Dang Kent! How do they stay there without falling out :). Mud swallows? Two of those are raising the second hatch this spring and a third is on the first. Once I learned to quit fighting them daubing mud I learned they'd reuse the same nests every year and not mud up every platform that would hold it. Every 3-4 years I have to get up and cut a nest down about 2/3 because it's stacked so high there's no more room under the eave, but by leaving them alone every window frame isn't daubed with mud. I can't conceive of how many mosquitos they must catch and eat every day. While they're raising their families, mosquitos around the house are just about non-existent. Go to the pasture and and you're a walking bangquet on legs. When they finish raising the families, the mosquitos are back. I think they eat a lot of hatching grasshoppers, too. I made peace with their mud-daubing ways years ago. Often, when the mud swallows are finished, the barn swallows will use the same nests and extend the nesting season and mosquito control. Often, though, the barn swallows would prefer to build inside the garage and I've drawn the line on allowing that.
Texas Zone 7b, USA