A rep for Save the Chimps tells TMZ ... all eyes are on their nonprofit after Tonka was seen thriving there in the final episode of "Chimp Crazy," which was created by the same director as "Tiger King."

In fact, Save the Chimps has seen a notable increase in donations ... a 200% increase, to be exact.

In the month since the series began, 206 new donors brought in over $20,000 in contributions ... significantly more than the 103 donors who brought in $5,450 previously.

Not only that, but Tonka has driven quite a bit of online traffic for the sanctuary, too ... including a 7,000% increase to their website. They have gained 5,500 new followers on social media since the series began -- 4,400 new followers on Instagram and 1,100 new followers on Facebook.

It probably helps that Tonka appeared so happy and healthy as "Chimp Crazy" wrapped up its run last week ... with countless fans wondering what became of the chimp after the cameras stopped filming.

We're told Tonka is doing quite well alongside his new family of 17 chimps at the sanctuary in Fort Pierce, Florida ... where he'll be turning 33 on October 5.

The org plans to do something really special for Tonka's big birthday ... including a fundraising drive, in which fans can "adopt" the beloved chimp or gift him some of his favorite things -- bananas, nuts and blankets.

Tonka was previously owned by Tonia Haddix, the self-proclaimed "Dolly Parton of Chimps," who lost custody of him after "Chimp Crazy" filmmakers informed PETA about the primate's whereabouts out of concern for his safety.