Unfortunately can't tell you anything about Ley Lines, but the same thing has happened to us before.
We have had a couple of pigeons at different times land in our garden and stay for a couple of days and then go.
Both of them tried to get in to our house too, we had to keep all the doors and windows shut, as they were so determined but the second one that landed actually managed to sneak in the back door and ended up in the back bedroom, I had to let it out the window and it never came back.