| 1. |
- Andueza, Miren, et al.
(author)
-
Geographic variation in body mass of first-year Reed Warblers Acrocephalus scirpaceus in Iberia
- 2014
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In: Ornis Fennica. - 0030-5685. ; 91:2, s. 88-99
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Journal article (peer-reviewed)abstract
- On their route to tropical Africa, European trans-Saharan migrants must cross two major geographical barriers, the Mediterranean Sea and the Sahara Desert, which necessitates the accumulation of large fuel loads. While northern Africa is the chief region where most migrants gain fuel for the Sahara crossing, Iberia is a target area to gain fuel before the sea crossing existing between Europe and Africa. Despite the large body of studies approach- ing the question of fuel accumulation before geographic barriers, it is still poorly known which factors apart from distance to a certain barrier shape the geographical pattern of fuel reserves. To investigate this question in detail we used data of first-year Reed Warblers from 12 localities within Iberia during the autumn migration period of 2009. We run linear models to analyze the effects of location in Iberia, date, and body size on body mass variation at each migratory flyway (eastern, central and western Iberia). Flight ranges from each site were also calculated. Our results showed that Reed Warblers in Iberia had the necessary fuel needed to arrive in northern Africa but not to tropical Africa. However, body mass patterns varied depending on the geographical region (eastern, central or west- ern Iberia). Date did not affect body mass in central and western Iberia, but in eastern Ibe- ria heavier birds tended to pass later. Thus, the factors shaping body mass of Reed War- blers in Iberia before the sea crossing to Africa seemed to be more complex than just the distance to this geographical barrier, with underlying stopover quality-associated factors possibly playing a relevant role.
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| 2. |
- Arzel, Céline, et al.
(author)
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Time use, foraging behavior and microhabitat use in a temporary guild of spring-staging dabbling ducks (Anas spp.)
- 2004
-
In: Ornis Fennica. - 0030-5685. - 0030-5685 ; 81:4, s. 157-168
-
Journal article (peer-reviewed)abstract
- Dabbling ducks were studied on a eutrophic mid-flyway staging site in spring. Six species made up a temporary guild, in order of decreasing abundance they were: Teal (Anas crecca), Shoveler (A. clypeata), Mallard (A. platyrhynchos), Wigeon (A. penelope), Pintail (A. acuta), and Garganey (A. querquedula). Species richness and total abundance peaked around 20 April, whereas guild evenness was highest after the staging peak. Time use during the staging peak differed between the sexes in Mallard, but not in the other species. Mallard spent the least time foraging, whereas Shoveler and Teal foraged the most. Foraging behavior differed among species; i.e. Wigeon was mainly on land, Shoveler mainly fed from the water surface, whilst Mallard and Teal were more generalist. For the guild as a whole, shallow inshore areas were overused compared to offshore habitats. Microhabitat use of foraging birds differed among species; Pintail and Shoveler mainly fed in the offshore end of the habitat gradient, whereas Teal, Garganey, female Mallard, and especially Wigeon used shallow microhabitats. Teal and female Mallard had the highest overlap in microhabitat use, Shoveler and Wigeon had the least. Abundance of invertebrate prey was low during the staging peak, but increased sharply thereafter. This study indicates that eutrophic mid-flyway sites may offer less food to staging birds than do breeding lakes to which many of them are headed.
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| 3. |
- Arzel, Céline, et al.
(author)
-
Time use, foraging behavior and microhabitat use in a temporary guild of spring-staging dabbling ducks (Anas spp.)
- 2004
-
In: Ornis Fennica. - : University of Helsinki. - 0030-5685. ; 81:4, s. 157-168
-
Journal article (peer-reviewed)abstract
- Dabbling ducks were studied on a eutrophic mid-flyway staging site in spring. Six species made up a temporary guild, in order of decreasing abundance they were: Teal (Anas crecca), Shoveler (A. clypeata), Mallard (A. platyrhynchos), Wigeon (A. penelope), Pintail (A. acuta), and Garganey (A. querquedula). Species richness and total abundance peaked around 20 April, whereas guild evenness was highest after the staging peak. Time use during the staging peak differed between the sexes in Mallard, but not in the other species. Mallard spent the least time foraging, whereas Shoveler and Teal foraged the most. Foraging behavior differed among species; i.e. Wigeon was mainly on land, Shoveler mainly fed from the water surface, whilst Mallard and Teal were more generalist. For the guild as a whole, shallow inshore areas were overused compared to offshore habitats. Microhabitat use of foraging birds differed among species; Pintail and Shoveler mainly fed in the offshore end of the habitat gradient, whereas Teal, Garganey, female Mallard, and especially Wigeon used shallow microhabitats. Teal and female Mallard had the highest overlap in microhabitat use, Shoveler and Wigeon had the least. Abundance of invertebrate prey was low during the staging peak, but increased sharply thereafter. This study indicates that eutrophic mid-flyway sites may offer less food to staging birds than do breeding lakes to which many of them are headed.
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| 4. |
- Beal, Martin, et al.
(author)
-
Habitat selection and foraging site fidelity in Caspian Terns (Hydroprogne caspia) breeding in the Baltic Sea
- 2021
-
In: Ornis Fennica. - 0030-5685. ; 98:4, s. 128-141
-
Journal article (peer-reviewed)abstract
- Habitat preferences and foraging strategies affect population-level space use and are therefore crucial to understanding population change and implementing spatial conservation and management actions. We investigated the breeding season habitat preference and foraging site fidelity of the under-studied and threatened, Baltic Sea population of Caspian Terns (Hydroprogne caspia). Using GPS devices, we tracked 20 adult individuals at two breeding colonies, in Sweden and Finland, from late incubation through chick-rearing. Analyzing foraging movements during this period, we describe trip characteristics for each colony, daily metrics of effort, habitat use, and foraging site fidelity. We found that daily time spent away from the colony increased throughout the season, with colony-level differences in terms of distance travelled per day. In general, terns selected shallow waters between 0-5 meters in depth with certain individuals using inland lakes for foraging. We show, for the first time, that individual Caspian Terns are faithful to foraging sites throughout the breeding season, and that individuals are highly repeatable in their strategies regarding foraging site fidelity. These results fill important knowledge gaps for this at-risk population, and extend our general knowledge of the breeding season foraging ecology of this widespread species.
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| 5. |
- Blicharska, Malgorzata, et al.
(author)
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Practical implementation of species' recovery plans - lessons from the White-backed Woodpecker Action Plan in Sweden
- 2014
-
In: Ornis Fennica. - 0030-5685. ; 91, s. 108-128
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Journal article (peer-reviewed)abstract
- Successful biodiversity conservation requires safeguarding viable populations of species. To work with this challenge Sweden has introduced a concept of Action Plans, which focus on the recovery of one or more species; while keeping in mind the philosophy of addressing ecosystems in a more comprehensive way, following the umbrella concept. In this paper we investigate the implementation process of the Action Plan for one umbrella species, the White-backed Woodpecker (WBW) Dendrocopos leucotos. We describe the plan's organisation and goals, and investigate its implementation and accomplishment of particular targets, based on interviewing and surveying the key actors. The achievement of the targets in 2005-2008 was on average much lower than planned, explained partially by the lack of knowledge/data, experienced workers, and administrative flexibility. Surprisingly, the perceived importance of particular conservation measures, the investment priority accorded to them, the money available and various practical obstacles all failed to explain the target levels achieved. However qualitative data from both the interviews and the survey highlight possible implementation obstacles: competing interests with other conservation actions and the level of engagement of particular implementing actors. Therefore we suggest that for successful implementation of recovery plans, there is a need for initial and inclusive scoping prior to embarking on the plan, where not only issues like ecological knowledge and practical resources are considered, but also possible conflicts and synergies with other conservation actions. An adaptive approach with regular review of the conservation process is essential, particularly in the case of such complex action plans as the one for the WBW.
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| 6. |
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| 7. |
- Byholm, Patrik, et al.
(author)
-
Losing your home : Temporal changes in forest landscape structure due to timber harvest accelerate Northern goshawk (Accipiter gentilis) nest stand losses
- 2020
-
In: Ornis Fennica. - 0030-5685. ; 97:1, s. 1-11
-
Journal article (peer-reviewed)abstract
- In Finland, forests are both one of the main national economic resources and the main source of biodiversity. Lack of detailed empirical evidence of how forestry affects biodiversity limits the development of sustainable forest management. Previous studies have found that the Northern goshawk (Accipiter gentilis) is a keystone species in mature coniferous boreal forests, and that its presence is associated with high local biodiversity. To understand how timber harvest affect goshawk nest-stand constancy and nest occupancy, we analyzed changes in nine landscape classes in two buffer zones (100 m, 250 m) around goshawk nests in Western Finland during 2005-2013. Patterns of nest occupancy and nest stand loss during 2005-2013 was compared with corresponding data from 1999-2005 to investigate possible long-term changes in the same. We found a positive connection between the proportion of mature spruce forest and nest occupancy. Nest stand constancy was at a lower level during 2005-2013 than during 1999-2005. This was mainly because of forest loss due to cutting of nest stands. Given that the loss of goshawk nest stands has accelerated and because timber harvest in the area was found to be specifically targeted towards forest types favoured by goshawks, forestry may have an even larger negative effect on biodiversity locally than previously thought given that goshawk nest stands are associated with high biodiversity. To render the Finnish forestry ecologically sustainable, we propose that protection of goshawk nest stands should be an integrated part of standard forestry practices in the future.
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| 8. |
- Cichon, M
(author)
-
Egg weight variation in Collared Flycatchers Ficedula albicollis
- 1997
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In: ORNIS FENNICA. - : FINNISH ORNITHOLOGICAL SOC. - 0030-5685. ; 74:3, s. 141-147
-
Journal article (other academic/artistic)abstract
- Inter-and intra-clutch egg size variation in Collared Flycatchers (Ficedula albicollis) were studied during 1994-1995 on the Baltic Sea island of Gotland (Sweden). The main question was whether Collared Flycatchers increased egg size in laying order and e
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| 9. |
- Dalby, Lars, et al.
(author)
-
The status of the Nordic populations of the Mallard (Anas platyrhynchos) in a changing world
- 2013
-
In: Ornis Fennica. - : Finnish Omithological Soc. - 0030-5685. ; 90:1, s. 2-15
-
Journal article (peer-reviewed)abstract
- Dabbling ducks (Anas spp.) are importantmigratory quarry species, protected as a shared resource under international legislation. However, there is a lack of sufficient high-quality data on vital demographic rates and long-term trends in numbers to judge the conservation status of many duck populations at the flyway level. In response to reported declines in the North-West European flyway population of theMallard, we compiled available data on this species in the Nordic countries up to 2010. Generally, national breeding numbers showed increasing trends, wintering abundance showed variable trends, and productivitymeasures indicated stable or increasing trends.Major knowledge gaps were identified, namely the size of hunting bags, the influence of the released Mallards and the role of short-stopping in explaining changing patterns of wintering abundance across the North-West European flyway. Numerically the Nordic breeding population appears in “good condition”, and the wintering numbers have been either stable or increasing in the last two decades. The annual number of releases needs to be determined in order to judge the sustainability of the current levels of exploitation. Overall, none of the indicators showed alarming signs for the Mallard population in the Nordic countries when considered in isolation. However, the widespread decline in wintering numbers elsewhere across North-western Europe requires urgent pan-European action.
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| 10. |
- Dalby, Lars, et al.
(author)
-
The status of the Nordic populations of the Mallard (Anas platyrhynchos) in a changing world
- 2013
-
In: Ornis Fennica. - : University of Helsinki. - 0030-5685. ; 90:1, s. 2-15
-
Journal article (peer-reviewed)abstract
- Dabbling ducks (Anas spp.) are important migratory quarry species, protected as a shared resource under international legislation. However, there is a lack of sufficient high-quality data on vital demographic rates and long-term trends in numbers to judge the conservation status of many duck populations at the flyway level. In response to reported declines in the North-West European flyway population of the Mallard, we compiled available data on this species in the Nordic countries up to 2010. Generally, national breeding numbers showed increasing trends, wintering abundance showed variable trends, and productivity measures indicated stable or increasing trends. Major knowledge gaps were identified, namely the size of hunting bags, the influence of the released Mallards and the role of short-stopping in explaining changing patterns of wintering abundance across the North-West European flyway. Numerically the Nordic breeding population appears in "good condition", and the wintering numbers have been either stable or increasing in the last two decades. The annual number of releases needs to be determined in order to judge the sustainability of the current levels of exploitation. Overall, none of the indicators showed alarming signs for the Mallard population in the Nordic countries when considered in isolation. However, the widespread decline in wintering numbers elsewhere across North-western Europe requires urgent pan-European action.
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| 11. |
- De Jong, Adriaan, et al.
(author)
-
Tracing the origin of vagrant Siberian songbirds with stable isotopes: the case of Yellow-browed Warbler (Abrornis inornatus) in Fennoscandia
- 2019
-
In: Ornis Fennica. - 0030-5685. ; 96, s. 90-99
-
Journal article (peer-reviewed)abstract
- Vagrant birds are mesmerizing birdwatchers worldwide, but the nature of vagrancy and the true origin of the vagrants are poorly known. To Western Europe, the massive Siberian land mass delivers most of the vagrant songbirds, e.g. Yellow-browed Warbler (YBW) (Abrornis inornatus, formerly Phylloscopus inornatus). In this study we used stable hydrogen isotope ratios in tail feathers (delta H-2(f)) from two ringing stations in northern Fennoscandia in an attempt to link vagrant YBW to potential regions of origin. We could do this thanks to a collection of samples from nestling and breeding adult YBW in Central Siberia. Compared with the nestling samples, the Fennoscandian delta H-2(f) data indicated origins in the western and/or southern parts of the breeding range. The assignment map created in IsoMAP showed high probabilities of origins in the Komi Republic, N/NW of the Ural Mountains. Although our study rules out a large proportion of the YBW breeding range, our method could not pin-point a precise region of origin. The main reason for this is the similarity of environmental hydrogen isotope ratios across longitudes in Eurasia. For increased precision, we propose a multi-method approach (e.g. stable isotopes and genetics) based on significantly more data from across the vast and challenging Siberian territory. More international collaboration will be vital for this endeavour.
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| 12. |
- Edenius, Lars
(author)
-
Short-term effects of wildfire on bird assemblages in old pine- and spruce-dominated forests in northern Sweden
- 2011
-
In: Ornis Fennica. - 0030-5685. ; 88, s. 71-79
-
Journal article (peer-reviewed)abstract
- Effects of wildfire on forest birds have rarely been studied in Fennoscandia. Hence, birds were surveyed three years after fire at two large areas that were not subjected to salvage logging, in northern Sweden. The 300- and 440-ha burns and surrounding forests were dominated by Scots pine and Norway spruce, respectively. Closed-nest breeders and ground-feeding insectivores were more abundant within the burns than in the surrounding forests, whereas ground- and shrub-breeders were nearly equally abundant in the burns and in unburned forests. Redpoll and Tree Pipit were more common within than outside the burns. Birds feeding on insects in the air and the Redstart were more abundant in burned than in unburned spruce-dominated forest but no such difference was found in pine-dominated forest, suggesting that the short-term effects of wildfire on these birds were stronger in spruce-dominated forest than in pine-dominated forest. A contributing factor might be that crown fire killed most trees in the spruce-dominated burn, but most of the large trees survived the ground fire in the pine-dominated burn.
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| 13. |
- Ekroos, Johan, et al.
(author)
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Declines amongst breeding Eider Somateria mollissima numbers in the Baltic/Wadden Sea flyway
- 2012
-
In: Ornis Fennica. - 0030-5685. ; 89:2, s. 81-90
-
Journal article (peer-reviewed)abstract
- We report on the status of the Baltic/Wadden Sea flyway Eider population based on trends in breeding and wintering numbers throughout the region, supplemented by changes in the sex ratio and proportion of young Eiders as monitored in the Danish hunting bag. At the flyway scale, total numbers of breeding pairs decreased by 48% during 2000-2009, after relatively stable breeding numbers in 1991-2000. The majority of the population nest in Finland and Sweden, where the number of breeding pairs has halved over the same period. After initial declines in winter numbers between 1991 and 2000, during 2000-2009, national wintering numbers increased in the Baltic Sea, but decreased in the Wadden Sea. The annual proportion of adult females in the Danish hunting bag data decreased from ca. 45% (1982) to ca. 25% (2009) and simultaneously the proportion of first-winter birds fell from ca. 70% to ca. 30%, indicating dramatic structural changes in the Danish wintering numbers. These results suggest that the total flyway population will experience further declines, unless productivity increases and the factors responsible for decreasing adult female survival are identified and ameliorated. We discuss potential population drivers and present some recommendations for improved flyway-level monitoring and management of Eiders.
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| 14. |
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| 15. |
- Felton, Adam, et al.
(author)
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Projecting impacts of anthropogenic climatic change on the bird communities of southern Swedish spruce monocultures : will the species poor get poorer?
- 2014
-
In: Ornis Fennica. - : University of Helsinki. - 0030-5685. ; 91:1, s. 1-13
-
Journal article (peer-reviewed)abstract
- The potential impact of climatic change on bird species' distributions in Europe was recently modeled for several scenarios of projected late 21st century climate. The results indicate mean range shifts of hundreds of kilometres north for many of European bird species. Here we consider the implications from such distributional shifts for the bird communities of Norway spruce (Picea abies) monocultures in southern Sweden, a forest type likely to remain prevalent due to forestry, despite climate change. Our assessment led us to three key findings. First, the monocultures offer suitable habitat to only two bird species projected to extend their breeding distribution northwards into southern Sweden this century. Second, species richness was projected to decline overall, which would accentuate the depauperate nature of these stands. Third, all conifer-associated arboreal granivores and three of four conifer-associated arboreal insectivores were projected not to occur, reducing both the functional richness and functional redundancy. We discuss caveats related to our approach, including the potential for bioclimatic projections - used in this study - to be hampered by the artificial retention of dominant vegetation. We also discuss the implications of our results for avian biodiversity in what is today the most prevalent forest type in southern Sweden and in many other regions of Europe.
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| 16. |
- Fox, Anthony D., et al.
(author)
-
Seeking explanations for recent changes in abundance of wintering Eurasian Wigeon (Anas penelope) in northwest Europe
- 2016
-
In: Ornis Fennica. - 0030-5685. ; 93:1, s. 12-25
-
Journal article (peer-reviewed)abstract
- We analysed annual changes in abundance of Eurasian Wigeon (Anas penelope) derived from mid-winter International Waterbird Census data throughout its northwest European flyway since 1988 using log-linear Poisson regression modelling. Increases in abundance in the north and east of the wintering range (Norway, Sweden, Denmark, Germany, Switzerland), stable numbers in the central range (Belgium, Netherlands, UK and France) and declining abundance in the west and south of the wintering range (Spain and Ireland) suggest a shift in wintering distribution consistent with milder winters throughout the range. However, because over 75% of the population of over 1 million individuals winters in Belgium, the Netherlands, UK and France, there was no evidence for a major movement in the centre of gravity of the wintering distribution. Between-winter changes in overall flyway abundance were highly significantly positively correlated (P = 0.003) with reproductive success measured by age ratios in Danish hunter wing surveys and less strongly and inversely correlated (P = 0.05) with mean January temperatures in the centre of the wintering range, suggesting that winter severity may also contribute to influence survival. However, adding winter severity to a model predicting population size based on annual reproductive success alone did not contribute to more effectively modelling the observed changes in population size. Patterns in annual reproductive success seem therefore to largely explain the recent dynamics in population size of northwest European Wigeon. Summer NAO significantly and positively explained 27% of variance in annual breeding success. Other local factors such as eutrophication of breeding sites and changes in predation pressure undoubtedly contribute to changes in the annual production of young and differences in hunting pressure as well as winter severity affect annual survival rates. However, it seems likely that the observed flyway population trend since 1988 has been mostly influenced by climate effects on the breeding grounds affecting reproductive success and marginally on the winter quarters affecting survival. We urge improved demographic monitoring of the population to better assess annual survival and reproductive success. We also recommend development of an adaptive management framework to remove uncertainties in our knowledge of Wigeon population dynamics as information is forthcoming to better inform management, especially to attempt to harmonise the harvest with annual changes in demography to ensure sustainable exploitation of this important quarry species now and in the future.
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| 17. |
- Hake, M., et al.
(author)
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The impact of water level fluctuation on the breeding success of the Black-throated Diver Gavia arctica in South-west Sweden
- 2005
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In: Ornis Fennica. - 0030-5685. ; 82:1, s. 1-12
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Journal article (peer-reviewed)abstract
- We evaluated the impact of water level fluctuation on the breeding success of the Black-throated Diver in South-west Sweden by using results from a one-year study of 43 lakes (49 pairs) in 1996 and surveys of a population of 16-22 pairs at the lake system Fegen-Svansjoarna in 1997-2000. At this lake system, the water level is regulated (for hydropower production) with a maximum amplitude of 1.75 m. In 1997 2000, an attempt was made to maintain a stable water level during the period 1 May-15 June. Flooding was the most important cause of breeding failure at the 43 lakes, whereas no failure could be related to this factor at Fegen-Svansjoarna. In the 43 lakes, the change in median water level during incubation was +6 cm for five flooded nests, compared to -5 cm for 14 hatched clutches and -6 cm for 13 clutches that failed because of other or unknown causes. The mean breeding success at Fegen-Svansjoarna was on the same level as for South-west Sweden in general during 1997-2000 (0.44 and 0.38 chicks per pair and year, respectively), but was higher than for the four years before the attempt to keep the water level stable (0.22 chicks). We conclude that flooding is a main cause of nesting failure, that rainfall is the main factor behind the water level fluctuations, and that the regulation of the water level for hydropower production may have an additional negative impact on some takes. Control of the water level during the incubation period may help to reduce the risk of failure caused by flooding, and Our results support previous recommendations to allow for a rise of only a few centimetres or a lowering of a maximum of 20-30 cm during the incubation period.
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| 18. |
- Heldbjerg, Henning, et al.
(author)
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Contrasting population trends of common starlings (Sturnus vulgaris) across Europe
- 2019
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In: Ornis Fennica. - 0030-5685. ; 96:4, s. 153-168
-
Journal article (peer-reviewed)abstract
- The greatest loss of biodiversity in the EU has occurred on agricultural land. The Common Starling (Sturnus vulgaris) is one of the many numerous and widespread European farmland breeding bird species showing major population declines linked to European agricultural intensification. Here we present results based on monitoring data collected since 1975 in 24 countries to examine the influence of changing extent of grassland and cattle abundance (based on results of earlier studies showing the importance of lowland cattle grazed grassland for the species), wintering provenance and temperature on national breeding population trends of Starlings across Europe. Positive Starling population trends in Central-East Europe contrast with negative trends in North and West Europe. Based on this indicative approach, we found some support for the importance of cattle stock and no support for grassland, temperature or wintering provenance to explain Starling population trends in Europe. However, we acknowledge such a European-wide analysis may conceal regional differences in responses and suggest that currently accessible national land use data might be insufficient to describe the detailed current changes in animal husbandry and grassland management that may be responsible for changes in food availability and hence breeding Starling abundance and their differences across Europe. Reviewing results from local studies relating Starling population trends to local agricultural change offer contradictory results, suggesting complex interacting processes at work. We recommend combining national datasets on demography, land-use/agricultural practices and from autecological research to better explain the reasons for contrasting Starling trends across Europe, to enable us to predict how changing agriculture will affect Starlings and potentially suggest mitigation measures to restore local populations where possible.
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| 19. |
- Iwajomo, Soladoye B., et al.
(author)
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Autumn phenology and morphometrics in the Garden Warbler Sylvia borin at the Ottenby Bird Observatory, Sweden
- 2012
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In: Ornis Fennica. - 0030-5685. ; 89:4, s. 233-240
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Journal article (peer-reviewed)abstract
- Trapping and ringing near ecological barriers can provide useful information about the migration strategies of bird species. In this paper we analyzed ringing data of the Garden Warbler, collected within the period of 1950-2008 at the Ottenby Bird Observatory, south-eastern Sweden, and describe patterns in migration phenology, morphometrics and fuel load. A total of 4,351 individuals aged as either adults or juveniles were ringed during the period (yearly averages 7.3 adults and 83.1 juveniles) in addition to 1,514 birds of unknown age. Both age-specific and combined yearly totals did not significantly vary over the years. Median passage dates were 24 August, 30 August and 2 September for adults, juveniles and birds of unknown age, respectively. Median passage did not change significantly over the years. Among adults, larger individuals passed the observatory earlier than smaller individuals. The average fuel load was estimated at 24.3% of Lean Body Mass (LBM), and late-migrating individuals had higher fuel deposits than early migrants. Maximum fuel load was estimated at 82.5% of LBM; such an individual may be capable of a direct flight from Ottenby region to the Mediterranean area.
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| 20. |
- Jiguet, Frédéric, et al.
(author)
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An update of the European breeding population sizes and trends of the Ortolan Bunting (Emberiza hortulana)
- 2016
-
In: Ornis Fennica. - : University of Helsinki. - 0030-5685. ; 93:3, s. 186-196
-
Research review (peer-reviewed)abstract
- Following recent updates proposed by BirdLife International and further updates across Europe gathered in the context of a continent-wide study of the migration strategy of the species, we propose here an update of national population sizes and associated recent trends of the Ortolan Bunting (Emberiza hortulana). Previous estimates for the period 1999-2002 reported 5,200,000 to 16,000,000 breeding pairs, for an area extending east to European Russia, and south to the Caucasus and Turkey. The countries holding the largest populations were Turkey (3-10 million pairs) and Russia (1.5-5.0 million pairs). The updated results give approximately 3,319,000 to 7,057,000 pairs in Europe (for the period 2012-2014), representing a c. 50% decrease in numbers over the last decade. This decrease is partly due to overestimates proposed in previous reports for the key country, Turkey, which is now considered to support only 500,000 to 1,000,000 pairs. Russia still holds 2.0-4.3 million pairs, although with an estimated decline of c.15-30% since 2000. Overall, within the 39 European countries assessed here, recent decadal trends (on average 2000-2012) in population size are reported as unknown in 15 countries, increasing in 2 countries (Germany and Serbia), stable or fluctuating in 6 countries, and decreasing in 16 countries including recent extinctions in Belgium, Hungary, Slovakia and the Netherlands. Overall, declining populations are mostly located in northern Europe, and fourteen of the 15 northern European countries with a known national trend have declining breeding populations, suggesting that northern breeders are of particular conservation concern.
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| 21. |
- Karell, Patrik, et al.
(author)
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Mammalian nest predation induces small-scale nest site switching in territorial tawny owl (Strix aluco) females
- 2020
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In: Ornis Fennica. - 0030-5685. ; 97:2, s. 45-52
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Journal article (peer-reviewed)abstract
- Nest predation is a major factor affecting fitness in birds. Individuals are expected to respond to nest predation by selecting safe nesting sites and by moving away from risky sites. Thereby, perceived risk or experience of predation should lead to shifts in nest site selection. Experimental studies on behavioural and life-history consequences of nest predation have traditionally manipulated the risk of predation and studied the immediate consequences thereof. Fewer studies have however analysed the behavioural consequences of perceived predation risk to future breeding events and we know little about how sedentary territorial species respond to nest predation. We experimentally manipulated tawny owl (Strix aluco) breeding nest site choice by providing an additional alternative nest box within the territory, nearby the original nesting sites. The new nest box was provided either after a successful reproductive event (control group), or following a failed reproductive event caused by a nest predator (i.e. pine marten Martes martes, predated group). We show that tawny owls generally switched to the alternative nest site in the current breeding season when the nest was predated in the previous year, whereas they used the same nest after a successful breeding. We found no effects of previous predation experience on the probability to breed nor on clutch size. We conclude that small scale movement within the territory are used by tawny owls to minimize predation risk and that the owls use information on past predation events and nest failure to optimize their breeding decision in the following season.
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| 22. |
- Kylin, Henrik
(author)
-
Nominate Lesser Black-backed Gulls (Larus fuscus fuscus) winter in the Congo basin
- 2010
-
In: Ornis Fennica. - 0030-5685. ; 87, s. 106-113
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Journal article (peer-reviewed)abstract
- After observing several nominate Lesser Black-backed Gulls (Larus fuscus fuscus) on Lake Tumba, Democratic Republic of the Congo, literature andmuseum studies were reviewed to compile observations of the species in the Congo basin. The Congo basin appears to be an important wintering area for these birds that are dispersed widely but thinly throughout the large network of rivers. Clearly, difficulties in performing fieldwork in the basin have, thus far, left this wintering area unrecognized.We suggest that the main wintering area for L. f. fuscus covers an area from the Rift Valley lakes westward into the Congo basin and, contrary to themainstream literature, only a small proportion of the population winter on the East African coast
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| 23. |
- Larsson, Kjell, Professor, 1958-
(author)
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Age and sex ratios in the declining West Siberian/North European population of Long-tailed Duck wintering in the Baltic Sea : Implications for conservation
- 2022
-
In: Ornis Fennica. - : BirdLife Finland. - 0030-5685. ; 99:4, s. 117-131
-
Journal article (peer-reviewed)abstract
- The West Siberian/North European population of Long-tailed Duck (Clangula hyemalis), which breeds in the Russian Arctic and northern Fennoscandia and winters in the Baltic Sea, has declined rapidly since the 1990s. To identify the causes of the decline and initiate effective conservation measures information on basic demographic parameters is needed. A photo survey method was used to estimate female age ratios and the proportion of males among adults in wintering Long-tailed Ducks at coastal and off-shore areas in the Baltic Sea. Female age ratios were defined as the number of first winter males, assumed equal to the number of first winter females, per adult female. Several thousand individuals were sampled each winter from 2008 to 2021. Female age ratios fluctuated between years and were consistently lower in the southern than in the central Baltic Sea. The proportion of males among wintering adults birds was male-biased, more so in the southern Baltic Sea than in other regions. A population model was used to analyse if low female age ratios between 2008 and 2021 has constrained population growth. Given that the estimated weighted mean female age ratio of 0.153 was representative at the population scale, an extremely high adult female mean annual survival rate of 0.872 would have been needed to maintain a stable population. Considering known sources of anthropogenic mortality in the Baltic Sea, and instead assuming a more realistic survival rate of ca. 0.80, a population decline of ca. 7.7% per year should have occurred during the study period.
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| 24. |
- Lehikoinen, Aleksi, et al.
(author)
-
The impact of weather and the phase of the rodent cycle on breeding populations of waterbirds in Finnish Lapland
- 2016
-
In: Ornis Fennica. - 0030-5685. ; 93:1, s. 31-46
-
Journal article (peer-reviewed)abstract
- Climate change may affect bird populations both directly by changing the weather conditions, and indirectly through changes in the food chain. While both theoretical and empirical studies have shown climate change having drastic impacts on polar areas, its consequences on Arctic bird species are still poorly known. Here we investigated how weather and changes in predator-prey interactions affected the annual growth rates of sub-Arctic birds by monitoring the breeding numbers of three duck and seven wader species in the alpine tundra of Finnish Lapland during 2005-2015 (except for 2006). We hypothesized that growth rates of waterbirds would be positively associated with warm and dry weather due to improved reproductive success. Furthermore, we tested the hypothesis that water-birds have a higher reproductive success during the cyclic rodent peaks, when predators mainly prey on rodents, than during the decline and low phases of the cycle, when predation pressure towards waterbirds increases. Results showed that population growth rates of breeding ducks were negatively associated with the sum of rainfall in the previous year. In waders, growth rates were positively associated with the phase of the rodent cycle in the same year. Our results emphasize the importance of monitoring Arctic bird populations on their breeding areas to explore what the consequences of climate change might be for breeding waterbirds by linking the effects of both weather and rodent abundance.
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| 25. |
- Lind, Johan, et al.
(author)
-
Compensatory bodily changes during moult in tree sparrows, Passer montanus, in Italy
- 2004
-
In: Ornis Fennica. - 0030-5685. ; 81:2, s. 75-83
-
Journal article (peer-reviewed)abstract
- To cope with fluctuating environments animals have evolved reversible phenotypic flexibility.Some birds demonstrate this phenomenon by changing mass and flight muscle according to changes in wing loading. During moult, birds suffer from reduced wing area because feathers are shed and replaced, resulting in a wing loading increase. Moult is rather well studied in birds, but the perspective of phenotypic flexibility has been neglected. Therefore,we tested predictions generated from experimental studies by collecting information about bodymass, flightmuscle size and fat stores from an Italian population of Tree Sparrows (Passer montanus) to investigate if they compensate physiologically for the wing area reductions they suffer from during moult. Our results did not corroborate predictions based on experimental studies; that is, the Tree Sparrows did not reduce body mass and increase in flight muscle size as a response to wing area reductions during midmoult. Instead, body mass increased throughout moult, flight muscle size did not change, and fat stores decreased asmoult progressed. To further investigate compensatory changes, we analysed bodily differences in midmoult between birds differing in moult gap size. Again, contrary to predictions from experimental studies, birds having larger moult gaps were found to have higher body mass. These birds were also found to keep the ratio between flight muscle size and body mass constant over the day whereas birds with small moult gaps reduced this ratio over the day. Birds with large moult gaps ere also found to store less fat than birdswith small gaps. Physiological constraints may help to explain these results and underlying reasons for the observed variation in bodily regulation in birds are discussed.
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| 26. |
- Lind, Johan, et al.
(author)
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Information, predation risk and foraging decisions during mobbing in great tits, Parus major
- 2005
-
In: Ornis Fennica. - 0030-5685. ; 82, s. 89-96
-
Journal article (peer-reviewed)abstract
- Tomaximise survival during foraging animalsmust decide when and for how long foraging should be interrupted in order to avoid predators. Previous experiments have shown that birds that hear other individuals’alarm calls resume feeding later than those that see a flying predator.However, the responses of prey animals to enemies are highly context-dependent. We therefore investigated how birds respond to a threat less serious than a flying hawk depending on different amount of information about the predator. We used Great Tits dyadswhere one individual saw a perchedmodel predator (sender), whereas the other individual could only hear the conspecific’s mobbing calls (receiver). The sender responded appropriately as shown by comparing their responses to how they responded to a control.We also found that while senders were exposed to the predator, receivers became more wary and reduced their activity level. However, despite the receivers having less information about predation risk they still did not prolong the time they took to resume foraging. Hence, once the mobbing ceased (and consequently the transmission of information about the predator stopped) therewas no effect of only having second-hand information. This also shows that receiver’s rely upon the sender’smobbing calls suggesting that mobbing calls may act as honest signals of the prevailing predation risk. In conclusion, our results support the view that responses of prey to predators are highly context-dependent and that birds’ anti-predator responses are a result of an interaction between the amount of information and the level of the threat.
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| 27. |
- Lomas Vega, Marta, et al.
(author)
-
Local weather, food resources and breeding stage influence Thrush Nightingale movement
- 2018
-
In: Ornis Fennica. - 0030-5685. ; 95:4, s. 151-159
-
Journal article (peer-reviewed)abstract
- Insectivorous migrants breeding at northern latitudes often time the breeding period with the seasonal peak of food resources. Whether this general pattern transfers to movement behaviour during the breeding season requires detailed study from a local perspective. We investigated fine-scale environmental correlates of movements by six actively-breeding adult Thrush Nightingales (Luscinia luscinia) at a breeding site in Denmark, using radio tracking and multiple regression models. Overall, the chick-rearing period coincided with the peak of vegetation greenness at the site. Adults flew further from nesting areas during stable weather and as vegetation greenness decreased. Adults were more active at higher environmental temperatures and when fledglings were older but still dependent on adults. These changes in local movements likely reflect adjustments to chick developmental needs and to specific local environmental conditions, including resource availability.
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| 28. |
- Milberg, Per, 1959-, et al.
(author)
-
Submerged vegetation and the variation in the autumn waterfowl community at Lake Tσkern, southern Sweden
- 2002
-
In: Ornis Fennica. - 0030-5685. ; 79:2, s. 72-81
-
Journal article (peer-reviewed)abstract
- We analysed data from 25 years of standardised mid-September counts of waterfowl at eutropic Lake Tσkern, southern Sweden. For eight species, counts were compared with a national index constructed from similar counts at numerous lakes and coastal sites. For Crested Grebes and Mute Swans there was a correlation between counts at Lake Tσkern and the national index, suggesting that they simultaneously vary in number over a large geographic area. Indirect gradient analysis (PCA) revealed a strong temporal trend in the data, which was covaried out in a partial PCA to expose residual patterns. This ordination separated Pochards and Tufted Ducks at one end of the first axis from Cormorants and Goosanders at the other. A direct gradient analysis, with biomass of submerged macrophytes (recorded for 14 of the 25 years) as the sole environmental variable, showed that bird species composition varied significantly with plant biomass. The piscivores, Cormorants and Goosanders, were abundant in years with small amounts of plant biomass, while several species were most abundant in years with large amounts. Our analyses suggest that the abundance of submerged macrophytes is an important determinant of the bird community composition in eutrophic lakes.
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| 29. |
- Månsson, Johan, et al.
(author)
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Territory size and habitat selection of breeding Common Cranes (Grus grus) in a boreal landscape
- 2013
-
In: Ornis Fennica. - 0030-5685. ; 90, s. 65-72
-
Journal article (peer-reviewed)abstract
- Information on how birds use different types of habitat and move within landscapes is crucial for avian ecology, conservation and management. The Common Crane Grus grus has the widest distribution of all crane species and covers both increasing and decreasing populations. Ecological knowledge is therefore necessary both for conservation and to mitigate bird-human conflicts. We studied territory size and habitat selection of breeding Common Cranes (n=11) at two spatial scales in south-central Sweden by using VHF and UPS transmitters. Breeding families of Cranes were strongly associated with farmlands and wetlands independent of spatial scale. However, 41% of positions were within forested habitats. According to a compositional analysis, moist and wet forests were selected more frequently than dry forests. Territory size was on average 250 ha +/- 47.8 SE. The territories showed little overlap between neighboring breeding pairs. Our study provides information necessary for estimating densities of breeding pairs, but also to indicate habitat types worth special attention by landscape managers and conservationists.
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| 30. |
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| 31. |
- Nyström, Jesper, et al.
(author)
-
Golden Eagles on the Swedish mountain tundra - diet and breeding success in relation to prey fluctuations
- 2006
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In: Ornis Fennica. - 0030-5685. ; 83:4, s. 145-152
-
Journal article (peer-reviewed)abstract
- We studied the diet and the relationship between prey density fluctuations and breeding success of a Golden Eagle (Aquila chrysaetos) population on the mountain tundra region of northern Sweden. We used a new PCR based method to analyse the DNA in bone fragments from Golden Eagle prey remains. This allowed us to accurately identify the Ptarmigan species that the bone fragments originated from, and hence, establish the proportions of Ptarmigan species in the eagle's diet. We could conclude that Ptarmigan species (Lagopus spp.) are the most important prey category for this Golden Eagle population (63% of all identified prey), and that Willow Ptarmigan (L. lagopus) occurred more frequently in the diet than Rock Ptarmigan (L. mutus) did (Willow Ptarmigan 38%, Rock Ptarmigan 25%). Other important prey included reindeer (Rang fer tarandus), mountain hare (Lepus timidus) and microtine rodents. The Golden Eagles managed to maintain a relatively broad food niche, despite an environment with low prey diversity. Microtine rodents, hare and Ptarmigan populations showed similar population fluctuations in the study area. The breeding success of the Golden Eagles showed a strong relationship to the yearly density index of the most important prey category, the Ptarmigan species.
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| 32. |
- Ojaste, Ivar, et al.
(author)
-
From northern Europe to Ethiopia : Long-distance migration of Common Cranes (Grus grus)
- 2020
-
In: Ornis Fennica. - 0030-5685. ; 97:1, s. 12-25
-
Journal article (peer-reviewed)abstract
- The majority of Common Cranes (Grus grus) breeding in northern Europe are short- to medium-distance migrants that overwinter in southern Europe, northern Africa, and the Middle East. However, some individuals migrate longer distances to as far as Ethiopia. Using data from 18 satellite-tracked juvenile Common Cranes, we assessed (1) the length and landscape composition of the migratory routes used and (2) the behaviour of neighbouring Finnish and Estonian (500 km apart in the north-south direction) sub-populations. Our results show that Common Cranes mainly use the East European flyway to reach the wintering grounds in Ethiopia, yet some individual cranes may alternatively use the Baltic-Hungarian migration route. Neither duration nor the number of stopovers used influenced the flight distances of the cranes. Further, 7-19 days of refuelling enabled the cranes to cover long flight distances, from 2,420 to 5,110 km in 6-15 days, without the need for settling down at potential stopovers on the route. Contrary to our expectations, the main refuelling sites of the Finnish breeding population were further south (in southern Ukraine) than those of the Estonian population (in Belarus). Despite the longer flight distances, Finnish cranes used three main migration stages, while cranes breeding at more southern sites generally used mainly four stages. Our findings demonstrate that large-sized social migrants such as the Common Crane may have spatially segregated, flexible migration patterns that involve only a few carefully selected stopovers during long-distance migration.
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| 33. |
- Ovegård, Maria, et al.
(author)
-
Diet of the Great Cormorant (Phalacrocorax carbo sinensis) at two areas at Lovstabukten, South Bothnian Sea, Sweden, based on otolith size-correction factors
- 2012
-
In: Ornis Fennica. - 0030-5685. ; 89, s. 157-169
-
Journal article (peer-reviewed)abstract
- This study determines Cormorant (Phalacrocorax carbo sinensis) diet composition and prey size at two areas 6 km apart, at Bay Lovstabukten, Sweden, in 2005. The study entails the examination of 333 pellets and 2,669 regurgitated fish. To determine the size of the predated fish based on worn otoliths found in pellets, size-correction factors were applied. Regression slopes between fish size and otolith size were applied to estimate the original size of the predated fish. Both pellet-based and regurgitated-fish-based analyses suggested the same dominating prey species by biomass. Based on pellets, Herring (Clupea harengus; 32.5%), European Perch (Perca fluviatilis; 20.9%) and Eelpout (Zoarces viviparus; 18.5%) dominated the diet. Regurgitated-fish samples contained species that were not found in pellets. These were mostly species with small and easily-eroding otoliths, such as Three-spined Stickleback (Gasterosteus aculeatus) and Greater Sand Eel (Hyperoplus lanceolatus). Cormorant diet between the two areas differed, and within both areas there were gradual changes in diet composition between incubation, nestling, chick and fledgling phases.
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| 34. |
- Redpath, Stephen, et al.
(author)
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Seeking greener pastures: crop selection by Greylag Geese (Anser anser) during the moulting season
- 2021
-
In: Ornis Fennica. - 0030-5685. ; 98, s. 16-32
-
Journal article (peer-reviewed)abstract
- Over the last 40 years, many goose populations have recovered from historic lows and are now more numerous than ever. At the same time, geese have shifted from natural foraging habitats to securing most of their nutritional demands from agricultural fields, leading to crop damage and conflict with agriculture. We studied field use by Greylag Geese (Anser anser) in the agricultural landscape surrounding a main breeding and moulting lake in Sweden. From 2012 to 2016, weekly roadside surveys were conducted from May to July. Data were collected on goose numbers, crop type and sward height in agricultural fields. Using a compositional analysis, we demonstrate that Greylag Geese show a strong selection for ley and pasture fields compared to other crop types (rank order: ley/pasture > oat > barley > wheat > other crops). This selection was consistent across years and between pre- and post-moult. Aside from ley and pasture, no other crop types were selected for, as they were used less than expected given their availability. Irrespective of crop type, geese foraged predominantly on short (0-10 cm) swards. The strong selection for ley and pasture may have been driven by higher nutritional quality of short, managed grass swards relative to other available foods. This suggests that during the summer grass fields may be more vulnerable to damage compared to other crop types. Our study provides a deeper understanding of the ecology of Greylag Geese, which may be used to inform management strategies focused on mitigating crop damage and alleviating conflict.
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| 35. |
- Rintamaki, PT, et al.
(author)
-
Blood parasites found in three passerine species during spring migration
- 1997
-
In: ORNIS FENNICA. - : FINNISH ORNITHOLOGICAL SOC. - 0030-5685. ; 74:4, s. 195-200
-
Journal article (other academic/artistic)abstract
- Blood samples from three common passerine bird species, Robin, Redstart and Lesser Whitethroat, were collected during spring migration in the south-western archipelago of Finland. A total of 10 parasitic haemosporidian and trypanosomid species were record
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| 36. |
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| 37. |
- Roberge, JM, et al.
(author)
-
How much time is required to survey land birds in forest-dominated atlas squares?
- 2003
-
In: Ornis Fennica. - 0030-5685. ; 80:3, s. 111-120
-
Journal article (peer-reviewed)abstract
- Using bird atlas data from south-central Sweden and information on survey effort for the corresponding 5 x 5 km grid squares, we assessed how much time is required to get reliable presence/absence data for forest birds. We restricted the analyses to a suite of 28 species considered common enough and sufficiently generalised in their requirements to be present in all survey squares largely dominated by forest. For a set of 183 squares having more than 2/3 of their area covered by forest, the non-linear relationship between survey duration and the number of species detected showed that a total survey duration of less than ca. 16 h was often insufficient for getting a reliable species list. There was, however, much variation in efficiency for such shorter survey durations. We conclude that a total survey duration of ca. 40-45 h should constitute a fair compromise between maximising survey quality and minimising effort, if the fieldwork is done by a range of birdwatchers of varying competence. However, longer surveys may be required for uncommon or specialised species. These findings have implications for the planning of further atlas work in forested areas and for the use of bird atlas data in various research fields.
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| 38. |
- Sandström, Ulf
(author)
-
Enhanced predation rates on cavity bird nests at deciduous forest edges : an experimental study
- 1991
-
In: Ornis Fennica. - 0030-5685. ; 68:3, s. 93-98
-
Journal article (peer-reviewed)abstract
- The size of a forest tract influences the composition of the fauna. If forests become fragmented this will affect the fauna in several ways. One of the main effects is enhanced nest predation. Several studies which confirm this effect have been carried out, but none has used natural cavities. I tested experimentally whether the predation rate was higher in natural tree-holes close to the forest/farmland edge than in the interior of the wood. In a fragmented deciduous forest, fresh Quail eggs were placed in natural cavities at various distances from the edge. The eggs were exposed during a period corresponding in length to the egg and nestling period of a hole-nesting bird. In the beginning of the period, the predation rate was higher close to the edge (< 20 m) than further inside the wood. This result may indicate that a predator first searches the ecotone and afterwards penetrates deeper inside the forest. The results is in accord with earliest observations than nests in natural cavities seem to be less vulnerable than other types of nests.
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| 39. |
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| 40. |
- Strong, Emily A., et al.
(author)
-
Seeking greener pastures : crop selection by Greylag Geese (Anser anser) during the moulting season
- 2021
-
In: Ornis Fennica. - : Finnish Omithological Soc. - 0030-5685. ; 98:1, s. 16-32
-
Journal article (peer-reviewed)abstract
- Over the last 40 years, many goose populations have recovered from historic lows and are now more numerous than ever. At the same time, geese have shifted from natural foraging habitats to securing most of their nutritional demands from agricultural fields, leading to crop damage and conflict with agriculture. We studied field use by Greylag Geese (Anser anser) in the agricultural landscape surrounding a main breeding and moulting lake in Sweden. From 2012 to 2016, weekly roadside surveys were conducted from May to July. Data were collected on goose numbers, crop type and sward height in agricultural fields. Using a compositional analysis, we demonstrate that Greylag Geese show a strong selection for ley and pasture fields compared to other crop types (rank order: ley/pasture > oat > barley > wheat > other crops). This selection was consistent across years and between pre- and post-moult. Aside from ley and pasture, no other croptypes were selected for, as they were used less than expected given their availability. Irrespective of crop type, geese foraged predominantly on short (0–10 cm) swards. The strong selection for ley and pasture may have been driven by higher nutritional quality of short, managed grass swards relative to other available foods. This suggests that during the summer grass fields may be more vulnerable to damage compared to other crop types. Our study provides a deeper understanding of the ecology of Greylag Geese, which may be used to inform management strategies focused on mitigating crop damage and alleviating conflict.
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| 41. |
- Strong, Emily A., et al.
(author)
-
Seeking greener pastures : crop selection by Greylag Geese (Anser anser) during the moulting season
- 2021
-
In: Ornis Fennica. - : University of Helsinki. - 0030-5685. ; 98:1, s. 16-32
-
Journal article (peer-reviewed)abstract
- Under de senaste 50 åren har åtskilliga gåspopulationer återhämtat sig från historiskt låga nivåer till att nu vara större än någonsin. Samtidigt har gäss i stor utsträckning övergivit sina ursprungliga födosöksmiljöer för att numer finna nästan all sin föda på jordbruksmark, något som ibland leder till konflikt på grund av betesskador. Vi studerade grödoval hos gragäss (Anser anser) i ett jordbruksdominerat landskap kring en viktig häcknings- och ruggningssjö i södra Sverige. Från 2012 till 2016 skedde inventeringar från vägar i studieområdet varje vecka under maj, juni och juli. Vi noterade antalet gäss, grödoslag och grödohöjd på alla fält med gragäss. Statistiska analyser (compositional analysis) visade att grägässen starkt föredrog fält med vall eller betesmark framför andra grödor (preferensordning: vall/betesmark > havre > korn > vete > övriga grödor). Preferensmönstret var det samma oberoende av år och period under sommaren (före resp. efter ruggning). Alla andra grödoslag än vall och betesmark var icke föredragna, eftersom de utnyttjades mindre än deras andel av studieområdet. Den starka preferensen för vall och betesmark kan vara en följd av en högre näringsmässig kvalitet hos gräs som ännu inte blivit högvuxet. Detta antyder i sin tur att fält med kort gräs är mer utsatta för gåsbete än andra grödor under sommarmånaderna. Denna studie ger ny kunskap om grágässens uppträdande på jordbruksmark under senvår och sommar, vilken kan ge förbättrade förvaltningsstrategier för att minska betesskador och reducera konflikten med jordbruksintressen.
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| 42. |
- Teräväinen, Malin, et al.
(author)
-
Field selection of greylag geese (Anser anser) : Implications for management of set-aside fields to alleviate crop damage
- 2022
-
In: Ornis Fennica. - : University of Helsinki. - 0030-5685. ; 99:2-3, s. 71-82
-
Journal article (peer-reviewed)abstract
- Greylag geese (Anser anser) have been increasing in numbers in Europe during the last decades. They forage and roost in agricultural landscapes and may cause damage to sensitive crops. We studied field selection of greylag geese around lake Sörfjärden in south central Sweden where geese aggregate during the growing season. In this area a set-aside field was established in 2010, i.e., a field where geese can graze undisturbed, with the aim to reduce damage in surrounding conventional fields. The goal of our study was to investigate the general selection of the different field types as well as the specific set-aside field. We used a point survey count to estimate goose numbers and regression analyses to evaluate the relationship between presence or absence of greylag geese and field characteristics such as crop type, distance to roost site and field size. According to the top-ranked model, the probability of presence of foraging greylag geese was higher in spring and in grass fields, while the probability decreased with distance to roost site. Our results also show that the set-aside field in general was used more than other fields in the area during spring and summer but not during autumn. We conclude that it is important to consider variables affecting the probability of field selection by geese, such as season, crop type and distance to roosts to understand the behaviour of geese when establishing set-aside fields.
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| 43. |
- Waldenström, Jonas, et al.
(author)
-
Migration and morphometrics of the Broad-billed sandpiper Limicola falcinellus at Ottenby, southern Sweden, 1950-2000
- 2001
-
In: Ornis Fennica. - 0030-5685. ; 78:4, s. 184-192
-
Journal article (peer-reviewed)abstract
- The Broad-billed Sandpiper Limicola f. falcinellus is a little studied European wader species with unfavourable conservation status. We describe the migration of the Broad-billed Sandpiper at Ottenby, southeast Sweden, from 1950-2000 using data from ringing activities and field observations. Numbers of ringed and observed Broad-billed Sandpipers varied considerably between years. There was no trend in numbers trapped over the study period, but a positive trend in numbers observed (probably explained by improved identification skills and observation possibilities). The populations passing Ottenby during autumn migration have probably been relatively constant in size during the last 50 years. The species was only rarely seen during spring migration (median 29 May). As shown by autumn ringing data, adult birds pass mainly in July (median date 21 July) and juveniles mainly in August (median date 17 August). Adult birds had on average somewhat longer wings and longer total-head than juvenile birds, but there were no significant differences in body mass between age groups. Broad-billed Sandpipers carried an average fuel load proportional to 25% of lean body mass, which is relatively low for migrating waders, but some individuals may have had fuel stores of up to 50-70%. In recaptured birds, the highest recorded mass gain rate was 7.1% of lean body mass per day, which is close to the maximum predicted for a species of this size. Broad-billed Sandpipers seem to prefer migrating with relatively small fuel stores, making use of several stopover sites along the migration route.
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| 44. |
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