Gardaí and the National Parks and Wildlife Service have begun investigations into the deaths of two white-tailed sea eagles in Co Kerry.
Last August, the eagles, which were protected under wildlife legislation, were re-introduced into Ireland for the first time in a century.
It is not yet known how the two birds died, but there are concerns that they may have been poisoned. It could be several weeks before this can be determined.
Minister for the Environment John Gormley has expressed his regret and concern at the news.
The National Parks and Wildlife Service became anxious yesterday afternoon when the two birds' transmitters remained stationary for too long.
Allan Mee, who is managing the reintroduction of the birds to Ireland, found one of the birds at around 5pm yesterday afternoon at an undisclosed location on the Iveragh Peninsula.
The second bird was found close-by this morning.
There was some controversy when the chicks first arrived into Ireland from Norway last June. Despite assurances, around 50 farmers protested at Kerry airport over fears that the birds would prey on their lambs.