A man and two boys who allegedly killed eight emu chicks in a South Australian national park have been charged with an animal cruelty offence as well as cannabis cultivation.

Police said two boys, aged 16 and 17, and a man aged 18, all from Port Lincoln on the state's west coast, entered the Lincoln National Park on February 12.

They alleged the trio deliberately ran over the chicks before doing a number of burnouts in the park and leaving.

Investigators also found more than 30 cannabis plants growing at two locations in the park and allege the trio were illegally cultivating the drug.

The males were arrested on Friday and have been charged with aggravated ill treatment of an animal, cultivating a commercial quantity of cannabis, introducing cannabis to a National Park, and the misuse of a motor vehicle.

The boys were bailed to appear in the Port Lincoln Youth Court on March 7.

The 18-year-old was bailed to appear in the city's Magistrate's court on March 30.