And, in a double blow for the sea eagle reintroduction programme, the remains have been found in Mayo of a young male eagle released in Kerry two years ago.
Preliminary toxicology tests of the remains, found on a small island on Lough Beltra near Castlebar, have not yet determined whether the rare bird was shot at or poisoned.
Allan Mee, project manager of programme, said the failed breeding attempt, in Co Clare, by a pair of young sea eagles was “disappointing and bit of a shock as the two were doing really well”.
The birds had been sitting on their eggs since Apr 9 and chicks were expected to hatch any day, he said.
Over 1,000 people travelled to Mountshannon, in one weekend alone, to see the birds after their location was made public.
Dr Mee said the pair abandoned their nest on a small island in Lough Derg just after 6pm on Tuesday.
The site was being monitored during daylight hours from telescopes located on the shore-side.
“The birds have been very attentive and they have been doing really well, but there was a change on Tuesday afternoon when they left the nest a couple of times and eventually abandoned it,” he said.
Ahead of a trip yesterday to the island to investigate, Dr Mee said: “The most likely case is that the chick hatched and died or it fell down where the parents couldn’t get to it.
“It was always going to be 50-50. They are first-time breeders. There was also high winds on Sunday night and that might have affected the nest.
“The hatching stage is the most difficult time.”
Mayor of Clare, Cllr Pat Hayes said: “It is disappointing that we see didn’t see history being created in east Clare. There has been huge excitement here over the past few weeks with people coming from all over Ireland to see the birds. It has provided a real tourism boost.”
Dr Mee said that the eagles will, most likely, remain in the area and the public will have to wait until next spring for the next breeding attempt.
“Once they have field territory, they hold it and they won’t move beyond a few kilometres up and down from where they are. They will have a lot more time on their hands now that they don’t have any chicks to feed.”
Dr Mee said the pair will have around 20 more breeding attempts.
The four-year-old male and three-year-old female were reintroduced here in 2008 and 2009. They were among 100 birds released in Killarney National Park, Co Kerry.
Meanwhile, the search for the eagle found dead had been instigated after transmitter signals from the bird, which had been electronically tagged, stopped some weeks ago.
The eagle had been dead for about 10 days before its remains were discovered.
Dr Mee said: “Finding the white-tailed eagle dead in such a beautiful part of Mayo was saddening.
“After releasing this male eagle in 2010 we had been following its movement with great interest.
“It’s tragic to think someone for some unknown reason would kill it.”