My best educated guess is that they are absconding swarms trying to get away from intolerable varroa levels.
Excellent guess, Here in the Midwest we get absconds from beetles in the fall, as well as poor performers. If you have a yard with a several hives sometimes a smaller one seems to sense it cannot compete unless it trys somewhere else. If you have that fall hive that has no resources, watch close as it is a good candidate for an abscond. Late season swarms come from queen events also. They try to raise a new queen and end up with several.
I also wondered about late swarms in AZ, seems to me from living there the desert floor area could swarm and survive about any time of the year.
Charles
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