Den här boken täcker tio övergripande naturvetenskapliga teman inom ämnena kemi, fysik, ekologi, mikrobiologi, geovetenskap och teknik. Innehållet har oftast sin utgångspunkt i vardagsfenomen som barnen själva uppmärksammar. I varje kapitel får man följa barns upplevelser av, frågor om och förståelser för olika naturvetenskapliga fenomen. Genom undersökningar och aktiviteter som är beskrivna i boken utvecklar barnen sina resonemang och får ökade insikter och ett vidgat perspektiv. Boken innehåller inte bara barnens kommentarer utan en dialog mellan barn och pedagog. Genom produktiva frågor och resonemang kopplade till aktiviteter hjälper pedagogen barnen att utveckla en ökad förståelse för naturvetenskap. Dialogen innehåller också lärarens barnanpassade förklaringar för att illustrera hur man på ett enkelt sätt kan göra avancerade naturvetenskapliga fenomen begripliga för barn. 

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.

More than three million farmed mallards are released annually for hunting purposes in Europe. The ecological impact of these releases depends on how many birds survive to join the wild breeding population. We estimated annual survival in farmed-released and wild-caught Swedish mallards, using mark-recapture data. In 2011–2018, we ringed 13,533 farmed ducklings before release (26.5% recovered). Most recoveries were birds shot at the release site, while only about 4% were found >3 km away. In 2002–2018, 19,820 wild mallards were ringed in Sweden, yielding 1369 (6.9%) recoveries. Like in farmed-released birds, most recoveries were by hunting, but 91.1% of recovered wild mallards were >3 km away from the ringing site. Annual survival rate in farmed-released mallards (ringed as pulli) was 0.02. In wild mallards (ringed as fledged or fully grown), annual survival was lower in females (0.64) than in males (0.71). At two sites in 2018, farmed ducklings were released in two batches 3 weeks apart to study the effect of early versus late release date, while controlling for body condition (BCI). Ducklings released early had a higher BCI and were recovered earlier (lower longevity) than those released late. Individual BCI and longevity were not correlated in recovered ducklings. Based on our estimate of annual survival in farmed-released mallards, a substantial number, i.e., 5000 (95% CI, 3040–6960), join the wild population annually. Despite being fed, a large proportion of released ducklings does not survive until the hunting season. Early releases may maximize pre-hunting survival. Repeated releases may prolong hunting opportunities and increase hunting bags.

• Gäss och svanar förekommer idag i större antal nära fler människor än någonsin tidigare, i Sverige och i övriga Västeuropa.

• De ökande antalen leder ibland till problem och konflikter. På jordbruksmark kan gäss och svanar orsaka kostsamma skador på oskördade grödor. Hårt bete kan också påverka naturlig växtlighet och då bli ett naturvårdsproblem.

• Gäss och svanar är vegetarianer och äter enbart blad, stjälkar, frön och rotdelar från växter, både på land och i vatten.

• Bete på växande grödor kan också skapa intressekonflikter i områden där gäss samlas i stora antal, till exempel vid skyddade och restaurerade våtmarker.

• Samtidigt bidrar gässen med många ekosystemtjänster, bland andra i form av naturupplevelser, jakt och kött. GÄSS OCH SVANAR SOM NÄRINGSTRANSPORTÖRER

• Gäss och svanar har en relativt sett näringsfattig kost och en ganska ineffektiv matsmältning. Därför måste de äta mycket och producerar följaktligen stora  mängder avföring.

• Dessa fåglar hittar mycket av sin föda på land, men vilar en stor del av dygnet  på våtmarker, där de också bajsar.

• Under höst, vinter och vår gör gäss och svanar omfattande dagliga förflyttningar  mellan födoplatser och viloplatser. De blir därmed naturliga transportörer av näringsämnen till våtmarker och sjöar.ÖVERGÖDNING I VATTENDRAG

• Under häckningstiden på sommaren är de flesta gäss och svanar glest utspridda över stora områden, samtidigt som flera arter häckar i våtmarker och sjöar som är naturligt näringsfattiga. Under dessa omständigheter är fåglarnas näringstransport från land till vattenmiljöer en naturlig process som snarast bidrar till ett rikare växt- och djurliv.

• Våtmarker där gäss och svanar samlas i stora antal under höst, vinter och vår  är dock sällan näringsfattiga, och många av dem har redan problem med över- gödning genom näringsläckage från jordbruksmark. Övergödning kan leda till  algblomning, försämrad vattenkvalitet och andra oönskade förändringar i våtmarks- ekosystemet.

• I områden som redan har problem med övergödning kan gäss och svanar göra att problemen ökar. Särskilt känsliga är små vattensamlingar med begränsat till- och utflöde, men också de som sommartid har kraftig avdunstning i kombination med stora antal fåglar.

• En betydande del av den samlade näringstillförseln till våtmarker sker under den tid på året då växterna är inaktiva och alltså inte tar upp näringsämnen. Detta leder till att de senare antingen sedimenterar (och frigörs en annan årstid), eller att de transporteras nedströms och kan orsaka övergödning där.

• Ett räkneexempel visar att 2 000 gäss som uppehåller sig i en våtmark i fyra månader kan bidra med 160 kg kväve och 40–80 kg fosfor. I vilken mån detta är problematiskt beror på hur mycket samma område påverkas av näringsläckage från jordbruk och andra mänskliga källor.

• Kunskapssammanställningen ger exempel på åtgärder man kan vidta för att öka eller minska en våtmarks attraktivitet för gäss och svanar.

• Swans and geese occur in larger numbers near more people than ever before, in Sweden as well as in Western Europe.

• Increasing populations sometimes lead to problems and conflicts. On agricultural land geese and swans can cause costly damage to growing crops. Intense grazing by these birds may also affect natural vegetation, sometimes leading to conflict with conservation and biodiversity goals.

• Geese and swans are obligate herbivores, consuming leaves, stems, seeds and root parts of terrestrial and aquatic plants.

• Grazing on growing crops may cause conflicts of interest also when geese and swans congregate in large numbers in wetlands adjacent to cropland.

• Geese and swans provide a multitude of ecosystem services, for example viewing, hunting, meat, and eco-tourism revenues. GEESE AND SWANS AS VECTORS OF NUTRIENTS

• Geese and swans eat large amounts of plant material, have a relatively inefficient digestive system, and produce a lot of droppings.

• These birds find most of their food on land, but spend a large part of the day  resting on wetlands, where they also defecate.

• In autumn, winter and spring most geese and swans make daily flights between feeding and roost sites, thereby becoming vectors of nutrients to wetlands and lakes

Many goose populations have increased dramatically over the past decades, which may influence inland waters used as roost sites. We reviewed the role of geese in the influx of nitrogen and phosphorus to freshwater systems. Several methods have been used to estimate guanotrophication impacts of geese. Water and sediment analysis have been conducted in areas of high and low geese presence; however, productive wetlands tend to attract more birds, and the causality is therefore ambiguous. Faecal addition experiments have attempted to estimate the impacts of droppings on water chemistry, sediments, algal growth, or invertebrate densities. The most common method of estimating goose guanotrophication is by extrapolation, usually based on multiplication of faecal production and its nutrient content. Based on such studies and those including information about daily migration patterns, we developed an approach to improve estimates of the nutrient contribution of geese. The relative role of geese in wetland eutrophication is also affected by the influx from alternative sources. The greatest guanotrophication impacts are likely found in areas with few alternative nutrient sources and with large goose flocks. Limited inflow and outflow of a freshwater system or a scarcity of wetland roosts may also increase problems at a local scale. Although several studies have looked at the impacts of geese on, for example, water chemistry or soil sediments, the effects are often smaller than expected, in part because no study to date has assessed the ecosystem response by including impacts on all levels, including water nutrient levels, nutrient sedimentation, chlorophyll content, and zooplankton response.

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.