| 61. |
- Elmberg, Johan, 1960-
(författare)
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Adaptiv skötsel av europeiska simänder för jakt, naturvård och sjukdomseffekter – slutår
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Projektet har slutfört ett antal delstudier som påbörjades inom ett tidigare treårigt projekt som redan redovisats till Naturvårdsverket. Denna redovisning omfattar ett slutfört doktorandprojekt, ett antal avnämarinriktade aktiviteter samt en rad publikationer: 16 vetenskapliga, 12 konferensbidrag och 10 populärvetenskapliga artiklar. Arbetet har utförts i ett nätverk av forskare i Sverige, Finland och Frankrike, men kollegor i ytterligare länder har varit inblandade i enskilda studier. De yttersta målen för detta och det föregående projekten sammantagna har varit att studera täthetsberoende processer och att tillämpa ett åretrunt- perspektiv på simandspopulationer. Med den nya kunskapen kan vi ge en rad råd om förbättringar och tillämpningar i förvaltningen av simänder på lokal, nationell och internationell nivå. Vi visar att fiskevård kan stå i konflikt till änders häckningsframgång, vilket inte har beaktats tidigare i förvaltningen. De viktigaste verktygen för adaptiv förvaltning finns nu tillgängliga, men bör kompletteras med bättre beståndsövervakning av häckande änder och ett internationellt perspektiv. Vi hittar små eller inga effekter av måttliga klimatförändringar på änders häckningsframgång. Metoder som utvecklats för att studera täthetsberoende boöverlevnad kan tjäna som modell för att utvärdera effekterna av en eventuell spridning av mårdhund i Sverige. Vi bekräftar också vikten av att övervakningen av fågelinfluensa hos vilda simänder i Sverige fortsätter.
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| 62. |
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| 63. |
- Elmberg, Johan
(författare)
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Are dabbling ducks main players or merely noise in limnic ecosystems?
- 2009
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Ingår i: Abstracts, 2nd Pan-European Duck Symposium. ; , s. 25-
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Konferensbidrag (refereegranskat)abstract
- For obvious reasons waterfowl ecologists consider ducks as focal organisms and main players when we study patterns and processes in wetland ecosystems. However, limnologists and fish biologists historically have ‘a bottom-up’ view of the same ecosystems, and they largely regard ducks and other waterbirds merely as ‘background noise’ much at the mercy of other and more powerful forces. Focussing on European studies of dabbling ducks I will review the evidence for and against these largely opposing views. I argue that a lot can be learned from using descriptive and pattern-oriented studies to produce explicit predictions that can be tested under more rigorous experimental circumstances. I will also explore why the lack of reliable information about annual variations in recruitment and harvest rates is a major obstacle for understanding population trajectories of dabbling duck populations. Finally, I will review the existing evidence for the major paradigms addressing population limitation in European dabbling ducks.
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| 64. |
- Elmberg, Johan, 1960-
(författare)
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Are dabbling ducks major players or merely noise in freshwater ecosystems? : a European perspective, with references to population limitation and density dependence
- 2009
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Ingår i: Wildfowl. - 0954-6324 .- 2052-6458. ; :Special issue 2, s. 9-23
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Tidskriftsartikel (refereegranskat)abstract
- Waterfowl ecologists consider ducks important players in patterns and processes of freshwater ecosystems. Limnologists and fish biologists, on the other hand, historically have “a bottom-up” view of the same systems, often regarding waterbirds as “background noise” compared to other biotic influences. Evidence for and against these largely opposing views is reviewed, focussing on European dabbling duck studies. In oligo- and mesotrophic wetlands at low breeding density, their role is likely to be overshadowed by biotic interactions between fish, invertebrates and plants. Conversely, many other freshwater systems may be affected by dabbling ducks in various ways, acting as dispersers of invertebrates and plants, as predators, and as eutrophicators. It is concluded that dabbling ducks affect freshwater systems more profoundly than has hitherto been acknowledged. In their turn, freshwater ecosystems affect the ducks’ population ecology. In a less comprehensive treatment, the evidence for the major paradigms addressing population limitation in dabbling ducks is discussed briefly from a European perspective. It is concluded that top-down (predation) as well as bottom-up (food limitation) processes may both affect population size, but evidence for either is correlative, necessitating more experimental studies based on explicit predictions from pattern-oriented studies. In a discussion of the prospects for adopting a more adaptive management approach for European dabbling ducks, it is argued that a lack of information about annual variation in recruitment and harvest rates are major obstacles to understanding population change and for adopting a more adaptive management. A compilation of European studies about density dependence in Mallard Anas platyrhynchos indicates that population regulation may be a common phenomenon in this species, with possible important ramifications for research as well as management programmes.
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| 65. |
- Elmberg, Johan, 1960-, et al.
(författare)
-
Breeding success of sympatric dabbling ducks in relation to population density and food resources
- 2003
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Ingår i: Oikos. - 0030-1299 .- 1600-0706. - 0030-1299 ; 100:2, s. 333-341
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 66. |
- Elmberg, Johan
(författare)
-
Conservation biology and behaviour : from frog perspective to a bird´s eye view
- 2014
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Ingår i: 10th Ecology & Behaviour meeting, Montpellier, Frankrike, 12-16/5, 2014. ; , s. 37-
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Konferensbidrag (refereegranskat)abstract
- My plenary will explore the historical and ecological roots of the subdisciplines ≪conservation biology≫ and ≪behavioural ecology≫, which together make up the backbone of this session. Based on arguments about moral and factual necessities to halt biodiversity loss, I will discuss why, how and to what extent conservation biology and behavioural ecology have come to merge. I will highlight how this has affected conservation efforts in a variety of contexts and geographic settings. In doing so, most of my examples of successful integration between these research fields concern amphibians, reptiles and birds, spanning a wide range of spatial and temporal scales. My emphasis will be more on the conceptual cross-fertilization between the research fields than on the technical development permitting it. Rapid deterioration and reduction of natural habitats crucial for upholding biodiversity provides a backdrop for an analysis of research needs and a horizon scan of further integration of conservation and the study of animal behavior.
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| 67. |
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| 68. |
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| 69. |
- Elmberg, Johan, 1960-
(författare)
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Density-dependent breeding success in mallards Anas platyrhynchos on a eutrophic lake
- 2003
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Ingår i: Wildlife Biology. - 0909-6396 .- 1903-220X. - 0909-6396 ; 9:1, s. 67-73
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Tidskriftsartikel (refereegranskat)abstract
- Census data from a eutrophic lake collected in 1987-1999 were used to study nesting and breeding success in mallards Anas platyrhynchos. In each year there were 6-19 pair counts and 13-34 brood counts. The maximum combined count of single males and pairs (i.e. on any day in any of three census periods in May) provided the best fit with subsequent estimates of breeding success. Nesting success (average brood:pair ratio = 0.52), brood size of older ducklings (mean = 5.7) as well as fledgling success (2.86 juveniles per nesting pair) were higher than in many previous mallard studies. Per capita brood production as well as per capita fledgling production was negatively density dependent, but the latter was not statistically independent of the former. There was no correlation between per capita fledgling success and duckling mortality on a year-by-year basis, hence the density-dependent pattern in breeding success appears to be mediated through variation in nesting success. The number of paired females at the start of the breeding season correlated positively with the production of fledged juveniles the year before.
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| 70. |
- Elmberg, Johan, 1960-, et al.
(författare)
-
Do intruding predators and trap position affect the reliability of catches in activity traps?
- 1992
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Ingår i: Hydrobiologia. - 0018-8158 .- 1573-5117. - 0018-8158 ; 239:3, s. 187-193
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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