These researchers made some amazing discoveries about the monitor lizards of northern Australia, how their underground engineering massively modifies the harsh environment, making it more livable for themselves – and many, many other species:

“…our research team discovered yellow-spotted monitor eggs in nests at depths up to 4 m — easily the deepest vertebrate nests on earth! This and further excavations revealed that the burrows were helical, like a work of art, much like fossil burrows of prehistoric beavers and stem reptiles that thrived tens to hundreds of millions of years ago…

“To our surprise, as we excavated warrens across a ~ 1,200-km stretch of northern Australia, we discovered small animal communities occupying the burrow systems. The labyrinth of fresh and older burrows hosted snakes, geckos, skinks, monitors, frogs, toads, scorpions, centipedes, beetles, ants, and a marsupial, sometimes one at a time, other times in great numbers. One warren even contained 418 individual frogs. Overall we found 747 individuals of 28 species of vertebrates in just 16 warrens and 14 individual foraging burrows…

“The timing of our excavations revealed clues as to why a given species was using the warrens. For example, the frogs we found were in aestivation/brumation because they are not active during the dry season winter, while the small reptiles were likely using the warrens as temporary refuges for thermoregulation, protection from predators, or foraging.” 

Ecosystem engineering by deep-nesting monitor lizards J. Sean Doody, Kari F. Soennichsen, Hugh James, Colin McHenry, Simon Clulow. Ecology (Dec. 18, 2020)