The West Wales Naturalists' Trust traces its origin to a meeting held in Haverfordwest in February 1938. It was convened by L. D. Whitehead, the Welsh industrialist and owner of Ramsey, and the naturalist and author R. M. Lockley, then living on Skokholm. Seventy-eight people were present at that inaugural meeting and on the motion of Mr. Hugh Lloyd-Philipps, of Dale Castle, the Pembrokeshire Bird Protection Society was formed. In 1943, the society was urged to promote the establishment of nature reserves in readiness for post-war conditions. A meeting in 1945 decided to widen its area, so as to cover the counties of Pembroke, Carmarthen, Cardigan, and Merioneth, in compliance with requests from those counties, and considered a selection of alternative names so as to indicate the extension of the Society's area and activities. The meeting favoured West Wales Field Society. The society purchased Dale Fort which it leased to the Council for the Promotion of Field Studies in August 1946. An arrangement was made in 1947 for the CPFS to operate the Bird Observatory on Skokholm. Dale Fort was sold to the Field Studies Council in 1959. In January, 1961, the Executive Council formerly resolved to recommend that the Society should be dissolved and reconstituted as the West Wales Naturalists Trust Ltd. In April 2018 it merged with the Brecknock Wildlife Trust.
The Wildlife Trust of South and West Wales is a membership organisation with charitable status. It states an objective to build an environment "rich in wildlife for everyone” by “rebuilding biodiversity and engage people with their environment”. The trust is works with volunteers and communities to protect habitats and species. Their work includes reviewing planning applications, managing over 80 reserves, and providing advice to a wide variety of groups. The objectives of the Wildlife Trust of South and West Wales are:
In September 2019 arsonists burnt down a Kingfisher Hide at the Welsh Wildlife Centre, damage which came at a cost of £20,000 to the Trust. On New Year's Day 2020, the site was again attacked by vandals, who damaged a badger sculpture.