The subsequent liquid release will leave a mark as well as a pungent odour.
Possum or rat in roof.
Possums will only be on your roof regularly for three reasons they are living in your roof they are living on your roof or they are using your roof to get from a to b.
They may eat fruit and other human leftovers but tend to feed on native vegetation and are not found as often as rats are scavenging indoors and or ransacking stored foodstuffs.
I have seen possums eating ratsack and seen one that had a rat trap on it s leg and if you think they are noisy running through the roof you should hear them when a rat trap is attached to their foot.
A possum is a large animal and it has no qualms relieving itself in your roof.
Other tell tale signs that a possum is living in your roof can be stains on a ceiling or drip marks down your walls caused by urine.
The is generally two animals which make noises in your roof.
Their droppings tend to be scattered everywhere within a roof whereas possum droppings are usually found in small clusters often around their chosen sleeping place.
The leave your roof at night and come back before dawn.
Rats and mice constantly move around except when nesting.
The 2nd noise could be rats or mice.
Rats either way if you think there may be possums in the roof then every effort must be made to get them out before you try and deal with rats.
Possums do nest in roofs but are mainly active at night and although they are agile climbers are heavier than rats in their movements.
They normally scurry around both day and night.
If they are nesting on the insulation in the roof this can become damaged through constant urination and will require replacing.