Before their release experts predicted the biggest threat to the birds would be foxes, so keepers planned to train the chicks to be scared of foxes.
They were going to let the chicks see a fox then squirt them with a water pistol to make them realise foxes are dangerous.
But the bustards got too big and had to be released before the training took place.
Only 12 chicks are still in the wild, but experts are still hopeful they will breed and increase their numbers.
The Great Bustard was hunted to extinction in Britain in the 1830s, partly because its tasty meat was very popular with diners.
It's the world's heaviest bird that can still fly.