Wood Warbler - 2003-07

This summer visitor is the largest and most colourful of the British leaf warblers, its green upperparts contrasting with its bright yellow breast and silky white belly. Seeing the male trembling while it delivers its trilling song is a fulfilling experience. Closed canopy woodland with little understory is the favoured habitat, where the nest is concealed on the ground among rank vegetation.

About a third of the UK population is found in Wales, where ideal habitat of deciduous woodland grazed by sheep has very little understory growth. Those breeding in Pembrokeshire are at the periphery of their distribution and have been found to be less abundant than in the main area. This may in part reflect the fact that the majority of county’s woodlands are not grazed and the understory and shrub layers are too dense for this species.

The UK population was estimated at 17,200 singing males in 1984–85 and the Pembrokeshire total at 250 singing males in 1988. A subsequent steady decline has been detected across northern and western Europe, the UK total being estimated at 9,000 -10,500 by the year 2000. The 2003-07 Pembrokeshire survey found that distribution had decreased by 50% compared with 1984-88, the remaining total being no more than 100 singing males, perhaps fewer.

Graham Rees

Fieldwork 2003-07 (based on 490 tetrads) 

Red = breeding confirmed = 3

Orange = breeding probable = 19

Yellow = breeding possible = 3

Total tetrads in which registered = 25 (5.1%)