The Hollyford Conservation Trust released 41 South Island robins/kakaruai in the valley, which had been flown from Chalky Island in Fiordland by Fiordland Helicopters.
It was the first translocation of the previously locally extinct New Zealand native bird.
The project was paid for by the David Comer Memorial Fund - Mr Comer, a photographer and location scout for The Lord of the Rings and The Hobbit series, had supported the foundation of the trust before he died in 2014.
The fund, established by a family friend, was set aside for the translocation of birds to the Hollyford and the robins were accompanied on their flight by his daughter, Billie Comer, and her mother, Peta Carey, who is also a Hollyford Conservation Trust trustee.
Trust chairman Ron Anderson said he asked those gathered to observe a minute's silence before the birds were released, but during that time the birdsong was "staggering".
"Many commented that they had never heard birdsong like it anywhere in New Zealand.
"Five years ago, when we started the Hollyford Conservation Trust, few people thought we could do it.
"Certainly no-one believed that in such a short space of time we would be able to bring the birds back," he said.
In that time intensive predator control has been carried out on more than 2600ha of the lower Hollyford Valley.
Mr Anderson said a group of hunters who visited the valley annually to hunt during the roar complained they couldn't hear the stags roar over the birds this year.
The trust owed "so much" and was "enormously grateful" to Mr Comer, the trust's stakeholders, contractors and trustees, he said.
The robins released on Thursday were the first of many - towards the end of next week a second translocation is planned, taking the population to 100.
Mr Anderson said the trust also planned to reintroduce mohua to the area and possibly kiwi.
