Lithengale

After catching a couple of Scarlapods (which I posted about on that page) that showed up after world quests, I caught a Lithengale right before doing a regular quest.  I guess the moral of the story is: always mouse over those vignettes.

Found mine as primary pet at /way 48.06 79.50 and another one right at /way 49.28 76.68, both uncommon quality

Found mine at (45, 69). :)

I just confirmed that these do in fact spawn just like those freaking Deepridgers. I killed Rock Martins for 30 minutes at 45.38 69.36.  one spawned and I killed it when a snake popped up at the same time.. 

I found one at 45.86, 68.57 as a main pet, I tried all other locations already noted in the comments and had no luck. Then randomly came across this place, hope this helps the next person looking for one of these birds :)

found one at 42.63, 75.75 on the road.

NPC ID 203358 - add to SilverDragon for scanning help

Found as primary near Glimmerog, @ 46.73, 77.90. Still looking for Scarlapod xD

Based on where people have seen these, I'm guessing they can spawn in place of any Rock Martin (also maybe just one up at a time, like the old Talador moths?). Certainly rare enough that I'd recommend just stoning the first one you find, unless you're VERY patient.

Caught one at 48.3/43.0, main pet.

Found mine in Cascades Column near 47.4 79.5

Acidbite Ravine and Cascades Column. Kill any non battle petss, they're place holders.

seems to be another rare spawn on a very long timer. found approximately 49, 44