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result(s) for
"Valkama, Jari"
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The Breeding Ranges of Central European and Arctic Bird Species Move Poleward
by
Brommer, Jon E.
,
Lehikoinen, Aleksi
,
Valkama, Jari
in
Altitude
,
Animal breeding
,
Animal Migration
2012
Climatic warming predicts that species move their entire distribution poleward. Poleward movement of the 'cold' side of the distribution of species is empirically supported, but evidence of poleward movement at the 'warm' distributional side is relatively scarce.
Finland has, as the first country in the world, completed three national atlas surveys of breeding birds, which we here use to calculate the sizes and weighted mean latitudes of the national range of 114 southern and 34 northern bird species during three periods (1974-1979; 1986-1989; 2006-2010), each denoting species presence in approximately 3 800 10 × 10 km2 squares. We find strong evidence that southern species (breeding predominantly in central Europe) showed a latitudinal shift of 1.1-1.3 km/year poleward during all three pairwise comparisons between these atlases (covering 11, 20.5 and 31.5 years respectively). We find evidence of a latitudinal shift of 0.7-0.8 km/year poleward of northern boreal and Arctic species, but this shift was not found in all study periods and may have been influenced by increased effort put into the more recent surveys. Species showed no significant correlation in changes in range size and weighted mean latitude between the first (11 year) and second (20.5 year) period covered by consecutive atlases, suggesting weak phylogenetic signal and little scope of species characteristics in explaining latitudinal avian range changes.
Extinction-driven avian range changes (at the 'warm' side) of a species' distribution occur at approximately half the rate of colonisation-driven range changes (at the 'cold' side), and its quantification therefore requires long-term monitoring data, possibly explaining why evidence for such changes is currently rare. A clear latitudinal shift in an assemblage of species may still harbour considerable temporal inconsistency in latitudinal movement on the species level. Understanding this inconsistency is important for predictive modelling of species composition in a changing world.
Journal Article
Promiscuous specialists: Host specificity patterns among generalist louse flies
by
Valkama, Jari
,
Mutanen, Marko
,
Pohjola, Pekka
in
Bar codes
,
Behavior
,
Biology and Life Sciences
2021
Ectoparasites such as louse flies (Diptera: Hippoboscidae) have tendency for host specialization, which is driven by adaptation to host biology as well as competition avoidance between parasites of the same host. However, some louse fly species, especially in genera attacking birds, show wide range of suitable hosts. In the presented study, we have surveyed the current status of bird specific louse flies in Finland to provide comprehensive host association data to analyse the ecological requirements of the generalist species. A thorough sampling of 9342 birds, representing 134 species, recovered 576 specimens of louse flies, belonging to six species: Crataerina hirundinis , C . pallida , Ornithomya avicularia , O . chloropus , O . fringillina and Ornithophila metallica . Despite some overlapping hosts, the three Ornithomya species showed a notable pattern in their host preference, which was influenced not only by the host size but also by the habitat and host breeding strategy. We also provide DNA barcodes for ten Finnish species of Hippoboscidae, which can be used as a resource for species identification as well as metabarcoding studies in the future.
Journal Article
Developing fine-grained nationwide predictions of valuable forests using biodiversity indicator bird species
2022
The use of indicator species in forest conservation and management planning can facilitate enhanced preservation of biodiversity from the negative effects of forestry and other uses of land. However, this requires detailed and spatially comprehensive knowledge of the habitat preferences and distributions of selected focal indicator species. Unfortunately, due to limited resources for field surveys, only a small proportion of the occurrences of focal species is usually known. This shortcoming can be circumvented by using modeling techniques to predict the spatial distribution of suitable sites for the target species. Airborne laser scanning (ALS) and other remote sensing (RS) techniques have the potential to provide useful environmental data covering systematically large areas for these purposes. Here, we focused on six bird of prey and woodpecker species known to be good indicators of boreal forest biodiversity values. We used known nest sites of the six indicator species based on nestling ringing records. Thus, the most suitable nesting sites of these species provide important information for biodiversity-friendly forest management and conservation planning. We developed fine-grained, that is, 96 96 m grid cell resolution, predictive maps across the whole of Finland of the suitable nesting habitats based on ALS and other RS data and spatial information on the distribution of important forest stands for the six studied biodiversity indicator bird species based on nesting-habitat suitability modeling, that is, the MaxEnt model. Habitat preferences of the study species, as determined by MaxEnt, were in line with the previous knowledge of species-habitat relations. The proportion of suitable habitats of these species in protected areas (PAs) was considerable, but our analysis also revealed many potentially high-quality forest stands outside PAs. However, many of these sites are increasingly threatened by logging because of increased pressures for using forests for bioeconomy and forest industry based on National Forest Strategy. Predicting habitat suitability based on information on the nest sites of indicator species provides a new tool for systematic conservation planning over large areas in boreal forests in Europe, and a corresponding approach would also be feasible and recommendable elsewhere where similar data are available.
Journal Article
Survival fluctuation is linked to precipitation variation during staging in a migratory shorebird
by
Brlík, Vojtěch
,
Pakanen, Veli-Matti
,
Koivula, Kari
in
631/158/1745
,
631/158/2039
,
631/158/2165
2022
Understanding how weather conditions affect animal populations is essential to foresee population changes in times of global climate shifts. However, assessing year-round weather impacts on demographic parameters is hampered in migratory animals due to often unknown occurrence in space and time. We addressed this by coupling tracking and weather data to explain extensive variation in apparent survival across 19 years in a northern European population of little ringed plovers (
Charadrius dubius
). Over 90% (n = 21) of tracked individuals followed migration routes along the Indo-European flyway to south India. Building on capture–recapture histories of nearly 1400 individuals, we found that between-year variation in precipitation during post-breeding staging in northern South Asia explained 47% of variation in apparent adult survival. Overall, the intensity of the monsoon in South Asia explained 31–33% of variability in apparent survival. In contrast, weather conditions in breeding, final non-breeding and pre-breeding quarters appeared less important in this species. The integration of multi-source data seems essential for identifying key regions and periods limiting population growth, for forecasting future changes and targeting conservation efforts.
Journal Article
Large-scale spatial synchrony in red squirrel populations driven by a bottom-up effect
by
Rintala, Jukka
,
Selonen, Vesa
,
Helle, Pekka
in
Abiotic factors
,
Abundance
,
Accipiter gentilis
2020
Spatial synchrony between populations emerges from endogenous and exogenous processes, such as intra-and interspecific interactions and abiotic factors. Understanding factors contributing to synchronous population dynamics help to better understand what determines abundance of a species. This study focuses on spatial and temporal dynamics in the Eurasian red squirrel (Sciurus vulgaris) using snow-track data from Finland from 29 years. We disentangled the effects of bottom-up and top-down forces as well as environmental factors on population dynamics with a spatiotemporally explicit Bayesian hierarchical approach. We found red squirrel abundance to be positively associated with both the abundance of Norway spruce (Picea abies) cones and the predators, the pine marten (Martes martes) and the northern goshawk (Accipiter gentilis), probably due to shared habitat preferences. The results suggest that red squirrel populations are synchronized over remarkably large distances, on a scale of hundreds of kilometres, and that this synchrony is mainly driven by similarly spatially autocorrelated spruce cone crop. Our research demonstrates how a bottom-up effect can drive spatial synchrony in consumer populations on a very large scale of hundreds of kilometres, and also how an explicit spatiotemporal approach can improve model performance for fluctuating populations.
Journal Article
Habitat Effects on the Breeding Performance of Three Forest-Dwelling Hawks
by
Valkama, Jari
,
Tomppo, Erkki
,
Laaksonen, Toni
in
Accipiter gentilis
,
Animal behavior
,
Animal breeding
2015
Habitat loss causes population declines, but the mechanisms are rarely known. In the European Boreal Zone, loss of old forest due to intensive forestry is suspected to cause declines in forest-dwelling raptors by reducing their breeding performance. We studied the boreal breeding habitat and habitat-associated breeding performance of the northern goshawk (Accipiter gentilis), common buzzard (Buteo buteo) and European honey buzzard (Pernis apivorus). We combined long-term Finnish bird-of-prey data with multi-source national forest inventory data at various distances (100-4000 m) around the hawk nests. We found that breeding success of the goshawk was best explained by the habitat within a 2000-m radius around the nests; breeding was more successful with increasing proportions of old spruce forest and water, and decreasing proportions of young thinning forest. None of the habitat variables affected significantly the breeding success of the common buzzard or the honey buzzard, or the brood size of any of the species. The amount of old spruce forest decreased both around goshawk and common buzzard nests and throughout southern Finland in 1992-2010. In contrast, the area of young forest increased in southern Finland but not around hawk nests. We emphasize the importance of studying habitats at several spatial and temporal scales to determine the relevant species-specific scale and to detect environmental changes. Further effort is needed to reconcile the socioeconomic and ecological functions of forests and habitat requirements of old forest specialists.
Journal Article
Competitive exclusion within the predator community influences the distribution of a threatened prey species
by
Valkama, Jari
,
Burgas, Daniel
,
Byholm, Patrik
in
Accipiter gentilis
,
Aerial locomotion
,
Animal and plant ecology
2012
While much effort has been made to quantify how landscape composition influences the distribution of species, the possibility that geographical differences in species interactions might affect species distributions has received less attention. Investigating a predator-prey setting in a boreal forest ecosystem, we empirically show that large-scale differences in the predator community structure and small-scale competitive exclusion among predators affect the local distribution of a threatened forest specialist more than does landscape composition. Consequently, even though the landscape parameters affecting Siberian flying squirrel (
Pteromys volans
) distribution (prey) did not differ between nest sites
of the predators Northern Goshawks (
Accipiter gentilis
) and Ural Owls (
Strix uralensis
)
, flying squirrels were heterospecifically attracted by goshawks in a region where both predator species were present. No such effect was found in another region where Ural Owls were absent. These results provide evidence that differences in species interactions over large spatial scales may be a major force influencing the distribution and abundance patterns of species. On the basis of these findings, we suspect that subtle species interactions might be a central reason why landscape models constructed to predict species distributions often fail when applied to wider geographical scales.
Journal Article
Age‐Specific Survival Estimation of a Eurasian Crane Population Highlights a Long‐Term Decline in Juvenile Survival
by
Salvi, Alain
,
Ticháčková, Markéta
,
Modrow, Michael
in
Adults
,
Age determination
,
Agricultural practices
2026
The Eurasian crane (Grus grus), a symbol of conservation success in Europe, has made an impressive recovery since the 1979 Birds Directive, with current estimates reaching around 590,000 individuals. However, this transition from vulnerability to abundance brings new challenges, particularly arising from interactions with human activities (e.g., conflicts with agriculture). Understanding the future dynamics of crane populations requires knowledge of demographic parameters that are crucial for predicting population trends and informing management and conservation measures. We analysed 37 years of data (1985–2021) from 5049 juvenile‐banded cranes and 172,725 resightings, providing estimates of survival rates across age classes and over time. Our findings indicate that juveniles exhibit the lowest survival rates, while sub‐adults have higher survival, and adults show a decrease in their survival probability with age, as expected with the senescence process. Over the study period, juvenile survival declined by almost 30% overall, while sub‐adults experienced a smaller decrease, and adults showed no change. Life expectancy at birth was 10 years, and maximum lifespan reached 25 years. We found no difference in the survival estimates of males and females. The decline in juvenile survival over the years highlights the growing challenges likely driven by habitat degradation, climate change, agricultural practices, and increasing population densities. These findings align with previous research on crane survival and underscore the importance of understanding age‐specific survival dynamics in response to environmental changes. This study highlights the challenges facing Eurasian crane populations, where further declines in juvenile and immature survival rates could lead to population declines unless compensated by a stable or higher adult survival. Effective conservation strategies will require further research into reproductive success and details on age‐specific mortality causes and environmental pressures, although targeted interventions can already be implemented to mitigate current impacts of habitat degradation and climate change. The Eurasian crane (Grus grus), a symbol of conservation success in Europe, has made an impressive recovery. However, our results show that over the study period, juvenile survival declined by almost 30% overall, while sub‐adults experienced a smaller decrease, and adults showed no change. The decline in juvenile survival over the years highlights increasing challenges likely driven by habitat degradation, climate change, agricultural practices, and rising population densities.
Journal Article
Climate change drives microevolution in a wild bird
2011
To ensure long-term persistence, organisms must adapt to climate change, but an evolutionary response to a quantified selection pressure driven by climate change has not been empirically demonstrated in a wild population. Here, we show that pheomelanin-based plumage colouration in tawny owls is a highly heritable trait, consistent with a simple Mendelian pattern of brown (dark) dominance over grey (pale). We show that strong viability selection against the brown morph occurs, but only under snow-rich winters. As winter conditions became milder in the last decades, selection against the brown morph diminished. Concurrent with this reduced selection, the frequency of brown morphs increased rapidly in our study population during the last 28 years and nationwide during the last 48 years. Hence, we show the first evidence that recent climate change alters natural selection in a wild population leading to a microevolutionary response, which demonstrates the ability of wild populations to evolve in response to climate change.
Organisms are expected to adapt to climate change because of selection pressures. Here, the authors demonstrate that brown morphs of Finnish owls are selected against in winters with plentiful snow, and concordantly, increasing winter temperatures and lower snow fall results in the selection of the brown morph.
Journal Article
Impact of Climatic Factors on the Developmental Stability of Mountain Birch Growing in a Contaminated Area
by
Valkama, Jari
,
Kozlov, Mikhail V.
in
air pollution
,
air temperature
,
Animal, plant and microbial ecology
2001
1. We examined developmental stability in mountain birch Betula pubescens ssp. czerepanovii along a strong pollution gradient in the Kola Peninsula, north-western Russia, over a period of 8 years (1993-2000). In particular, we investigated whether climatic factors or aerial pollution could increase developmental instability, which was assessed through leaf fluctuating asymmetry (FA). 2. Contrary to our expectations, leaf FA was not correlated with either distance from the pollution source, or with the levels of nickel and sulphur dioxide pollution in the study plots, or with shoot length or leaf size. There was, however, variation in FA between years: highest values of developmental instability were recorded during the coldest summers. 3. There was also considerable among-tree variation in FA within plots, suggesting that birch genets either responded differently to environmental stress or demonstrated a different degree of genetic stress. The significant interaction between study year and birch genet suggests that the detected variation was a consequence of different sensitivity of the trees to climatic fluctuations rather than of different sensitivity to pollution. 4. Growth rate of birch correlated positively with developmental stability, i.e. faster leaf growth was associated with lower FA both at the scale of individual trees (presumably genetic differences) and at the scale of study years (environmental differences). 5. The lack of detectable response to aerial pollution by mountain birch in this study may be an outcome of selection for pollution-resistant genotypes, which may have occurred due to an exceptionally high emission pressure during the past decades. On the other hand, resistance to temperature variations may not have evolved because warm and cold periods appear to occur somewhat regularly in the Kola Peninsula, and therefore variation in temperature optima between genotypes is favoured by natural selection. 6. Our results demonstrate that FA may serve as a useful measure of climatic stress in plants.
Journal Article