Toads are very secretive creatures. They are most active in the dark and twilight hours, and when inactive, many toads have a habit of burying themselves in dirt.
Toads bury themselves in the dirt for several reasons, including cooling off from the heat, hiding from predators, hibernating, and ambushing prey.
Many species of toads have hardened knobs on their back legs which they use to dig themselves backwards down into the ground.
That said, it’s important to note that not all toads bury themselves in dirt.
Rather than burying themselves in the dirt, some toads choose to hide under rocks, logs, natural holes, or abandoned small mammal burrows.
Toads Bury Themselves to Escape the Heat or Cold
Toads are ectothermic or “cold-blooded” animals. This means that toads cannot generate their own body heat, so their body temperatures are close to the temperature of their environment.
In other words, their environment is the main influence on their body temperature.
This is in contrast to endothermic (warm-blooded) animals, like humans whose bodies can generate their own internal heat through their metabolism.
Due to being cold-blooded, toads are very vulnerable to temperature extremes.
If the temperature rises above a certain point, a toad can overheat and be killed or injured.
On the opposite end, If the temperatures drop too low, a toad can be harmed.
For this reason, many toads bury themselves in soft soil or mulch to escape extreme temperatures and only emerge when the conditions are more favorable.
While buried, toads rely on cutaneous respiration to breathe, and can even change their body positions to adjust heat exchange via conduction and radiation.
Toads Bury Themselves to Hide From Predators
Toads are fairly small creatures and are preyed on by many animals, such as birds, snakes, certain, small mammals, fish, and even large spiders.
For this reason, toads have developed many ways to defend themselves against predators.
Depending on the species, toads may rely on camouflage, toxic skin secretions, mimicry, and other tactics to ward off predators.
Many toads may also bury themselves in soft soil to go unnoticed by predators.
Toads Bury Themselves to Ambush Prey
Toads are generally not fast-moving creatures. This means they can not actively chase after prey as some other predators do. Instead, they wait for the prey to come to them, by using a passive ‘sit and wait’ hunting strategy.
This is an ambush-style technique where the toad hides in shady areas or burrows slightly in the mud and then pounce on any prey that passes by.
Toads have sticky tongues that allow them to catch any moving insect that comes into range quickly.
Once a toad spots an insect, it launches its tongue to catch the prey. After catching the prey, the tongue wraps around it and coats it with sticky saliva.
The toad will then yank its tongue back with a force equal to twelve times greater than the force of gravity.
Once the insect is in the mouth, the toad will swallow it whole.
A toad can shoot out its tongue, capture an insect, and pull it back into its mouth within 07 seconds; which is five times faster than the human eye can blink. This speed makes it effective at catching even fast-flying insects such as flies.
Toads Bury Themselves to Hibernate
During the winter, toads in cold regions hibernate to protect themselves from freezing temperatures.
Many toads will hibernate underground, where the frost does not penetrate.
This could be in natural holes or abandoned mammal burrows that are deep enough that the frost does not penetrate all the way to the bottom.
However, some toads will dig their own hibernacula (hibernating space).
They use their back legs to ‘knead’ their bodies into the soil, submerging themselves completely until they are below the frost line.
Toads will die if they freeze, so they need to stay below the frost line all winter.
How deep they dig varies from year to year depending on the temperatures and snow cover.
For example, many toads will burrow anywhere from 6 inches to over 3 feet deep; they tend to stay a couple of inches of the frost line and will move up and down throughout the winter as the frost line changes.
Toads Bury Themselves to Escape Arid Conditions
Frogs and toads have thin membranous skin that they use to breathe and absorb water.
Due to their permeable skin, toads are very prone to water loss from the skin, particularly in arid conditions.
During dry periods, some toads will bury themselves to reduce water loss.
Once buried toads may estivate as they wait for the rain to come and the temperatures to drop.
Some toad species even form a cocoon of dead skin cells around their bodies to limit water loss.
Conclusion
Most toads will spend some of their underground. This could be in natural holes or abandoned mammal burrows.
Some toads will also burrow into soft soil, and bury themselves.
While buried, toads meet their oxygen needs by absorbing oxygen from the surrounding soil via the skin (cutaneous respiration).
Sources:
Reynolds SJ, Christian KA, Tracy CR. The cocoon of the fossorial frog Cyclorana australis functions primarily as a barrier to water exchange with the substrate. Physiol Biochem Zool. 2010 Sep-Oct;83(5):877-84. doi: 10.1086/656218. PMID: 20687829.