Ant hill or snake hole? The edge pattern that can reveal what moved into your yard

Just the smallest gap on the lawn can instantly cause panic in many people. Most homeowners notice the perfect gap and immediately make an assumption that it belongs to a snake, but animal behavior scientists claim that the thing that really matters is not the hole at all; it is the hole's perimeter.

As claimed by animal behavior experts, the presence of a high perimeter around the hole, a crater, or a well-tended soil mound indicates the activities of ants rather than any kind of snake movements. The difference is that ants actually dig, carry out, and organize soil around the entrance point to their nest, while snakes mostly use existing holes.

That is why the perimeter of the hole is more important than the gap itself.

Why the raised rim matters

In research reported in Behavioral Ecology and Sociobiology, ants build structured nests by constantly moving and dropping soil extracted during excavation outside the nest entrance to form mounds, craters, and turrets that do not easily dissipate. From the research, the structures are not just randomly accumulated soil but are rather products of structured excavation by the colony.

The National Library of Medicine reports another research that found mound-building ants normally build nests with round entrances and structured earth formations. The earth mounds have the same function as signatures for ant presence. In essence, if there is a hole dug out on the lawn with raised borders, chances are that ants are responsible rather than snakes.

Why snakes usually are not the builders

This difference is significant since snakes do not build their burrows with noticeable spoil rings. As shown by the study on Malayan kraits that appeared in Ecology and Evolution, snakes commonly live in burrows created by other animals, such as rodents. However, the snakes inhabit the burrows, they are usually not the diggers.

It explains why the experts in wildlife do not recommend making a generalization and assuming that all yard holes are "snake holes." As reported by reptile evolution studies featured in Biological Reviews, some reptiles are specialists when it comes to digging underground burrows. While some fossorial reptiles may create their burrows, many prefer using the preexisting underground cavities rather than leaving visible mounds.

So, a newly formed raised border suggests that ants created the hole.

How ants create the crater-like pattern

Behavioral stories emerge from the pattern itself. It is well known that ants dig and move the soil around collectively in order to build entrance structures. This has been reported by research published in Proceedings of the National Academy of Sciences, in that collectively digging ants arrange the soil neatly around their entrance instead of creating disorder. Eventually, the soil will end up forming symmetrical crater borders surrounding the hole.

Some older studies on grass-cutting ants report that certain types of ants create turrets, or chimneys, and mound structures built near the entrance of their nests. The structure formed depends largely on the kind of soil, but the common thing about all these is that they dig soil out from their holes and arrange it. The border made of the soil dug out from holes is often the first thing a homeowner can see when looking at their yard.

Ant mounds are more than dirt piles

The scientific community also acknowledges that ant hills are more than just transient dirt heaps. A study of harvester ant hill soils revealed that the soils found in the hills had different biological characteristics compared to soils located outside the hills, which included differences in nutrients and microorganisms. In another experiment, the researchers discovered that the soil in red wood ant hillscapes hosted higher earthworm densities than neighboring soil.

To put it simply, the boundary surrounding an ant hill may develop into a permanent habitat rather than just dirt scattered around the hill.

On the other hand, snakes generally look for cover and thermal stability. Snakes do not alter the composition of the soil to produce a defined mound boundary. Hence, a more organized hole with minimal surrounding soil would be more indicative of a reused burrow.

Why the edge is often more informative than the hole

Experts have repeatedly highlighted that there is no characteristic feature that can provide a complete diagnosis. Ant nests differ significantly, depending both on the type of ant and the composition of the soil. Some ants build impressive hills while others create subtle changes on the surface.

Nevertheless, the existence of a precisely defined and elevated border should be considered one of the most significant visual signs of excavation activity. Overall, this study teaches us that soil features can speak about the nature of the animal's activities beneath the surface. For example, ants excavate, transport, and build piles and hills while creating their nests. The snakes utilize natural openings created by other animals.

Therefore, when homeowners find an underground hole framed by an orderly pit or hill, it is better to assume that snakes have not moved into it. As the study results show, the chances are high that this phenomenon is related to the efforts of ants or other excavating species building their nests.

Perhaps, the next time someone spots an unexplained hole in the garden, he/she will need to pay attention not to the opening itself but to the border around it.