You have to go pretty far back (to proto-Celtic, it looks like) to find a linguistic ancestor for the word “gull” that doesn’t just mean “that specific bird.”

But in proto-Celtic, it looks like “weilanna” probably meant “wailer.” As in, “one who wails,” though we don’t know exactly what the suffix “-anna” means. A similar word in that language would’ve been “wailos,” which even though it sounds similar seems to have been unrelated to our modern term “wolf,” as it comes from a different proto-indo-european root.

Anyway, the word “gull” does refer to the sounds that it makes more than anything else. So in figuring out what a landgull, airgull, and firegull might be, we need to find something noisy. Or just something annoying, given the derisive connotation of “wail.”

Edit: This is, of course, assuming that we’re looking for different existing types of animals to be these creatures, rather than just (for instance) creating new, elemental forms of gulls; or “reskinning” seagulls with different elements; or inventing all-new animals to fill those roles.