Locustella naevia – TROELLWR BACH – Breeding summer visitor and passage migrant.
Earlier records are summarised in Grasshopper Warbler 1994
| Year | First date | Last date | Notes |
| 1993 | 13 April | 18 September | 9 singing on 80 hectares at Dowrog |
| 1994 | 18 April | 23 August | |
| 1995 | 26 March | 5 September | First to be recorded in March in Pembrokeshire, 12 days earlier than previously recorded. 7 territories mapped on Dowrog Common |
| 1996 | 13 April | 4 September | |
| 1997 | 14 April | 22 September | 8 territories mapped on Dowrog Common |
| 1998 | 5 April | 3 October | 8 territories mapped on Dowrog Common |
| 1999 | 6 April | 20 September | 5 breeding territories Dowrog, 3 at Teifi Marshes |
| 2000 | 16 April | 28 September | |
| 2001 | 12 April | 12 September | A min. of 2 pairs bred Castlemartin Range. |
| 2002 | 6 April | 20 September | Widespread reports for April & May; max. 5 Strumble Hd 21 Apr, 6 Skomer 21/22 Apr, 4 Fishguard – Dinas 24 Apr, 4 Rhoslanogfach 26 Apr. In autumn: singles, Castle Martin 28 July, Gelly 5 Aug, Skomer 20 Sept – only records received |
| 2003 | 4 April | 21 September | Widespread spring records at mainly coastal sites. |
| 2004 | 11 April | 31 October | Recorded widely Apr-May, mainly at coastal sites. |
| 2005 | 21 April | 1 August | 7 singing Goodwick Moor 24 April |
| 2006 | 21 April | 25 September | Recorded from 12 sites during Apr with 6 reported from suitable breeding habitat thereafter. The first autumn migrant Skokholm 6 Aug and the final record Skomer 25 Sept. |
| 2007 | 12 April | Some 100 records across the county April – September, with the highest counts being of 7 singing males at Goodwick on 21 April, 3+ pairs breeding pairs at Llangloffan Fen. | |
| 2008 | 12 April | 31 August | 18 singing birds Teifi Marshes on 8th June |
| 2009 | 10 April | 20 Sept | Max count was of five at Pencarnen on 18 April |
| 2010 | 9 April | 9 October | |
| 2011 | 2 April | 1 October | |
| 2012 | 20 April | Max count was of eight singing birds at Trefieddan Moor on 2nd May | |
| 2013 | 12 April | 8 August | |
| 2014 | 12 April | 25 September | A total of six reeling at Trefeiddan Moor at midnight on 1st May |
| 2015 | 15 April | 2 October | Last recorded Marloes Mere on 31st July and on Skomer on 1st & 2nd Oct. |
| 2016 | 11 April | not reported after June. | Recorded from at least 13 1km squares, with breeding evidence from at least 7 of these. |
| 2017 | 7 April | 25 September | Recorded from at least 26 1km squares. Presence of singing males noted from half of these but no confirmed breeding reported. Single seen on The Smalls 19th & 21st April. |
| 2018 | 13 April | 24 September | Reported from at least 23 1km square locations. Breeding evidence at five of these was limited to reeling birds only. |
| 2019 | 8 April | 26 August | Reported from 29 locations. Breeding evidence was reported from six locations. Largest counts received were of three: at Teifi Marshes 8 Apr, The Gann 1 June & Llangloffan Fen NNR 22 June, and on passage on Skokholm 1 May. |
| 2020 | 9 April | 19 September | Summer / breeding season records came from: Folkstone Farm, Gann, Heathfield Gravel Pits, Maenclochog, Mullock Bridge. Southwood Farm (Nolton), Teifi Marshes (four), Trefeiddan, Trehenlliw Farm and Ty-rhyg. |
