They are out looking for real-estate. Like the reality show "Buying The Bayou". They are know as cruisers.
What happens when the water drops 10 degrees in the next 4 weeks?
That looks like a bed to me. I believe there are a few fish that spawn early when ready. As the water temp. drops more and more, it will move those out that are thanking about spawning and in the shallows looking. Then a warming trend comes along and they will be right back wanting to make beds again.
If the weather was consistent then there would be a great pattern; but it is not which makes it difficult to work spawning fish. So a few spawn here and a few spawn there; the first thing you know it is all over with.
The farther south you go the more consistent the weather becomes. That is why Falcon and Mexico is so much fun. Then on the other hand when unstable weather does come in on those southern lakes it really turns them off until it gets back to normal. It doesn't even have to drop the water temperature. It can just be cloudy and air temp drop 10 degrees.