At the time of the breeding bird atlas, in 1988, the Yellowhammer breeding population in Pembrokeshire was estimated at 35-40 pairs per tetrad, that is c.10 pairs per km2. This equated to an estimated breeding population of 14,000-15,000 pairs.
At present, in October 2022, there are only two locations in Pembrokeshire known to support a breeding population of more than 10 pairs, with c.20 pairs at Folkestone Farm managed by the National Trust and the estimated 12 pairs at Templeton Airfield. Elsewhere, the only known concentration is a population of 5 to 8 pairs associated with hay meadows to the south of Hundleton. Away from these areas, in 2021 and 2022, only a handful of singing males have been reported from well scattered locations. As such, it is feasible that the current Yellowhammer breeding population in Pembrokeshire numbers less than 100 pairs. If this is the case, it would represent a decline of more than 99.5% on the 1988 population estimate.
For more information on the status of Yellowhammers, here are some helpful links: