There's a large colony of Cliff Swallows right under the 528 North bridge over Lake Arthur in Moraine State Park, PA. My father lives only a few miles away and I have seen them there for many years. Believe it or not I'd actually forgotten they were there as it's been so long since I've been there during nesting season. I witnessed large flocks of them arriving back to their nests with the morning's catch of insects freshly hatched off the lake. They'd all try to land and get inside to feed the young at the same time, resulting in little swarms of swallows. Once all the food was distributed I got to enjoy having them all fly in circles around me. They began to climb the warming air caused by the rising sun on the lake, the bridge itself caught the lite wind angling it upwards. I'd thought there were a lot just at the one little section of bridge I happened to be standing under. It wasn't until the entire flock, the whole bridge full in fact, was all the way up that I saw the size! I didn't even try to photograph the swarm as I became enthralled by just being in the moment. It was then that I noticed these two little guys peeking out of their mud houses.
From Moraine State Park - My Home Waters