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  • 1.
    Arzel, Céline
    et al.
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Stervander, Martin
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Simändernas ekologi studeras närmare2003Inngår i: Vår fågelvärld, ISSN 0042-2649, Vol. 62, nr 4, 25- s.Artikkel i tidsskrift (Annet vitenskapelig)
  • 2.
    Bengtsson, Daniel
    et al.
    Linnaeus University.
    Avril, Alexis
    Linnaeus University.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Elmberg, Johan
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Söderquist, Pär
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Norevik, Gabriel
    Ottenby Bird Observatory.
    Tolf, Conny
    Linnaeus University.
    Safi, Kamran
    Max Planck Institute for Ornithology.
    Fiedler, Wolfgang
    Max Planck Institute for Ornithology.
    Wikelski, Martin
    Max Planck Institute for Ornithology.
    Olsen, Bjorn
    Uppsala University.
    Waldenstrom, Jonas
    Linnaeus University.
    Movements, home-range size and habitat selection of mallards during autumn migration2014Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, nr 6, e100764- s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mallard (Anas platyrhynchos) is a focal species in game management, epidemiology and ornithology, but comparably little research has focused on the ecology of the migration seasons. We studied habitat use, time-budgets, home-range sizes, habitat selection, and movements based on spatial data collected with GPS devices attached to wild mallards trapped at an autumn stopover site in the Northwest European flyway. Sixteen individuals (13 males, 3 females) were followed for 15-38 days in October to December 2010. Forty-nine percent (SD = 8.4%) of the ducks' total time, and 85% of the day-time (SD = 28.3%), was spent at sheltered reefs and bays on the coast. Two ducks used ponds, rather than coast, as day-roosts instead. Mallards spent most of the night (76% of total time, SD = 15.8%) on wetlands, mainly on alvar steppe, or in various flooded areas (e.g. coastal meadows). Crop fields with maize were also selectively utilized. Movements between roosting and foraging areas mainly took place at dawn and dusk, and the home-ranges observed in our study are among the largest ever documented for mallards (mean = 6,859 ha; SD = 5,872 ha). This study provides insights into relatively unknown aspects of mallard ecology. The fact that autumn-staging migratory mallards have a well-developed diel activity pattern tightly linked to the use of specific habitats has implications for wetland management, hunting and conservation, as well as for the epidemiology of diseases shared between wildlife and domestic animals.

  • 3.
    Bengtsson, Daniel
    et al.
    Linnaeus University.
    Safi, Kamran
    Tyskland.
    Avril, Alexis
    Linnaeus University.
    Fiedler, Wolfgang
    Tyskland.
    Wikelski, Martin
    Tyskland.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH).
    Elmberg, Johan
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH).
    Tolf, Conny
    Linnaeus University.
    Olsen, Björn
    Uppsala University.
    Waldenström, Jonas
    Linnaeus University.
    Does influenza A virus infection affect movement behaviour during stopover in its wild reservoir host?2016Inngår i: Royal Society Open Science, E-ISSN 2054-5703, Vol. 3, nr 2, 150633Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The last decade has seen a surge in research on avian influenza A viruses (IAVs), in part fuelled by the emergence, spread and potential zoonotic importance of highly pathogenic virus subtypes. The mallard (Anas platyrhynchos) is the most numerous and widespread dabbling duck in the world, and one of the most important natural hosts for studying IAV transmission dynamics. In order to predict the likelihood of IAV transmission between individual ducks and to other hosts, as well as between geographical regions, it is important to understand how IAV infection affects the host. In this study, we analysed the movements of 40 mallards equipped with GPS transmitters and three-dimensional accelerometers, of which 20 were naturally infected with low pathogenic avian influenza virus (LPAIV), at a major stopover site in the Northwest European flyway. Movements differed substantially between day and night, as well as between mallards returning to the capture site and those feeding in natural habitats. However, movement patterns did not differ between LPAIV infected and uninfected birds. Hence, LPAIV infection probably does not affect mallard movements during stopover, with high possibility of virus spread along the migration route as a consequence.

  • 4. Bengtsson, Daniel
    et al.
    Waldenström, Jonas
    Elmberg, Johan
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH).
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Änders rörelser kartlagda2014Inngår i: Vår fågelvärld, ISSN 0042-2649, Vol. 73, nr 5, 46-48 s.Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 5.
    Blomqvist, Maria
    et al.
    Section of Clinical Bacteriology, Department of Medical Sciences, Uppsala University.
    Christerson, Linus
    Section of Clinical Bacteriology, Department of Medical Sciences, Uppsala University.
    Waldenström, Jonas
    Section for Zoonotic Ecology and Epidemiology, Linnaeus University, Kalmar.
    Lindberg, Peter
    Department of Contaminant Research, Swedish Museum of Natural History, Stockholm.
    Helander, Björn
    Department of Zoology, Gothenburg University.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Sektionen för lärande och miljö.
    Herrman, Björn
    Section of Clinical Bacteriology, Department of Medical Sciences, Uppsala University.
    Olsen, Björn
    Section of Infectious Diseases, Department of Medical Sciences, Uppsala University.
    Chlamydia psittaci in birds of prey, Sweden2012Inngår i: Infection Ecology and Epidemiology, ISSN 2000-8686, Vol. 2, 8435- s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Chlamydia psittaci is an intracellular bacterium primarily causing respiratory diseases in birds but may also be transmitted to other animals, including humans. The prevalence of the pathogen in wild birds in Sweden is largely unknown. Methods: DNA was extracted from cloacae swabs and screened for C. psittaci by using a 23S rRNA gene PCR assay. Partial 16S rRNA and ompA gene fragments were sequence determined and phylogenies were analysed by the neighbour-joining method. Results and conclusion: The C. psittaci prevalence was 1.3% in 319 Peregrine Falcons and White-tailed Sea Eagles, vulnerable top-predators in Sweden. 16S rRNA and ompA gene analysis showed that novel Chlamydia species, as well as novel C. psittaci strains, are to be found among wild birds.

  • 6. Blomqvist, Maria
    et al.
    Christerson, Linus
    Waldenström, Jonas
    Lindberg, Peter
    Helander, Björn
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Sektionen för lärande och miljö.
    Herrman, Björn
    Olsen, Björn
    Prevalence of Chlamydophila psittaci in Swedish birds2011Konferansepaper (Fagfellevurdert)
  • 7.
    Elmberg, Johan
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö.
    Dessborn, Lisa
    Högskolan Kristianstad, Sektionen för lärande och miljö.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Sektionen för lärande och miljö.
    Nummi, Petri
    Helsingfors universitet.
    Pöysä, Hannu
    Finska vilt- och fiskeriforskningsinstitutet.
    Sjöberg, Kjell
    Sveriges lantbruksuniversitet, Umeå.
    Forskare vill ha inventering före fågeljakt2008Inngår i: Jakt och Jägare, ISSN 1401-8306, nr 6, 45- s.Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 8.
    Elmberg, Johan
    et al.
    Högskolan Kristianstad, Sektionen för Lärarutbildning.
    Folkesson, Karin
    Högskolan Kristianstad, Sektionen för Lärarutbildning.
    Guillemain, Matthieu
    Office National de la Chasse et de la Faune Sauvage, CNERA Avifaune Migratrice, La Tour du Valat, Le Sambuc, Arles.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Sektionen för Lärarutbildning.
    Putting density dependence in perspective: nest density, nesting phenology, and biome, all matter to survival of simulated mallard Anas platyrhynchos nests2009Inngår i: Journal of Avian Biology, ISSN 0908-8857, E-ISSN 1600-048X, Vol. 40, nr 3, 317-326 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Breeding success in ground-nesting birds is primarily determined by nest survival, which may be density-dependent, but the generality of this pattern remains untested. In a replicated crossover experiment conducted on 30 wetlands, survival of simulated mallard nests was related to "biome" (n=14 mediterranean and 16 boreal wetlands), breeding "phenology" (early vs late nests), and "density" (2 vs 8 nests per 225 m shoreline). Local abundances of "waterfowl", "other waterbirds", and "avian predators" were used as covariates. We used an information-theoretic approach and Program MARK to select among competing models. Nest survival was lower in late nests compared with early ones, and it was lower in the mediterranean than in the boreal study region. High-density treatment nests suffered higher depredation rates than low-density nests during days 1-4 of each experimental period. Nest survival was negatively associated with local abundance of "waterfowl" in the boreal but not in the mediterranean biome. Effect estimates from the highest-ranked model showed that nest "density" (d 1-4) had the strongest impact on model fit; i.e. three times that of "biome" and 1.5 times that of "phenology". The latter's effect, in turn, was twice that of "biome". We argue that our study supports the idea that density-dependent nest predation may be temporally and spatially widespread in waterfowl. We also see an urgent need for research of how waterfowl nesting phenology is matched to that of prey and vegetation.

  • 9.
    Elmberg, Johan
    et al.
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Density-dependent nest predation in mallards Anas platyhynchos: patterns and implications2006Konferansepaper (Fagfellevurdert)
  • 10.
    Elmberg, Johan
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Sektionen för lärande och miljö.
    Konstgjorda reden ger riktiga svar2011Inngår i: Svensk Jakt, Vol. 1, 92-94 s.Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
    Abstract [sv]

    Häckningen är en känslig och farlig fas i fåglarnas årliga cykel. Många rovdjur utgör ett hot mot ägg och ungar. Viltforskare vid Högskolan Kristianstad berättar här om nya rön om samspelet mellan gräsänder och de rovdjur som rövar deras bon.

  • 11.
    Elmberg, Johan
    et al.
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Manipulated density of adult mallards affects nest survival differently in different landscapes2007Inngår i: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 85, nr 5, 589-595 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Breeding success in many birds including wildfowl is mainly determined by nest predation. Few studies address cues used by predators to find duck nests, and the same is true for spacing patterns that ducks might use to reduce predation. We designed a crossover experiment in agricultural and forested settings to test the assumption that nest predation rate is related to density of adult birds on a lake. We used introduced wing-clipped mallards (Anas platyrhynchos L., 1758) to increase local pair density and semi-natural nests to assess predation rate. Depredation patterns were analyzed by model fitting in program MARK, using introduction and landscape type as main effects and abundance of avian predators and wild waterbirds as covariates. Depredation was higher at agricultural lakes than at forest lakes. Nest survival decreased with increasing abundance of wild waterfowl, whereas it tended to increase with the abundance of "other waterbirds". There was a landscape-dependent effect of increased mallard pair density: positive at agricultural lakes and negative at forest lakes. Avian predators found 91% of depredated "known-predator" nests at agricultural lakes and 25% at forest lakes; mammals found 9% at agricultural lakes and 75% at forest lakes. The landscape-dependent density effect may in part be due to different predator communities in these landscape types.

  • 12.
    Elmberg, Johan
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Svältrisk orsak till att flera västerbottniska sjöar saknar häckande änder2012Inngår i: Fåglar i Västerbotten, ISSN 0348-1166, Vol. 37, nr 1, 10-13 s.Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 13.
    Elmberg, Johan
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Sektionen för lärande och miljö.
    Änder klarar sig bättre utan grannar2012Inngår i: Anser, ISSN 0347-9595, Vol. 51, nr 1, 22-27 s.Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
    Abstract [sv]

    Häckningen är på många sätt den viktigaste delen av fåglarnas årscykel, men den är också en av de farligaste.

    Ett bo fullt med ägg är ju en fantastisk måltid för många rovdjur. mFågelekologer vid Högskolan Kristianstad berättar här om nya rön om samspelet mellan gräsänder och de rovdjur som gillar deras bon. Det finns mycket att vinna för de änder som häckar vid rätt tidpunkt och placerar sina bon på rätt ställe!

  • 14.
    Elmberg, Johan
    et al.
    Högskolan Kristianstad, Sektionen för Lärande och Miljö.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Sektionen för Lärande och Miljö.
    Dessborn, Lisa
    Högskolan Kristianstad, Sektionen för Lärande och Miljö.
    Jonzén, Niklas
    Pöysä, Hannu
    Valkama, Jari
    Gräsandens liv och död2008Inngår i: Svensk Jakt, nr 10, 82-84 s.Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 15.
    Elmberg, Johan
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Nummi, Petri
    Finland.
    Pöysä, Hannu
    Finland.
    Sjöberg, Kjell
    SLU.
    Density dependent breeding success in mallards2003Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Breeding success in wild mallards was studied on small eutrophic nemoral lakes in a two-year cross-over experiment in which wing-clipped conspecifics were added to increase pair density. The number of wild mallards that came to the lakes to nest (prior to introductions) did not differ between years. Introduction treatment led to a significant reduction in brood number in wild mallards, but it did not alter the number of stage 2+ ducklings finally produced on a lake. Introduction had no effect on lake utilization by broods, ducklings and non-breeding adults (cumulative days over the entire breeding season). Abundance of invertebrate prey differed greatly among lakes, but it did not correlate with breeding success. Breeding success was thus subject to sequential density-dependence; i.e. a lower number of broods still produced the same number of 2+ ducklings. We speculate that predation is the most likely process behind both patterns. We conclude that late and snapshot measures of duckling productivity may mask density dependent population processes of fundamental importance to regulation and harvest policy.

  • 16.
    Elmberg, Johan
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Nummi, Petri
    Pöysä, Hannu
    Sjöberg, Kjell
    Farligt att vara andägg2002Inngår i: Svensk jakt, ISSN 0039-6583, Vol. 140, nr 10, 18-20 s.Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 17.
    Elmberg, Johan
    et al.
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Pöysä, Hannu
    Finska vilt- & fiskeriforskningsinstitutet, Joensuu.
    Nummi, Petri
    Helsingfors universitet.
    Sjöberg, Kjell
    Sveriges lantbruksuniversitet, Umeå.
    Hur många får ligga i orubbat bo?2003Inngår i: Vår fågelvärld, ISSN 0042-2649, nr 3, 28-29 s.Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 18.
    Elmberg, Johan
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Pöysä, Hannu
    Finland.
    Sjöberg, Kjell
    SLU, Umeå.
    Nummi, Petri
    Finland.
    Within-season sequential density dependence regulates breeding success in mallards Anas platyrhynchos2005Inngår i: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 108, 582-590 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Density dependence in vital rates is a key issue in population ecology but remains largely unexplored experimentally. We studied breeding success, lake use, and prey availability in wild mallards Anas platyrhynchos on small nemoral lakes in a replicated, two-year cross-over experiment in which pair density was increased. The number of wild mallards that settled on lakes prior to introductions of extra pairs did not differ between control and introduction years. Introductions led to a lake-level reduction in the number of broods observed. However, the number of stage 2/ (almost fledged) ducklings did not differ between treatments, nor did lake utilization by nonbreeding adults, broods and ducklings. Prey resource availability differed greatly among lakes, but it did not correlate with breeding success. Partialling out the possible effect of food competition from wild adult nonbreeding mallards did not change this conclusion. Our study demonstrates sequential density dependence in breeding success; introductions caused a decrease in brood number, but despite fewer broods a similar number of nearly fledged ducklings were produced. We suggest that predation and/or lake change of broods soon after hatching created these patterns. We conclude that using a single and late measure of breeding success such as fledged birds can mask regulatory processes. Implications of density dependence and its relation to individual reproductive success are understood better if breeding success is decomposed into nest success, duckling survival and fledgling survival.

  • 19.
    Elmberg, Johan
    et al.
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Pöysä, Hannu
    Finnish Game and Fisheries Research Institute, Joensuu Game and Fisheries Research.
    Sjöberg, Kjell
    Department of Animal Ecology, Swedish University of Agricultural Sciences, Umeå.
    Nummi, Petri
    Department of Applied Biology, University of Helsinki.
    Within-season sequential density dependence regulates breeding success in mallards (Anas platyrhynchos)2005Inngår i: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 108, nr 3, 582-590 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Density dependence in vital rates is a key issue in population ecology but remains largely unexplored experimentally. We studied breeding success, lake use, and prey availability in wild mallards Anas platyrhynchos on small nemoral lakes in a replicated, two-year cross-over experiment in which pair density was increased. The number of wild mallards that settled on lakes prior to introductions of extra pairs did not differ between control and introduction years. Introductions led to a lake-level reduction in the number of broods observed. However, the number of stage 2+ (almost fledged) ducklings did not differ between treatments, nor did lake utilization by nonbreeding adults, broods and ducklings. Prey resource availability differed greatly among lakes, but it did not correlate with breeding success. Partialling out the possible effect of food competition from wild adult nonbreeding mallards did not change this conclusion. Our study demonstrates sequential density dependence in breeding success; introductions caused a decrease in brood number, but despite fewer broods a similar number of nearly fledged ducklings were produced. We suggest that predation and/or lake change of broods soon after hatching created these patterns. We conclude that using a single and late measure of breeding success such as fledged birds can mask regulatory processes. Implications of density dependence and its relation to individual reproductive success are understood better if breeding success is decomposed into nest success, duckling survival and fledgling survival.

  • 20.
    Elmberg, Johan
    et al.
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Sjöberg, Kjell
    Nummi, Petri
    Pöysä, Hannu
    Finns det mer andrum?2005Inngår i: Svensk jakt, ISSN 0039-6583, Vol. 143, nr 8, 80-82 s.Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 21.
    Elmberg, Johan
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Waldenström, Jonas
    Latorre-Margalef, Neus
    Olsen, Björn
    Vart tog fågelinfluensan vägen?2010Inngår i: Vår fågelvärld, Vol. 69, nr 3, 8-12 s.Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 22.
    Elmberg, Johan
    et al.
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Nummi, Petri
    Department of Applied Biology, University of Helsinki.
    Pöysä, Hannu
    Finnish Game and Fisheries Research Institute, Joensuu Game and Fisheries Research.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Sjöberg, Kjell
    Department of Animal Ecology, wedish University of Agricultural Sciences, Umeå.
    Early breeding teal Anas crecca use the best lakes and have the highest reproductive success2005Inngår i: Annales Zoologici Fennici, ISSN 0003-455X, Vol. 42, nr 1, 37-43 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Teal (Anas crecca) broods were studied in 1988-2003 in a boreal watershed comprising 51 permanent wetlands. Brood size of near-fledged ducklings was negatively related to the hatching date, i.e. early pairs had higher reproductive success than late pairs. However, brood size of newly hatched ducklings was not related to the hatching date, implying that the advantage of early breeding is due to processes operating during the brood stage rather than during nesting. Half of the lakes never produced a brood, and among the 26 lakes that actually did, two `preferred' lakes generated 44% of the broods and 55% of the near-fledged ducklings. Early broods were over-represented on such `preferred' lakes, and late broods over-represented on `less preferred' lakes. Our study suggests that lake selection and early nesting may have important fitness consequences in teal.

  • 23.
    Elmberg, Johan
    et al.
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Nummi, Petri
    Pöysä, Hannu
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Sjöberg, Kjell
    Krickan - okänd kändis som vet att välja rätt sjö2005Inngår i: Vår fågelvärld, ISSN 0042-2649, Vol. 64, nr 3, 32-33 s.Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 24.
    Elmberg, Johan
    et al.
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Nummi, Petri
    Finland.
    Pöysä, Hannu
    Finland.
    Sjöberg, Kjell
    Swedish University of Agricultural Sciences, Umeå.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Clausen, Preben
    Danmark.
    Guillemain, Matthieu
    Frankrike.
    Rodrigues, David
    Portugal.
    Väänänen, Veli-Matti
    Finland.
    The scientific basis for a new and sustainable management of migratory European ducks2006Inngår i: Wildlife Biology, ISSN 0909-6396, E-ISSN 1903-220X, Vol. 12, nr 2, 121-127 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It is an axiom in ecology that knowing the sheer number of individuals in a population is of very little help if the objective is to understand future and past changes in population size. Yet, this is exactly how migratory European ducks are monitored, many of which are important quarry species in several countries. We argue that present monitoring is insufficient to address objectives of wise use and sustainability such as those emphasised in recent management directives and multilateral international agreements. The two main problems are the almost total lack of reliable data on recruitment and mortality. We advocate a pan-European monitoring system based on undisputed scientific principles; i.e. a long-term, coordinated and standardised scheme that produces data about vital rates of duck populations as well as about harvest size. Data from such a scheme can be used by game biologists to produce predictive tools, thus providing a functional basis for management decisions for adaptive harvesting and conservation alike.

  • 25.
    Elmberg, Johan
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö.
    Söderquist, Pär
    Högskolan Kristianstad, Sektionen för lärande och miljö.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Sektionen för lärande och miljö.
    Vad händer med utsatta änder?2012Inngår i: Svensk Jakt, ISSN 0039-6583, Vol. 150, nr 8, 88-89 s.Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 26.
    Elmberg, Johan
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH).
    Söderquist, Pär
    Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH). Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH).
    Thulin, Carl-Gustaf
    SLU, Umeå.
    Champagnon, Jocelyn
    Frankrike.
    Guillemain, Matthieu
    Frankrike.
    Kreisinger, Jakub
    Tjeckien.
    Prins, H. H. T.
    Nederländerna.
    Crooijmans, R. P. M. A.
    Nederländerna.
    Kraus, R. H. S.
    Tyskland.
    Farmed European mallards are genetically different and cause introgression in the wild population following releases2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The practice of restocking already viable populations to increase harvest potential has since long been common in forestry, fisheries and wildlife management. The potential risks of restocking native species have long been overshadowed by the related issue of invasive alien species. However, during the last decade releases of native species with potentially non-native genome have received more attention. A suitable model to study genetic effects of large-scale releases of native species is the Mallard Anas platyrhynchos, being the most widespread duck in the world, largely migratory, and an important quarry species. More than 3 million unfledged hatchlings are released each year around Europe to increase local harvest. The aims of this study were to determine if wild and released farmed Mallards differ genetically, if there are signs of previous or ongoing introgression between wild and farmed birds, and if the genetic structure of the wild Mallard population has changed since large-scale releases started in Europe in the 1970s. Using 360 Single Nucleotide Polymorphisms (SNPs) we found that the genetic structure differed among historical wild, present-day wild, and farmed Mallards in Europe. We also found signs of introgression in the wild Mallard population, that is, individuals with a genetic background of farmed stock are part of the present free-living population. Although only a small proportion of the released Mallards appears to survive to merge with the free-living breeding population, their numbers are still so large that the genetic impact may have significance for the wild population in terms of individual survival and longterm fitness.

  • 27. Gillman, Anna
    et al.
    Muradrasoli, Shaman
    Söderström, Hanna
    Holmberg, Fredrik
    Latorre-Margalef, Neus
    Tolf, Conny
    Waldenström, Jonas
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Olsen, Björn
    Järhult, Josef D
    Oseltamivir-Resistant Influenza A (H1N1) Virus Strain with an H274Y Mutation in Neuraminidase Persists without Drug Pressure in Infected Mallards2015Inngår i: Applied and Environmental Microbiology, ISSN 0099-2240, E-ISSN 1098-5336, Vol. 81, nr 7, 2378-2383 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Influenza A virus (IAV) has its natural reservoir in wild waterfowl and emerging human IAVs often contain gene segments from avian viruses. The active drug metabolite of oseltamivir (oseltamivir carboxylate (OC)), stockpiled as Tamiflu® for influenza pandemic preparedness, is not removed by conventional sewage treatment and has been detected in river water. There, it may there exert evolutionary pressure on avian IAV in waterfowl, resulting in development of resistant viral variants. A resistant avian IAV can circulate among wild birds only if resistance does not restrict viral fitness and if the resistant virus can persist without continuous drug pressure. In this in vivo Mallard (Anas platyrhynchos) study we tested if an OC-resistant avian IAV strain (A(H1N1)/NA-H274Y) could retain resistance while drug pressure was gradually removed. Successively infected Mallards were exposed to decreasing levels of OC, and fecal samples were analyzed for neuraminidase sequence and phenotypic resistance. No reversion to wild-type virus was observed during the experiment, which included 17 days of viral transmission in 10 ducks exposed to OC concentrations below resistance induction levels. We conclude that resistance in avian IAV, induced by OC exposure of the natural host, can persist in absence of the drug. Thus, there is a risk that human pathogenic IAVs that evolve from IAVs circulating among wild birds may contain resistance mutations. An oseltamivir resistant pandemic IAV would be a substantial public health threat. Therefore, our observations underscore the need for prudent oseltamivir use, upgraded sewage treatment and resistance surveillance of IAV in wild birds.

  • 28.
    Guillemain, Matthieu
    et al.
    Office National de la Chasse et de la Faune Sauvage, CNERA Avifaune Migratrice, La Tour du Valat, Le Sambuc, Arles.
    Pöysä, Hannu
    Finnish Game and Fisheries Research Institute, Joensuu Game and Fisheries Research.
    Fox, Anthony D.
    Thomas Eske Holm & Thomas Kjær Christensen, Department of Bioscience, Aarhus University.
    Arzel, Céline
    Department of Biology, Section of Ecology, University of Turku.
    Dessborn, Lisa
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Ekroos, Johan
    Centre for Environmental and Climate Research, Lund.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Eske Holm, Thomas
    Thomas Eske Holm & Thomas Kjær Christensen, Department of Bioscience, Aarhus University.
    Kjær Christensen, Thomas
    Thomas Eske Holm & Thomas Kjær Christensen, Department of Bioscience, Aarhus University.
    Lehikoinen, Aleksi
    Department of Biological and Environmental Sciences, University of Helsinki.
    Mitchell, Carl
    Wildfowl & Wetlands Trust, Slimbridge.
    Rintala, Jukka
    Finnish Game and Fisheries Research Institute, Helsinki.
    Pape Møller, Anders
    Laboratoire Ecologie Systématique et Evolution (UMR 8079), Université Paris-Sud XI, Orsay.
    Effects of climate change on European ducks: what do we know and what do we need to know?2013Inngår i: Wildlife Biology, ISSN 0909-6396, E-ISSN 1903-220X, Vol. 19, nr 4, 404-419 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The consequences of climate change for bird populations have received much attention in recent decades, especially amongst cavity-nesting songbirds, yet little has been written on ducks (Anatidae) despite these being major elements of wetland diversity and important quarry species. This paper reviews the major known consequences of climate change for birds in general, and relates these to the limited information available specifically for ducks. Climate change can influence migration distance and phenology, potentially affecting patterns of mortality, as well as distribution and reproductive success in ducks. Studies addressing effects of climate change are, however, restricted to very few duck species, including mallardAnas platyrhynchos and common eider Somateria mollissima. Shifts in winter duck distributions have been observed, whereas the mismatch hypothesis (mistiming between the periods of peak energy requirements for young and the peak of seasonal food availability) has received limited support with regard to ducks. We propose a range of monitoring initiatives, including population surveys, breeding success monitoring schemes and individual duck marking, which should later be integrated through population modelling and adaptive management to fill these gaps.

  • 29.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Richard Ottvall, 2004: Population ecology and management of waders breeding on coastal meadows.2005Inngår i: Ornis Svecica, ISSN 1102-6812, Vol. 15, nr 1, 61-62 s.Artikkel, omtale (Annet vitenskapelig)
  • 30.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH). Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Strandängarna i Kristianstads Vattenrike – hotade “hot spots”2015Inngår i: Forskningsmiljön Man & Biosphere Health: Högskolan Kristianstads miljöforskning i biosfärområde Kristianstads Vattenrike / [ed] Ingemar Jönsson, Kristianstad: Kristianstads kommun , 2015, 7-11 s.Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [sv]

    På relativt kort tid har flera arter strandängsvadare minskat dramatiskt i Kristianstads Vattenrike. Pågående forskning bedrivs för att utröna om nedgångarna kan ha orsakats av faktorer längre ner i näringsväven. I speciellt fokus för forskningen är produktionen av vegetation och ryggradslösa djur.

  • 31.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Survival patterns and density-dependent processes in breeding mallards Anas platyrhynchos2007Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Measuring and assessing vital rates such as births and deaths are prerequisites for understanding population dynamics. Vital rates may be affected by the density of individuals, even though the importance of density dependence on population dynamics has been debated for a long time. The mallard Anas platyrhynchos is one of the foremost game species in the Holarctic, with millions of birds in hunters’ bags annually. Still, basic knowledge about regulation of mallards’ vital rates is poor, and experimental studies on this topic are rare.

    In this thesis I have studied survival patterns and density dependence in mallards breeding in Sweden and Finland. Long-term ringing data from both countries were analysed for mortality patterns and causation, as well as for e.g. survival rate estimation. Most of the studies were, though, experiments run over two years involving manipulations of the density of nests, broods and/or adults, in southern and northern Sweden, comprising different biotic regions. Common response variables were survival of nests, ducklings and hens, mainly analysed with program MARK.

    About 90% of the recovered mallards in Finland and Sweden were hunting kills. However, survival rates were high, ranging from 0.66 to 0.81 for most groups (sex*age). The generality of density dependence was evident since such processes were detected in all studies. Consequently, depredation rate was higher in high nest density compared to low nest density. Survival of ducklings was density-dependent in both boreal and nemoral biotic regions, with food limitation being evident in the former region but not in the latter. In spite of their generality, density-dependent patterns varied within as well between years, and for nest predation rates also between landscape types.

    The findings about density dependence in breeding mallards in this thesis are novel since they are based on experiments. They are potentially of general interest for management because they embrace a variety of lakes in two geographically distant areas, each being representative for large temperate areas in the northern hemisphere. Detection of density dependence at the local scale may be important at larger scales, too, following the principle of ‘ideal preemptive distribution’ in a source-sink dynamic system.

  • 32.
    Gunnarsson, Gunnar
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Vem äter vad på Håslövs ängar?: mätningar av betestryck med kopplingar till det ekologiska samhället2013Konferansepaper (Annet (populærvitenskap, debatt, mm))
  • 33.
    Gunnarsson, Gunnar
    et al.
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Elmberg, Johan
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Density-dependent nest predation: an experiment with simulated Mallard nests in contrasting landscapes2008Inngår i: Ibis, ISSN 0019-1019, E-ISSN 1474-919X, Vol. 150, nr 2, 259-269 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Breeding success is a key element of animal population dynamics. In many taxa including birds, nest success, or the proportion of laid clutches that actually hatch, is mainly determined by predation. Previous research gives an inconsistent picture of the prevalence of density-dependent nest predation and one reason for this is the general lack of well-designed replicated experiments. Using simulated Mallard Anas platyrhynchos nests and a crossover design for 20 lakes in the nemoral and boreal biotic zones, we tested the predictions that nest survival is negatively density-dependent and that nest predation is higher in agricultural than in forested landscapes. Study day and daily abundance of waterfowl, other waterbirds, as well as avian predators were included as covariates in the analysis. Model fitting in program mark revealed a general negative effect of nest density on nest survival. In addition, nest survival rate was higher at forest lakes than at lakes in agricultural landscapes, irrespective of nest density. The only covariate producing model improvement was study day; older nests had higher survival rates than recently initiated ones. This is the first replicated lake-level experimental study showing that nest predation is density-dependent in waterfowl. The pattern was consistent between landscape types, implying that density-dependent nest predation may affect habitat choice and population dynamics over large parts of the Mallard's range.

  • 34.
    Gunnarsson, Gunnar
    et al.
    Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH). Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Elmberg, Johan
    Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH). Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Density-dependent nest predation in dabbling ducks2002Konferansepaper (Fagfellevurdert)
  • 35.
    Gunnarsson, Gunnar
    et al.
    Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH). Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Elmberg, Johan
    Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH). Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Predation regulates the survival of mallard nests as revealed by an experiment in two landscape types2006Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Ecological theory frequently postulates that most animal species are subject to density-dependent mechanisms in some stage of the year or life. However, few avian studies have succeeded to give evidence for regulatory mechanisms by replicated experiments in natural habitats. Breeding success is to a great extent determined by conditions during the nesting period and the major cause of nesting failure is nest predation. In addition, predators may possibly regulate fluctuating populations and to test the hypothesis that nest survival is negatively density-dependent we conducted an experiment with manipulated densities of semi-natural Mallard nests and adult pairs using 32 small to medium sized lakes (~3-5 hectares) in southern Sweden during two nesting seasons (2003-2004). Predicting that predation rates are higher in open compared to more vegetated habitats, half of the lakes were in agricultural and the other half in forest landscapes. Using real Mallard eggs, nests were constructed in two densities; either 2 nests per lake (low density) or 8 nests per lake (high density). Model fitting in program MARK revealed that nest survival was negatively affected by nest density but not by pair density. Further, predation rates were much higher in agricultural landscapes than in forested. The effects of nest density and habitat were consistent in the two years. Covariates added to the model matrix revealed a negative effect of other waterfowl present on the lakes and a positive effect of study day. However, the number of avian predators observed at the lakes did not affect survival. Our experiment is the first to demonstrate density-dependent nest predation in Mallard. The consistency of the density effect between years and habitats shows that regulatory mechanisms may be truly significant for Mallard, possibly affecting population dynamics of the species.

  • 36.
    Gunnarsson, Gunnar
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Elmberg, Johan
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Dessborn, Lisa
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Jonzén, Niclas
    Department of Theoretical Ecology, Lund University.
    Pöysä, Hannu
    Finnish Game and Fisheries Research Institute, Joensuu.
    Valkama, Jari
    Finnish Museum of Natural History, Helsinki.
    Survival estimates, mortality patterns, and population growth of Fennoscandian mallards Anas platyrhynchos2008Inngår i: Annales Zoologici Fennici, ISSN 0003-455X, Vol. 45, nr 6, 483-495 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Long-term mallard capture-recapture data from Sweden and Finland were analyzed to describe temporal mortality patterns and reasons. We used program MARK and Seber models to estimate annual survival (S) and recovery (r) rates. Survival rates were used in a Monte Carlo simulation to evaluate the correspondence between observed and predicted annual population sizes of a Finnish sub-population. About 90% of recovered birds died from hunting. Most recoveries were from the hunting season, and more males than females were shot. Predation was the most common cause of natural mortality. Finnish capture-recapture data fitted best the global model in which survival and recovery vary with age and sex. Annual survival and recovery rates for adult and juvenile males and females were overlapping, ranging from 0.46 to 0.90 (survival) and 0.07 to 0.17 (recovery), whereas pulli had lower survival rates (0.21-0.42). Pulli that were successfully sexed at the time of ringing had higher recovery rates (female pulli: 0.23; male pulli: 0.32) than juveniles and adults. Density-dependent fledgling production was detected in the Finnish sub-population and was accounted for in the Monte Carlo simulation, which estimated predicted breeding population size quite well, although one of the observed annual values (2003) fell outside the 95% confidence limits.

  • 37.
    Gunnarsson, Gunnar
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Elmberg, Johan
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Pöysä, Hannu
    Joensuu Game and Fisheries Research, Finnish Game and Fisheries Research Institute.
    Sjöberg, Kjell
    Department of Wildlife, Fish, and Environmental Studies, Swedish University of Agricultural Sciences, Umeå.
    Dessborn, Lisa
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Arzel, Céline
    Section of Ecology, Department of Biology, Turku University.
    Density dependence in ducks: a review of the evidence2013Inngår i: European Journal of Wildlife Research, ISSN 1612-4642, E-ISSN 1439-0574, Vol. 59, nr 3, 305-321 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Density dependence (DD) is a central concept in population ecology and in the management of harvested populations. For example, DD underpins the idea of additive versus compensatory mortality and is a tenet in the paradigm of resource limitation and regulation. Yet the prevalence and importance of DD remains disputed in most organisms, including ducks, which are focal in game management, conservation and zoonotic diseases. Based on 154 data entries from 54 studies in the peer-reviewed literature, we here synthesize and evaluate the prevalence of DD in breeding ducks in relation to (1) species and guild (dabbling versus diving ducks), (2) stage in the breeding cycle (nesting, duckling, recruitment) or, alternatively, in terms of population dynamics, (3) study type (descriptive/nonmanipulative versus experimental), (4) continent (Europe versus North America), (5) spatial level (wetland, landscape, regional, continental) and (6) biome (tundra, boreal, nemoral, prairie, mediterranean). One conclusion from this review is that it is difficult to find general patterns about the prevalence of DD unless data are broken down to subsets, for example, to stage or spatial level. With respect to stage, DD effects occur at all stages of the breeding cycle. During the nesting and duckling stages, the frequency of cases detecting versus not detecting DD is roughly the same. However, in cases referring to the recruitment stage, i.e. to survival of fledged ducks until 1 year old at the most, DD was the rule, suggesting that DD processes may operate mainly outside the breeding season. Further subdivision of data shows that spatial scale is important to the prevalence of DD in nesting ducks—rare on the wetland level and more common on higher spatial levels. In studies of population dynamics (i.e. based on time series data only), DD was more often found in diving than in dabbling ducks. This corroborates previous suggestions that dabbling ducks largely should be considered as r-selected species, in contrast to more K-selected diving ducks, which start to reproduce at an older age and often breed in more stable wetland environments where resources may be easier to track and populations thus often are closer to carrying capacity. However, the picture of DD in ducks is far from complete, and knowledge gaps for future studies to address include: (a) data from Russia, which holds a large part of the breeding ducks in the Northern hemisphere, (b) experimental studies on more species to separate density-dependent factors from other drivers of population change and to tease apart spatial and temporal interactions in the underlying processes, (c) time series analyses addressing population dynamics, especially from outside North America, (d) studies relating duck numbers to limiting resources, which arguably is the most relevant measure of density, (e) the timing of DD processes in relation to harvest and natural mortality.

  • 38.
    Gunnarsson, Gunnar
    et al.
    Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH). Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Elmberg, Johan
    Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH). Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Sjöberg, Kjell
    SLU.
    Pöysä, Hannu
    Finland.
    Nummi, Petri
    Finland.
    Experimental evidence for density-dependent breeding success in mallards2005Konferansepaper (Fagfellevurdert)
    Abstract [en]

    It is unresolved to what extent waterfowl populations are regulated by density-dependent pro cesses. By doing a 2-year crossover perturbation exper iment on ten oligotrophic boreal lakes we addressed the hypothesis that breeding output is density depen dent. Wing-clipped mallard (Anas platyrhynchos) hens were introduced with their own brood and then moni tored for 24 days. Predicted responses were that per capita duckling and hen survival would be lower in high-density than in low-density treatments. Survival was evaluated by model fitting in program MARK. Density, year, and lake were used as main effects, while day after introduction, a weather harshness index, and presence of hens were covariates. Daily survival in ducklings was lower in the high-density treatment, but this effect was year dependent. The highest-ranking model for duckling survival also included a positive effect of duckling age and presence of hens, and a nega tive effect of harsh weather. Density did not affect female survival although there was a prominent year effect. The highest-ranking model for female survival also included negative effects of day after introduction and harsh weather. This is the first study to report den sity-dependent survival in experimentally introduced ducklings in a natural setting. Implications for population dynamics and management of harvested populations are far-reaching if such regulation occurs in some years, but not in others.

  • 39.
    Gunnarsson, Gunnar
    et al.
    Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH). Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Elmberg, Johan
    Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH). Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Sjöberg, Kjell
    SLU.
    Pöysä, Hannu
    Finland.
    Nummi, Petri
    Finland.
    Food limits survival in breeding mallards2003Inngår i: Integrating wildlife with people, 10th International Perdix Symposium, Braga, Portugal, September 1st-6th 2003: abstracts and contributing authors, Braga: International Union of Game Biologists , 2003Konferansepaper (Fagfellevurdert)
  • 40.
    Gunnarsson, Gunnar
    et al.
    Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH). Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Elmberg, Johan
    Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH). Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Sjöberg, Kjell
    SLU.
    Pöysä, Hannu
    Finland.
    Nummi, Petri
    Finland.
    Food limits survival of breeding boreal mallards Anas platyrhynchos2003Konferansepaper (Fagfellevurdert)
    Abstract [en]

    During the breeding period dabbling ducks (Anas sp.), and especially newly hatched ducklings, face heavy mortality. The reasons are not clear, but suggested factors contributing are scarce food, predation, chilling and disease. We highlighted the question why many of the boreal lakes in Scandinavia are without breeding ducks and why mortality is considerable during brood period. In an experimental study in 2002 we hypothesized food being a major factor deciding duck survival during breeding. One wing-clipped hen mallard with her own newly hatched brood (10 ducklings) was introduced onto each of 10 lakes. Food was added ad libitum at 5 of these lakes (experimental lakes), whereas the other five lakes (controls) did not get any extra food added. Survival of hens, broods as well as each individual duckling was monitored regularly until 24 days after introduction. At all three levels (i.e. duckling, brood and adult), survival was significantly higher on lakes with food added than on control lakes, although the difference was most pronounced on the duckling level. Direct consequences (i.e. dying from starvation) as well as indirect (e.g. undernourished individuals being more easily taken by predators) may both explain this pattern. Our results clearly show that food is a major limiting factor on mallard survival in this environment. Also, our results may explain why many boreal lakes in Scandinavia do not have any breeding waterfowl at all. It seems likely that such lakes are too poor to raise broods and even to sustain adults.

  • 41.
    Gunnarsson, Gunnar
    et al.
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Elmberg, Johan
    Högskolan Kristianstad, Institutionen för matematik och naturvetenskap.
    Sjöberg, Kjell
    Department of Animal Ecology, Swedish University of Agricultural Sciences, Umeå.
    Pöysä, Hannu
    Finnish Game and Fisheries Research Institute, Joensuu Game and Fisheries Research.
    Nummi, Petri
    Department of Applied Biology, University of Helsinki.
    Why are there so many empty lakes?: food limits survival of mallard ducklings2004Inngår i: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 82, nr 11, 1698-1703 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Food is an important factor affecting survival in many bird species, but this relationship has rarely been explored experimentally with respect to reproductive output of precocial birds. In a field experiment we tested the hypothesis that food abundance limits reproductive output in breeding dabbling ducks. Onto 10 oligotrophic lakes in northern Sweden we introduced one wing-clipped female mallard (Anas platyrhynchos L., 1758) and a brood of 10 newly hatched ducklings, and survival was monitored for 24 days. Food was added ad libitum at five of the lakes, but not at the other five. Duckling survival was best modelled to include a treatment effect, with higher survival on lakes with food added, and a negative effect of harsh weather. As expected, duckling survival increased nonlinearly with age. Only one female remained on control lakes after 24 days, whereas four remained on lakes with food added. This is the first experimental demonstration that food may limit survival and reproductive output in breeding precocial birds. We argue that food limitation may be one reason why duckling mortality is high and why many lakes throughout the Holarctic have no breeding dabbling ducks.

  • 42.
    Gunnarsson, Gunnar
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Elmberg, Johan
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Waldenström, Jonas
    Section for Zoonotic Ecology and Epidemiology, School of Natural Sciences, Linnaeus University, Kalmar.
    Trends in body mass of ducks over time: the hypotheses in Guillemain et al. revisited2011Inngår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 40, nr 3, 338-340 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 43.
    Gunnarsson, Gunnar
    et al.
    Högskolan Kristianstad, Sektionen för Lärarutbildning.
    Elmberg, Johan
    Högskolan Kristianstad, Sektionen för Lärarutbildning.
    Waldenström, Jonas
    Olsen, Björn
    Änderna, influensan och jakten2010Inngår i: Svensk jakt: Svenska jägareförbundets tidskrift, ISSN 0039-6583, nr 6, 74-75 s.Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 44.
    Gunnarsson, Gunnar
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Hessel, Rebecca
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Ottvall, Richard
    Ottvall et al.
    Bristande födotillgång och torrare vårar på strandängarna i Kristianstads Vattenrike: möjliga orsaker till vadarnas tillbakagång?2013Rapport (Annet vitenskapelig)
    Abstract [sv]

    Strandängsvadarna har minskat påtagligt i antal längs nedre Helgeån i Kristianstads Vattenrike. Orsaken till minskningarna är inte uppenbara, men ett antal möjliga faktorer har lyfts fram. I den här rapporten presenteras studier som genomfördes 2012 med målet att undersöka två av dessa faktorer, nämligen (1) vadarnas födotillgång (dvs. förekomst av ryggradslösa djur) och hur den kan ha påverkats av sommaröversvämningen 2007, samt (2) om det finns stöd i väder- och hydrologiska data att vårarna har blivit torrare.

    Tillgången på föda var överlag god på själva strandängarna. I våtmarkerna (vätor, Helge å, Hammarsjön) var det däremot stora skillnader mellan lokaler i Vattenriket, med högre förekomster av ryggradslösa djur längre ner i Helge å-systemet (dvs. närmare utloppet i Hanöbukten) än högre upp. Detta kan vara en kvarvarande effekt av sommaröversvämningen 2007.

    Några tydliga tendenser till torrare vårar under perioden 1990–2012 kunde inte skönjas vid analyser av väder- och hydrologiska data. Möjligen kan man säga att vårarna i början av 1990-talet var relativt torra för att följas av våtare vårar under andra halvan av 1990-talet och att 2000-talet har dominerats av torra vårar. Det är emellertid inte möjligt att utifrån befintliga data göra några säkra uttalanden om eventuella långtgående förändringar som kan ha påverkat vadarnas livsmiljöer eller häckningsframgång.

    För att vända den negativa trenden med sviktande populationer av strandängsvadare behövs drastiska och omedelbara åtgärder. Dessa inbegriper främst att få bukt med alltför kortsnaggade och ensartade ängar, för hög predation, och vätor som torkar ut för snabbt.

  • 45.
    Gunnarsson, Gunnar
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö.
    Jourdain, Elsa
    Wahlgren, John
    Latorre-Margalef, Neus
    Svensson, Lovisa
    Waldenström, Jonas
    Sahlin, Sofie
    Lundkvist, Åke
    Falk, Kerstin
    Bröjer, Caroline
    Olsen, Björn
    Mallards with fever: experimental infection with low-pathogenic influenza A viruses2009Konferansepaper (Fagfellevurdert)
  • 46.
    Gunnarsson, Gunnar
    et al.
    Högskolan Kristianstad, Sektionen för Lärarutbildning.
    Jourdain, Elsa
    Section for Zoonotic Ecology and Epidemiology, School of Pure and Applied Natural Sciences, University of Kalmar.
    Waldenström, Jonas
    Section for Zoonotic Ecology and Epidemiology, School of Pure and Applied Natural Sciences, University of Kalmar.
    Helander, Björn
    Department of Contaminant Research, Swedish Museum of Natural History, Stockholm.
    Lindberg, Peter
    Department of Zoology, University of Gothenburg.
    Elmberg, Johan
    Högskolan Kristianstad, Sektionen för Lärarutbildning.
    Latorre-Margalef, Neus
    Section for Zoonotic Ecology and Epidemiology, School of Pure and Applied Natural Sciences, University of Kalmar.
    Olsen, Björn
    Section for Zoonotic Ecology and Epidemiology, School of Pure and Applied Natural Sciences, University of Kalmar.
    Zero prevalence of influenza A virus in two raptor species by standard screening2010Inngår i: Vector Borne and Zoonotic Diseases, ISSN 1530-3667, E-ISSN 1557-7759, Vol. 10, nr 4, 387-390 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Disease can have severe impact on animal populations, especially in rare species. Baseline data for atypical host species are missing for a range of infectious diseases, although such hosts are potentially more affected than the normal vectors and reservoir species. If highly pathogenic avian influenza strikes rare birds of prey, this may have crucial impact on the predator species itself, but also on the food web in which it interacts. Here we present the first large-scale screening of raptors that regularly consume birds belonging to the natural reservoir of influenza A viruses. Influenza A virus prevalence was studied in two rare raptors, the white-tailed sea eagle (Haliaeetus albicilla) and the peregrine falcon (Falco peregrinus). Nestlings were screened for active (181 white-tailed sea eagles and 168 peregrine falcons) and past (123 white-tailed sea eagles and 6 peregrine falcons) infection in 2006-2007, and an additional 20 succumbed adult white-tailed sea eagles were sampled in 2003-2006. Neither high- nor low-pathogenic influenza infections were found in our sample, but this does not rule out that the former may have major impact on rare raptors and their food webs.

  • 47.
    Gunnarsson, Gunnar
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Latorre-Magalef, N.
    Hobson, K.A.
    van Wilgenburg, S.L.
    Elmberg, Johan
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Olsen, B.
    Fouchier, R.A.M.
    Waldenström, J.
    Within-season trends in natal orgin, body size, and influenza a virus subtypes in migrating mallards2012Konferansepaper (Annet vitenskapelig)
  • 48.
    Gunnarsson, Gunnar
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Latorre-Margalef, Neus
    Hobson, Keith A
    Van Wilgenburg, Steven L
    Elmberg, Johan
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Olsen, Björn
    Fouchier, R A M
    Waldenström, Jonas
    Within-season trends in natal origin, body size, and influenza A virus subtypes in migrating Mallards2012Konferansepaper (Fagfellevurdert)
  • 49.
    Gunnarsson, Gunnar
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Latorre-Margalef, Neus
    Hobson, Keith H
    Van Wilgenburg, Steven L
    Elmberg, Johan
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Olsen, Björn
    Fouchier, R A M
    Waldenström, Jonas
    Within-season trends in natal origin, body size, and influenza A virus subtypes in migrating Mallards2012Konferansepaper (Fagfellevurdert)
  • 50.
    Gunnarsson, Gunnar
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö.
    Latorre-Margalef, Neus
    Section for Zoonotic Ecology and Epidemiology, School of Natural Sciences, Linnaeus University, Kalmar.
    Hobson, Keith
    ldlife and Landscape Science, Environment Canada, Saskatoon.
    Steven, Van Wilgenburg
    ldlife and Landscape Science, Environment Canada, Saskatoon.
    Elmberg, Johan
    Högskolan Kristianstad, Sektionen för lärande och miljö.
    Olsen, Björn
    Section of Infectious Diseases, Department of Medical Sciences, Uppsala University Hospital, Uppsala.
    Fouchier, Ron
    Department of Virology, Erasmus Medical Center, Rotterdam.
    Waldenström, Jonas
    Section for Zoonotic Ecology and Epidemiology, School of Natural Sciences, Linnaeus University, Kalmar.
    Disease dynamics and bird migration: linking mallards Anas platyrhynchos and subtype diversity of the influenza A virus in time and space2012Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, nr 4, e35679- s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mallard Anas platyrhynchos is a reservoir species for influenza A virus in the northern hemisphere, with particularly high prevalence rates prior to as well as during its prolonged autumn migration. It has been proposed that the virus is brought from the breeding grounds and transmitted to conspecifics during subsequent staging during migration, and so a better understanding of the natal origin of staging ducks is vital to deciphering the dynamics of viral movement pathways. Ottenby is an important stopover site in southeast Sweden almost halfway downstream in the major Northwest European flyway, and is used by millions of waterfowl each year. Here, mallards were captured and sampled for influenza A virus infection, and positive samples were subtyped in order to study possible links to the natal area, which were determined by a novel approach combining banding recovery data and isotopic measurements (δ2H) of feathers grown on breeding grounds. Geographic assignments showed that the core natal areas of studied mallards were in Estonia, southern and central Finland, and northwestern Russia. This study demonstrates a clear temporal succession of latitudes of natal origin during the course of autumn migration. We also demonstrate a corresponding and concomitant shift in virus subtypes. Acknowledging that these two different patterns were based in part upon different data, a likely interpretation worth further testing is that the early arriving birds with more proximate origins have different influenza A subtypes than the more distantly originating late autumn birds. If true, this knowledge would allow novel insight into the origins and transmission of the influenza A virus among migratory hosts previously unavailable through conventional approaches.

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