The holes pictured do not resemble those created by insect wood-borers; they are too uniform in placement on the trunk, for one. Instead, these do appear to be classic indications of Yellow-bellied Sapsucker feeding. They are a native woodpecker that spends the winter in our region (they'll be migrating north and west soon, if they haven't already). They create two types of holes in tree bark in order to get sap to flow out. They either feed on the sap itself, any insects attracted to it, or both. One hole type looks like this -- fairly rounded and in horizontal rows. The other is more of a rectangular patch, shallower and in more of a vertical or gridded arrangement, almost like lace when the bark is riddled with this "sap well" type. As a protected bird, people cannot directly interfere with their activities, though frankly there isn't really a reliable way to discourage them from "tapping" a tree anyway. You can learn more about the birds on the linked pages (one includes an image gallery where you can view the sap well types).

Sapsucker trunk damage rarely causes serious health problems for a tree, though when it does, nothing can be done except to cut back any canopy dieback. (This is more likely on a smaller shrub with extensive damage, such as for hollies and viburnums, rather than on trees.) As noted in N.C. State's page about this bird, you might be able to wrap the trunk of a vulnerable species in burlap (taking care not to make it too taut), but keep in mind that such an attempt might accidentally let actual insect pests harbor underneath, or trap moisture against the bark. Plus, even if a successful deterrent is used, the birds will simply pick other trees in the area, possibly spreading one damage event into several.

If you do re-mulch (it doesn't look degraded enough to need it, but it's hard to tell from that distance), be sure to keep the mulch off of the trunk base entirely, only covering the root zone as far out as you wish to go with no thicker than a 3-inch layer. Mulch that is piled against the bark or laid too thickly covers the root flare, which can cause health problems for a tree down the road, potentially being quite expensive to fix (if curable at all).

No action is needed for the sapsucker holes; don't coat them or treat them with anything. Trees that don't suffer any ill consequences of sapsucker drilling will gradually seal-off and scar-over those holes over time. Fortunately, we've seen examples of much older Magnolia and Cedar trees with years of extensive cumulative sapsucker drilling and no discernable impacts on their health or longevity.

Miri