Barn swallows, infamous for their mud nests in doorways, are returning. Once they make a nest, you can't legally remove them.

Barn swallows provide a unique opportunity to explore the speciation process as it unfolds. These birds are one of the most common and widespread species on our planet.

Amid barn swallow migration, a Texas A&M AgriLife Extension Service expert provides tips on preventing nesting while adhering to federal law.