Last updated: 23 April 2008
This island reserve in the middle of the Bristol Channel was designated a Site of Special Scientific Interest in 1972 in recognition of its gull population, grass species and geological characteristics.
The gulls on the island include the herring gull, lesser black backed gull and the greater black backed gull.
Half the island is managed for the birds, and the other half for the grasses.
You can enjoy short day trips by boat to Flat Holm. Take in a guided walk during your three hour stay - and remember to keep a look out for George, the island's wild tortoise. Scheduled crossings depart Cardiff Bay from March to October.
For more information, visit the Flat Holm Society website.
Tick off what you've spotted with our handy wildlife spotter guides.
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