Skomer's guillemots: Prof Tim Birkhead explains 40-year study
Professor Tim Birkhead, a zoologist at Sheffield University, has been monitoring guillemots on the south of Skomer for 40 years.
He explains to BBC Wales environment correspondent Iolo ap Dafydd how the birds were affected by last winter's storms - and how they carry out their research.
04 Jul 2014
- From the section Wales