Abscond

[Kurt Bower]

I was working the rest of my hives yesterday and noticed one was particularly poor in size. I had noted to feed and possibly re-queen very soon.
About 5 minutes later I noticed a flurry of activity. The kind where you know you are losing your bees. Sure enough, they decided to leave and move onto the trunk of a small tree.
I verified that everything was still OK inside the hive. No disease and no infestation of small hive beetles or wax moth.
It's not the first time, but I find it very strange.