Researchers at the University of Bristol have discovered that some species of ants will increase the efficiency of their pathways by using their bodies to plug holes or smooth out uneven terrain:
Certain workers stretch their bodies over gaps in the forest floor, allowing their food-carrying sisters to march over them.The ants carefully size-match to the holes that they plug. [Researchers] Powell and Franks stuck planks with different sizes of hole in the path of the ant column, and found perfect matches between ant and hole.
By smoothing the trail home, they ensure that other workers can return food to the colony as fast as possible.
The article notes that these specialist ants improve the performance of the colony as a whole even though they are not directly carrying food or other supplies.