The Washington correspondent for RTE enraged viewers after he failed to wear a suit and tie for the Six One News funeral report on Saturday.
Charlie wore an open-necked, dark green shirt and a suit jacket, as he stood outside the Basilica of Our Lady of Perpetual Help, Boston, where the funeral took place, while President Barack Obama and other dignitaries paid their respects.
RTE has received up to 30 complaints from viewers who were deeply offended by Bird's dressing down.
One complainant told the Herald: "I thought it was totally inappropriate.
"He was standing there in a jacket and an open neck shirt.
"It was at a State funeral, and the general view is that he let the side down badly."
Three of the former American presidents, George Bush, Bill Clinton and Jimmy Carter, attended the funeral of the younger brother of John F Kennedy, who died of brain cancer last Tuesday aged 77.
The viewer stressed: "It was a very poor show by RTE to have this guy dressed like that in front of the camera on such an important occasion.
"The American president and former presidents, the Taoiseach, and very important people were there."
Meanwhile, RTE says it is taking on board the "small number" of complaints it has received about Bird's wardrobe choice.
A spokesperson for station said: "RTE received a small number of complaints about this matter.
"As it happens, weather conditions were very bad on Saturday and our correspondent had to change clothes prior to his first live report for the Six One News."
She added that the reporter was wearing a suit and tie for the next broadcast on Saturday.
"He was able to get more appropriate attire for the 9pm News bulletin," she said.