Second sapsucker working at base of tree--where it would be least frozen

I found this male Williamson's Sapsucker at Centennial Park today and like the other sapsucker it was working near the base of the tree--the place on a pine tree where the sun shines the most and where the tree is least frozen. Also they both worked on the south exposures of the trees, again very adaptive. The sap holes visible on this tree are those this bird likely drilled today, one even shows the glint of sap albeit likely quite frozen.

The fact that there have been 4 different sapsuckers trying to feed on bark, wood and sap that clearly is frozen in this harsh weather may indicate some level of desperation for food since leaving wherever it is that they are finding shelter would expend energy that badly need in these conditions, and especially all the flying/moving about I observed by the birds today would seem to use a lot of energy. The fact that the two males today moved around and between trees would seem to point out the difficulty of finding food. Their feeding on the lower trunks of trees and especially near the base would seem adaptive as this is where the trees would get the most solar exposure that might help thaw them out. Each location where I saw them drilling/chiseling was on the southern exposure, again where the most sun would warm the trees. I suspect that these sapsuckers have experience with freezing temperatures and trees during the breeding season as they would be at higher elevation both early and late in that season when temperatures fall quite low at the elevations where they are usually found; however, they would not likely have to deal with such very low and sustained low temperatures, which makes feeding difficult and would logically be the reason they are known to migrate further south in winter. SeEtta