Black kites concentrate at grassfire fronts across Africa, Asia and Australia, hunting insects and small vertebrates driven out by flame and smoke. That much is uncontroversial and long recorded.
The contested step is deliberate fire spreading. A 2017 paper by Bonta and colleagues assembled Indigenous Australian accounts and around twenty independent non-Indigenous observations describing black kites, whistling kites and brown falcons picking up smouldering sticks and dropping them in unburnt grass, which pushes the fire front and produces new flushes of prey. The Indigenous knowledge behind it is far older than the paper.
Critics note that the report rests on eyewitness testimony rather than video or systematic observation, and that accidental transport of a burning stick could produce the same outcome without intent. No controlled study has yet resolved it, so this sits as a strong ethnographic and observational case awaiting harder evidence.