There are fears puffin numbers in the Farne Islands are on the decline.
Initial findings from the latest five-yearly count carried out by the National Trust suggested an overall 12% reduction in breeding pairs.
The seabirds, listed as "vulnerable" to extinction, also returned to their breeding grounds about four weeks late due to the prolonged harsh winter.
The trust, which has so far surveyed four out of the eight islands, described the findings as "concerning".
However, figures from the two largest islands surveyed so far are contradictory, with the population on Brownsman down 42% but Staple showing a 18% increase.
The trust, which has been looking after the islands for 93 years, will now be stepping up monitoring of the seabirds to better understand what is going on.
Ranger Tom Hendry said: "Initial findings are concerning.
"Numbers could be down due to stormy or wetter weather as well as changes in the sand eel population, which is one of their staple foods, or something else altogether."