International Animal Rescue said it was also having to rescue orangutans from the fires, with 46 of the critically endangered animal moved to safety so far.
Dr Kamale Sanchez, who works for the charity in Indonesia, told the BBC she was sleeping deep within the forests to rescue more.
She said forest fires in the area “have got even more out of control”.
“We are experiencing a very hot season,” said Sanchez, explaining that it was about five to six degrees above normal temperatures for the time of year.
This year’s wildfire season has been called one of Indonesia’s worst in years.
It is primarily caused by illegal slash-and-burn practices used by farmers and companies as a cheap method to clear vegetation, though experts say the “super” El Niño this year has exacerbated drought conditions.
Human activities, such as the burning of fossil fuels, are driving climate change that is making extreme weather events more common and intense, say scientists.
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