The Origins of moulting Goosanders on the Eden

• Main Authors: P. Leslie Hatton, M. Marquiss
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: designated as a Local Nature Reserve; Site of Special; Furness; Norway; Northern Norway
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.586.6846; http://blx1.bto.org/pdf/ringmigration/22_2/hatton.pdf

moulting birds, and their provenance, as determined from subsequent sightings. Goosanders only started to moult on the Eden estuary in the 1980s and their numbers have increased since the late 1980s. This increase also occurred elsewhere on other, geographically similar, Scottish east-coast estuaries. The birds are adult females, and many, though not all, seem faithful to their moult site. Moulting flocks persist from June to October, with a turnover of birds occurring during this period. The moulting birds are drawn primarily from wintering and breeding areas to the south and west of the Eden estuary, in southwest Scotland, England and Wales. Like most other wildfowl, Goosanders Mergus merganser undertake a complete post-nuptial moult, during which they experience a flightless period lasting approximately a month (Cramp & Simmons 1977, Owen & Black 1990). Males moult earlier in the year than females and most males from western European breeding populations migrate to northern Norway to moult their flight feathers (Little & Furness 1985). Some females, mainly those with late broods (Marquiss & Duncan 1994a), moult on their riparian breeding grounds. All early and failed breeding females, however, leave their breeding sites to moult elsewhere in Britain, usually in estuaries and shallow coastal firths (Little & Marchant 2002). This paper documents the increase in size of moulting flocks of female Goosanders on the Eden estuary, Fife, UK from the 1970s to the 1990s, and presents information on their origin. METHODS Study area The Eden estuary (56 ° 22'N 2 ° 50'W) is one of a series of small estuaries situated on the Scottish east coast. It lies immediately north of St Andrews and is characterised by its extensive sheltered shallows. The area is