Very rare passage migrant, formerly a summer breeding visitor.

Hertfordshire is at the eastern edge of the Wood Warblers range in Britain, and Stevenage was one of their strongholds in the County in the late 1970’s, unfortunately they are now rare passage migrants. Nationally they have declined by 75%.

Recorded by Foster (1914) as, “rare and very local in big woods”. One was recorded at Stevenage on 17 April 1935.

In the 1960s they were recorded from: Box Wood (male from 7 to 31 May 1968); Monks Wood (two on 19 June 1966); Tilekiln Wood (three on 4 May 1968).

The 1970s records are: present in the 1973 breeding season at Box Wood; one at Tilekiln Wood on 25 June 1974; one at Watery Grove from 20 April to 8 May 1977; pair at Box Wood on 18 June 1978, where young birds were seen being fed on 20 June and a fledged youngster seen on 1 July 1978; five pairs at Watery Grove 1978, where a fledged youngster was seen on 1 July; Astonbury 1979; male Watery Grove 6 May 1979; Box two Box Wood on 13 May 1979.

The records for the 1980s and 1990s are: pair at Box Wood July 1980; three at Box Wood on 18 May 1984; one at Box Wood 11 May 1985; one at Watery Grove 30 April 1988; singing male at Pryors Wood 7 May 1990; one singing at the Town Centre Gardens on 5 May 1993.

The 1973 Breeding Atlas considered breeding as possible from the tetrads covering Chesfield Park and Boxbury Farm. Gladwin (1986) recorded that less than four pairs nested annually in various woodlands around Knebworth and Stevenage. The 1992 Atlas considered breeding as probable from the tetrad covering Boxbury Farm and, possible from those covering Norton Green and, Bragbury End. None were recorded in the 2012 Atlas.

The most recent records are of three spring passage birds: one at Fairlands Valley Lakes on 17 April 2007; one at Fairlands Valley Lakes on 7 and 8 May 2015; a singing male at the Warren Springs Laboratory (GSK) on 8 April 2019.