A scheme to rid an island off the north Devon coast of black rats so birds like the Manx shearwater and puffin can breed appears to be paying off.
A further survey will be carried out in September to look for chicks
The RSPB says there are signs of chicks on Lundy, in the Bristol Channel, for the first time since rats were removed in 2003.
Experts claimed the cull was necessary as the rats ate the eggs and chicks.
But animal campaigners opposed to the cull say that the rats were not to blame for the decline in bird numbers.
The Seabird Recovery Project is a partnership between English Nature, the National Trust, the Landmark Trust, and the RSPB.
For the past few weeks the RSPB has been monitoring burrows on the island by playing tapes of bird calls into them.
If a bird calls back from inside the burrow it is counted as an "apparently occupied nest".
A further survey will be carried out in September to look for chicks.
RSPB has been monitoring burrows on the island
"In the past couple of years we've been finding good numbers of chicks so we're optimistic for them since the removal of the rats," said the RSPB's Helen Booker.
"We are very encouraged by what we are finding."
The RSPB said there had been no record of Manx shearwater chicks on Lundy for about 50 years, and 30 years for the puffin, before the rats were removed.
But Mark Gold of Animal Aid does not agree the rats are to blame.
"The rats have been there for 400 years and there has been no great increase in number," he said.
"The bird population has only been declining in the last 50, it couldn't have been the rats, it's more likely to have been over-fishing."