Broadleaf retention benefits to bird diversity in mid-rotation conifer production stands

Retention forestry involves saving important forest structures for flora and fauna during the final felling of a stand, including dead wood and variable amounts of living trees, i.e. green tree retention (GTR). Here we evaluate the long-term effects on avian diversity from GTR by surveying forest birds in 32 mid-rotation stands in southern Sweden, in which broadleaf GTR was present or absent. Complementing the many studies that have assessed GTR in clear-cuts, our results indicated that bird assemblages can also benefit from broadleaf GTR several decades after final felling in conifer dominated production stands. The GTR stands harboured a higher bird abundance and species richness than the control stands without GTR, and also appears to have benefited several important guilds, such as broadleaf-associated birds and cavity nesters. However, variation in the number trees retained, the species composition of retained trees, and their environmental context within the stand (e.g. density and proximity of surrounding production trees), limited our capacity to detect threshold requirements for GTR. In summary, our study provides a "glimpse into the future" as mid-rotation production stands with such old and large retained trees are unusual in today's landscape, but are expected to become more common in the decades to come, in Sweden and many other nations. Our study thereby provides provisional support for the continued and future use of this practice, and indicates that the biodiversity contribution of retention trees continues to occur several decades into the stand's rotation

Time use and foraging behaviour in pre-breeding dabbling ducks Anas spp. in sub-arctic Norway

We studied time budgets and foraging methods in pre-breeding Mallard Anas platyrhynchos, (Eurasian) Teal Anas crecca, Wigeon Anas penelope, Pintail Anas acuta, Shoveler Anas clypeata and Gadwall Anas strepera in subarctic Norway in May. Among all six species studied, foraging accounted for the most common use of time, ranging from 19 % in male Pintail to 40–60 % in female Mallard, Teal, Pintail and Gadwall. Comfort behaviours amounted to 20–34 % of the time budget, and interaction and disturbance were marginal. Vigilance time ranged from 8 % in female Mallard to 20 % in male Pintail. Movement amounted to some 20 % of the time in most species and sexes. In Wigeon, sexes did not differ in time use, whereas in Mallard, Pintail and, in particular, Teal, females foraged more and engaged less in vigilance and interactions than did males. In addition, Teal and Mallard males engaged in the riskier foraging methods less than females, but more in those permitting vigilance. Although overlap in feeding methods was large among these species, Mallard and Teal were generalists, feeding at all depths, Wigeon foraged mainly in shallow water and Pintail foraged essentially in deep water. Our results support the income/capital breeder hypothesis with respect to males only; compared to lighter species, heavier species allocated less time to foraging but more to vigilance. We found no support for the hypothesis that long-distance migrants forage more to compensate for energy loss due to migratory flight. Foraging time in females was related to breeding phenology; early nesters spent more time feeding than later nesters.</p

Leapfrog migration and residents: New migratory habits in Swedish Greylag geese

Knowledge about intraspecific and individual variation in bird migration behavior is important to predict spatiotemporal distribution, patterns of phenology, breeding success, and interactions with the surrounding environment (e.g., human livelihoods). Such variation is key to adaptive, evolutionary responses, i.e., how individuals respond spatiotemporally to the environment to maximize fitness. In this study we used GPS location data from one to three full annual cycles from 76 Greylag geese (Anser anser) to test the hypothesis that geese originating at five latitudinally separated capture sites in Sweden have different migration strategies. We also assessed individual consistency in movement strategy over consecutive annual cycles. We used the scale-independent net squared displacement modeling framework to quantify variables of autumn and spring migration for geese from each capture site: distance, timing, and duration. Our results demonstrate a positive correlation between migration distance and latitudinal origin. Geese from the northernmost site on average migrated farther south and about 15 times as far as the short-moving or resident geese from the two southernmost sites. Movement strategies of individual geese varied considerably both within and among capture sites. Individual consistency in movement strategy from one annual cycle to the consecutive was high in geese from the northern sites moving the farthest, whereas the resident or short-moving geese from the southernmost sites generally showed lower or no individual consistency. These changes have come about during a time span so short (i.e., ca. 35 years or 8-10 generations) that it can unlikely be explained by classical Darwinian between-generation adaptation. Consequently, and given that young geese follow their parents during their first migration, we presume an important role of within-family, inter-generation change as a driver behind the large-scale changed migration habits in Swedish Greylag geese

Effects of released farmed mallards on species richness of breeding waterbirds and amphibians in natural, restored and constructed wetlands

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.Peer reviewe

Changes in species richness and composition of boreal waterbird communities : a comparison between two time periods 25 years apart

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.Peer reviewe

Migration patterns of Swedish Greylag geese Anser anser-implications for flyway management in a changing world

Significant population growth of some European goose populations has led to initiatives to implement management at the flyway level. Understanding migration routes and spatiotemporal distribution is crucial for the successful and coordinated management of migratory species such as geese. In this study, we describe movements across the entire annual cycle in 76 Greylag geese (Anser anser) fitted with GPS tracking devices at five catch sites in Sweden. We show that Greylag geese breeding in Sweden still use a NE-SW migration path. However, the wintering range has undergone a northward shift during the last decades. Compared to previous studies, our data suggest a continued reduction in migration distance, being most pronounced in birds in southernmost Sweden. Greylag geese tagged in southernmost Sweden spent almost the entire annual cycle in Sweden and Denmark (97 and 100% of all GPS locations). In contrast, the flyway of Greylag geese from the northern catch sites still covers countries from Sweden to Spain, but presently, only a small fraction of the population migrates to Spain. Instead, most of the annual cycle is spent in Sweden, Denmark, the Netherlands, or Germany. The contrasting spatiotemporal distribution in geese of different geographical origin indicates that management initiatives for the NW/SW European Greylag Goose population need to consider that different migration strategies occur within previously defined management units. As a consequence, coordination of management actions (e.g. monitoring, harvest quotas, reserves) may need to consider different spatial scales, i.e. from the regional to the international scale depending on the origin of the Greylag geese

Individuals and Multilevel Management: A Study of the Perceived Adaptive Capacity of the Goose Management System among Farmers in Sweden

Agricultural damage by geese is a growing problem in Europe and farmers play a key role in the emerging multilevel adaptive management system. This study explored how characteristics associated with the farmer and the farm, along with experience of damage, cognitive appraisals, emotions, and management beliefs were associated with the perceived adaptive capacity of the goose management system among farmers in the south of Sweden (n = 1,067). Survey results revealed that owning a larger farm, a farm closer to water or formally protected areas, along with cultivating cereal and root crops, were associated with geese evoking stronger negative emotions. Further, more previous experience of damage was related to stronger negative emotions and lower levels of perceived adaptive capacity. However, even more important determinants of perceived adaptive capacity were cognitive appraisals, emotions, and management beliefs. Bridging the ties between individual farmers and the system is important for improved multilevel management