AUSTIN (KXAN) -- Love them or hate them, it's the season for a special kind of flying squatter to return to Central Texas. Barn swallows are migrating back into our area, and once they set up on your porch, there isn't anything you can legally do to remove them, or the mess they leave behind, un til they choose to vacate on their own. These barn swallows are infamous for their mud nests above doorways and for transforming front porches into bathrooms. If you don't want to fall victim to these squatters, you must take action before they show up. Otherwise they'll be back year after year. KXAN's Tom Miller talked with Texas A&M AgriLife Extension Expert Liz Tidwell about how to get ahead of the birds. This interview has been lightly edited for clarity and brevity. Barn Swallows wait for food. (Courtesy: Getty Images) Tom Miller: If you've never had a barn swallow on your property, you might not know what the big deal is. Can you explain some of the issues that can arise? Liz Tidwell: The biggest thing for a lot of people is the fact that they don't like the mess that they provide. Birds don't fly off, they don't go use the bathroom. They use it right where they are. If you have a nest right above your doorway, they're going to leave you nice little surprises on your front porch all of the time. For a lot of people, that's a major issue. Another one is the parents are just trying to protect their offspring. They will have a tendency to dive-bomb you a little bit. They're not as aggressive as birds like Blue Jays, so they're probably not going to touch you, but at least until they get used to you, they're probably going to dive on you. Miller: What are some of the proposed strategies to prevent these barn swallows from nesting on your property before they arrive? Tidwell: The biggest thing is just going to be removing those nests that were there the previous year. These guys do reutilize those nests from one year to the next, so removing those old nests, as well as using physical barriers, are going to be another way to prevent these guys from nesting on your property. Making a surface slick is going to be the best way. If it's slick, using either plastic or metal, they're not going to be able to adhere their nest to that surface. If they can't build their nest, they're not going to hang around. You can also use wire, or mesh netting is another method. I do caution with netting, there is a chance that the birds could get caught up in that netting. It should always be taut. Swallows practice their song on a stick. (Courtesy: Getty Images) Miller: If the birds are already on your property, there could be legal implications here. How does the Migratory Bird Treaty Act factor into this? Tidwell: The Migratory Bird Treaty Act legally protects these birds, meaning you cannot disturb them. You cannot legally possess any part of them. You can't possess feathers, the nest, the eggs. Once they are physically occupying the nest - there are eggs, there are nestlings or fledglings in there - you have to leave the nest alone until they vacate that nest. Once they vacate the nest, you can then go in and physically remove the nest so they don't use it a second time. Miller: We're making the barn swallow out to be a bit of a bad guy, but I'm sure they have some benefits too, right? Tidwell: They provide what we call an ecological service, meaning that they provide a free service to us humans. That's something they do naturally. Barn swallows are what we call insectivores. They eat bugs. Humans, we don't like bugs generally. They eat things like bees and wasps and crickets and all those little flying things that we don't want around our house. We don't have to pay a contractor or insect person to come out and get rid of them. They're just going to do it naturally because it's what they eat to survive. ...read more read less