Six of the 28 Great Bustards that were reintroduced into the wild in Britain are still alive and well.
The birds, last seen in the UK in 1832, were released on Salisbury Plain in Wiltshire last September.
The leader of the project to bring the Bustard back to Britain said he was happy, given how many of their babies normally die in the wild.
Forty more of the world's heaviest flying bird are set to be released into the wild in September.
It's thought the birds that died were killed by disease, or by foxes, which are their biggest threat.
Bustards can weigh up to 20kg, and until the birds were released in the UK, were only found in the wild in Russia.