That’s interesting. I had a similar occurance
We have a red ceramic apple bird house suspended from a tree limb. It has been there for yers, un occupied. Last year the Chickadees nested in it.
This year the wrens who have always lived here nested there, then the Chickadees and then the wrens again.
This is yet another examlpe of how wild life has adapted to living with humans.
The trap was successful but I stopped using it when I discovered a chickadee dead inside the box.
So I removed the front of the box and replaced it with another that had a smaller entrance hole that only the chickadees could enter. That solved the problem with the sparrows.........
I found the best way to deal with the sparrows is with a .177 pellet rifle as they feast on the bird seed on the ground under the bird feeder.......Same with the grackles who travel in flocks and will occasionally find my feeder and chase the song birds way......
As for the shot sparrows, there is a feral cat around my house who hides in bushes on the back of the house behind me. I call her my "retriever" cat since within 5 minutes of a successful sparrow kill, she comes running out to pick it up and take it away........
As for the shot grackles, she sniffs them then turns and walks away. That's weird, since they would be a bigger meal. Maybe they just stink............
Since I have been shooting the house sparrows, I have noticed a tremendous increase in the numbers of purple finches and house finches........