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Agricultural intensification has significantly impacted habitat structures in agricultural landscapes and is one of the main drivers of biodiversity decline, especially in farmland birds. Birds are considered to reflect well the trends in other biodiversity elements and are therefore often used as indicator species. We studied common pheasant (Phasianus colchicus) brood habitat use in a small-grain-dominated farmland in southern Finland. The broods significantly preferred field margins compared to their availability. The importance of field margins was underlined, as 68% of pheasant brood observations in grain fields were within a 25-m-wide zone from the field edge, despite the availability being only 40% of the field area. Our results support the idea that field margins and their proximity act as possible biodiversity reservoirs even in intensive farming systems. Increasing the amount of field margins can be an effective management method when aiming to improve success of common pheasant broods while simultaneously benefitting farmland biodiversity. Identifying key habitats and landscape features that allow the co-existence of biodiversity and effective food production is crucial when aiming to halt the ongoing biodiversity collapse.

Several alien predator species have spread widely in Europe during the last five decades and pose a potential enhanced risk to native nesting ducks and their eggs. Because predation is an important factor limiting Northern Hemisphere duck nest survival, we ask the question, do alien species increase the nest loss risk to ground nesting ducks? We created 418 artificial duck nests in low densities around inland waters in Finland and Denmark during 2017–2019 and monitored them for seven days after construction using wildlife cameras to record whether alien species visit and prey on the nests more often than native species. We sampled various duck breeding habitats from eutrophic agricultural lakes and wetlands to oligotrophic lakes and urban environments. The results differed between habitats and the two countries, which likely reflect the local population densities of the predator species. The raccoon dog (Nyctereutes procyonoides), an alien species, was the most common mammalian nest visitor in all habitats and its occurrence reduced nest survival. Only in wetland habitats was the native red fox (Vulpes vulpes) an equally common nest visitor, where another alien species, the American mink (Neovison vison), also occurred among nest visitors. Although cautious about concluding too much from visitations to artificial nests, these results imply that duck breeding habitats in Northern Europe already support abundant and effective alien nest predators, whose relative frequency of visitation to artificial nests suggest that they potentially add to the nest predation risk to ducks over native predators.

Summary: Effect of forest clear-cutting areas on nests depredation of ground nesting birds – an artificial nest experiment. Nest predation is one of the most important factor affecting bird’s offspring production. However, nest predation is not very well studied, and the real role of different predator species predating ground nesting birds’ nests is still widely unclear. We especially need more information of nest predation and predators in different habitat types, such as boreal forests. The need is especially urgent, because there has been a fast increase of alien predator populations in Finland and Europe during the past decades. Alien predators pose a potential enhanced risk to many native bird species, such as forest grouses. Here, we study the nest depredation of ground nesting birds in barren coniferous forests, which are relatively far away from human settlements and fields. There are also only small number of lakes and ponds in our study area. The area is situated in the middle part of Finland in Suomenselkä region. We created 156 artificial nests with four pheasant eggs in low densities in 2018 and monitored them for seven days after construction using wildlife cameras to record whether nest predators visit and prey upon the nests. From the 156 artificial nest 26 (17 %) were depredated: in clear-cutting area 10 (19 %), forest edge 9 (17 %) and 7 (13 %) inside forests. The most common nest visitors were avian predators, which took 19 nets (raven Corvus corax 10, great tit Parus major 5, jay Garrulus glandarius 3 and great spotted woodpecker Dendrocopos major 1 nest). Mammals depredated only 2 nest (red fox Vulpes vulpes 1 and moose Alges alges 1 nest. In five nest depredation cases we did not succeeded to identify nest predators because of camera failure. All in all, nets depredation rate on barren coniferous forest seem to be relatively low. We used GLMM (Generalised linear mixed model) to find explanatory fosters explaining nest depredation risk in two different landscape scale (250 m and 500 m wide radius around nets). Results indicate that 250 wide buffer area around nest may explain better nest depredation risk, but results were not statistically significant. In our best model small forest road and electric power line areas explain best nest depredation risk (250 m radius). The size of the clear-cut did not affect the nest probability to become depredated. Even though we have relative big number of artificial nest, only few were depredated and thus the sample size was too low to find significant results. Therefore, more data is needed to find more precise depredation risk level of ground nesting birds in barren forests. Absence of raccoon dog was a bit surprising, because it is the most common nest predator in an agricultural–forest landscape and near lakes and ponds. Our results suggest that nest depredation risk is low in forests far from human settlements and fields.

Common practices in current game management are wetland restoration and creation, as well as releases of quarry species. We studied the impact of releases of mallard ducklings on species richness of wild waterbirds and amphibians on three types of wetlands: natural, constructed and restored. Data on species richness, macrophyte cover and water characteristics (total phosphorous and pH) were collected at 32 sites in an agricultural landscape in southern Sweden. In total, 14 species of waterbirds were recorded, ranging from zero to seven per wetland and survey. Amphibians were present in 24 of the 32 wetlands; in total five species were found, ranging from zero to three per wetland. By using generalized linear modelling we found that wetland type best predicted waterbird species richness. Constructed wetlands had significantly more waterbird species, regardless of whether they were used for mallard releases or not. There were breeding amphibians in 62% of natural, 100% of restored and 77% of constructed wetlands. Breeding amphibians were present in 84% of wetlands without, and in 62% of wetlands with releases. However, included variables did not explain amphibian species richness in the wetlands. Releasing large numbers of mallards on a wetland and providing food ad libitum is likely to affect water quality, nutrient availability and predation pressure. Indeed, phosphorous levels were significantly higher in release wetlands, but no differences were found between wetland types.This means that mallard releases may increase nutrient loads in environments that are already eutrophied. However, in our study system releases did not influence species richness of waterbirds and amphibians locally. Constructing wetlands for mallard releases can thus have positive local effects on species richness.

Annual Finnish breeding duck surveys over the last 30 years show declining abundance among several species and greater declines on eutrophic waters than oligotrophic lakes. It has been suggested that habitat-related differences in the rate of increase in predation pressure is a potential explanation for contrasting duck population trajectories between habitats. We assessed potential duck nest predation risk and predator presence in various duck breeding habitats in Finland and Denmark by monitoring 333 artificial duck nests with wildlife cameras during 2017-2019. Predation rates differed between landscapes and habitats: nest predation rate and predator diversity were lowest in forested and highest in agricultural landscapes. Forest nests further from water bodies survived better than nests around shorelines of permanent lakes. Of the 16 different predator species detected, the most common were Eurasian magpie (Picapica), hooded crow (Corvus corone) and raccoon dog (Nyctereutes procyonoides). While predation by specific native predator species was typically associated with particular habitats and landscapes, the alien raccoon dog appeared to be a true habitat generalist, ubiquitous and common across all habitats and landscapes. Based on these results, the higher duck nest predation pressure along shorelines, especially in agricultural landscape lakes, due to increased diversity and abundance within the predator community, may contribute to the declining population trends of ducks. (C) 2020 Gesellschaft fir okologie. Published by Elsevier GmbH. All rights reserved.

Wetlands are declining worldwide, and there is a great need for their restoration and creation. One natural agent of wetland engineering is beavers,Castorspp., which have returned or are returning to many parts of their former range. We initially studied the facilitative effect of the beaverCastor canadensison a waterbird community consisting of three waders and four ducks in boreal wetlands in southern Finland. Both waterbird species diversity and abundance increased when beavers impounded a pond. Common tealAnas creccaand green sandpiperTringa ochropuswere the species showing the most positive numerical response, but the other five species also increased upon flooding. This article evaluates how the results of the study have been used in management, both in theory and practice. The whole-community facilitation concept has been taken up in numerous articles considering the restorative effects of beavers. It has also been used as ecological background when planning and executing man-made wetland projects in Finland within both the public and the private sectors. Our study and its publication inAquatic Conservation: Marine and Freshwater Ecosystemshave set a foundation for further evidence-based management of waterbird communities. As the results show, having beavers as wetland managers is a feasible tool for creating and restoring wetlands for waterbirds and other biota. Moreover, wetland restoration projects are becoming more popular endeavours, owing to an understanding of the diverse benefits of wetlands. Flooding by beavers is used as a model for managers when creating man-made wetlands; for example, in urban areas where it is difficult to maintain beavers. 1.2.3.4.

Avian species respond to ecological variability at a range of spatial scales and according to life history stage. Beaver dams create wetland systems for waterbirds that are utilized throughout different stages of the breeding season. We studied how beaver?induced variability affected mobile pairs and more sedentary broods along with the production of Common Teal Anas crecca at the patch and landscape scale on their breeding grounds. Beavers Castor spp. are ecosystem engineers that enhance waterfowl habitats by impeding water flow and creating temporary flooding. Two landscapes in southern Finland with (Evo) and without (Nuuksio) American Beavers Castor canadensis were used in this study. To investigate the patch?scale effect, pair and brood densities along with brood production were first compared at beaver?occupied lakes and non?beaver lakes in the beaver landscape. Annual pair and brood densities/km shoreline and brood production were compared between beaver and non?beaver landscapes. Facilitative effects of beaver activity were manifest on brood density at both patch and landscape scales: these were over 90 and 60 percent higher in beaver patches and landscapes, respectively. An effect of beaver presence on pair density was only seen at the landscape level. Pair density did not strongly affect brood production, as shown earlier for relatively mildly density?dependent Teal populations. Because the extent of beaver flooding was a crucial factor affecting annual Teal production in the study area, we infer beaver activity has consequences for the local Teal population. Ecosystem engineering by the beaver could therefore be considered as a restoration tool in areas where waterfowl are in need of high?quality habitats. This article is protected by copyright. All rights reserved.

Increasing anthropogenic pressures have affected the status of surface freshwater ecosystems. Eutrophication, water browning, acidification, and several other processes may be channelled through the food web. In this study, we evaluate the role of hydrology impacting anthropogenic pressures, flows from urban, farmland and ditched forest areas, and how they explain the physico-chemical quality of lakes and ponds in the boreal biome of Finland. We study the long-term effect around 445 waterfowl survey sites that had physico-chemical measurements (total phosphorus, total nitrogen, pH, water clarity and colour) produced by Finnish environmental authorities done in years 1986-2020. Furthermore, we investigate whether a long-term national-level citizen science study focusing on rather robust visible habitat structures measured by the volunteers can reveal physicochemical water quality using data from >270 lakes where the waterfowl habitat survey and physico-chemical measurements could be spatio-temporally matched. Farmland occurrence around the lakes was positively associated with pH, colour and nutrient concentrations but negatively associated with water clarity. Furthermore, ditch length was positively associated with nitrogen concentration and water colour, while being negatively associated with pH and water clarity. Overall, the studied lakes showed a negative trend in nutrients and clarity but a positive trend in pH and colour. As expected, nutrient concentration increased and clarity decreased along the gradient from oligotrophic to eutrophic lake habitat classifications, which suggests that the citizen science classification seem to reflect the subsurface physico-chemical status of the lakes. We conclude that farming and forest ditching practices in particular seem to associate with the state of the study lakes and that the ecological impacts of intensified turbidity and brownification in wetland ecosystems should be studied further in the future. Sustainable improvement of water quality rests upon scientific understanding of biogeochemical processes in lake ecosystems and the primary sources of the nutrient and sediment loading. (c) 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Zusammenfassung: Wiedererstarken der Singschwäne-Populationen verursacht durch das Grasen im gleichen Habitat keinen Rückgang der Pfeifente 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.

Understanding drivers of variation and trends in biodiversity change is a general scientific challenge, but also crucial for conservation and management. Previous research shows that patterns of increase and decrease are not always consistent at different spatial scales, calling for approaches combining the latter. We here explore the idea that functional traits of species may help explaining divergent population trends. Complementing a previous community level study, we here analyse data about breeding waterbirds on 58 wetlands in boreal Fennoscandia, covering gradients in latitude as well as trophic status. We used linear mixed models to address how change in local abundance over 25 years in 25 waterbird species are associated with life history traits, diet, distribution, breeding phenology, and habitat affinity. Mean abundance increased in 10 species from 1990/1991 to 2016, whereas it decreased in 15 species. Local population increases were associated with species that are early breeders and have small clutches, an affinity for luxurious wetlands, an herbivorous diet, and a wide breeding range rather than a southern distribution. Local decreases, by contrast, were associated with species having large clutches and invertivorous diet, as well as being late breeders and less confined to luxurious wetlands. The three species occurring on the highest number of wetlands all decreased in mean abundance. The fact that early breeders have done better than late fits well with previous research about adaptability to climate change, that is, response to earlier springs. We found only limited support for the idea that life history traits are good predictors of wetland level population change. Instead, diet turned out to be a strong candidate for an important driver of population change, as supported by a general decrease of invertivores and a concomitant increase of large herbivores. In a wider perspective, future research needs to address whether population growth of large-bodied aquatic herbivores affects abundance of co-occurring invertivorous species, and if so, if this is due to habitat alteration, or to interference or exploitative competition.

Surface water browning affects boreal lakes in the Northern Hemisphere. This process is expected to increase with global warming. Boreal lakes are the most numerous lakes on Earth. These ecosystems are particularly sensitive to disturbances due to their low biodiversity compared to other aquatic environments. The recent darkening of surface water is expected to hinder key ecosystem processes, particularly through lower primary productivity and loss of biodiversity. However, studies based on long-term data collections have rarely been conducted on the ecological consequences of water browning on aquatic food webs, especially concerning its impacts on invertebrate communities. For the first time, our analysis based on two decades of data collection in Finnish lakes highlighted a relation between water browning and a decline in aquatic macroinvertebrate abundances. Aquatic invertebrates are the main food resource for many secondary predators such as fish and waterbirds, hence such effect on their populations may have major consequences for boreal ecosystem functioning.

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.

Global measures of biodiversity indicate consistent decline, but trends reported for local communities are more varied. Therefore, we need better understanding of mechanisms that drive changes in diversity of local communities and of differences in temporal trends between components of local diversity, such as species richness and species turnover rate. Freshwater ecosystems are vulnerable to multiple stressors, and severe impacts on their biodiversity have been documented. We studied species richness and composition of local boreal waterbird communities in 1990/1991 and 2016 at 58 lakes distributed over six regions in Finland and Sweden. The study lakes represented not only local trophic gradients but also a latitudinal gradient in the boreal biome. While species richness tended to be lower in 2016 than in 1990/1991, species turnover was relatively high. Within foraging guilds, local species richness of diving ducks and surface feeding waterbirds decreased, whereas that of large herbivores increased. The number of species gained in local communities was higher in lakes with rich vegetation than in lakes with sparse vegetation. Conservation of boreal freshwater ecosystems would benefit from recognizing that large-scale environmental changes can affect local diversity via processes operating at finer scales.

European populations of many ground-nesting farmland birds have declined in recent decades. Increases in predator populations and nest predation may play an important role in this decline, along with habitat loss. However, the role of various predators has often remained unclear. We conducted a study with artificial nests and wildlife cameras (n=104) in agricultural landscapes during 2015-2016 in South Finland. Our trials formed a 400-m wide gradient from forest to field. The aim of our study was to monitor nest survival and nest predators in a spatial and temporal scale. We tested the effect of distance to the forest and nest visibility to nest predation. During an 8-day period, 39.4% of the artificial nests were predated. Fifty percent of the predators were birds, 40% mammals, and 10% remained unknown. The three dominant predators of our artificial nests were the raccoon dog (Nyctereutes procyonoides) with 11 nests and the hooded crow (Corvus corone cornix) and the magpie (Pica pica) with 10 depredated nests each. Our analysis indicates that avian predators preyed upon nests in open fields further away from the forest edge, whereas mammalian predation concentrated closer to the forest edge. Predation occurred more likely at the beginning of the survey and nest survival increased as days passed. Our study highlights the efficiency of using wildlife camera traps in nest predation studies. We also suggest that the ongoing expansion of alien predators across Europe may have a greater impact on ground-nesting bird populations than previously anticipated.

Breeding habitats strongly influence duck reproduction and survival. The boreal biome harbours a large share of the world’s wetlands, which are important breeding sites for several duck species. Based on 98 studies in the peer-reviewed literature, we here synthesize and evaluate which habitat characteristics affect habitat use and reproduction of ducks breeding in boreal freshwater wetlands with respect to (1) species and guild (dabbling, diving and piscivorous ducks) and (2) breeding cycle stage (settling by pairs, nesting and brood rearing). We consider the following aspects related to habitat: wetland morphology and spatial aggregation, water characteristics, habitat structure and vegetation, and biotic interactions. Most of the peer-reviewed studies of duck habitat use in boreal wetlands are from North America and Fennoscandia, while nearly half of the boreal area lacks such studies. Few species dominate research thus far while several others have not been studied at all. Nest site use and success are mainly related to predator avoidance. Food resources and habitat structure are the key characteristics affecting habitat use by duck pairs and broods as well as breeding success, although there are differences between duck guilds. Among the commonly studied variables, there is little evidence that water characteristics affect duck habitat use or survival. The most notable knowledge gaps are found in the effects of anthropogenic activities on habitat use and breeding success of ducks. Because boreal breeding environments are increasingly affected by human activities, we underline the need for future studies combining climate variation with natural and anthropogenic disturbances.

Eurasian migratory duck species represent a natural resource shared between European countries. As is evident throughout human harvest history, lack of coordinated management and monitoring at appropriate levels often leads to 'the tragedy of the commons', where shared populations suffer overexploitation. Effective management can also be hampered by poor understanding of the factors that limit and regulate migratory populations throughout their flyways, and over time. Following decades of population increase, some European duck populations now show signs of levelling off or even decline, underlining the need for more active and effective management. In Europe, the existing mechanisms for delivering effective management of duck populations are limited, despite the need and enthusiasm for establishing adaptive management (AM) schemes for wildlife populations. Existing international legal agreements already oblige European countries to sustainably manage migratory waterbirds. Although the lack of coordinated demographic and hunting data remains a challenge to sustainable management planning, AM provides a robust decision-making framework even in the presence of uncertainty regarding demographic and other information. In this paper we investigate the research and monitoring needs in Europe to successfully apply AM to ducks, and search for possible model species, focusing on freshwater species (in contrast to sea duck species) in the East Atlantic flyway. Based on current knowledge, we suggest that common teal Anas crecca, Eurasian wigeon Mareca penelope and common goldeneye Bucephala clangula represent the best species for testing the application of an AM muddling approach to duck populations in Europe. Applying AM to huntable species with relatively good population data as models for broader implementation represents a cost effective way of starting to develop AM on a European flyway scale for ducks, and potentially other waterbirds in the future.

The growth rate of populations usually varies over time, often in a density-dependent manner. Despite the large amount of literature on density dependence, relatively little is known of the mechanisms underlying the density-dependent processes affecting populations, especially per capita natality. We performed a 20-year study on the density dependence of brood production in two duck species differing in the stability of habitat use. Our study was conducted in a boreal watershed in southern Finland. We predicted that a diving duck common goldeneye Bucephala clangula, with more stable habitat use, would show stronger density dependence than a dabbling duck common teal Anas crecca. We investigated reproductive output in relation to the duck pair density per se as well as in relation to per capita food availability. As predicted, the reproductive output of the goldeneye showed a more density-dependent pattern than that of the teal. The number of goldeneye broods per pair decreased when the pair density increased. This was not the case with the teal. However, when the breeding success was measured by taking into account per capita food availability, both species showed density dependence. Our results imply that the occurrence of density dependent processes may vary even in sympatric ducks breeding in the same, relatively stable landscape. Our analysis also emphasizes that it is important to take into account per capita resource availability when studying the density dependence of breeding success. Both findings have important implications for the management and conservation of species.

SUMMARY 1. Boreal forest lakes are normally considered stable environments, but from a duck’s point of view, both resource abundance and habitat quality in the lakes may differ from 1 year to another. Duck species differ in their flexibility to respond to variation in environmental factors, such as habitat quality, habitat variability and weather. Anas crecca, the common teal, has been suggested to be a species that can readily colonise newly formed habitat. 2. We studied the effect of habitat quality (invertebrate food resources, amount of spring flood, beaver flood abundance, predation pressure), weather (temperature, precipitation, timing of ice breakup) and pair abundance on breeding success of teal at the landscape scale in Southern Finland. We used 20 years of data (1989–2008) from a study area consisting of 50 lakes. This is typical boreal breeding area for the teal, whose population size is markedly variable. We express breeding success as number of broods in two different age classes. 3. The number of broods in both age classes was explained well by habitat quality, but different variables seem to operate during different phases of the breeding season. Increases in abundance of breeding pairs and of food led to increased production of younger broods. Habitat factors including food and flood abundance were the most important predictors for older broods, which are the more influential in terms of recruitment. These factors manifested in an age-specific manner, highlighting the importance of comprehensive breeding time surveys of boreal breeding ducks to understand variation in their recruitment. 4. Our research underlines the importance of high-quality habitats for breeding teal populations in the boreal forest landscape. The existence of these habitats depends substantially on human actions, such as managing beaver populations and preserving seasonal pond habitats.

Wetlands are rich in biodiversity, but globally threatened. After a long period of regional extirpation, beavers have recently returned to many European areas and are now restoring wetlands. The beaver is remarkable regarding the large impacts it has not only on individual species but on entire communities and ecosystems. In fact, beavers are referred to as ‘ecosystem engineers’. The facilitative effect of the beaver Castor canadensis on a waterbird community of seven species of waders and ducks in boreal ponds was studied by using the before–after control–impact method (BACI) and analysing the effect of the duration of flooding. The before–after setting could be used since beavers had caused disturbance by flooding several forest ponds during the course of this long-term study (1988–2009). The study took place in southern Finland, where waterbirds were surveyed four times during the breeding season. The number of waterbird species per pond per year was significantly higher during beaver inundation than before beaver activity, as was the waterbird abundance per survey. Changes were negligible in the controls. The numbers of all seven species increased during flooding, although the increase was significant in only three species. Common teal Anas crecca and green sandpiper Tringa ochropus showed the most positive numerical response to flooding. Mallard Anas platyrhynchos and wigeon Anas penelope were new species entering the duck guild in the flooded wetlands. The beneficial effect of the flood lasted the whole period of inundation, although the most substantial increase in species number appeared during the first two years of flooding. The beaver acted as a whole-community facilitator for waterbirds. It was inferred from previous studies that this was done by modifying the habitat to make it more productive and structurally favourable. It is concluded that favouring beavers is a worthwhile tool in restoring wetlands to promote waterbird communities. Copyright © 2014 John Wiley & Sons, Ltd.

The boreal biome harbours a large share of the world s wetlands, and is the main breeding area for several duck species. Breeding habitats strongly influence duck reproduction. In this study, the habitat use of ducks and their breeding success was estimated in a boreal landscape in southern Finland. A review of duck habitat use in boreal wetlands was additionally made. Boreal forest lakes are normally considered stable environments, but from a duck s point of view both resource abundance and habitat quality in the lakes may differ from one year to another. In this study the vegetation of boreal freshwater lakes was found to slowly change during the 20-year study period. Beavers (Castor canadensis) caused pronounced alterations in the lakes by flooding them. Flooding rendered lake vegetation structure more luxuriant and increased the lake use by ducks. In general, duck brood lake use was positively associated with both the coverage of wide belts of tall emergent plants and the abundance of emerging insects and aquatic invertebrates. The relative importance of these factors varied between species. The brood production of common goldeneyes (Bucephala clangula) was regulated by density dependence per se, but fluctuated with food availability per capita. No spatial density-dependent effects were found for the common teal (Anas crecca), but the breeding success was instead explained well by habitat quality variation. Both food and flood abundance had a positive effect, but different variables seemed to operate during different phases of the breeding season. Many aspects of boreal breeding ducks are still poorly studied. Especially lacking are studies concerning duckling survival and the effects of anthropogenic actions on duck habitat use. This research underlines the importance of high quality habitats for breeding duck populations in the boreal landscape. The varying habitat requirements of duck species should be considered when implementing wetland management. Boreaalisen biomin vesistöt ovat monien sorsien tärkeimpiä lisääntymisympäristöjä. Tässä tutkimuksessa selvitettiin sorsien elinympäristön käyttöä ja lisääntymismenestystä boreaalisilla kosteikoilla Evolla Hämeessä. Lisäksi boreaalisten alueiden sorsia käsittelevistä julkaisuista koottiin kirjallisuuskatsaus. Boreaalisia järviä pidetään yleensä vakaina ympäristöinä, mutta sorsien kannalta sekä ravinnon saatavuus että ympäristön laatu voivat vaihdella vuodesta toiseen. Tässä tutkimuksessa havaittiin järvikasvillisuuden muuttuneen hitaasti 20 tutkimusvuoden aikana. Amerikanmajavan (Castor canadensis) aiheuttamat tulvat muuttivat kasvillisuutta nopeasti ja voimakkaasti. Tulvaaminen lisäsi järvien kasvillisuuden rehevyyttä ja houkutteli varsinkin sorsapoikueita. Sorsapoikueiden elinympäristönkäytössä korostuivat rantakasvillisuuden ja kuoriutuvien hyönteisten sekä veden selkärangattomien määrä. Näiden tekijöiden merkitys kuitenkin vaihteli sorsilla lajikohtaisesti. Eri sorsalajien elinympäristövaatimukset tulisi huomioida kosteikkojen hoidossa. Erilaisten ravintoresurssien käyttö sekä territoriaalisuus heijastuivat myös lajien ympäristön käytön vakauteen. Telkän (Bucephala clangula) ympäristönkäytön havaittiin olevan paljon vakaampaa kuin tavin (Anas crecca). Territoriaalisen telkän poikuetuottoa sääteli suora tiheysriippuvuus, mutta myös vuotuinen ravintoresurssien vaihtelu heijastui alueelliseen poikuemäärään. Tavilla suoraa tiheysriippuvuutta ei havaittu, vaan poikuetuotto vaihteli elinympäristön laadun mukaan. Sekä ravinto että tulvat vaikuttivat positiivisesti tavipoikueiden määrään, mutta tekijät toimivat eri tavoin eri lisääntymisvaiheissa. Boreaalisilla alueilla sorsien elinympäristön valintaa ja lisääntymismenestykseen vaikuttavia tekijöitä tunnetaan vielä huonosti. Varsinkaan poikasten selviytymiseen vaikuttavia tekijöitä ja puolisukeltajasorsien pesäpaikan valintaa ei ole tutkittu. Ihmistoimien, kuten maankäytön muutosten ja järvien virkistyskäytön, vaikutusta sorsien lisääntymismenestykseen ei ole tutkittu lähes lainkaan. Tämä tutkimus korostaa hyvälaatuisten elinympäristöjen, kuten tulvikoiden, merkitystä boreaalisilla alueilla lisääntyville sorsille. Tulvikoita on boreaalisessa maisemassa suhteellisen vähän ja lisäksi ilmastonmuutoksen otaksutaan vähentävän niiden määrää entisestään sekä heikentävän niiden laatua. Majavan luomien tulvikoiden määrä on kasvanut lajin palatessa entisille elinalueilleen. Majava-tulvikoita voidaan edelleen lisätä suosimalla majavaa kosteikoiden ennallistajana.

We studied the population growth and expansion of Barnacle Goose (Branta leucopsis) in Helsinki archipelago, southern Finland. Barnacle Goose breeding was first recorded in Helsinki in 1989. During our study 1996-2013 the number of nesting geese increased from 24 to 740 pairs. We analyzed the role of protected islands in the population growth, and the factors behind differences in growth rates. Our study data consisted of 104 islands. Of these, 29 are protected from private recreational activity (nature reserve ormilitary areas) and were established prior to the start of our study. We predicted that protected areas would have a positive impact on Barnacle Goose population growth. In part of the study period (2002-2013) the population growth in our study area was much steeper in protected islands compared to islands with open access. However, breeding densities in those unprotected islands were higher than in protected islands in the early years of the study. We found that the most important factors affecting pair numbers in islands are island size and the time it has been inhabited, in addition to island distance from the islands southeast of Helsinki, where breeding expansion started. Island protection had no effect on the breeding geese numbers or current densities on the islands. Results indicate that early breeders like Barnacle Geese do not benefit from island protection probably because the recreational use of the islands is scant early in the spring.