Barn swallow nest

"Our" barn swallows are back today but I just realized that I never knocked down their mud nest from last year. Should I or just leave it? My dh and I differ in opinions. I think they'll come and see a nest already there and might leave. He thinks they'll see a nest and use it. I think their instinct is to build a nest and they won't. He thinks maybe we'll get lazy birds. ha

Won't they build a new nest on top of the old? I've seen pictures of multiple nests when they were building over cowbird nests.

They'll use the same nest over - saves them quite a lot of time not having to re-build, which means they can get their young fledged earlier.

Resin

Thanks! I love them so I'm happy to help them out!