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Södertälje, Sweden

Hellstrom M.,Ottenby Bird Observatory | Waern M.,Carl Malmstens Vag 21
British Birds | Year: 2011

The Common Stonechat Saxicola torquatus is a widespread breeding species in the Palearctic region. This paper discusses the reliability of characters that enable birds from Europe (S. t rubkola) to be separated from those breeding in western Siberia and central Asia (S. t maurus), particularly during the breeding season when differences become subtle. The current understanding of plumage variability within and between these races is discussed, and some gaps in our knowledge of Siberian birds are addressed. Emphasis is placed upon assessing the validity of the different characters. The timing and extent of moult and wear are crucial to the understanding of these characters and of how they can affect appearance over time. Other Palearctic races are discussed where relevant. Careful observation and attention to detail are essential when faced with a potential maurus in Europe in spring but individuals of both sexes should provide sufficient clues for identification, if seen well. © British Birds 104. May 2011.

Iwajomo S.B.,Copenhagen University | Iwajomo S.B.,University of Jos | Hedenstram A.,Ottenby Bird Observatory | Hedenstram A.,Lund University | Ottosson U.,University of Jos
Ornis Fennica | Year: 2012

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 inmigration phenology, morphometrics and fuel load.Atotal 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.

Bengtsson D.,Linnaeus University | Avril A.,Linnaeus University | Gunnarsson G.,Kristianstad University College | Elmberg J.,Kristianstad University College | And 11 more authors.
PLoS ONE | Year: 2014

The mallard (Anas platyrhynchos) is a focal species in game management, epidemiology and ornithology, but comparably little research has focused on the ecology of the migration seasons. We studied habitat use, time-budgets, home-range sizes, habitat selection, and movements based on spatial data collected with GPS devices attached to wild mallards trapped at an autumn stopover site in the Northwest European flyway. Sixteen individuals (13 males, 3 females) were followed for 15-38 days in October to December 2010. Forty-nine percent (SD = 8.4%) of the ducks' total time, and 85% of the day-time (SD = 28.3%), was spent at sheltered reefs and bays on the coast. Two ducks used ponds, rather than coast, as day-roosts instead. Mallards spent most of the night (76% of total time, SD = 15.8%) on wetlands, mainly on alvar steppe, or in various flooded areas (e.g. coastal meadows). Crop fields with maize were also selectively utilized. Movements between roosting and foraging areas mainly took place at dawn and dusk, and the home-ranges observed in our study are among the largest ever documented for mallards (mean = 6,859 ha; SD = 5,872 ha). This study provides insights into relatively unknown aspects of mallard ecology. The fact that autumn-staging migratory mallards have a well-developed diel activity pattern tightly linked to the use of specific habitats has implications for wetland management, hunting and conservation, as well as for the epidemiology of diseases shared between wildlife and domestic animals. © 2014 Bengtsson et al.

Moller A.P.,University Paris - Sud | Christiansen S.S.,Ottenby Bird Observatory | Mousseau T.A.,University of South Carolina
Behavioral Ecology | Year: 2011

Adults of many species display extravagant sexual signals during the reproductive season, apparently evolved as a means of attracting mates or repelling potential competitors, thereby inadvertently also attracting the attention of predators. Many studies have shown predation costs of sexual display. Therefore, we should expect species with the most exaggerated signals to have evolved antipredator behavior that reduces or eliminates predation costs of sexual signaling but also to have evolved behavior that allows for escape from a predator once captured. We quantified 6 aspects of escape behavior in 2105 free-living birds belonging to 80 species when handled after capture for banding. Escape behavior was species specific as demonstrated by significant consistency in behavior among individuals. Escape behavior was significantly related to susceptibility to predation by cats Felis catus and goshawks Accipiter gentilis, showing that escape behavior is under current selection. Escape behavior was related to the ease of feather loss estimated in a previous study but also to the frequency of tailless individuals recorded in the field. Thus, escape behavior reported here was cross-validated against other aspects of antipredator behavior shown to reflect risk of predation. Aspects of escape behavior differed significantly between males and females (biting, fear screams, and feather loss). Sexually dichromatic species differed in escape behavior from monochromatic species by having a reduced frequency of fear screams and increased tonic immobility. These findings suggest that exposure to risk of predation has modified escape behavior in relation to sexual coloration. © 2011 The Author.

Iwajomo S.B.,Copenhagen University | Iwajomo S.B.,University of Jos | Stervander M.,Lund University | Helseth A.,Ottenby Bird Observatory | Ottosson U.,University of Jos
Ringing and Migration | Year: 2013

Long-term ringing data are useful for understanding population trends and migration strategies adopted by migratory bird species during migration. To investigate the patterns in demography, phenology of migration and stopover behaviour in Wood Sandpipers Tringa glareola trapped on autumn migration at Ottenby, southeast Sweden, in 1947-2011, we analysed 65 years of autumn ringing data to describe age-specific trends in annual trappings, morphometrics and phenology, as well as fuel deposition rates and stopover duration from recapture data. We also analysed the migratory direction of the species from recovery data. Over the years, trapping of both adults and juveniles has declined significantly. Median trapping dates were 10 July for adults and 6 August for juveniles. Average migration speed of juvenile birds was 58.1 km d-1. Adults stayed on average 3.5 days and juveniles 5.2 days, with average fuel deposition rates of 2.5 and 0.7 g day-1 respectively. Juvenile birds probably vary their strategy according to time of season and prevailing conditions. Both adults and juveniles followed the Mediterranean Flyway, but juveniles displayed significantly more southerly and significantly more scattered migratory directions. © 2013 Copyright British Trust for Ornithology.

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