This Blue Dasher is in the obelisk position with his abdomen pointing straight upwards. Dragonflies perch in this position to minimize surface area exposed to the sun on hot days as a means of keeping cool or as a threat to other males. I think this particular Blue Dasher is posed in a threat posture towards other males because he was angled wrong for keeping cool and was actually absorbing more of the sun's rays than he would have been if he was perched horizontally.
 
There were numerous male Blue Dashers in the area, all constantly interacting with each other. At one point a female came along, one of only three I saw this morning compared to the many males I saw, and a male grabbed her, mated and she then proceeded to lay eggs after the male released his grip. The male didn't go away, however, but guarded the female very closely, driving all other males away while she laid her eggs, until she was done, at which point both parted ways.