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Age and sex determination of mallards Anas platyrhynchos in autumn
Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. (Centre for Ecology and Evolution in Microbial Model Systems (EEMiS))
Ottenby Bird Observatory.
Ottenby Bird Observatory.
Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. (Ctr Ecol & Evolut Microbial Model Syst)ORCID iD: 0000-0002-1152-4235
2016 (English)In: Ornis Svecica, ISSN 1102-6812, Vol. 26, 61-81 p.Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
2016. Vol. 26, 61-81 p.
National Category
Ecology
Research subject
Natural Science, Ecology
Identifiers
URN: urn:nbn:se:lnu:diva-49800OAI: oai:DiVA.org:lnu-49800DiVA: diva2:903768
Note

Ej belagd 20170515

Available from: 2016-02-16 Created: 2016-02-16 Last updated: 2017-05-15Bibliographically approved
In thesis
1. Stopover Ecology of Mallards: Where, when and how to do what?
Open this publication in new window or tab >>Stopover Ecology of Mallards: Where, when and how to do what?
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The mallard (Anas platyrhynchos) is the most numerous and widespread duck in the northern hemisphere and a model species in ecology and harvest management. Migration is a crucial life stage for many birds and understanding the drivers of migration has important implications for conservation biology and assessment of animal population responses to global changes. Furthermore, mallard migration is a fundamental determinant of the epidemiology of many diseases of major relevance for both animal and human health. For example, it is the reservoir host for influenza A viruses (IAV), a widespread zoonosis causing mortality and economic damage. Improved knowledge of mallard behaviour during migration and the impacts of infection in mallards is needed to determine the role of wild birds in global IAV dynamics.

This thesis focuses on mallard stopover ecology, an explicitly important part of the annual life cycle that is not well understood. The study area was southern Öland, SE Sweden, where mallard stopover behaviour was scrutinized by a combination of telemetry and ringing data analyses. Specifically, habitat preferences, movements, and emigration decisions were studied in-depth. Potential effects of low pathogenic avian influenza (LPAIV) infection on movement parameters were also investigated. Radio-tracking revealed that stopover mallards adhered to a strict diel pattern, in which they spent the days resting along the coast, visited crop fields at dawn and dusk, and foraged on inland water bodies during the darkest night hours. Notably, the importance of residual maize, as well as small ephemeral wetlands on the unique alvar steppe habitat that predominates on Öland, was previously unknown. LPAIV infection status did not affect movement behaviour, highlighting the possible risk of spread of IAV from wild mallards to poultry along the migratory flyway. Through capture-mark-recapture modelling, it was confirmed that weather, particularly wind direction, was the most important determinant of departure from the stopover site. In contrast, the body condition of departing mallards was less crucial. Taken together, the research presented in this thesis contributes to improved knowledge about mallard stopover ecology and its role in LPAIV disease dynamics.

Place, publisher, year, edition, pages
Växjö: Linnaeus University Press, 2016
Series
Linnaeus University Dissertations, 242/2016
Keyword
Age characters, body condition, departure decision, effects of influenza A virus, habitat selection, mallard, movement, Ottenby Bird Observatory, stopover ecology, weather, wild birds
National Category
Ecology
Research subject
Natural Science, Ecology
Identifiers
urn:nbn:se:lnu:diva-49801 (URN)978-91-88357-00-7 (ISBN)
Public defence
2016-03-11, Fullriggaren, Landgången 4, Kalmar, 09:30 (English)
Opponent
Supervisors
Available from: 2016-02-18 Created: 2016-02-16 Last updated: 2017-04-19Bibliographically approved

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