The 2018 overview of Isalo herpetofauna says about this species: "Phelsuma hielscheri is quite difficult to observe in Isalo. Individuals were spotted during the daytime, active on Pandanus sp. leaves." We must have been lucky, because we saw several. They were indeed on Pandanus sp. leaves, as shown in these photos.

Here is a list of all the reptiles and frogs I saw on this 2023 trip to Madagascar.