Red squirrels have crossed from Anglesey to the mainland
Anglesey's unique population of red squirrels are being genetically tested to ensure they are not inbred.
Samples of hair from 100 animals have been sent to a special lab in Edinburgh and the results are expected this Easter.
Dr Craig Shuttleworth of the Friends of the Anglesey Red Squirrels hopes the tests will prove the island has become a 'Noah's Ark' of endangered squirrel bloodlines after extensive work to create a varied gene pool.
When similar tests were done in 2002, it was found that the small population still clinging on in Pentraeth did suffer from inbreeding.
This can lead to future abnormalities and susceptibilities to diseases in the young.
"In 2002 we found a unique Welsh bloodline of red squirrel, which was very exciting," said Dr Shuttleworth.
"But when we started re-introducing more reds to the island, we had to get squirrels from various breeding institutions and did some testing to ensure they were varied.
"We discovered some Scottish, English and European bloodlines, and some types which were unique; they must have come from wild populations which are now extinct."
There are now over 150 adults squirrels in Newborough, Plas Newydd and Beaumaris and Dr Shuttleworth hopes to see a genetic buoyancy in the population.
The hairs used for testing come from the tails of dead reds, or those caught in grey squirrel traps.
"This is the biggest project of its kind ever done on red squirrels," said Dr Shuttleworth, delighted to be working with two Bangor University PhD graduates who have now set up a rare species genetics lab in Edinburgh.
"It will be fascinating to know what we've created here.
"We may be able to spot the flow of animals between the colonies on the island and I'd love to find out more about those squirrels which have crossed over the bridges to the mainland."
The results will also guide work on the next step in the project when red squirrels will be introduced to the Dingle, Llangefni.
It is possible that one particular bloodline has been more successful at breeding than others, which would not be welcome news.
"I will be disappointed if we've got a boring one or two types of squirrel, though" said Dr Shuttleworth.
"I'm betting on seeing a great diversity of bloodlines, but we'll have to wait to find out."
The re-introduction of red squirrels on Anglesey has been one of the most successful projects of its kind in the UK.
The mammal has been under threat since the North American grey squirrel, stronger and more robust than its red cousin, was brought to Britain in the 19th Century.