All countries have their own version of the Possum. New Zealand and Australia have the Brush tail possum and America has their Virginia possum. The Virginia possum is the only marsupial found in the United States. The saying “playing possum” comes from these small animals pretending to be dead when under threat from another source.
They have all become at ease in the backyards and gardens of suburbia in all the countries they are found. After discovering, a hole in the eaves of a house or garage makes a great shelter from the weather. They move in and take up residence very easily.
You know they are there, by the considerable noise they make moving around.
In order to eliminate this, when a new house is built, it is built to expect that there would be no possible entry for the possums.
When you already have a resident possum, you will be aware of their movements, so when you know they have gone out for the night. You may be able to see them leave if you have not found the point of entry. Another way is listening for where the loudest noises are in your roof and having a good look during the day for the exit.
Climb into the roof space with a flashlight and try to locate the animal while it is sleeping to ascertain the area that it is likely to be coming and going from, and follow the clues. Be aware that they can get into some very small holes.
When you have temporarily blocked the exit at night, you will need to effect a strong repair the next day. Possums can be very persistent and want to get back into their home.
Wash the exterior with something with a strong smell in order to eliminate the possum smell. It may be worth trying ammonia, camphor to distract the possums.
How did they get up into the roof? Are there trees that give them easy access? The obvious is to eliminate any means they have of reaching the hole in the building.
They can also reach a house by power lines. Place a meter band of metal around the pole in order to lessen their grip and stop them from climbing it to reach the lines.
Cut any tree branches that are close to the house and are a possible means of entry.
In Australia, they are a protected species so encouraging them not to eat your garden can be difficult. You may have to give them their own food. They do like apples and bread. Cover important plants with their own netting enclosure.
In New Zealand, they are hunted to eliminate them. It is unlikely they will ever be eradicated so we all have learn to live with them, as far as possible within the laws of the land.