She helped rescue them from the cages of a research laboratory 25 years ago and taught them how to live in the wold.

Now animal behaviorist Linda Koebner has received all the thanks she needed from the animals she hasn't seen for all those years - a 'welcome back' hug.

Koebner, who founded the non-profit chimpanzee sanctuary Chimp Haven in Louisiana, spent four years teaching the chimps how to be wild in southern Florida after they were released from the hepatitis research lab where they lived.

She then returned to the enclosure and was greeted with open arms by the chimps, which was captured on camera and featured on the PBS documentary The Wisdom of the Wild.

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Loving reception: This is the moment Linda Koebner was reunited with one of the chimps she helped ease back into the wild after they lived in a test lab for six years

All smiles: The chimp, named Swing, cracks a huge smile as she suddenly recognized Koebner

Embrace: The two lovingly hug after seeing each other for decades, as Koebner is reduced to tears

Koebner, who founded the non-profit chimpanzee sanctuary Chimp Haven in Louisiana, spent four years teaching the chimps how to be wild in southern Florida after they were released from a hepatitis research lab

'Do you remember me?': The chimps live in a special enclosure in southern Florida and Koebner went to visit

'You look good': Koebner returned to the enclosure and was greeted with open arms by the chimps

Koebner, a graduate at the time, helped ease the chimps into living outside and how to fend for themselves.

But she hadn't been back in two decades, so decided to visit the few who remained, The Dodo reported.

'It's been so long,' she says in the documentary. 'Oh, you look great.'

In the footage, Koebner takes a boat over a small body of water to where the chimps live.

As she nears the other side, a chimp comes to greet her.

'Do you remember me?' she asks.

A chimp named Swing reaches out a hand to Koebner from the dock, and cracks a huge smile.

Then suddenly another chimp, named Doll, runs over excitedly.

Koebner is overcome with tears as the two chimps lovingly embrace her.

Flashback: The chimps were released in 1974 and Koebner - then a grad student - was part of a team charged with helping them learn to live in the wild

Koebner recalls in the documentary how the chimps struggled to even get out of their transport cages

'Whether it was afraid to step on the grass, they hadn't been on anything but hard bars for years,' Koebner said

'Chimpanzees have provided us so much in this world,' Koebner says in the film.

'So much knowledge about ourselves, about our social lives, about our dispositions, because they are so much like us as beings.'

'These chimpanzees have taught me about resilience.

'All of these have gone through such tremendous adversity, and yet they're forgiving, and they're whole again.'

But the animals have a lot to thank her for. Koebner remembers how, when the chimps were finallly released from the cages they had lived in for six years, they didn't know what to do.

She says it was difficult for them to embrace the outdoors.

Back for a visit: Koebner returned to enclosure from the sanctuary that she runs in Louisiana

'Chimpanzees have provided us so much in this world,' Linda Koebner says in the film

'They were terrified to get out of the security of their transport cage,' Koebner says in the documentary.

'Whether it was afraid to step on the grass, they hadn't been on anything but hard bars for years, or just the feel of the wind and the sun.

'They just huddled in the doorways and wouldn't come out.'

Chimpanzees share 98.8 percent of human DNA and have been used as test subjects for drugs and vaccines.

This experimentation only stopped in the US last year, when chimpanzees were listed as an endangered species.