Unfortunately, this turned out to not be the case! We found them there the next evening, and the morning after that, and every evening after that. I began to think that they already had a nest in the garage somewhere, and we looked for it but couldn't find one.
Then we discovered what was going on. They were looking for a nesting place and had decided that the garage door bracket above my truck would make a perfect place!
At first I thought it would be a really cool experience - to watch them build their nest, watch the babies grow and fly away. Then I saw the mess on the garage floor underneath the beginnings of their nest. Um... OK, maybe not so cool after all.
I had no idea swallows would be so messy! They always look so cool and aerodynamic when they're swooping around the yard eating up all those nasty bugs. I just assumed their nests would be neat and clean like the birds appeared to be. Apparently, I was very wrong!
They were flying in and out the back door that we leave open so the dogs can get out into the fenced-in back yard. As the week progressed, and their nest got slightly bigger, and the mess on the floor got grosser and began to involve the side of my truck, Brian and I discussed several options to try to keep them out of the garage.
We could fix the dog door in the back door. It worked fine - for dogs that weren't lame, like Lakota is. We could cut the hole in the door all the way to the ground, so he wouldn't have any problems stepping over the area under the dog door... But then we couldn't secure the back door - anyone would be able to crawl right in!
We could rig up a "dog door" made of those long heavy-duty plastic strips, like they have in commercial freezers and such. Those are very expensive and would take quite a bit of time to install.
So, I started looking online at others who had had the problem of barn swallows making nests in unwanted areas. One person said they were using those roll-up screen garage doors to keep them out, and that gave me an idea. I remembered seeing those hanging screen door type things that are made for patio doors and such. They are basically two flaps of screen with magnets that secure them together in the middle and weight at the bottom. They're supposed to make it easy for people and dogs to go in and out, while keeping bugs out at the same time.
Off Brian went to Lowe's to see if they had anything like this. (I'd rather not pay shipping costs AND have to wait for it to arrive - the birds were making great headway on their nest!) Well, they didn't have that, but they had an inexpensive (I didn't want to say "cheap") screen door with "decorative" dividers on the outside. We could install the door and then cut one of the bottom sections out as a flap for the dogs to go in and out.
That would work just fine! $30 later and a little sanding here and there to make it fit just right, and we hopefully have an impenetrable swallow barrier!
Though I am very glad we have swallows around, and I hope they continue to eat all the bugs they want, I would really like it if they stayed in barns where they're supposed to be!
Our new swallow-proof (hopefully!) back garage door.