I found one when exploring the lake/river in the redwoods, it was getting dark so I decided to rest beside a cliff for safety when I heard a scream and seen a white blurry past me, luckily it was running face first into the rocks so I threw a bola and smacked it with a club until it went to sleep, now I have a really cute parachute lizard bird.
Go to the redwood, look at the trees they'll often fly from one tree to the next. It can take some time to find but when you do they spawn in bunches. Now here's a nifty trick. Not all "grab point" on tree work perfectly, if the archa can't grab the tree it'll just fall vertically to the ground for not only an easy time to tranq it, but also other archas might fall to the ground near the same spot when they come along to feed! I tamed 3 archa in one spot for the price of one (fourth one got away).
Careful about the wildlife especially the angry birds
I literally find hundreds just chillin on trees in the redwoods. It's really helpful to make a tree platform and just wait until one lands on your tree and then shoot it with tranqs. It's much easier then trying to shoot one from the ground, and trying to find it once it's knocked out.
like most small to medium sized creatures, a decent lvl horse can knock them out quick before they can escape. nice utility tames (organic parachute) as far as encountering goes....well good luck distinguishing them from microraptors......
I found that if you use a pheromone dart (you need ammonite bile) then it attracts them to the Dino you shoot, but after they kill it they start attacking me, this makes it easy for me to knock them out and tame them