Incidental Commensalism
Sometimes the commensal is incidental to the provider. Orchids and mosses grow on the trunks or branches of trees, getting the light they need, along with nutritional runoff from the tree. The tree is unharmed.
Birds follow army ant raids on the forest floor. The ferocious ant colony stirs up various flying insects who flee from the onslaught on the ground. The birds following the ants snag the fleeing fliers.
Cattle egrets forage alongside bovine who stir up insects as they graze; a meal for the egrets.
In the Pacific Ocean, a titan triggerfish improves foraging prospects for smaller fish by shifting rocks too large for the littler ones to move.
