Whitethroat - 2003-07

Whitethroats are perky, largely brown warblers are widespread in the county during the summer. They are particularly evident during their frequently performed song flights, when their disjointed, scratchy song draws attention to their presence. They inhabit heathlands, scrub, hedgerows, woodland edge and very young tree plantations. Nests are placed in low bushes, nettles, brambles and tall grass.

The map shows a similar distribution between the two local surveys at the tetrad level. Some minor changes were noted at a more local level, where young plantations had grown to the point where they became untenable for Whitethroats. Assessing population levels at any given time has been complicated by periodic collapses in numbers. In 1969 the British population was reduced by about 77%. This was associated with drought conditions in the African area where Whitethroats winter. Subsequent recovery has been interrupted by further population crashes of varying magnitude. By 1974 the breeding population had stabilized at approaching half the pre 1969 level but the subsequent recovery was interrupted by another crash in 1984. The 1984-88 Pembrokeshire survey took place in a period of recovery and by 1988 it was estimated to have reached an average density of 20 pairs per tetrad, giving a county total of 8,000 pairs. The similar returns for the 2003-07 survey would seem to indicate no change in the county population but in the meantime the BBS calculated a 10% increase between 1994 and 2007 but a decrease of 18% between 2000 and 2005. It seems that the estimate of 8,000 pairs in Pembrokeshire by 2007 is realistic, despite fluctuations during the time between the two local surveys.

Graham Rees

 

Fieldwork 2003-07 (based on 490 tetrads) 

Red = breeding confirmed = 115

Orange = breeding probable = 289

Yellow = breeding possible = 12

Total tetrads in which registered = 416 (84.9%)