I saw 8 on the shed at one time. They would light on the shed wall or roof and periodically fly out over the yard (I'm presuming, to snag an insect).
Because of the variation in appearance of the different dragonflies, I thought I was seeing more than one species; however, when I looked up information on dragonflies, I concluded I was seeing male and female of one species, the common whitetail skimmer.
(mature male that has developed pruinescence on its adomen)
The scientific name is libellula lydia, which to me sounds pretty funny. One thing I haven't found is whether they make a clicking noise. I thought I heard them make a clicking noise in flight, but maybe I just got buzzed by a hummingbird.
I hope they ate lots of gnats and mosquitoes.