A chara,
The slender /r/ is pronounced with a French /j/ in Ceathrú Thaidhg, Baile na Cilleadh, Port a’ Chlóidh, Corrán Buí and Ceathrú na gCloch. Here are such examples:
For
Ag ghrian, we say /an jr’ien/
Ag obair, we say /ag ob’ij/
Ag gáire, we say /ag gá’jí’
Please see ‘ The Irish of Erris, Co, Mayo: A Phonetic Study’ by Éamonn Mac am Fhailligh (1968)