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Stopover Ecology of Mallards: Where, when and how to do what?
Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
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 [en]
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: urn:nbn:se:lnu:diva-49801ISBN: 978-91-88357-00-7 (print)OAI: oai:DiVA.org:lnu-49801DiVA: diva2:903770
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
List of papers
1. Movements, Home-Range Size and Habitat Selection of Mallards during Autumn Migration
Open this publication in new window or tab >>Movements, Home-Range Size and Habitat Selection of Mallards during Autumn Migration
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2014 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 6, e100764Article in journal (Refereed) Published
Abstract [en]

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.

National Category
Ecology
Research subject
Ecology, Zoonotic Ecology
Identifiers
urn:nbn:se:lnu:diva-36835 (URN)10.1371/journal.pone.0100764 (DOI)000338512200058 ()2-s2.0-84903532165 (Scopus ID)
Available from: 2014-09-10 Created: 2014-09-10 Last updated: 2017-12-05Bibliographically approved
2. Age and sex determination of mallards Anas platyrhynchos in autumn
Open this publication in new window or tab >>Age and sex determination of mallards Anas platyrhynchos in autumn
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.

National Category
Ecology
Research subject
Natural Science, Ecology
Identifiers
urn:nbn:se:lnu:diva-49800 (URN)
Note

Ej belagd 20170515

Available from: 2016-02-16 Created: 2016-02-16 Last updated: 2017-05-15Bibliographically approved
3. Tailwind better than full tank? How weather and body condition affect departure decision in an autumn-staging migrant
Open this publication in new window or tab >>Tailwind better than full tank? How weather and body condition affect departure decision in an autumn-staging migrant
(English)In: Article in journal (Refereed) Submitted
National Category
Ecology
Research subject
Natural Science, Ecology
Identifiers
urn:nbn:se:lnu:diva-49799 (URN)
Available from: 2016-02-16 Created: 2016-02-16 Last updated: 2017-07-26
4. Does influenza A virus infection affect movement behaviour during stopover in its wild reservoir host?
Open this publication in new window or tab >>Does influenza A virus infection affect movement behaviour during stopover in its wild reservoir host?
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2016 (English)In: Royal Society Open Science, E-ISSN 2054-5703, Vol. 3, no 2, 1-11 p., UNSP 150633Article in journal (Refereed) Published
Abstract [en]

The last decade has seen a surge in research on avian influenza A viruses (IAVs), in part fuelled by the emergence, spread and potential zoonotic importance of highly pathogenic virus subtypes. The mallard (Anas platyrhynchos) is the most numerous and widespread dabbling duck in the world, and one of the most important natural hosts for studying IAV transmission dynamics. In order to predict the likelihood of IAV transmission between individual ducks and to other hosts, as well as between geographical regions, it is important to understand how IAV infection affects the host. In this study, we analysed the movements of 40 mallards equipped with GPS transmitters and three-dimensional accelerometers, of which 20 were naturally infected with low pathogenic avian influenza virus (LPAIV), at a major stopover site in the Northwest European flyway. Movements differed substantially between day and night, as well as between mallards returning to the capture site and those feeding in natural habitats. However, movement patterns did not differ between LPAIV infected and uninfected birds. Hence, LPAIV infection probably does not affect mallard movements during stopover, with high possibility of virus spread along the migration route as a consequence.

National Category
Infectious Medicine Ecology
Research subject
Ecology, Zoonotic Ecology
Identifiers
urn:nbn:se:lnu:diva-49798 (URN)10.1098/rsos.150633 (DOI)000377969000024 ()2-s2.0-84958073847 (Scopus ID)
Available from: 2016-02-16 Created: 2016-02-16 Last updated: 2017-11-30Bibliographically approved

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