Ice Age
Studies by Anne Eastham on the bird bones in the Hoyles Mouth and Little Hoyle caves near Tenby show that Black Grouse were present in the area 10,000 years ago. The bones were found in a scree deposit left at the end of the last glaciation. This included bones that have been carbon-dated to 9,980 +/- 800 years before present.
A variety of species were present - listed in the original paper.
Eastham A. (2016) Goosey goosey Gander with Jemima Shelduck in attendance: two Stone Age occupation caves in South Pembrokeshire. Pembrokeshire Historical Society.