Hello, Arthur,
I did have a look in various dictionaries, including this website of Urdu Mahir, but could not find any a direct reference to Wildlife; although they give, not surprisingly, the meaning of Wild. Your own suggestion seems to be on the right lines, except that the word Jungli does not seem to fully convey the connotation of Wildelife. I would suggest that Wildlife can perhaps be translated as Mukhlooq-i-ByabaN (Creatures of the Wilderness).
Your own suggestion for Sanctuary as " Pannah Gah" certainly conveys part of the connotation of Sanctuary, but Pannah is somewhat limited, as its prominent meaning is " Refuge"; whereas Sanctuary is more than a Refuge. Similarly Gaah seems to be more specific. A Persian Dictionary gives an example of this word as Shikar-Gaah, a place for hunting. I would hence suggest that Sanctuary can best be translated in Urdu as Jaa-i-AmaaN.
So Wildelife Sanctuary : Jaa-i-AmaaN braai Mukhluq-i-BiyanbaaN.It sounds very poetic.
Regards
Kabir.Khan