I have seen such problems first hand. Buddy lives in an area that has no trash curb pickup, there are numerous dumpsters around the area you take your trash to an drop off. Well, folks drop off about anything you can think of, goats,horses,chickens cats and dogs to just name a few. These dumpster places are void of any birds or other small critters. He and his wife feed these ditch lions. They have caught a few and had them neutered or spayed, then turn them loose again.
Imho it does little for the real problem. Now I am not animal hater, but those that will dump an animal to fend for itself just isn’t right. Once again it’s as much a people problem as it is an animal issue.
If this were happening in my vicinity I would have taken action by now. Dump feed, wait a minute and when ther is a dozen around the feed pile and open choked shotgun with some 6’s or 5’s would do the trick.
Since the city invaded me, I leave the coyotes and foxes alone, I have seen them catch feral cats
More than once. I will go out of my way to discretely dispatch cats and ground hogs.