On two occasions, the one at my house yesterday and in 2013, I saw the bees making preparation to abscond, carrying out white larvae, and attributed it to their being hygienic about varroa.
But here's what Mark Winston says about it:
"Absconding can be defined as the abandoning of a nest by a colony which forms a swarm and presumably reestablishes itself elsewhere. Absconding swarms differ from reproductive swarms in that few or no workers and no adult or viable immature queens are left behind in the original colony. Absconding from feral nests is generally either disturbance induced or resource induced." (Winston, Mark, The Biology of the Honey Bee, p. 218)
Absconding is not the same as putting a swarm in a colony and having the entire swarm leave. For example, once I hived a swarm in a top bar hive with a screened bottom board. They left and gathered on the ground rather than be in that hive. I put them back in the hive and they left again. Then I put boards under the screened bottom board, closing out the space and light. This time they stayed. They were not involved in planning absconding.
Resource-induced absconding, according to Winston, happens during the dearth when nectar and other resources are scarce. We are in a dearth in Atlanta right now. When absconding happens because of a disturbance like the forest fire in the mountains in 2016, the bees don't prepare as well. So those bees left behind frames and frames of what turned out to be prize-winning honey. But for absconding like my bees were planning yesterday, lots of preparation is involved.
Winston says that sometimes for weeks ahead of time, bees prepare for absconding due to a resource shortage. They reduce brood-rearing about 25 days before they leave and "rear no new larvae in the 10 - 15 days preceding absconding." (Winston, p. 219) If the queen lays a few eggs during this time, the workers eat them. They appear to time their absconding to happen just after the last brood has emerged so the result is that they leave with lots of new, young bees to help start the new colony.
Just before going, they engorge with honey (way more than if a hive is preparing to swarm) so that all that they leave in the hive box are wax combs. Winston suggests that they consume the pollen which then stores protein in their fat bodies and hypopharyngeal glands. He also says that unlike swarms, the bees don't send out scouts ahead of leaving. Instead they fly long distances (as much as 100 miles) before scouting for a new place. They will fly through areas of poor forage to find somewhere with a source of food for them before settling down. And they often settle in what Winston calls "interim locations" in their search for a better living situation.
So this doesn't bode well for my moved almost-absconding colony, although the community garden has vast resources for them and it is very close to the Atlanta Botanical Garden. And maybe my jars of honey in the interior Boardman feeders will suggest that food is available. I am going to walk the dog to the community garden and see how they seem to be doing. They were orienting yesterday, but they would have to orient to any interim spot as well.
Thank you, Mark Winston. Whenever I have a question about how the bees function, his Biology of the Honey Bee has the answer. Every beekeeper should own and read this book: