Why does a tomcat spray urine on the garden
wall?
Tom-cats mark their territories by squirting
a powerful jet of urine backwards on to vertical features of their
environment. They aim at walls, bushes, tree-stumps, fence-posts or
any landmark of a permanent kind. They are particularly attracted
to places where they or other cats have sprayed in the past, adding
their new odour to the traces of the old ones already clinging
there.
The urine of tomcats is notoriously strongly
scented, so much so that even the inefficient human nostrils can
detect it all too clearly. To the human nose it has a particularly
unpleasant stench and many people are driven to having toms
neutered in attempts to damp down this activity. Other cat odours
are almost undetectable by humans. The glands on the head, for
example, which are rubbed against objects to deposit another form
of feline scent-mark, produce an odour that is of great
significance to cats but goes completely unnoticed by the animals'
human owners.
Some authorities have claimed that the
squirted urine acts as a threat signal to rival cats. Hard evidence
is lacking, however, and many hours of patient field-observation
have never revealed any reactions to support this view. If the
odour left on the landmarks was truly threatening to other cats, it
should intimidate them when they sniff it.
They should recoil in fear and panic and
slink away. Their response is just the opposite. Instead of
withdrawing, they are positively attracted to the scent-marks and
sniff at them with great interest.
If they are not threatening, what do the
territorial scent-marks signify? What signals do they carry? The
answer is that they function rather as newspapers do for us. Each
morning we read our papers and keep up to date with what is going
on in the human world. Cats wander around their territories and, by
sniffing at the scent-marks, can learn all the news about the
comings and goings of the feline population.
They can check how long it has been since
their own last visit (by the degree of weakening of their own last
scent-spray) and they can read the odoursigns of who else has
passed by and sprayed, and how long ago.
Each spray also carries with it considerable
information about the emotional state and the individual identity
of the sprayer. When a cat decides to have another spray itself, it
is the feline equivalent of writing a letter to The Times,
publishing a poem, and leaving a calling card, all rolled into one
jet of urine.
It might be argued that the concept of
scent-signalling is far-fetched and that urine-spraying by cats is
simply their method of getting rid of waste products from the body
and that it has no other significance whatsoever. If a cat has a
full bladder it will spray; if it has an empty bladder it will not
spray. The facts contradict this. Careful observation shows that
cats perform regular spraying actions in a set routine, regardless
of the state of their bladder. If it happens to be full, then each
squirt is large. If it is nearly empty, then the urine is rationed
out. The number of squirts and the territorial areas which are
scent-marked remain the same, no matter how much or how little
liquid the cat has drunk. Indeed, if the cat has completely run out
of urine, it can be seen continuing its scent-marking routine,
laboriously visiting each scent-post, turning its back on it,
straining and quivering its tail, and then walking away. The act of
spraying has its own separate motivation, which is a clear
indication of its importance in feline social life.
Although it is not generally realized,
females and neutered cats of both sexes do spray jets of urine,
like tom-cats. The difference is that their actions are less
frequent and their scent far less pungent, so that we barely notice
it.