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Title: Changes in migration strategy and wintering behaviour of common chiffchaff Phylloscopus collybita
Author: Conway, Gregory John
ISNI:       0000 0004 2722 2295
Awarding Body: University of East Anglia
Current Institution: University of East Anglia
Date of Award: 2011
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Common chiffchaff Phylloscopus collybita is an insectivorous migrant passerine, which has been noted wintering in Britain and Ireland, in small numbers, from the early 1800's. Since the early 1970's the frequency of winter individuals has increased considerably, with around 1,000 estimated to have wintered in 1982/83. This thesis investigates the observed changes in wintering abundance and distribution in a novel wintering range during a period of rapid climate change. The majority of wintering individuals are found in the south and west of the British Isles, associated with the maritime climate and elevated temperatures compared to co1der inland and northern locations. At inland and northern sites locally warmer micro-climates are utilised, particularly waste water treatment works, which provide a regular source of invertebrate food above that available from the surrounding countryside. Winter abundance was investigated over 38 winters, and show that a 20 fold increasing in observer wintering numbers had occurred. Occupied winter range, between surveys in the 1980's and mid 2000's had also increased, with more inland sites were being occupied. The two main drivers behind this increase was reduction in winter severity and an increasing western European breeding population. Temporal trends in migration timing in Europe, over a 44 year period, showed that spring departure had commenced earlier and autumn migration was later, however, there was no change in distance travelled between western and central European populations. Genetic and morphological analysis showed that the British wintering population was comprised mostly of individuals originating from western Europe, with a small but increasing number for Asia and a minority from northeast Europe. Estimates of annual survival showed that birds at wintering sites had similar survivors hip to British breeding birds, which winter further south in Europe, indicating that southern England is a viable wintering location.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available