| 1. |
- Dalby, Lars, et al.
(författare)
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The status of the Nordic populations of the Mallard (Anas platyrhynchos) in a changing world
- 2013
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Ingår i: Ornis Fennica. - : Finnish Omithological Soc. - 0030-5685. ; 90:1, s. 2-15
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Tidskriftsartikel (refereegranskat)abstract
- Dabbling ducks (Anas spp.) are importantmigratory quarry species, protected as a shared resource under international legislation. However, there is a lack of sufficient high-quality data on vital demographic rates and long-term trends in numbers to judge the conservation status of many duck populations at the flyway level. In response to reported declines in the North-West European flyway population of theMallard, we compiled available data on this species in the Nordic countries up to 2010. Generally, national breeding numbers showed increasing trends, wintering abundance showed variable trends, and productivitymeasures indicated stable or increasing trends.Major knowledge gaps were identified, namely the size of hunting bags, the influence of the released Mallards and the role of short-stopping in explaining changing patterns of wintering abundance across the North-West European flyway. Numerically the Nordic breeding population appears in “good condition”, and the wintering numbers have been either stable or increasing in the last two decades. The annual number of releases needs to be determined in order to judge the sustainability of the current levels of exploitation. Overall, none of the indicators showed alarming signs for the Mallard population in the Nordic countries when considered in isolation. However, the widespread decline in wintering numbers elsewhere across North-western Europe requires urgent pan-European action.
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| 2. |
- Elmberg, Johan, 1960-, et al.
(författare)
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Hur utsatta är utsatta änder?
- 2012
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Ingår i: Vår fågelvärld. - 0042-2649. ; 71:2, s. 40-42
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Utsättningar av djur och växter har förekommit mycket länge. Slottens svandammar har kommit till av detta skäl, godsen har satt ut jaktbart vilt. Jordbruk och skogsbruk bygger på idén att plantera ut för att sedan skörda, och även naturvården ägnar sig åt ”stödutplanteringar”. Ingen fågelart sätts ut i så stora antal som gräsanden. Men vad är det för änder det handlar om? Vilka blir effekterna?
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| 3. |
- Elmberg, Johan, 1960-, et al.
(författare)
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Utsatta änder inte som vilda
- 2018
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Ingår i: Svensk Jakt. ; :10, s. 51-51
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 4. |
- Elmberg, Johan, 1960-, et al.
(författare)
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Vad händer med utsatta änder?
- 2012
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Ingår i: Svensk Jakt. - 0039-6583. ; 150:8, s. 88-89
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 5. |
- Söderquist, Pär, et al.
(författare)
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Effects of released farmed mallards on species richness of breeding waterbirds and amphibians in natural, restored and constructed wetlands
- 2021
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Ingår i: Wildlife Biology. - 0909-6396 .- 1903-220X. ; 2021, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 6. |
- Söderquist, Pär, et al.
(författare)
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Effekter av utsättningar av farmade änder ämnade för jakt
- 2018
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Ingår i: Man and Biosphere Health –. - Kristianstad : Högskolan Kristianstad. - 9789187973352 ; , s. 41-47
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- I över 40 år har det i Sverige pågått ett storskaligt, ekologiskt experiment där hundratusentals gräsänder årligen har fötts upp i fångenskap och satts ut i våtmarker för att öka på den jaktbara populationen. Genom uppfödning i fångenskap riskerar man att de farmade gräsänderna blir annorlunda gentemot de vilda. För att studera effekterna på den vilda populationen av dessa utsättningar startades 2010 ett doktorandprojekt finansierat av Naturvårdsverket. Projektet kom fram till att farmade änder skiljer sig i beteende och utseende mot de vilda. Det går även att genetiskt skilja på farmade och vilda gräsänder. Ett nytt projekt startades 2017 för att vidare studera effekter av utsättningar, nu även på miljön och den biologiska mångfalden där änderna sätts ut. Projekten om effekter av utsättningar av farmade änder involverar forskare från olika lärosäten i Sverige, men också från flera olika europeiska länder. Ett nära samarbete med olika lokala privata aktörer som uppfödare, markägare, jägare och viltmästare samt större organisationer somViltmästareförbundet och Svenska Jägareförbundet är avgörande för projektens framgång. Att kommuniceraresultaten på så väl vetenskapliga konferenser som för icke akademiker involverade i projekten samt i undervisning på Högskolan Kristianstad och på gymnasieskolor har hela tiden varit en målsättning. Projekten har också en tydlig plats i forskningsmiljön MABH vars kompetenser inom t.ex. vattenvård, sjukdomsspridning och landskapsutnyttjande kanknytas till projekten.
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| 7. |
- Söderquist, Pär, et al.
(författare)
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Longevity and migration distance differ between wild and hand-reared mallards Anas platyrhynchos in Northern Europe
- 2013
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Ingår i: European Journal of Wildlife Research. - : Springer Verlag (Germany). - 1612-4642 .- 1439-0574. ; 59:2, s. 150-166
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Tidskriftsartikel (refereegranskat)abstract
- The mallard Anas platyrhynchos is the world’s most widespread and numerous dabbling duck. It is also farmed and released to the wild by the millions each year, but the effects of this on wild populations remain little studied. By using historical national ringing–recovery data from Sweden and Finland, we here address three predictions based on previous studies: (1) longevity is higher in wild than in hand-reared mallards, (2) wild mallards migrate longer than hand-reared, and (3) migration distance in wild ducks surviving long enough to start fall migration has decreased over the last 50 years. Indeed, wild mallards lived longer than hand-reared (19 versus 9 months in Swedish birds and 13 versus 4 months in Finnish birds). Compared to wild mallards, a smaller proportion of hand-reared birds survived long enough to have the chance to enter the wild breeding population; less than 25 % of the Swedish birds and less than 10 % of the Finnish birds lived a year or longer. Wild birds migrated farther than hand-reared (mean distance in Swedish birds, 676 versus 523 km; in Finnish birds, 1,213 versus 157 km), a pattern caused by both shorter life span and lower migration speed in hand-reared birds. Mean migration distance in wild Swedish mallards was 787 km in 1947–1972 but 591 km in 1977–1993. This difference was not statistically significant, though, possibly due to the limited sample size and lack of data from the last two decades. In general, our study provides a conservative test of the predictions addressed, calling for more research about the consequences of restocking duck populations.
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| 8. |
- Söderquist, Pär, et al.
(författare)
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Survival of wild and farmed-released mallards : the Swedish example
- 2021
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Ingår i: European Journal of Wildlife Research. - 1612-4642 .- 1439-0574. ; 67:2
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 9. |
- Söderquist, Pär, et al.
(författare)
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Wild mallards have more ‘‘goose-like’’ bills than their ancestors : a case of anthropogenic influence?
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 9:12
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Tidskriftsartikel (refereegranskat)abstract
- Wild populations of the world’s most common dabbling duck, the mallard (Anas platyrhynchos), run the risk of genetic introgression by farmed conspecifics released for hunting purposes. We tested whether bill morphology of free-living birds has changed since large-scale releases of farmed mallards started. Three groups of mallards from Sweden, Norway and Finland were compared: historical wild (before large-scale releases started), present-day wild, and present-day farmed. Higher density of bill lamellae was observed in historical wild mallards (only males). Farmed mallards had wider bills than present-day and historical wild ones. Present-day wild and farmed mallards also had higher and shorter bills than historical wild mallards. Present-day mallards thus tend to have more “goose-like” bills (wider, higher, and shorter) than their ancestors. Our study suggests that surviving released mallards affect morphological traits in wild population by introgression. We discuss how such anthropogenic impact may lead to a maladapted and genetically compromised wild mallard population. Our study system has bearing on other taxa where large-scale releases of conspecifics with ‘alien genes’ may cause a cryptic invasive process that nevertheless has fitness consequences for individual birds.
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