---

I'm no taxonomist, but they look just right to me too, and I'll bet it was a warm, sunny, windless day, which the ones in my area always choose for males to gather in groups on sunlit leaves, and buzz off to chase passing females, and then form mating pairs in vegetation nearby. There were probably some cattle or horses around nearby as well; they're known as "face flies" as they target secretions from livestock especially from the eyes (and often transmit infections...) and lay eggs in dung.