Swarm take over of small hive?

[Aroc]

 Is this even possible? A fellow beekeeper asked me today if that?s possible. Has had a problem with a couple of beehives this spring. One died, the other is very very small. This morning he noticed what appeared to be a swarm coming in to his hive? Can a swarm take over an existing hive?

[texanbelchers]

Absolutely, usurpation is the correct term.  From what I've read AHB seem to do it more than others, but all can and do at times.

[Bush_84]

Absolutely, usurpation is the correct term.  From what I've read AHB seem to do it more than others, but all can and do at times.

What he said. With you location ahb are not a concern. So a swarm saw the bees living there as no threat and took over.

[BeeMaster2]

I have personally watched usurpation happen in my apiary. On top of that one swarm moved into a small hive took it over and then moved into another smaller hive the next day and then they left with all of the bees from both of my boxes. Put a queen excluder over the entrance for about 4 days to force them to settle.
Jim

[Michael Bush]

Q. I had 32 colonies of bees, and I have lost five of them. They will swarm and come out of their own hive and settle on the outside of some of the other hives, and leave their own hives empty, with lots of honey in them. When they settle on the other hives it causes a fight. What makes the bees do this?

A. Bees sometimes seem to have a mania for deserting their hives in spring and trying to force their way into other hives, and it isn't easy to say just why. Some think because they are weak and discouraged. Some think because they have started a lot of brood, and then the old bees have died off so rapidly that enough are not left to cover the brood. In any case the advice given is to have only strong colonies in the fall. This is sound advice on general principles, even if there should be some absconding the following spring in spite of strong colonies.
--C.C. Miller, A thousand answers to Beekeeping Questions, 1917

[GSF]

Can a swarm take over an existing hive

Yes. I've also seen a few swarms land on an active hive instead of a tree limb.