You know it's pretty awesome how smart these Wels Catfish are:
The Birds can simply fly away, and they are scared by any splash, so, it stands to reason the Wels Catfish is "learning" the behavior. I've watched a lot of footage of people fishing for them, and, after a while, if they hook into a Wels Catfish, and the Wels comes off the hook, they instantly change out the lure as the Wels won't hit it again.
Once you hook into a Wels with a given lure the Wels learns what that is, and you're stuck changing it. You can see in the footage they sit on the bottom near the shore, and watch. When they see a bird closer in the water, they seem to work out in their heads where to strike, and not get beached of course.
It sucks so hard these things are totally banned in America.... I'd LOVE to have a chance to catch one and play with one. I admit, a huge Wels, is one of the VERY few Cats you'd need not worry about me hopping in with it.... They aren't trying to learn their owner the way a Red Tail Catfish will, they are pure predator and I would not survive if it was over 7 feet, which wouldn't be a record in any way.
German newspapers from the 15 century or so, say that Wels were accurately measured at 16 feet long..... 16 feet long.... That's big enough to say "Oh wow where did the Brown Bear go?? There was a splash and it was gone!".... Haha.