thats what theyd when they "swarm"
What happens is this the brood hatches another queen and then the hive splits, somw time with a new queen, sometimes with the old one. They will lite on a post, tree, bush, what ever. The queen sets down first then the workers settle with her till the worker bees find a suitable home (usually within a day or two), then the swarm will move to the new habitat
This is why beekeepers put a queen seperator between the hive and the supers to keep the queen from over populating the supers with larva (honey storage) and can keep control of the queen population in a hive. Most keepers will replace their queens every couple of years to keep the orig. one at her peak strength as she will normally kill off the new queen when hatched
With the influx of african bees keepers are now in the practice of replacing the queen every year to keep the strain fresh
And for what it is worth thats not a lot of bees, a good size swarm as "swarms" go but about average
btw keeping bees is a hobby of mine, Ive had up to 20 seperate hives at one time, and put up a LOT of honey