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  • 101.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment.
    Dessborn, Lisa
    Kristianstad University, School of Education and Environment.
    Gunnarsson, Gunnar
    Kristianstad University, School of Education and Environment.
    Nummi, Petri
    Helsingfors universitet.
    Pöysä, Hannu
    Finska vilt- och fiskeriforskningsinstitutet.
    Sjöberg, Kjell
    Sveriges lantbruksuniversitet, Umeå.
    Forskare vill ha inventering före fågeljakt2008In: Jakt och Jägare, ISSN 1401-8306, no 6, p. 45-Article in journal (Other (popular science, discussion, etc.))
  • 102. Elmberg, Johan
    et al.
    Edenius, L.
    Abundance patterns in bird communities in old boreal forest in relation to stand structure and local habitat configuration1999In: Ornis Fennica, ISSN 0030-5685, Vol. 76, no 3, p. 123-133Article in journal (Refereed)
  • 103.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Teacher Education.
    Folkesson, Karin
    Kristianstad University, School of Teacher Education.
    Guillemain, Matthieu
    Office National de la Chasse et de la Faune Sauvage, CNERA Avifaune Migratrice, La Tour du Valat, Le Sambuc, Arles.
    Gunnarsson, Gunnar
    Kristianstad University, School of Teacher Education.
    Putting density dependence in perspective: nest density, nesting phenology, and biome, all matter to survival of simulated mallard Anas platyrhynchos nests2009In: Journal of Avian Biology, ISSN 0908-8857, E-ISSN 1600-048X, Vol. 40, no 3, p. 317-326Article in journal (Refereed)
    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.

  • 104.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Forskningsmiljön Man and Biosphere Health (MABH).
    Green, M.
    Gustafsson, R.
    Haas, F.
    Liljebäck, N.
    Lindström, Å.
    Nilsson, L.
    Ottosson, U.
    Ottvall, R.
    Svensson, M.
    Svensson, S.
    Tjernberg, M.
    Hur många fåglar finns det i verkligheten?2013In: Vår fågelvärld, ISSN 0042-2649, Vol. 72, no 2, p. 58-59Article in journal (Other academic)
  • 105.
    Elmberg, Johan
    et al.
    Kristianstad University, Department of Mathematics and Science.
    Gunnarsson, Gunnar
    Kristianstad University, Department of Mathematics and Science.
    Density-dependent nest predation in mallards Anas platyhynchos: patterns and implications2006Conference paper (Refereed)
  • 106.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment.
    Gunnarsson, Gunnar
    Kristianstad University, School of Education and Environment.
    Konstgjorda reden ger riktiga svar2011In: Svensk Jakt, Vol. 1, p. 92-94Article in journal (Other (popular science, discussion, etc.))
    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.

  • 107.
    Elmberg, Johan
    et al.
    Kristianstad University, Department of Mathematics and Science.
    Gunnarsson, Gunnar
    Kristianstad University, Department of Mathematics and Science.
    Manipulated density of adult mallards affects nest survival differently in different landscapes2007In: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 85, no 5, p. 589-595Article in journal (Refereed)
    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.

  • 108.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Forskningsmiljön Man and Biosphere Health (MABH).
    Gunnarsson, Gunnar
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Forskningsmiljön Man and Biosphere Health (MABH).
    Svältrisk orsak till att flera västerbottniska sjöar saknar häckande änder2012In: Fåglar i Västerbotten, ISSN 0348-1166, Vol. 37, no 1, p. 10-13Article in journal (Other (popular science, discussion, etc.))
  • 109.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment.
    Gunnarsson, Gunnar
    Kristianstad University, School of Education and Environment.
    Änder klarar sig bättre utan grannar2012In: Anser, ISSN 0347-9595, Vol. 51, no 1, p. 22-27Article in journal (Other (popular science, discussion, etc.))
    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!

  • 110.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment.
    Gunnarsson, Gunnar
    Kristianstad University, School of Education and Environment.
    Dessborn, Lisa
    Kristianstad University, School of Education and Environment.
    Jonzén, Niklas
    Pöysä, Hannu
    Valkama, Jari
    Gräsandens liv och död2008In: Svensk Jakt, no 10, p. 82-84Article in journal (Other (popular science, discussion, etc.))
  • 111.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap.
    Gunnarsson, Gunnar
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap.
    Nummi, Petri
    Finland.
    Pöysä, Hannu
    Finland.
    Sjöberg, Kjell
    SLU.
    Density dependent breeding success in mallards2003Conference paper (Refereed)
    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.

  • 112.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Forskningsmiljön Man and Biosphere Health (MABH).
    Gunnarsson, Gunnar
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Forskningsmiljön Man and Biosphere Health (MABH).
    Nummi, Petri
    Pöysä, Hannu
    Sjöberg, Kjell
    Farligt att vara andägg2002In: Svensk jakt, ISSN 0039-6583, Vol. 140, no 10, p. 18-20Article in journal (Other (popular science, discussion, etc.))
  • 113.
    Elmberg, Johan
    et al.
    Kristianstad University, Department of Mathematics and Science.
    Gunnarsson, Gunnar
    Kristianstad University, Department of Mathematics and Science.
    Pöysä, Hannu
    Finska vilt- & fiskeriforskningsinstitutet, Joensuu.
    Nummi, Petri
    Helsingfors universitet.
    Sjöberg, Kjell
    Sveriges lantbruksuniversitet, Umeå.
    Hur många får ligga i orubbat bo?2003In: Vår fågelvärld, ISSN 0042-2649, no 3, p. 28-29Article in journal (Other (popular science, discussion, etc.))
  • 114.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap.
    Gunnarsson, Gunnar
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap.
    Pöysä, Hannu
    Finland.
    Sjöberg, Kjell
    SLU, Umeå.
    Nummi, Petri
    Finland.
    Within-season sequential density dependence regulates breeding success in mallards Anas platyrhynchos2005In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 108, p. 582-590Article in journal (Refereed)
    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.

  • 115.
    Elmberg, Johan
    et al.
    Kristianstad University, Department of Mathematics and Science.
    Gunnarsson, Gunnar
    Kristianstad University, Department of Mathematics and Science.
    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)2005In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 108, no 3, p. 582-590Article in journal (Refereed)
    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.

  • 116.
    Elmberg, Johan
    et al.
    Kristianstad University, Department of Mathematics and Science.
    Gunnarsson, Gunnar
    Kristianstad University, Department of Mathematics and Science.
    Sjöberg, Kjell
    Nummi, Petri
    Pöysä, Hannu
    Finns det mer andrum?2005In: Svensk jakt, ISSN 0039-6583, Vol. 143, no 8, p. 80-82Article in journal (Other (popular science, discussion, etc.))
  • 117.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Research environment Man and Biosphere Health (MABH).
    Gunnarsson, Gunnar
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Research environment Man and Biosphere Health (MABH).
    Waldenström, Jonas
    Latorre-Margalef, Neus
    Olsen, Björn
    Vart tog fågelinfluensan vägen?2010In: Vår fågelvärld, Vol. 69, no 3, p. 8-12Article in journal (Other (popular science, discussion, etc.))
  • 118.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Forskningsmiljön Man and Biosphere Health (MABH).
    Hagman, Mattias
    Stockholms universitet.
    Löwenborg, Kristin
    Stockholms universitet.
    Kärvemo, Simon
    Sveriges lantbruksuniversitet, Uppsala.
    Snokens barnkammare försvinner2013In: Fauna och flora : populär tidskrift för biologi, ISSN 0014-8903, Vol. 108, no 1, p. 10-16Article in journal (Other academic)
  • 119.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Research environment Man and Biosphere Health (MABH).
    Hessel, Rebecca
    Fox, Anthony David
    Department of Bioscience, Aarhus University.
    Dalby, Lars
    Department of Bioscience, Aarhus University.
    Interpreting seasonal range shifts in migratory birds: a critical assessment of 'short-stopping' and a suggested terminology2014In: Journal of Ornithology = Journal fur Ornithologie, ISSN 0021-8375, E-ISSN 1439-0361, Vol. 155, no 3, p. 571-579Article, review/survey (Refereed)
    Abstract [en]

    The term 'short-stopping' is increasingly used in ecology to describe spatio-temporal changes in occurrence of migratory species. Spurred by the insight that it has been used in a variety of contexts, we reviewed its use in avian ecology. A literature search yielded 59 papers explicitly treating short-stopping in birds, most of them in peer-reviewed journals. The term was first used in 1967 to describe a northward shift in wintering Canada Geese in North America and has been used with increasing frequency to the present day. Geese dominate the short-stopping literature, which is confined to the northern hemisphere. Short-stopping has been used to describe (1) a shortened autumn migration that results in a wintering distribution closer to breeding areas, (2) a shortened spring migration that results in a breeding distribution closer to wintering areas, and (3) a delay in autumn migration that leads to a perceived reduced abundance in some part of the winter range. We advocate that short-stopping should be used only to describe (1) range shifts that involve shortening of the migratory corridor, and that they are qualified explicitly by season (i.e. breeding/winter) and degree (i.e. full or partial range shift). In other cases of breeding, wintering or entire range shifts where the migratory corridor is elongated or remains the same, we recommend using the term 'range shift', qualified by season, geography and orientation (i.e. the direction of the range shift). We also discuss the need for spatially explicit avian count monitoring mechanisms (rather than capture-recapture or hunting bag data) designed specifically to track such changes in distribution in the future.

  • 120.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap.
    Hirschfeld, E
    Svensk fågelrapportering: bra måste bli bättre!2005In: Vår fågelvärld, ISSN 0042-2649, Vol. 64, no 8, p. 36-37Article in journal (Other (popular science, discussion, etc.))
  • 121.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Forskningsmiljön Man and Biosphere Health (MABH).
    Hirschfeld, Erik
    Cardoso, Helder
    Diurnal seabird movements at Cabo Carvoeiro (Peniche, Portugal): observations in early October 20122013In: Seabird, ISSN 0267-9310, Vol. 26, p. 24-30Article in journal (Refereed)
    Abstract [en]

    The ecology and movements of seabirds are still inadequately understood, mainly because they can rarely be studied efficiently from land. The potential of Cabo Carvoeiro (Peniche, Portugal) for monitoring seabird movements from land is poorly known internationally, as few results from this site have been published in English. Here we present data from standardised counts in October 2012 and draw attention to recent organised seabird counts in Portugal. Despite unfavourable weather conditions for concentrating seabirds towards land, we observed a strong passage of Northern Gannet   Morus bassanus, Cory’s Shearwater Calonectris diomedea, Great Skua  Stercorarius skua, and Balearic Shearwater Puffinus mauretanicus (mean morning passage of 252, 99, 19, and 21 birds / hour, respectively). Manx Shearwater Puffinus puffinus, Sooty Shearwater P. griseus and Great Shearwater P. gravis occurred regularly in low numbers. Extrapolation indicates that thousands of seabirds passed daily within a few kilometres from land. The high counts of some species and the fairly high species diversity observed by us and in the RAM (Rede de observação de Aves e Mamiferos marinhos) initiative show that Cabo Carvoeiro is an outstanding site for monitoring and studying seabirds in the eastern Atlantic, as it is also located further south in the flyway than most other seawatch points. We hope this note will inspire ornithologists from other countries to participate in standardised seabird counts at Cabo Carvoeiro and other Portuguese sites.

  • 122.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Research environment Man & Biosphere Health (MABH).
    Hirschfeld, Erik
    Cardoso, Helder
    Portugal.
    Hessel, Rebecca
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Research environment Man & Biosphere Health (MABH).
    Passage patterns of seabirds in October at Cabo Carvoeiro Portugal, with special reference to the Balearic Shearwater Puffinus mauretanicus2016In: Marine Ornithology, ISSN 1018-3337, E-ISSN 2074-1235, Vol. 44, no 2, p. 151-156Article in journal (Refereed)
    Abstract [en]

    Land-based counts of migrating seabirds remain essential to increase knowledge about their numbers and movements. To assess the value of Cabo Carvoeiro (Peniche, Portugal) as a monitoring site in the East Atlantic, we studied seabird species composition, passage patterns and flock size during mid-October 2014. During standardized counts, we observed nearly 8 000 seabirds of 17 species. The ratio of individuals passing in a southerly to southwesterly direction was >96% in all species, showing that genuine migrants were counted. The passage rate (birds/hour) was higher for Northern Gannets Morus bassanus than for any other species, by a factor of approximately 50 (morning mean 906/h, afternoon mean 1 153/h). The globally endangered Balearic Shearwaters Puffinus mauretanicus, Great Skuas Stercorarius skua and Pomarine Skuas S. pomarinus had passage rates of 10–25/h. Flock size distribution in the 11 most numerous species showed that most migrated singly or in groups of two. Flock size was larger in Balearic Shearwaters than in both Cory’s Calonectris borealis and Manx Shearwaters P. puffinus. Among skuas, flock size was larger in Pomarine than in Great Skuas. The passage rate of Manx Shearwaters was positively correlated with that of Northern Gannets, Great Skuas and Sandwich Terns Sterna sandvicensis. Northern Gannets showed a positive co-variation with Pomarine Skuas. Balearic and Sooty Shearwaters Ardenna griseus were the only species that did not show any significant co-variation with another species. Morning and afternoon passage rates did not differ significantly in any of the six most numerous species (Northern Gannets, Cory’s and Balearic Shearwaters, Great and Pomarine Skuas, and Sandwich Terns), or in Sooty Shearwaters (less numerous). Thus, the passage rates at Cabo Carvoeiro in October of Balearic Shearwaters and five other species were as high or higher than those reported from any other seawatch in Portugal, indicating the international value of seabird monitoring at Cabo Carvoeiro during the autumn migration.

  • 123.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment.
    Kilpi, M.
    Clausen, P.
    Klimatförändring och andfåglar: nordiskt nätverk bildat!2011In: Vår fågelvärld, ISSN 0042-2649, Vol. 70, no 1, p. 35-Article in journal (Other (popular science, discussion, etc.))
  • 124.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap.
    Lindberg, N
    Edenius, L
    Vart tog de vägen?: en översikt av återfynd av fåglar ringmärkta på Stora Fjäderägg2005In: Fåglar i Västerbotten, ISSN 0348-1166, Vol. 30, no 4, p. 4-9Article in journal (Other (popular science, discussion, etc.))
  • 125.
    Elmberg, Johan
    et al.
    SLU.
    Lindbladh, M
    Dagens skötselmetoder räcker inte2000In: Skogen, ISSN 0037-640X, Vol. 3, p. 66-Article in journal (Other (popular science, discussion, etc.))
  • 126.
    Elmberg, Johan
    et al.
    Department of Animal Ecology, University of Umeå.
    Lundberg, Per
    Department of Wildlife Ecology, Swedish University of Agricultural Sciences, Umeå.
    Intraspecific variation in calling, time allocation and energy reserves in breeding male common frogs Rana temporaria1991In: Annales Zoologici Fennici, ISSN 0003-455X, E-ISSN 1797-2450, Vol. 28, no 1, p. 23-29Article in journal (Refereed)
    Abstract [en]

    Time allocation during breeding was studied in unmated male common frogs Rana temporaria Linnaeus in three populations along a gradient of altitude, climate and length of feeding season. The length of the breeding period decreased with increased altitude. All three populations had low activity levels (0-33% of the time during peak chorusing). Peak chorusing in the lowland population was due to more males participating in the chorus, and not to increased individual calling activity. An increase in mating effort at this time was nevertheless indicated by the males 'using more time for moving in the pond. At both montane localities, males called more sparsely, and not at all at night. During peak chorusing, calling and moving males became significantly rarer with increased altitude. Aggressive males were significantly rarer in the alpine population. Between-locality variation was evident in fat reserves after hibernation and during breeding; the relative fat body mass was significantly higher in lowland males than in mid-altitude and alpine males. We discuss male mating activity (here: calling, mate searching and aggression) in ultimate terms as a trade-off between mate acquisition and survival.

  • 127.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap.
    Müller, Lothar
    The first records of grey-headed gull Larus cirrocephalus in Egypt2003In: Sandgrouse, ISSN 0260-4736, Vol. 25, no 1, p. 67-68Article in journal (Refereed)
  • 128.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap.
    Nilsson, B
    Nilsson, G E
    Ett fågeltorn berättar: gräsänderna i Nasen2001In: Vår fågelvärld, ISSN 0042-2649, Vol. 60, no 4, p. 16-18Article in journal (Other (popular science, discussion, etc.))
  • 129.
    Elmberg, Johan
    et al.
    Kristianstad University, Department of Mathematics and Science.
    Nummi, Petri
    Department of Applied Biology, University of Helsinki.
    Pöysä, Hannu
    Finnish Game and Fisheries Research Institute, Joensuu Game and Fisheries Research.
    Gunnarsson, Gunnar
    Kristianstad University, Department of Mathematics and Science.
    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 success2005In: Annales Zoologici Fennici, ISSN 0003-455X, E-ISSN 1797-2450, Vol. 42, no 1, p. 37-43Article in journal (Refereed)
    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.

  • 130.
    Elmberg, Johan
    et al.
    Kristianstad University, Department of Mathematics and Science.
    Nummi, Petri
    Pöysä, Hannu
    Gunnarsson, Gunnar
    Kristianstad University, Department of Mathematics and Science.
    Sjöberg, Kjell
    Krickan - okänd kändis som vet att välja rätt sjö2005In: Vår fågelvärld, ISSN 0042-2649, Vol. 64, no 3, p. 32-33Article in journal (Other (popular science, discussion, etc.))
  • 131.
    Elmberg, Johan
    et al.
    Kristianstad University, Department of Mathematics and Science.
    Nummi, Petri
    Department of Applied Biology, University of Helsinki.
    Pöysä, Hannu
    Finnish Game and Fisheries Res. Inst., Joensuu Game and Fisheries Research.
    Sjöberg, Kjell
    Department of Animal Ecology, Swedish University of Agricultural Sciences, Umeå.
    Breeding success of sympatric dabbling ducks in relation to population density and food resources2003In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 100, no 2, p. 333-341Article in journal (Refereed)
    Abstract [en]

    Breeding success in sympatric mallard Anas platyrhynchos, teal A. crecca and wigeon A. penelope in a boreal watershed in Finland was studied for 12 years. Benthic and surface-emerging prey animals were trapped to obtain annual indices of food abundance. Mallard and teal were equally abundant over the years, being roughly twice as numerous as wigeon. Pair density, brood:pair ratio and duckling:pair ratio were used to test the hypothesis that per capita breeding success decreases in a density-dependent fashion as either pair density or the number of nesting pairs per available food unit increases. In mallard we found no density-dependent patterns at all. In teal per capita brood production decreased as prey animals became relatively scarcer, but this interpretation may not be robust. In wigeon, however, there were two independent significant patterns of direct density-dependence in a temporal succession, i.e. between pair density and per capita brood production in the early part of the breeding season, and then between per capita abundance of surface-emerging insect prey and the number of ducklings per pair. Despite wide dietary overlap and frequent co-occurrence on single lakes among species in the guild, we found no evidence for interspecific density-dependent effects. We hypothesize that there is no or infrequent food limitation for breeding dabblers in this system, and that behavior may be the process behind the pattern of density-dependence in wigeon.

  • 132.
    Elmberg, Johan
    et al.
    Department of Wildlife Ecology, Swedish University of Agricultural Sciences, Umeå.
    Nummi, Petri
    Department of Applied Ecology, University of Helsinki.
    Pöysä, Hannu
    Finnish Game and Fisheries Research Institute, Evo Game Research Station.
    Sjöberg, Kjell
    Department of Wildlife Ecology, Swedish University of Agricultural Sciences, Umeå.
    Do intruding predators and trap position affect the reliability of catches in activity traps?1992In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 239, no 3, p. 187-193Article in journal (Refereed)
    Abstract [en]

    Forty lakes in Sweden and Finland were sampled in 1990 with activity traps to evaluate the effects of trapped predators on invertebrate catch. Vertebrate (fish, newts) and invertebrate (leeches, dragonflies, water beetles, backswimmers and water scorpions) predators were considered separately. Invertebrate predators affected neither the abundance nor the taxonomic diversity of the catches. Vertebrate predators had no effect on the abundance but reduced the taxonomic diversity of the catches significantly. Thus, vertebrate predators are a possible source of bias in activity trap catches, but oily concerning taxonomic diversity. Within the depth gradient studied (0.25-0.75 m), trap position (suspended in mid-water versus on the bottom) did not affect the percentages of nektonic and benthic invertebrates in the catches. The relative abundance of all taxa was similar in the catches from different trap positions, but the relative abundance of the most numerous taxa as well as the diversity of the catches differed between trap positions. We conclude that both mid-water and bottom traps are suitable for monitoring aquatic invertebrates, and that bottom traps may be preferred for practical reasons.

  • 133.
    Elmberg, Johan
    et al.
    Deptartment of Animal Ecology, Swedish University of Agricultural Sciences, Umeå.
    Nummi, Petri
    Deptartment of Applied Zoology, University of Helsinki.
    Pöysä, Hannu
    Finnish Game and Fisheries Research Institute, Evo Game Research Station.
    Sjöberg, Kjell
    Deptartment of Animal Ecology, Swedish University of Agricultural Sciences, Umeå.
    Factors affecting species number and density of dabbling duck guilds in North Europe1993In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 16, no 3, p. 251-260Article in journal (Refereed)
    Abstract [en]

    We addressed how species number and pair density in guilds of co-existing species is related to habitat structure, and to the abundance and diversity of food resources. using the assemblage of seven species of dabbling ducks (genus Anas) breeding in 60 lakes distributed over six regions in temperate north Europe. Partial correlation and multiple regression revealed that species richness was best predicted by habitat structural diversity as indexed by a principal component analysis based on 18 vegetation and lake characteristics, and by the abundance of aquatic and emergent prey. We found no effect of lake size or prey size diversity on species richness. Pair density was correlated with the percentage of shoreline with horsetails (Equisetum), by habitat structural diversity and by the abundance of emergent invertebrate prey. Neither prey size diversity nor abundance of aquatic prey correlated with pair density. Species richness and pair density in North European duck guilds vary both with habitat structure and prey availability.

  • 134.
    Elmberg, Johan
    et al.
    Department of Animal Ecology, Swedish University of Agricultural Sciences, Umeå.
    Nummi, Petri
    Pöysä, Hannu
    Sjöberg, Kjell
    Relationships between species number, lake size and resource diversity in assemblages of breeding waterfowl1994In: Journal of Biogeography, ISSN 0305-0270, E-ISSN 1365-2699, Vol. 21, no 1, p. 75-84Article in journal (Refereed)
    Abstract [en]

    Breeding waterfowl, habitat diversity and food diversity were studied in 31 boreal lakes in Finland and Sweden. Lakes were 2-48 hectares in size, and had zero to eleven waterfowl species each. In all, sixteen species of Gaviiformes, Podicipediformes, Anseriformes and Fulica were recorded. The observed species distribution deviated from the 'null' expectation derived from a model of random placement, indicating a low importance of lake area per se. However, lake area was found to be a better predictor of species number than was length of shoreline, and lake area-species number regressions gave values between 0.255 and 0.345. We further evaluated 'the area per se (sampling)' hypothesis and 'habitat diversity' hypothesis separately by multiple stepwise regressions, in which lake area explained most of the variation in species number in species dependent on the lake for brood-rearing. Richness of more mobile species and of all species was best explained by the number of prey taxa encountered in the lake.

  • 135.
    Elmberg, Johan
    et al.
    Kristianstad University, Department of Mathematics and Science.
    Nummi, Petri
    Finland.
    Pöysä, Hannu
    Finland.
    Sjöberg, Kjell
    Swedish University of Agricultural Sciences, Umeå.
    Gunnarsson, Gunnar
    Kristianstad University, Department of Mathematics and Science.
    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 ducks2006In: Wildlife Biology, ISSN 0909-6396, E-ISSN 1903-220X, Vol. 12, no 2, p. 121-127Article in journal (Refereed)
    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.

  • 136.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap.
    Nummi, Petri
    Finland.
    Sjöberg, Kjell
    SLU.
    Pöysä, Hannu
    Finland.
    Andkonferens på prärien2001In: Vår fågelvärld, ISSN 0042-2649, Vol. 60, no 8, p. 25-Article in journal (Other (popular science, discussion, etc.))
  • 137.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap.
    Olsen, Björn
    Flyttfåglarna är inte några livsfarliga influensamissiler2006In: Dagens Nyheter, ISSN 1101-2447, no 03-02Article in journal (Other (popular science, discussion, etc.))
  • 138.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Research environment Man & Biosphere Health (MABH).
    Pöysä, H.
    Knipa och gräsand är goda grannar2012In: Vår fågelvärld, ISSN 0042-2649, Vol. 71, no 4, p. 39-Article in journal (Other (popular science, discussion, etc.))
  • 139.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment.
    Pöysä, Hannu
    Finnish Game and Fisheries Research Institute, Joensuu Game and Fisheries Research.
    Is the risk of nest predation heterospecifically density-dependent in precocial species belonging to different nesting guilds?2011In: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 89, no 12, p. 1164-1171Article in journal (Refereed)
    Abstract [en]

    Nest predation is a key source of mortality and variation in fitness, but the effect co-occurring species belonging to different nesting guilds have on each other’s nest success is poorly understood. By using artificial nests, we tested if predation on cavity nests of Common Goldeneyes (Bucephala clangula (L., 1758)) is increased in the presence of ground nests of Mallards (Anas platyrhynchos L., 1758) and vice versa. Specifically, by adding ground nests in the vicinity of cavity nests, we tested the hypothesis that predation on cavity nests is heterospecifically density-dependent. A shared predator, the pine marten (Martes martes (L., 1758)), was intensively hunted in one of the study areas, but not in the other, leading to most individuals in the former being naïve immigrants. Cavity-nest fate was not affected by addition of ground nests. Similarly, ground-nest survival did not decrease when nearby cavity nests were depredated. Fate of nests in a given nest cavity was highly predictable between years in the study area with minimal removal of pine martens, but not in the one with intensive removal. Predation rate was higher on cavity nests than on ground nests. Predation on ground nests was lower in the study area with intensive removal of pine martens. We conclude there was neither apparent competition between guilds nor heterospecific density-dependence in predation risk.

  • 140.
    Elmberg, Johan
    et al.
    Department of Animal Ecology, Swedish University of Agricultural Sciences, Umeå.
    Pöysä, Hannu
    Finnish Game and Fisheries Research Institute, Evo Game Research Station.
    Sjöberg, Kjell
    Department of Animal Ecology, Swedish University of Agricultural Sciences, Umeå.
    Nummi, Petri
    Department of Applied Zoology, University of Helsinki.
    Interspecific interactions and co-existence in dabbling ducks: observations and an experiment1997In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 111, no 1, p. 129-136Article in journal (Refereed)
    Abstract [en]

    We studied the possible role of resource limitation and interspecific competition in assemblages of dabbling ducks on breeding lakes in Finland and Sweden with observational and experimental data. After initial vegetation mapping and yearly censuses of ducks in 1985-1990, we collected observational data in 1991-1994 from 28 lakes with natural populations of mallard Anas platyrhynchos and teal A. crecca. Mallard and teal co-occur over vast areas in the Holarctic and they are the only breeding dabbling ducks on many oligotrophic lakes. Both species are migratory in our study regions, teal arriving later in spring than mallards. Log-linear model analysis of observational presence/absence data revealed a positive, not a negative, association between the species. This association was independent of habitat diversity as well as of lake size. Mallard-teal interaction was also studied in a cross-over introduction experiment in 32 other lakes in two years. Wing-clipped mallards were introduced to breeding lakes before the arrival of teal to induce resource limitation and interspecific competition, hypothesized to reduce lake use by teal. The density of mallard pairs on experimental lakes was 2.9-8.0 times higher than on controls, but there was no negative response by teal to the treatment. This is the first combined observational-experimental demonstration of lack of interspecific competition in waterfowl. Our results indicate that heterospecific attraction may affect species co-existence in dabbling ducks.

  • 141.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap.
    Sjöberg, Kjell
    SLU.
    Nummi, Petri
    Finland.
    Pöysä, Hannu
    Finland.
    Hur påverkas andstammarna av jakt?2000In: Jakt och jägare, ISSN 1401-8306, Vol. 60, no 10, p. 44-45Article in journal (Other (popular science, discussion, etc.))
  • 142.
    Elmberg, Johan
    et al.
    Department of Animal Ecology, Swedish University of Agricultural Sciences, Umeå.
    Sjöberg, Kjell
    Department of Animal Ecology, Swedish University of Agricultural Sciences, Umeå.
    Nummi, Petri
    Department of Applied Zoology, University of Helsinki.
    Pöysä, Hannu
    Finnish Game and Fisheries Research Institute, Evo Game Research Station.
    Patterns of lake acidity and waterfowl communities1994In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 279-280, no 1, p. 201-206Article in journal (Refereed)
    Abstract [en]

    Breeding waterfowl communities were studied in 28 lakes in three areas in North Europe, along gradients of acid precipitation and alkalinity that result in lake conditions ranging from unaffected to strongly acidified. Acidic lakes had generally sparser and less complex vegetation, and fewer invertebrates were caught in activity traps. There was neither correlation between pH and waterfowl species richness (genus Anas, family Anatidae, and waterfowl sensu latu tested separately), nor between pH and waterfowl diversity (Simpson's index). Further, pH and waterfowl population density (genus Anas, family Anatidae, and waterfowl sensu latu) were not correlated, but when functional rather than taxonomic groups were considered, pH and relative abundance of fish-eating species (Gaviidae and Podicipedidae) were correlated. However, the relative abundance of Bucephala clangula, a diving duck that may compete with fish for food, was not correlated with pH. Although individual species may be affected, community level responses of waterfowl to acidity are either absent or hard to detect at our sites.

  • 143.
    Elmberg, Johan
    et al.
    SLU.
    Sjöberg, Kjell
    SLU.
    Nummi, Petri
    Finland.
    Pöysä, Hannu
    Finland.
    Vitlök eller lingonsylt till andbröstet: avgör jakten hur mycket änder vi har?2000In: Vår fågelvärld, ISSN 1942-2015, Vol. 59, no 3, p. 26-27Article in journal (Other (popular science, discussion, etc.))
  • 144.
    Elmberg, Johan
    et al.
    Department of Animal Ecology, Swedish University of Agricultural Sciences, Umeå.
    Sjöberg, Kjell
    Department of Animal Ecology, Swedish University of Agricultural Sciences, Umeå.
    Pöysä, Hannu
    Game and Fisheries Research Institute, Evo Game Research Station, Kaitalammintie, Evo.
    Nummi, Petri
    Department of Applied Zoology, University of Helsinki.
    Abundance-distribution relationships on interacting trophic levels: the case of lake-nesting waterfowl and dytiscid water beetles2000In: Journal of Biogeography, ISSN 0305-0270, E-ISSN 1365-2699, Vol. 27, no 4, p. 821-827Article in journal (Refereed)
    Abstract [en]

    Aim To compare patterns in local abundance, regional distribution and body size in waterfowl and dytiscid beetles sampled from the same lakes. Location Thirty Swedish lakes, 56-63 degrees N. Methods Birds were censused repeatedly, at which time submerged activity traps were placed on the littoral to catch invertebrates. Avian patterns were analysed separately for four different selections of species, each motivated on functional or phylogenetical grounds. Patterns in dytiscid beetles have been described earlier in Nilsson, Elmberg & Sjoberg (1994). Results Although there were large differences between individual lakes, there was no significant latitudinal gradient at the lake level in either species richness or abundance in any of the bird groupings. Lakes which were rich in species and numbers of dytiscid beetles were also rich in species and numbers of all four waterfowl groups. Three of the four bird groups conform with the general pattern of widely distributed species being more abundant locally, as do dytiscid beetles in the same lakes. Body mass and local abundance were correlated in one of the four birds groups only, i.e. dabbling ducks, (Anas spp.). Main conclusions We find evidence for a similar and positive local abundance-distribution relationship in dytiscid beetles and waterfowl breeding in the same lakes, but no common general pattern in local abundance vs. body size.

  • 145.
    Elmberg, Johan
    et al.
    SLU.
    Sjöberg, Kjell
    SLU.
    Pöysä, Hannu
    Finland.
    Nummi, Petri
    Finland.
    Positive association in nesting mallard and teal: resource limitation and interspecific competition in the light of sensus data and a depletion experiment2000Conference paper (Refereed)
    Abstract [en]

    Wing-clipped mallards were introduced on breeding lakes before the arrival of teal to induce resource limitation and interspecific competition, hypothesized to reduce lake use by teal. Experimental lakes had 2.9-8.0 times higher pair density of mallards than controls, but there was no negative response by teal to the treatment. We believe this is the first combined observational-experimental demonstration of lack of interspecific competition in waterfowl. Our results indicate that heterospecific attraction may affect co-existence in dabbling ducks.

  • 146.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap.
    Svensson, M
    Tjernberg, M
    Skedand2007Other (Other academic)
  • 147.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Research environment Man & Biosphere Health (MABH).
    Söderquist, Pär
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Research environment Man & Biosphere Health (MABH).
    Hur utsatta är utsatta änder?2012In: Vår fågelvärld, ISSN 0042-2649, Vol. 71, no 2, p. 40-42Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    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?

  • 148.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment.
    Söderquist, Pär
    Kristianstad University, School of Education and Environment.
    Gunnarsson, Gunnar
    Kristianstad University, School of Education and Environment.
    Vad händer med utsatta änder?2012In: Svensk Jakt, ISSN 0039-6583, Vol. 150, no 8, p. 88-89Article in journal (Other (popular science, discussion, etc.))
  • 149.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Research environment Man & Biosphere Health (MABH).
    Söderquist, Pär
    Kristianstad University, Research environment Man & Biosphere Health (MABH). Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap.
    Gunnarsson, Gunnar
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap. Kristianstad University, Research environment 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 releases2016Conference paper (Refereed)
    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.

  • 150.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment, Avdelningen för Naturvetenskap.
    Tjernberg, I
    Nilsson, SG
    Forslund, P
    Swanberg, P-O
    Nötkråka2007Other (Other academic)
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