They are among Africa's most endangered mammals.
But staff at a popular Lowestoft attraction are celebrating a new arrival.
The latest and rare baby to be born at Africa Alive! is a 'very welcome addition' to the park's family of drill monkeys.
The rare primate was born on February 17 at the Africa Alive! wildlife park in Kessingland. Drills are found in only a small area of Africa and are listed by the IUCN as the highest conservation priority of all African primates.
A spokesman for Africa Alive! said: 'Parents Donga and Rouka, arrived from Bristol Zoo and Edinburgh Zoo in 2015. Neither had ever bred before, so this baby is extremely important to the captive population and we are thrilled that Rouka is proving to be such a good and attentive mother. This is yet another important addition to the park and Donga and Rouka's baby will hopefully play a crucial role in assisting with the European breeding programme for this incredibly endangered species.'
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