Seagulls were presented in some topics, but that is either just because they are “animals” or because people cannot find the birds… others complain about the loss in frame rate, on approach, when you get near the swarm. Dunno if that is still the case, my vanilla GPU has no problem with this, I use 20fps. And it is fun. They MOVE…
You can shoot nice pictures with a drone, but I wanted to fly near. First, pick a plane. Take the smallest and slowest plane you have, best chance to encounter them for longer than a second and make pictures. Set out a course airborne, that is about 300 Feet up (use nav-log) some 4 miles on either side of the location in Chile, where the seagulls are on the world map.
The sign moves along… Set “Fauna landmarks” on to see the marker, you’ll need it…
Overview is good, this will take some time with the ultralight, I approach from below so I have minimal speed when encountering them. Use flaps if the dive went too fast.
If you approach the lower end of the marker (follow the height !), you’ll end up under the swarm, hear them squeek and see this,
Most times it just looks like that. I’m reluctant to try more: in real life you don’t fly directly into a swarm of birds. When your screen is overpopulated with birds, this is going to happen when you do not fly damage… 
dirty splash on the windscreen… and it’s very bad for your engine. Colliding with a seagull with the ultralight I got a black screen mid air when I put damage on. Just don’t come too close, don’t try to fly into the swarm to get big birds on display. Use the drone if you really need that.
Chase them, don’t crash them… Aerolite 103 is perfect for this game. Stay behind the swarm, on about the same speed (30-40mph), else they will pass too quickly or you crash into one of them. Most images you see are from below, or from above, that also works perfectly.
It goes quick ! Catch the moment, stand by when you hear their squeeks (50-20 depending on the height). and make the snapshot on approach, without pause. A break/pause does not work in this case, the seagulls will ignore your lunch break… and just fly elsewhere 
this was the best I got sofar, at this point I could watch them 5-10 seconds. The short feeling of actually flying with birds
