to investigate the associations between cardiovascular fitness individually and in combination with cognitive performance at age 18 and risk of early-onset dementia and mild cognitive impairment later in life. We performed a population-based cohort study of over 1.1 million Swedish, 18-year-old, male conscripts, who underwent conscription exams between 1968 and 2005. These males were then followed for up to 42 years. Objective data on cardiovascular fitness and cognitive performance were collected during conscription exams and were subsequently linked with hospital registries to calculate later risk of early-onset dementia and mild cognitive impairment using Cox proportional hazards models controlling for several confounders. The scores from the exams were divided into tertiles (low, medium, high) for the analyses. The mean follow-up time for the analyses was 25.7 years (standard deviation: 9.3) and the median was 27 years. In total, 30 195 315 person-years of follow-up were included in the study. In fully adjusted models, both low cardiovascular fitness and cognitive performance (compared to high) at age 18 were associated with increased risk for future early-onset dementia (cardiovascular fitness, n = 662 events: hazard ratio 2.49, 95%, confidence interval 1.87-3.32; cognitive performance, n = 657 events: hazard ratio 4.11, 95%, confidence interval 3.19-5.29) and mild cognitive impairment (cardiovascular fitness, n = 213 events: hazard ratio 3.57, 95%, confidence interval 2.23-5.74; cognitive performance, n = 212 events: hazard ratio 3.23, 95%, confidence interval 2.12-4.95). Poor performance on both cardiovascular fitness and cognitive tests was associated with a >7-fold (hazard ratio 7.34, 95%, confidence interval 5.08-10.58) and a >8-fold (hazard ratio 8.44, 95%, confidence interval 4.64-15.37) increased risk of early-onset dementia and early-onset mild cognitive impairment, respectively. In conclusion, lower cardiovascular fitness and cognitive performance in early adulthood were associated with an increased risk of early-onset dementia and mild cognitive impairment later in life, and the greatest risks were observed for individuals with a combination of low cardiovascular fitness and low cognitive performance.
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| 7. |
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