Thanks Dennis, Steve, Gary, Bill Karen and Reyno. These swallows have been building their nests under this bridge for years. At the bank end of the bridge where I was, the nest and birds in these shots were just outside the minimum focus distance for the Bigma, maybe 10-12 feet. I used the tripod and as I stood there, the birds would swoop very close to me, literally over my shoulder, within inches, and they weren't freaked out at all by my being there.
I have spent hours there, watching them build new nests with the mud they get from the receding waters of the wetlands, the same place I shot that series of Black Jack Grackle. The process is fascinating to watch, but it takes several days to complete a nest. They bring mud from the flats in their mouths, then dab little bits of it together, just like building a brick wall, and just like that, they lay one course of wet mud, then they have to wait for it to dry before putting in the next row.
I have wondered if this fact doesn't in part, determine when they return from the South. It must require a certain temperature and low humidity to dry the mud fast enough to build the nests. If they started when it was too cold, or rainy, the nests wouldn't hold together.