We see this 'dung visiting' habit on numerous occasions every year.

It is not often actually the dung we see them at, more often it is
sucking up the ghastly black liquor coming out of the base of the mounds
the farmers have built to allow the dung to rot down. This continues all
conditions, and even with liberal supplies of clean water nearby.

We always assumed it was the bees seeking to address some kind of
mineral deficiency, but I have also been told that this liquor is quite
high in sugar. (I never quite plucked up the courage to taste it!)

Our little darlings do have some foul looking habits.
--
Murray McGregor