Hello aj,
Cats dislike Rue (Ruta graveolens), and Coleus canina which is now sold as a
deterrent against cats and rabbits. The latter is not hardy, but may be
replaced by cuttings. Thompson & Morgan sell young plants in cells: 6 for
£7.99; 12 for £12.99; 24 for 17.99.
Prickly plants would also be a deterrent.
I happen to have a loveable rogue of a cat called Cougar, so do not go along
with the shooting/maiming lobby. However, a cat-friendly diversion may
help; for example an aesthetically pleasing (to humans!) post, sprayed or
underplanted with catnip would relieve pressure on your tree. (It would
also help to wash down the trunk of the tree so that it's odour was more
neutral to your visitors).
The siting of this post is crucial. Cats use prominent structures, like
your tree, as landmarks. They are signed (tiddled on) by cats and read by
them almost like we use calling cards and newspapers. Therefore, you will
need to use a little cat psychology when surveying the site for this
instalment.
Although cats do have some unpleasant habits, they do deter mice, squirrels
and birds from stealing our bulbs, tree fruits, etc.
Regards,
Spider

aj wrote in message ...
my neighbour has 7 cats (seven) & my birch tree which stands about 12 feet
tall is scarred from top to bottom with them using it as a scratching
post,will this cause permanent damage & is there anything i can do to stop
them damaging it?
thanks.