The National Parks and Wildlife Service is appealing for information after a rare white-tailed eagle was found dead on lands between counties Cavan and Westmeath in November.
The eagle, which is part of a national re-introduction programme undertaken by the NPWS, was found to have been killed by ingesting poison used as a "pest control".
The NPWS is also urging people to be aware that the use of poisonous substances for the control of species such as foxes and crows is illegal.
The juvenile male white-tailed eagle who was just over a year old had been brought in as a chick in 2021 from Norway under phase two of a national re-introduction programme.
It had been fitted with a small satellite tag prior to its release on Lough Derg in 2021.
The NPWS had observed the bird had been largely spending time around Lough Sheelin in Co Westmeath but it became concerned when it noticed the bird had been in the one spot for a "troubling length of time".
The bird was recovered and tests were carried out which ruled out Avian Flu, illegal shooting or trauma.
Further tests confirmed the bird had been poisoned with an illegal substance, known as Carbofuran.
It is not clear how the eagle ingested this substance, but the NPWS say it could possibly be from eating a dead animal laced with it.
NPWS Regional Manager Maurice Eakin said that white-tailed eagles are a protected species under the Wildlife Acts, and this latest fatality once again highlights how prevalent this illegal practice continues to be.
"In this instance, it is particularly disturbing that the reckless laying of poison has resulted in the death of a White-tailed eagle, one of our largest and most majestic bird species, which had been persecuted to extinction by the early 1900s," he said.
The potential for positive economic benefits from the re-introduction of the eagles has been demonstrated in Mountshannon, Co Clare, when the first breeding pair in Ireland in over a century nested within sight of the village in 2012.
Mr Eakin said although some landowners may have in the past used poisons to control crows and foxes, especially around lambing time, the use of poisonous substances for the control of foxes and crows is illegal and has been since 2010.
The NPWS is seeking any information from the public in the Westmeath/Cavan region, particularly anyone who may have seen anyone or any vehicles acting suspiciously in recent weeks in the area between Lough Sheelin and Lough Ramor.
