Barn Swallow Issues!!!?

Even if they migrate they will be back next year and so will their babies to breed. If you don't want them in yoru barn then you need to find a smelly kind of something that won't harm them but discourage them from breeding there. They have stuff like that for deer, fox, squirrel, raccoon, etc so they must have it for birds. It is non toxic and sometimes is usually just some form of a plant that the animals don't like so they stay clear. I use it around my bird sanctuary I built to keep the rabbits and squirrels away. They don't like the smell so they won't go in the sanctuary which is about a 12 x 14 foot area. It's not harmful to them or the birds but they just don't like it. I think it has some sort of hot pepper in it but you can get that from Lowes, etc so ask them what you can do to discourage birds. You can't kill them because it is against the law to kill any bird that is native to the country it is native to so if you live in the USA the only bird not native to this country that is wild is the House Finch. It was brought to the USA in the 60's to NYC to kill the pests in the park there and now they are all over the USA. All other wild bird are protected unless they are used for hunting and then you can only kill them with a lisence and during that season of hunting like the pheasant and the turkey. Good luck.