Elephants are so crafty they carry out their raids on plantations to coincide with the darkest nights, scientists have found.

Scientists at Anglia Ruskin University in UK found the huge animals track the lunar cycle and avoid organising their raids when the moon is full.

The findings show that elephants are aware that they are doing something risky, that humans are a threat and they work out a plan to minimise the risk of contact.

The researchers carried out their work at the Mikumi National Park in Tanzania. Five villages on the park's northern boundary were selected for the research, which recorded instances of elephants raiding crops being grown close to and within human settlements, 'The Times' reported.

The study found that the number of elephant 'raid nights' varied throughout the lunar cycle, with significantly fewer raids occurring during a full moon. The extent of crop damage also fell considerably during the full moon phase.

"Elephants are cathemeral, meaning they are active during day and night, but they raid crops almost exclusively at night, suggesting they only venture close to villages when they believe they are harder to detect," said co-author Rachel Grant, lecturer in animal behaviour at Anglia Ruskin.

"An elephant's awareness of the higher risk of being detected on moonlit nights, because of the visual advantage gained by humans, could account for the changes in their behaviour during the lunar cycle and explain why elephants are less likely to venture close to villages during the full moon," Grant said.

The study was published in the African Journal of Ecology.