All lined up

Two or three dozen of these beautifully iridescent Tree Swallows were flying overhead when I drove SW of the city on 14 May. There were two nesting boxes maybe 30' apart - a pair of Mountain Bluebirds was protecting one box and the swarm of Tree Swallows kept flying down to the barbed-wire at the second box. I was surprised to see so many of them! Too early for any new young ones, so would they be a mix of female and male adults plus last year's young? It never occurred to me that last year's youngsters would still be around with their parents.