As far as belly heat goes, I'm somewhat confused as to why some say it is so necessary. In the wild, BPs are terrestrial; hiding in dark burrows. Where would any source of belly heat, that some say is so necessary for digestion, be present in the wild?

I'm just curious because I've read so many things that all have different stances on heating for BPs.

(I personally think that providing belly heat can aid in digestion, but I was just wondering if this is a concept found only in captivity, or one that we copy from the conditions in their wild habitat)