Tahiti has no snakes in any area of Tahiti so you don't need to worry about seeing snakes or being bitten by any snakes if you visit Tahiti.
My brother went to Tahiti around 5 years ago and he said he saw no snakes on his trip there but I guess there could've been but since he saw no snakes I would say that he's right about no snakes being in Tahiti as some other forums state that no snakes live in Tahiti either.
Fiji has some snakes though but not Tahiti.