Answer: Usually this begins by chance when a loose
piece of paper catches there attention, or sometimes, when they begin to scratch
as the wooden surrounds of doorways and accidentally tear the wallpaper as they
are doing so. Either way, they soon learn how much fun it can be, particularly
with the heavier or cloth-like papers.
If both cats are doing this, it is an indication that they have too little
to do and that there is too little stimulation in the home.
Try providing them access to outdoors if it is safe and they are old enough,
or provide climbing frames, shelving or tree branches on which they can climb
(make sure they are non-poisonous such as apple wood), dangling toys for them
to play with in strategic places.
Try to make more of an effort to play with them yourselves too.
Once they are getting more stimulation, you will need to break the habit of
tearing off the wallpaper. To do this, pull off all spare pieces of paper, place
a piece of furniture in front and position a scratching post close to the wall
next to the piece of furniture.
If you see them playing with the wallpaper, gently transfer them to their
scratching post or climbing frame, and praise them if they begin to scratch or
play.