Why are termite mounds often the preferred target over scattered ant lines when available?

They offer a better caloric return per digging effort.

The preference between ants and termites often comes down to efficiency and energy return for the labor invested in excavation. Termite colonies are typically centralized within large, robust mounds, meaning that once the aardvark successfully breaches the fortress walls, it gains access to a massive, localized reward of biomass. This centralized energy source provides a far better caloric return for the effort expended digging compared to tracking dispersed ant lines or visiting numerous smaller, less robust ant nests. Therefore, local resource density dictates foraging strategy; if termites are abundant, the efficiency of raiding a large mound usually wins out over searching for scattered ants.