Coastlines

 

Winter 2003

Sedge Warblers

Article by Tony Duckles, South West Lancashire Ringing Group

One of the regular immigrants that pass through our coastal dune system every spring and autumn is the sedge warbler (Acrocphalus schoenobaenus) though a small number remain locally to breed in suitable areas.

Sedge warbler copyright John gramauskasOver the past 40 years members of the South-West Lancashire Ringing Group (SWLRG) have been monitoring (by ringing) this species and their records give some indication of their site loyalty (breeding), their longevity of life and their migratory patterns to and from their wintering quarters.

The sedge warbler is a small (12cm) but stocky bird with a distinctive, loud song. It can often be found singing from a perch or on short display flights. The SWLRG's records suggest the longevity of the birds to be about 4 to 5 years.

Sedge warblers are common breeding birds throughout much of Europe and Russia. They require dense vegetation close to the ground to nest in. They prefers lowland marsh and waterside habitats for breeding, although it can be frequently found in drier areas including hedges, scrub and arable crops. In Sefton they can be found in areas associated with dense vegetation such as creeping willow in dune slacks, vegetation along side ditches at Marshside, and the ponds and canal at Brookvale and the meadows at Hightown.

The Sedge Warbler despite its small size migrates to and from the UK every year to its over wintering grounds in Africa, south of the Sahara from Senegal to Ethiopia and as far south as Namibia and South Africa. The birds begin their migration to Africa in early Autumn and return the following Spring. The birds in the UK feed voraciously on insects and build up large fat reserves for their migration.

From the SWLRG's efforts birds ringed in Sefton have been recorded as far away as Senegal (4500km). Other individuals recorded in Northern France, Dorset and Cornwall provide evidence of one of their migration routes heading South West out of the UK. It has been suggested that the UK birds stop over in France to further increase their fat reserves during migration, presumably there are several other 'top-up' stops during migration. Other records in Lincolnshire and Sussex provide evidence of a second migration route on a South East bearing out of the UK.