Meaning of Bluegills splashing on surface?

[captpierre]

I’ve seen it several times now this fall on Pigeon.  On mid lake humps.  Multiple Bluegills splashing in a 3-4 ft area. 
Are they chasing bait or are they being chased 🤷🏻‍♂️

[dave524]

Bugs on the surface ???

[CrowMan]

Bluegills will often linger on the surface on a cool morning to warm themselves in the sun

[BillM]

Most likely chasing bait who in turn is chasing some sort of bug hatch.   I've been seeing big largies eating off the surface the past few times I've been muskie fishing.