Once at the dam Dooro began explaining the fine art of dam building. He told them a dam needs to be wider at the bottom than the top. That instead of one big tree being used as a foundation, many saplings and limbs of older trees heavy with brush go into the construction. Then branches are laid side by side in line with the direction of the current and anchored into the mud by rocks and stones, so as not to wash away. With a web of interlaced branches acting like a net, all manner of driftwood and debris are entrapped. Dooro explained that once the foundation is laid, to be watertight the dam needs a plaster of mud, pebbles, and grasses and that this plastering of mud must be done on the upstream side first or it will wash away. And finally, the heaviest logs are added to the dam on the downstream side and pushed against it at right angles for more strength.
Being only three weeks old, Dooro's brothers were hardly attentive. They perked up, however, at the mention of mud. "We want to plaster. Can we do that?" they begged.
It was what Dooro had in mind.
He took them to the bottom of the pond where he showed them how to scoop up armfuls of mud, old leaves and pebbles. His forepaws with their five toes and strong claws were particularly dexterous, and with the support of his paddle-like tail he could walk on his hind legs underwater. Arms full, Dooro actually walked up the side of the eight-foot dam to the surface where he began shoving mud into place with paws and snout. In following his example, the beaver kits were barely successful. Because of their size and underdeveloped coordination, mud melted from their grasp and they quickly discovered stealing Dooro's was an easier way to plaster. He good-naturedly allowed it, although a lot of mud seemed to be drifting back from where it came.