Full "Easy Farming" Playlist for Ultra Hard here: • Horizon Forbidden West - Ultra Hard (New G...
Full spreadsheet for all upgrade resources (except for NG+ gear) provided here: https://docs.google.com/spreadsheets/...
Stormbirds feel like they took a significant nerf from Horizon: Zero Dawn. They go into Knockdown easily and feel more fragile in general. In spite of that, they still manage to be one of the most annoying machine types in the game. Why? Because there are only two of them and both are in extremely inconvenient locations for farming.
This location is available from the beginning of the game, however it's very difficult to reach without a Sunwing. There are a few angles where you can make the trek by fighting with the mountain's terrain, or you can come down a more normal route from the Slaughterspine north of here. The latter makes it too difficult to get to the position I'm using without also riling up the Dreadwing, and the former takes too long. If the Stormbird kills you with a lucky shot (as he will from time to time) it's infuriating. So bottom line, I recommend putting this particular farm off until you have the Sunwing Override, even though that's very late in the game.
The key to this is to be very careful of your positioning. There's a specific rock formation I'm hiding behind, and it's just the right size and shape to allow you to shoot around but it will still catch the incoming Storm Cannon shots. You've got to continuously make adjustments to your position, trying to stay within the range of the Sharpshot Bow without exposing yourself to the Storm Cannon. For Coils, I recommend either one or both Instant Brittle +2% on your Sharpshot Bow. Only rarely will the Stormbird stay within range of the Hunter Bow, and landing the occasional Brittle will speed things along.
Even with the proper setup there's a lot that can go wrong. Stormbird AI is about as wonky as it was in the first game, and he'll often just get stuck flying away from you or flying up into the sky forever, costing you a kill. If he tends to keep flying away, I find that hopping on and off of your Sunwing will usually taunt him into flying over to fight you up close. This is another reason to wait and do this farm only once the Sunwing Override is available.
4:55 At some point in the fight you're likely to destroy the Storm Cannon, and what happens after that is hard to predict. Either the Stormbird will leave your range and become uncooperative, or he'll try to get in close like he does at 7:33, allowing for an easy kill.
You'll need 9 of these to complete all of the game's gear upgrades, which fortunately isn't too many since this is an annoying farm. For the Storm Cannons there's an easier method at the other location, shown here: • Horizon Forbidden West - Ultra Hard (New G... . However if you haven't progressed the game to Faro's Tomb and stubbornly want additional Storm Cannons, you can farm them here as well with Tearblast arrows.