Durrell has released 20 endangered ploughshare tortoises back into the wild.
The golden-domed ploughshare tortoise is the most threatened tortoise on Earth and exists only at a remote site in Madagascar.
A team from the Conservation Charity made a two day 150km trek to the remote spot, Beaboaly, to release the creatures last week.
Durrell started working Madagascar 28 years ago. The ploughshare tortoises were on the verge of extinction due to decades of uncontrolled burning ruining their home. There have also been other issues since 1986, including the black market value of the tortoise's shell rocketing.
Durrell says it is delighted at the release of the creatures, but knows that the scale of poaching threatens the future of them so conservation efforts are focussing on anti-poaching, law enforcement and capacity-building.