Sunset and Cave Swallows

I wanted to watch the wintering Cave Swallows under the Parmer Lane bridge return to their roost for the night, so at about 5:15 yesterday evening I went to the Parmer Village drainage pond and waited and watched. The weather was just about perfect and eventually there was a beautiful sunset behind me. Other birds that were around included Mourning Doves, American Pipits, meadowlarks, Great Blue Herons, and a single Great Egret. (I don't know if the meadowlarks were Eastern Meadowlarks or Western Meadowlarks. We get them both here in the winter and the only way I can tell them apart is by sound.) At about 5:50 I spotted a single Cave Swallow flying over the bridge, and it soon disappeared underneath. 10 minutes later at 6:00 on the dot, 20 Cave Swallows appeared over the bridge. They swirled around in the air for less than a minute. Then they joined the first bird, swooping down and disappearing under the bridge. What a great way to end the day.