Forest structural complexity strongly influences habitat suitability for forest-dwelling species. Airborne laser scanning (ALS) provides efficient nationwide quantification of three-dimensional forest structure, but its applications in animal ecology remain limited, particularly for understudied mustelids. Here, we combined nationwide ALS data from 173 flight campaigns with species presence-absence observations, an unprecedented scale for mustelid studies, to assess how ALS-derived forest structural metrics predict the occurrence of pine marten, stoat, and least weasel in Finland. We modeled occurrences using spatial hierarchical generalized linear mixed-effects models. ALS metrics capturing vertical complexity and canopy cover, alongside landscape and climate variables, explained broad-scale habitat associations for pine marten and stoat. Least weasel occurrence was less predictable, likely reflecting its microhabitat preferences and dependence on voles. Key predictors of mustelid occurrence included canopy height variability, mid- and upper-canopy density, and canopy cover of tree layer. Our findings show that nationwide ALS combined with species occurrence data can reveal habitat preferences of small and medium-sized mustelids, supporting conservation, monitoring and management planning.

The circulation of tick-borne pathogens is influenced by the availability of ticks, the hosts of ticks and pathogens, and the environmental conditions that affect both the ticks and their hosts. Lyme borreliosis (LB), caused by Borrelia burgdorferi sensu lato and transmitted by Ixodes spp. ticks, is the most common tick-borne disease in the Northern Hemisphere. Understanding the spatio-temporal dynamics of human LB incidence regarding abundance of ticks and hosts and environmental factors is essential for effective disease risk management. We analyzed long-term (1997–2018) and spatially extensive (277 municipalities covering 230,000 km2) data on human LB incidence in Finland. Using dynamic species distribution models, we assessed the effects of (i) the abundance of pathogen reservoir hosts used by immature ticks (voles and squirrels), (ii) abundance of the key reproductive hosts for adult ticks (moose and deer), (iii) landscape characteristics, and (iv) climatic variables on the risk of LB. LB presence and incidence varied across the study area and exhibited a clear increasing trend. While host species showed temporal and regional variation in abundance, their relationships with LB risk were inconsistent. In contrast, environmental variables showed more consistent patterns: increased forest fragmentation, longer growing seasons, and higher humidity were generally associated with elevated LB risk. Our study suggests that the factors explaining LB epidemiology cannot be generalized spatially but depend on local climate, landscape, and host community. Given the available data, environmental conditions seem to play a more predictable role in LB epidemiology than the estimated abundances of hosts at the municipality level, yet we cannot exclude host abundance effects. Hence, the key to enhancing our understanding of the complex mechanisms underlying the epidemiology of LB and other tick-borne infections is to clarify how tick distribution and abundance respond to alterations in the host community, habitat features, and local climate.

Changes in land use and climate pose major threats to biodiversity 1–5 . However, variation in species responses to climate and land use across space, time, and taxa remains poorly understood 3,6–10 , hindering our ability to predict and mitigate biodiversity change. Here, we evaluate the relative importance of concurrent changes in climate and land use in driving the occurrence and abundance patterns of 503 terrestrial animal species of various taxa over 20 years in Finland. Habitat composition proved to be the main driver of biodiversity patterns but how much and with what uncertainty it explained species distributions depended highly on the context. Specifically, habitat was the dominant driver for butterflies, birds, and small mammals, while habitat and climate were equally important for large mammals and moths. Additionally, species patterns between biogeographical regions were mainly explained by climate, while habitat was the main driver within regions. Traits, such as, body size, pace of life, habitat and diet specialization modulated the relative importance of both drivers’ impacts. Climate and habitat impact on most species were also partially correlated, highlighting the tight connection between the drivers. Our findings emphasize that land use is a major force in shaping terrestrial biodiversity, while highlighting its tight connection with climate. Considering functional and spatial contexts is thus essential for building effective management and conservation strategies for biodiversity under rampant global change.

Over the past few decades, Europe has made significant efforts to restore and construct wetlands to halt the ongoing habitat and biodiversity losses. These endeavours require considerable time, investment, and effort, making it crucial to ensure that they are highly effective in achieving their objectives, one of which is biodiversity conservation, including waterbirds. We monitored waterfowl communities at 146 constructed wetlands in unprotected landscapes across Finland. We studied the effects of habitat and landscape (at two spatial scales) variables on four breeding waterfowl metrics - species richness, pair abundance, brood abundance, and mean brood size. We also investigated how these metrics vary as wetlands age over time, and depending on gull populations. We found that wetlands with larger perimeters, more islands, and greater gull abundance supported higher species richness and more breeding pairs and broods. However, mean brood size was unexpectedly lower at wetlands with more islands. Pair and brood abundance peaked seven and four years after establishment, respectively, while species richness declined linearly with age. At the local scale (200 m), wetlands surrounded by more peat-associated elements and built-up cover had lower species richness and mean brood size, respectively. Brood abundance was higher in wetlands surrounded by broad-leaved forest at both the local and regional (2 km) scale, while regional marsh cover positively influenced species richness and pair abundance. Such findings provide valuable feedback on wetland construction and restoration projects, helping to ensure that future initiatives can improve their biodiversity conservation outcomes.

The spatial ecology of stalk-and-ambush predators like the Eurasian lynx Lynx lynx depends on prey availability and environmental features, yet the relative roles of these factors remain unclear at large spatial scales. In this study, we analysed lynx habitat use across central and southern Finland using snow-track data from the Wildlife Triangle Scheme (2016-2020) and a joint species distribution modelling framework (HMSC) to assess both environmental drivers and spatial predator-prey associations. The Finnish lynx population offers a unique opportunity to study a contiguous population with stark regional differences in prey availability, enabling inferences about environmental and prey effects on space use. Across the study area, lynx habitat use was primarily associated with structurally complex forests and terrain, as expected for a stalk-and-ambush predator. Overall, environmental conditions explained habitat use patterns to a greater degree in the central region than in the south, which we posit is due to differences between the regions in prey species. In the central region, habitat use by lynx and its prey, the mountain hare Lepus timidus, was similar, in contrast to the southern region, where lynx were spatially associated with roe deer Capreolus capreolus and white-tailed deer Odocoileus virginianus, both of which showed habitat use patterns differing from those of lynx. These results indicate that lynx adjust their space use according to prey availability, while still retaining a core preference for complex habitat, as expected for a stalk-and-ambush predator. Our results are a clear demonstration of how the interplay between environmental conditions and community composition of prey shapes a generalist predator's habitat use and how this can contribute to overall resilience at the population level. Our study captures insights into habitat use at the landscape scale across contrasting ecological contexts, with implications for the management and conservation of large carnivores in human-modified environments.

The use of predator control as a conservation tool, for example to protect ground-nesting bird populations, remains a subject of ongoing debate. To justify the control or eradication of a predator, managers need to provide evidence on the success of the program. We evaluated the effectiveness of a raccoon dog control program (2021–2024) organized by governmental bodies around wetlands important for waterfowl conservation in Finland. The raccoon dog is an invasive species and a nest predator of waterfowl. We assessed control effectiveness by analysing how hunting methods and effort influenced catch and how varying hunting intensity across wetlands affected raccoon dog abundance measured with camera-traps. There was a moderate negative relationship between previous hunting efforts and monthly catch, indicating diminishing returns, but full eradication was not achieved. Among the four used hunting methods, hunting from dens proved the most efficient hunting method in relation to time used. The impact of catch on the subsequent number of camera-trap observations varied. Winter camera-trap data from feeding sites showed no decline in raccoon dog presence, potentially due to autumn immigration. However, hunting success showed a negative effect on raccoon dog camera-trap observations in spring (waterfowl breeding season), suggesting a substantial, but incomplete, raccoon dog population reduction. Consistent with this, raccoon dog predation of artificial nests decreased, without compensatory increases by other predator species, resulting overall in reduced nest predation. We conclude that control efforts reduce raccoon dog numbers and potentially benefit wetland bird species, but long-term success requires substantial and sustained effort.

ABSTRACT Species distributions in forest‐dominated landscapes are closely tied to vegetation structure and heterogeneity, which can vary across spatial scales. As Fennoscandian wolverines recolonize their historical range in boreal forests, specific structural features linked to better resources, such as prey availability, cover, and suitable denning habitats, may promote occupancy in these areas. We studied wolverine (Gulo gulo) occurrence in mainland Finland between 2009–2010 and 2018–2022. We conducted a multi‐scale analysis using wildlife and field triangle data and Multi‐Source National Forest Inventory (MS‐NFI) remote sensing products. We applied generalized linear mixed models (GLMMs) to assess the influence of forest and landscape variables on the probability of occurrence at two spatial scales: local (3.13 km radius) and landscape (20 km radius). Occupied and unoccupied sites were distinguished by landscape fragmentation, tree volume, tree species composition, and distance to clearcuts. Sites were more likely to become occupied when forests were less fragmented and had broadleaved trees, while the probability of occurrence decreased if the total volume of trees was high or fresh clearcuts were in close proximity. Landscape scale seems to be more relevant than local scale when studying the overall forest structure's impact on wolverine occurrence. Our findings provide new insights into the occurrence of wolverines in Finnish boreal forests and could be used to aid species conservation and forest management planning.

The Eurasian teal (_Anas crecca_, hereafter “teal”), a small dabbling duck that breeds across temperate Eurasia and winters farther south, numbers about 670,000 wintering birds in northwest Europe and is an important huntable species. Despite regionally increasing numbers of wintering birds, the European Commission is working to identify key actions to address threats to this species because of its recent classification as "Decreasing" in the EU due to breeding declines in parts of Europe. Teal population dynamics are largely driven by reproductive output rather than by small changes in annual survival. Hence, key actions to increase the extent of highly productive breeding habitats can potentially make a vital contribution to restoring teal to a more favourable population status. Nesting teal thrive on peatlands and acidic wetlands, so peatland restoration can potentially contribute to increased breeding abundance. Results from a literature review and key case studies showed that rewetting and ditch blocking to restore cut-over and drained peatlands for other purposes also attracts nesting teal or significantly increases their local breeding abundance, likely by creating suitable brood rearing habitats that provide abundant invertebrate prey. Results suggest that ditch blocking and associated high shoreline-to-open-water ratios may support higher breeding densities than large blocks of open water. Given the alignment of peatland restoration with EU environmental policies to reduce greenhouse gas emissions, such projects, supported by funding programmes, create favourable conditions for breeding teal by expanding shallow water areas and invertebrate populations. Despite abundant evidence for such effects, further research and especially monitoring are needed to optimise peatland restoration practices for the benefit of teal and other species.

The recovery of some apex predators has led to concerns for endangered prey that may have developed risky habitat selection tactics during predator-free eras. Environmental heterogeneity affects predator–prey coexistence, but spatial redistribution of prey has rarely been studied. A predator–prey system with white-tailed eagles and common eiders provides a unique opportunity to study the effect of returning predators on an abundant but declining prey population. Our objective was to investigate how the physical environment affects predator–prey relationships and subsequently the spatial redistribution of the prey population over time, and to perform a large-scale assessment of the population status and distribution of eiders in the North-Eastern Baltic Sea. Using extensive survey data from the Finnish coast from 1997 to 2020 on predator and prey breeding numbers, we constructed a spatiotemporal model explaining the distribution of eiders on > 3600 islands across highly variable coastal regions. We assessed how the proximity of nesting eagles affected eider abundance, mediated by properties related to physical nest shelter (archipelago type and island forest cover). Breeding eider numbers decreased on exposed islands particularly near eagle nests, while they increased near eagle nests in the sheltered archipelago. We observed population-scale predator-induced shifts in the breeding distribution, likely reflecting both excess mortality on exposed islands and a shift of the population core to low-risk habitats. We show that a returning predator can affect the distribution and density of its prey in a habitat-specific manner, which is important to consider in parallel with effects of human-induced ecosystem changes during conservation planning.

Policy-relevant environmental indicators are needed to support effective management of marine environments. Here, we present common challenges in selecting a set of seabird indicator species, whose abundances are used as indicators, and propose potential solutions. We use examples from the Baltic Sea and emphasize the requirements of the EU’s Marine Strategy Framework Directive (MSFD). Processes that confound indicators can be classified as 1) contradictory indirect anthropogenic effects, e.g. poor state of Baltic cod stocks increasing auk abundances, 2) drivers affecting seabird abundance but not the state of the sea, e.g. decreased availability of dumps for gulls, and 3) transient dynamics and species interactions, e.g. the steep population growth of Great Cormorant and White-tailed Sea Eagle, and the resulting predation impact of the latter on Common Eider. To assess the spatial scale of seabird population dynamics, we compared population trends of the Baltic Sea with the North Sea, and trends of the Finnish coast with inland lakes. On average, trends in the Baltic Sea and Finnish coast were more stable or positive compared to the North Sea and inland, respectively. Finally, we propose two phases of indicator formation: i) a filtering phase – in which unwanted variation is filtered out from the species’ population trajectories – and ii) an indicator-generating phase – which aggregates relevant multi-species patterns into one or several indicators. We suggest statistical methodological approaches that cover both phases, separately or simultaneously. At best, seabird abundance indicators are useful summary statistics for monitoring joint effects of a wide range of anthropogenic pressures.

Anthropogenic environmental change is altering biodiversity at unprecedented rates, threatening the stability of ecosystem services on which humans depend. However, most of what is known about biodiversity-stability relationships comes from experimental studies making extrapolation to real ecosystems difficult. Here, we ask whether the shape and underlying mechanisms of the biodiversity-stability relationship vary among taxa in real-world communities. Our study harnesses the power of six terrestrial and aquatic long-term monitoring datasets, encompassing entire assemblages at hundreds of georeferenced sites providing 20 years long community measurements, covering a 1200 km latitudinal gradient across Finland. In general, we detect a positive relationship between species richness and stability. Structural equation modelling reveals that this relationship is modified by functional trait community composition, with specific mechanisms varying among the taxa. Our study is among the first to highlight the importance of functional traits in elucidating both general and taxon-specific impacts of biodiversity on community stability.

Integrating spatial aspects in forest planning is essential to account for management effects across scales. Forest management impacts wildlife habitat quality by reducing key reproductive resources, posing challenges for balancing timber production with habitat conservation. Because forest species respond to habitat features at multiple spatial scales, the impact of management on habitat quality also varies across scales but remains poorly understood. In this study we evaluate how trade-offs between timber yield and habitat availability vary across species with different habitat needs and spatial scales. We simulated and optimized three boreal Finnish production landscapes spanning a gradient of management intensities using the MELA2.0 forest simulation package. Production possibility frontiers revealed trade-off between economic value (Net Present Value (NPV) of timber) and ecological value (grouse occupancy). Occupancy was modelled for four forest grouse species (hazel grouse, black grouse, capercaillie and willow grouse) using nationwide wildlife triangle census data and predictors related to forest structure and composition at biologically relevant scales: local (stand, ∼0.05 km), home-range (1 km) and landscape (5 km). A 1 % reduction in NPV increased occupancy on average by 7 % at the stand, 9 % at the home-range, and 26 % at the landscape scale. While patterns at smaller scales often mirrored broader trends, discrepancies in certain species-scale combinations highlighted the risk of mismanagement. Habitat quality peaked under conservation-oriented management, NPV under intensive forestry, while compromise solutions emerged from balanced management. The variation in trade-offs at different scales underscores the need for tailored, multi-scale planning to align economic and ecological objectives.

Climate warming has led to phenological changes over time, typically displayed as earlier emergence of various organisms in spring or summer in temperate terrestrial and marine systems alike. Similarly, warm conditions can extend seasonal occurrence. Using a time series of zooplankton data from a coastal area in the Gulf of Finland, we calculated the start, end and the length of the season for the occurrence in rotifers and for adult and juvenile stages of three calanoid copepods. We investigated whether the start and end of the season of these taxa have shifted earlier and later, respectively, and whether the season length has increased. We further investigated if potential changes are driven by climate warming. We show that both copepods and rotifers do indeed emerge earlier, but that the pattern in recent years was not conclusive, and that both temperature and ice conditions influenced the seasonal abundance patterns of some taxa. Warmer years led to earlier occurrence of Temora longicornis copepodites. Earlier ice break-up coincided with longer seasons for Acartia and earlier emergence of Eurytemora affinis. The phenological changes in zooplankton demonstrated here may have cascading effects on other trophic levels in the food web. We also demonstrate how decreased sample number influences the ability to capture intra-annual abundance patterns and discuss the implications for monitoring.

The Skellam model describes discrete-time population dynamics of a single species assuming uniform (i.e., random or Poissonian) individual distribution and intraspecific contest competition. Apart from studies on individual-based models derived from first principles, it has rarely been applied to ecological research. However, in specific situations, it may be more appropriate than, for instance, the frequently used Ricker model. This is derived from assuming scramble competition among individuals. In this paper, we offer insight into the first principles underlying the Skellam model. In addition, we provide an alternative parameterization of the model in terms of two commonly used parameters: intrinsic rate of population increase and carrying capacity. In light of these findings, the Skellam model may be a useful alternative for a range of purposes where it has previously been overlooked, e.g., in fitting population models to time series data.

Partial migrants have populations consisting of both migratory and resident individuals. These migrants and residents experience unequal ecological conditions during winter and the underlying factors driving their decision to stay on their breeding grounds or to migrate remain debated—both from the viewpoint of populations and individuals. Here, we studied partial migration in a small raptor, the Eurasian Sparrowhawk (Accipiter nisus), from two different but interconnected perspectives: 1) explaining the patterns and variation in the ratio of migrants to residents (migratoriness) at the population level and 2) revealing how age and sex may affect the individual decision to be migratory or resident. We used citizen observation data over four decades to explore the temporal and spatial variation in the age and sex ratio of wintering resident sparrowhawks in Sweden. We found that the migratoriness unexpectedly increased with higher annual temperatures and showed long-term trend across the study period. Also, this migrant-to-resident ratio increased with smaller winter prey abundance. The average winter sex ratio was male-biased and became increasingly so over the years. We suggest that residency benefits territory-establishing males as early presence gives a competitive advantage in obtaining high-quality territories. Moreover, the distribution of overwintering individuals (regardless of sex) moved gradually northwards as the winter progressed, suggesting that smaller-scale migration occurs among the resident fraction of the population. These results provide suggestions for the underlying drivers and regulation of partial migration.

In Europe, the gray wolf and Eurasian lynx populations are recovering after various levels of persecution. The two species differ in their social structure and spatial patterns of aggregation. Using model selection, we investigated the consistency of the available time series data on local wolf and lynx sub-populations with a number of single-species population growth models that pertain to two types of intraspecific competition, namely, scramble (SC) and contest competition (CC), and reflect random (R) or aggregated (A) distribution of individuals. The applied models of population growth-the Ricker (SCR), Skellam (CCR), Hassell (SCA), and Beverton-Holt (CCA) models-were all parameterized in terms of intrinsic growth rate and carrying capacity with unified definitions. The projected carrying capacity was allowed to show a temporal trend, which was justified by an observed increase in prey abundance in recent decades. For both species, the models pertaining to contest competition outperformed the scramble competition models, and the Beverton-Holt model had the greatest weight. However, for the lynx, the difference of performance between the scramble and contest competition models was considerably smaller than that for the wolves. In most of the models, when it was meaningful, an optional time lag operator was added to account for a delay in individual maturity and reproduction. However, the models with a time lag had a worse fit than the models without it. This study promotes the application of population models that reflect intraspecific competition for modeling population dynamics in a single- or multi-species framework.

Human disturbance compromises the ecological integrity of forests, negatively affecting associated species. Assessing the impact of forest integrity on biodiversity is complex due to the interplay of various human activities, ecological factors, and their interactions. Current large-scale indices assess forest integrity but often lack a direct connection to the biotic environment. We tested the effectiveness of the global Forest Landscape Integrity Index (FLII) in evaluating aspects of anthropogenic forest degradation on the biotic community. We analyzed the relationship between changes in the ecological integrity of Finnish forests and variations in mammal species abundance, using the number of tracks from 17 different species collected during the winter seasons between 2016 and 2020 in south-central Finland. Beyond the FLII, we analyzed forest and canopy cover to enhance the accuracy of habitat preference assessments. We found that the FLII captures the varying degrees of forest integrity, as reflected by the correlation between the abundance of winter tracks and the FLII for most mammals. Species that were positively associated with forest integrity were all native to the boreal forest, while mammals that adapt well to human-disturbed environments including two invasive species were more common in lower FLII forests. Significant differences in habitat preferences were also observed in relation to forest and canopy cover, revealing additional nuances that the FLII alone did not capture. This study demonstrates that the FLII, when combined with a comprehensive dataset and supplemented with region-specific factors, can assess species' adaptability to human-modified forests, aiding in the development of conservation strategies.

AbstractWetland habitats are changing under multiple anthropogenic pressures. Nutrient leakage and pollution modify physico‐chemical state of wetlands and affect the ecosystem through bottom‐up processes, while alien predators affect the ecosystems in a top‐down manner. Boreal wetlands are important breeding areas for several waterbird species, the abundances of which potentially reflect both bottom‐up and top‐down ecosystem processes. Here, we use long‐term national monitoring data gathered from c. 130 waterbird breeding sites in Finland from the 1980s to the 2020s. We hypothesised that the physico‐chemical state of the waters and increasing alien predator abundance both play a role in steering the waterbird population trends. We set out to test this hypothesis by relating population changes of 17 waterbird species to changes in water chemistry and to regional alien predator indices while allowing species‐specific effects to vary with foraging niche (dabblers, invertivore divers, piscivorous divers, herbivores), nesting site, female mass and habitat (oligotrophic, eutrophic). We found niche and nesting site‐specific, habitat‐dependent changes in waterbird numbers. While the associations with higher phosphorus levels and browning water were in overall positive at the oligotrophic lakes, the numbers of invertivore and piscivore diving ducks were most strongly negatively associated with higher phosphorus levels and browning water at the eutrophic lakes. Furthermore, increased pH levels benefitted piscivores. Invertivore diving duck species nesting on the wetlands had declined most on sites with high alien predator indices. Large herbivorous species and species preferring oligotrophic lakes seem to be successful. We conclude that the large‐scale breeding waterbird decline in Finland is closely connected to both bottom‐up and top‐down processes, where negative associations are emphasised especially at eutrophic lakes. Niche‐, nest site‐ and habitat‐specific management actions are required to conserve declining waterbird populations. Managing wetlands on catchments level together with alien predator control may provide important approaches to future wetland management.

The characteristic spatial scale at which species respond strongest to forest structure is unclear and species-specific and depends on the degree of landscape heterogeneity. Research often analyzes a pre-defined spatial scale when constructing species distribution models relating forest variables with occupancy patterns. This is a limitation, as forest characteristics shape the species use of habitat at multiple spatial scales. To explore the drivers of this relationship, we conducted an in-depth investigation into how scaling forest variables at biologically relevant spatial scales affects occupancy of grouse species in boreal forest. We used 4,790 grouse observations (broods and adults) collected over 39,303 stands for 15 years of four forest grouse species (capercaillie, black grouse, hazel grouse, and willow grouse) obtained from comprehensive Finnish wildlife triangle census data and forest variables obtained from Airborne Laser Scanning and satellite data originally sampled at 16 m resolution. We fitted Generalized Additive Mixed Models linking grouse presence/absence in the Finnish boreal forest with forest stand structure and composition. We estimated the effects of predictor variables aggregated at three spatial scales reflecting the species use of the landscape: local level at stand scale, home range level at 1 km radius, and regional level at 5 km radius. Multi-grain models considering forest-species relationships at multiple scales were used to evaluate whether there is a specific scale at which forest characteristics best predict local grouse occupancy. We found that that the spatial scale affected the predictive capacity of the grouse occupancy models and the characteristic scale of habitat selection was the same (i.e., stand scale) among species. Different grouse species exhibited varying optimal spatial scales for occupancy prediction. Forest structure was more important than compositional diversity in predicting grouse occupancy irrespective of the scale. A limited number of forest predictors related to availability of multi-layered vegetation and of suitable thickets explained the occupancy patterns for all the grouse species at different scales. In conclusion, modeling grouse occupancy using forest predictors at different spatial scales can inform forest managers about the scale at which the species perceive the landscape. This evidence calls for an integrated multiscale approach to habitat modelling for forest species.