THE BIRDS OF SOUTH GLOUCESTERSHIRE          Northern Willow Warbler - phylloscopus trochilus acredula

 

There are two clearly differentiated races that lie at opposite ends of the species range, the main differences between them involve size and colour. The nominate form 'trochilus' occurring in the south-west are on average smaller and more olive-green and yellow, 'yakutensis' occurring in the east are generally larger and more pale brown and white. The group lying in between are named 'acredula', but these populations are highly variable, ranging from pale olive-green and typically 'acredula' to brown and white forms 'eversmannii'. These two forms and many intermediates, occur sometimes side by side in the north of range of 'acredula'.

 

There have been two Northern Willow Warblers reported from S. Gloucestershire;

 

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1st

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2013 (c.1)

One, a very pale individual and possibly this form, was seen at Severn View Services and Aust STW on April 16th. (David Gibbs)

 

1932 (1)

A presumed adult was ‘obtained’ sometime in April near Stoke Gifford.

 

1913 (1)

One, a presumed adult was 'obtained' sometime in May near Thornbury. This occurrence constitutes the first record of this form in S. Gloucestershire.

 


©TBOSG November 2005 - All rights reserved