A reward has been offered by the Addo Elephant National Park after 36 jackals and two crows were poisoned.
"We are offering a reward of R10,000 for information which may lead to the successful prosecution of the persons responsible for the poisoning," SA National Parks spokeswoman Fayroush Ludick said on Friday.
"The 36 is what we are aware of. Addo covers about 180,000 hectares. We found the first carcass on Sunday, August 10, and the last carcass on Monday, August 18."
She said there were also unconfirmed reports that two bat-eared foxes were affected.
Ludick said traces of the poison had not been found yet, but that a toxicology report by the ARC-Onderstepoort Veterinary Institute confirmed they died of a poisonous pesticide known as methomyl, which is usually used by citrus farmers.
"Conservation staff members are still combing the park for any further carcasses and any trace of the substance."
Ludick said a case relating to the discarding of toxic chemicals under the Protected Areas Act had been opened with police.
She said vehicle searches in and out of the park had been intensified because of the poisoning.