Rats typically burrow down about 18 inches to nest (if they can't find an indoor home), but they are capable of digging much deeper if a foundation is in the way and they think food is on the other side. Predator pee probably isn't going to stop them. But your mention of steel wool and concrete is on the right track.
Spicy, powdered pepper of any variety is an excellent rodent deterrent to consider. You can apply pepper near the rim of the hole and even inside of the hole, which will send any nesting rodents fleeing, so be aware of this! This is an excellent method to use against a large rat infestation as well.
Rat Holes. Rats leave dirt, waste and grease in their paths. They are also capable of chewing through wood and concrete. Rat holes are both unsightly and dangerous; not only do they allow entry to a variety of other pests, but they also can lead to short-circuit fires if the rats gnaw on electrical wires..
To identify a rat hole, look for a hole with rough edges or a uniform shape, as well as small tracks around the hole. Rat holes can also be identified by the presence of rat droppings near the entrance. To confirm that a rat hole is active, look for signs of fresh dirt or sawdust outside the entrance.
Rats are creatures of habit. Once they're set up, they prefer to keep to the same given paths to get around your garden. Look for burrows and greasy stains along things like the tops of fences and garden beds-these are rat “highways”.
Seal any holes you find to stop rodents from entering. Fill small holes with steel wool. Put caulk around the steel wool to keep it in place or use spray foam. Use lath screen or lath metal, cement, hardware cloth, or metal sheeting to fix larger holes.
Digging mammals—such as bettongs, potoroos, bilbies and bandicoots—were once abundant and widespread across Australia, turning over large amounts of soil every night with their strong front legs as they dig for food or create burrows for shelter.
It is better not to spray bleach at rat exits or entry points. Rats are stubborn enough to find another way in and will do even more damage to your property. Bleach can be considered a viable solution. Yet, it cannot be a permanent one.
If they aren't coming around during the day, where are they hiding? Rats prefer to hide in places that are tucked out of the way and that aren't often disturbed. Outdoors they will hide under piles of debris, under trash piles, in dumpsters and trash cans, in trees, and in sewers.
While rats might leave a nest temporarily if disturbed, they will likely only nest somewhere else close by, no doubt creating multiple nests that exacerbate the issue. On top of that, there's also a risk that they will return to the same space if you haven't properly dealt with the nest.
RATS AND MICE ARE AGILE MAMMALS. A mouse can get through a small, 6-7 mm hole (about the diameter of a normal-sized pen) and a rat can get through a 20 mm hole.
Steel wool is a great way to block the small holes pests use to enter your home. First off, steel wool is tough but flexible; it can be pushed into all shapes and sizes of cracks and crevices. Pests like rats and mice hate chewing through steel wool, since the sharp edges hurt them the more they try to chew.
By filling up the burrows and sealing up the entrances, you can discourage rats from living near your property. Not only does this destroy their home, filling a burrows disrupts the rats' daily routine—something rats hate. Such a disruption often causes them to leave and find new areas to make their nest.
When there are no animals in the nest, fill it with concrete or sand. If possible, locate the main entry hole and all of the exit holes and pack them full. You can pack steel wool or hardware mesh that rats can not chew through into the hole as well. Be sure all the rats are out of the burrow.
Essential oils are some of the best natural rat repellents. Rats have a highly developed sense of smell, which makes strong odors such as pine oil, cinnamon oil, and even peppermint oil offensive to them. Cayenne pepper, cloves, and a mixture of vinegar and ammonia will keep rats away as well.
Rats and mice are nocturnal with most activity taking place between approximately one half hour after sunset to about one half hour before sunrise.
Failing to report a rat infestation is not wise – they do not disappear of their own accord and they will likely spread.
Rats are nocturnal which means they're most active at night and during dawn and dusk. What's more, even though they can be brazen at times, they will generally do everything they can to avoid human contact. Typically, they will wait until it's very quiet before venturing out.
Baking soda combines with the stomach acids to produce carbon dioxide gas which rats are unable to tolerate. In turn, it builds up within their system and eventually causes internal blockage and rupture. Soon enough, you will have the rat-free environment you always deserved.
Peppermint Oil
On a cotton ball use no more than 5 drops of 100% peppermint essential oil. Spread the oil on areas that you want rats to avoid, in your case, around the garden.
Rats cannot survive with more than 70 to 75 grams (0.16 lbs) of salt in their bodies. Any additional amount of salt can cause severe neurological problems such as muscle paralysis, deafness, blindness, and overall weakness. This is in addition to ailments like gastroenteritis and general inflammation of the system.
Generally, holes in your lawn can be caused by animals like gophers, moles, voles, rats, or pest insects such as ground wasps. Burrows can be of various sizes – small holes for insects and larger holes for rodents. In addressing the issue, it isn't enough to fill the hole and hope it doesn't return, because it will.
Possums mainly dig holes to find food. Contrary to what some may think, they don't usually dig burrows for themselves. A hole in the yard is not proof positive that a possum is in the area.
Okay, now: Did 'a-possums' make those holes? Probably not. These creatures are mostly arboreal and prefer to live in trees; hanging out on the limbs of the trees in the summer and inside holes and cavities in the winter. But they will use burrows that other creatures have dug in the ground.