There's two areas where the gagana can be found. One is right outside the Reach where you fly up to the west side and find level 67 Gagana. The other is on the part of the Fringes where it becomes desert. Lesser Gagana.

I dunno why but the 67 ones like to actually drop leathers more for me than the Lessers. However it takes a bit more time to kill them. The eggs are used in some pretty handy recipes. Baklava and Egg Foo Young are CUL collectible turn ins, Tempura Platter...the godsend food for crafters also can be a turn in as well.