Sunday, 13 May 2012

A declining migrant

Singing male Wood Warbler Phylloscopus sibilatrix, Alexandra Park, London, 12 May 2012.
Spring has been rather late this year for many species, so even with a third of May over I was still hopeful of some migrants moving through my local patch of Alexandra Park yesterday morning. But plans for a sky-watch from the viewpoint we optimistically term the 'obs' were abandoned within two minutes when I heard a distinctive but all too infrequent song coming from the tree-covered slope below: Wood Warbler!

The bird occasionally showed well  as it clambered about the mid and upper storeys of its favoured oak.
Alexandra Park has something of a track record for this species, although it is not annual and records sometimes involve silent migrants in autumn. I rang around local birders immediately and, after it initially went missing, the bird reappeared to sing intermittently in oaks and birches at the south-west corner of the pitch n' putt course. Andrew Gardener, Bob Watts, Gaz Richards and Alan Gibson all managed to see it well before it went AWOL mid-morning.



As well as its evocative trilling song (I recorded the above unedited sequence on my iPhone), the bird also uttered the alternative, somewhat melancholy, piu-piu-piu series of notes. At one point it gave occasional single piu call notes, the first time I have heard this as a 'solo' vocalisation, and a good learning opportunity as a potential way to pick up non-singing migrants in future.

Wood Warbler has become something of a rarity in the London Area over the years, mirroring the national decline of the breeding population. Whereas in 1994 there was one breeding pair, 23 singing birds on spring passage and 20 more in autumn, the total number of sites where the species was recorded during the five-year period 2004-2008 were 1, 10, 16, 8 and 7 respectively (London Bird Reports passim).

Here the bird can be seen successfully reducing the park's caterpillar population by one.

2 comments:

  1. Haringey has a good reputation for the species, in Bruce Castle Park/Tottenham Cemetery they were record most years with one in every three years producing singing spring birds and the autumn picking up to three birds. This was my patch from the mid 1980's throughout to mid 1990's. Late April to early May for the spring and anytime from early August through to early September, always best after two days of east winds there. Oaks and silver birches for the spring whilst in the autumn it used to be lime trees, alders and silver birches. Just a wonderful bird to see and hear, esp in London. Well done Dom.

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  2. Wood Warblers in Surrey are now extremely rare. The Thursley village visitor at the weekend has been the only record this year. Canons Farm (that place again) had the only recorded sighting last spring. The breeding pairs at the Devil's Punchbowl, near Hindhead, are now sadly a thing of the past. What a pity because they are such fantastic little birds.

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