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  • 1.
    Barshep, Yahkat
    et al.
    A.P. Leventis Ornithological Research Institute, Nigeria.
    Ottosson, Ulf
    A.P. Leventis Ornithological Research Institute, Nigeria.
    Waldenström, Jonas
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Hulme, Mark
    British Trust for Ornithology, UK.
    Non-breeding ecology of the Whinchat Saxicola rubetra in Nigeria2012In: Ornis Svecica, ISSN 1102-6812, Vol. 22, p. 25-32Article in journal (Refereed)
    Abstract [en]

    This study on the non-breeding ecology of the Whinchat Saxicola rubetra was conducted in central Nigeria from February through April. The core site was at Gwafan (N09°53', E08°57'), an open scrubland located 10 km east of the city of Jos. The density of Whinchats at Gwafan was 0.58 individuals/ha, almost three times the overall density around Jos. Time budget observations of colour banded Whinchats, including six birds fitted with radio-transmitters, showed that they spent 80% of their time perching, 11% foraging, 7% preening, and 2% flying. The main method of catching insects was a swoop to the ground. There was no change in perching, preening or flying time but the time some Whinchats spent foraging increased towards the end of the study period. GPS positions of individuals showed that all birds held clearly demarcated territories and defended them against neighbours. Aggressive interactions were also recorded between Whinchats and other bird species. Three birds colour-ringed in 2006 returned to the study site in 2007 and one occupied almost the same territory, indicating site fidelity.

  • 2.
    Bengtsson, Daniel
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Andersson, Stina
    Ottenby Bird Observatory.
    Hellström, Magnus
    Ottenby Bird Observatory.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Age and sex determination of mallards Anas platyrhynchos in autumn2016In: Ornis Svecica, ISSN 1102-6812, Vol. 26, p. 61-81Article in journal (Refereed)
    Abstract [en]

    The mallard is a well-known and important species in migration ecology, game management,and epidemiology. Males and females are generally easily told apart, whereas ageing isproblematic, due to individual timing of the moult cycle and lack of easily defined agecriteria. From examination and photographic documentation of mallards caught within a longtermringing program at Ottenby Bird Observatory (56°12′N, 16°24′E), we describe ninecharacters of plumage and bare parts to be used for ageing mallards in autumn. The reliabilityof these characters was tested by letting experienced bird ringers determine putative age ofbirds from photos. Age determination from any single character proved to be uncertain, as therate of correctly assigned mallard photos of each character was in the range of 51-85% formales and 48-89% for females. For both sexes, the lowest figure represented post-humeralsand the highest represented tertials. Rectrices, tertial coverts, and greater coverts also hadreasonably high scores (71-85%). With all characters at hand, 91% of the males and 95% ofthe females were correctly identified to age. As young mallards, with the progress of prebreedingmoult (completed from October onwards), acquire tail and tertials identical to adults,untypical individuals are better not assigned to an age category.

  • 3.
    Betzholtz, Per-Eric
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Berger, Tobias
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Petersson, J.
    County Administrative Board of Kalmar.
    Stedt, Johan
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    What do population viability analyses tell about the future for Baltic Dunlin Calidris alpina schinzii and Montagu’s Harrier Circus pygargus on Öland?2010In: Ornis Svecica, ISSN 1102-6812, Vol. 20, p. 93-102Article in journal (Refereed)
    Abstract [en]

    Population viability analysis (PVA) has become an important tool in conservation biology. Even though detailed outcomes of PVA:s are constrained by data quality, it is a useful approach when the objective is exploratory, aiming to identify important parameters for viability or to guide future field work on endangered species. In this study we perform PVA:s based on scarce data to explore viability of two endangered bird species, Baltic Dunlin and Montagu’s Harrier, on Öland. Our simulation results underline that both species are under severe threats, with a median time to extinction of 24 years in Baltic Dunlin and 63 years in Montagu’s Harrier. Sensitivity analyses show that population growth rate is the most important factor for the model outcome in both species. Since there are no apparent threats for adult birds on Öland, this suggests that conservation measures should focus on improving conditions for successful breeding on the island. In additional simulations we explore some threats in more detail. In the case of Baltic Dunlin nest predation of eggs and chicks increase the extinction risk. In Montagu’s Harrier viability increases if breeding attempts within agricultural areas are detected and safeguarded. In order to enhance the PVA model, and build a stage-structured model, we suggest that detailed data on fecundity and survival should be collected.

  • 4.
    Gierow, Peter
    et al.
    Department of Biochemistry, University of Lund .
    Gierow, M
    Breeding biology of the Lapland Bunting Calcarius lapponicus in Lapland1991In: Ornis Svecica, ISSN 1102-6812, Vol. 1, p. 103-111Article in journal (Refereed)
  • 5.
    Larsson, Kjell
    et al.
    Uppsala University, Sweden.
    Tydén, Lars
    Uppsala University, Sweden.
    Effekter av oljeutsläpp på övervintrande alfågel Clangula hyemalis vid Hoburgs bank i centrala Östersjön mellan 1996/97 och 2003/04: Effects of oil spills on wintering Long-tailed Ducks Clangula hyemalis at Hoburgs bank in central Baltic Sea between 1996/97 and 2003/042005In: Ornis Svecica, ISSN 1102-6812, Vol. 15, p. 161-171Article in journal (Refereed)
    Abstract [en]

    The Baltic Sea is an important marine area for wintering birds. Surveys in the 1990s showed that more than 25 % of the European Long-tailed Duck Clangula hyemalis population wintered at Hoburgs bank and east of Gotland. A shipping route with very frequent traffic goes from southwest Baltic Sea via Öland, Hoburgs bank and east of Gotland to the Gulf of Finland. In year 2000 about 58 500 ships passed east of Öland along this route. Hundreds of oils spills are registered along the route each year. Weekly surveys of oiled birds at southern Gotland and analyses of birds that had drown in fish nets showed that tens of thousands of ong-tailed Ducks were injured by oil each year in central Baltic Sea. Of 998 birds that drowned in fish nets at Hoburgs bank 11.8 % were found to have oil in the plumage. There was no clear relationship between the number of oiled birds observed and the number of registered oil spills in different years. Many sea duck have a life history in which variable or low productivity is compensated for by relatively high adult survival. This makes sea duck populations very susceptible to extra adult mortality caused by oil spills.

  • 6. Svanberg, Staffan
    et al.
    Waldenström, Jonas
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Population fluctuations and timing of spring migration of the Scandinavian Bluethroat Luscinia svecica svecica at Ottenby Bird Observatory, Sweden, 1955-20082011In: Ornis Svecica, ISSN 1102-6812, Vol. 21, p. 92-100Article in journal (Refereed)
    Abstract [en]

    In this study, 54 years (1955–2008) of consecutive trappingdata from Ottenby Bird Observatory on the islandof Öland, SE Sweden, was used to analyze the springpassage of the Scandinavian subspecies of the BluethroatLuscinia svecica svecica. The aim was to investigatetrends in the numbers of Bluethroat passing this site andto provide statistics related to the phenology of migration.Trapping of Bluethroats at Ottenby may be seen asan index of population numbers in the recruitment area,especially for the latest decades when trapping conditionshave been standardized. The number of trapped individualswas stable both in the long and short term, butmedian spring passage has become significantly earlierover the study period. The spring migration of the speciesshowed clear age and sex related differences in timing.Male Bluethroats preceded females with about threedays, and adult birds preceded juveniles of both sexes.Finally, the local weather during the peak passage significantlyaffected the number of trapped individuals, withthe largest number trapped in days with head winds fromthe northwest sector.

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