From: altar@beaufort.sfu.ca (Ted Wayn Altar)
Subject: Vegetarian Cats2: Environmental Cost?
Organization: Simon Fraser University, Burnaby, B.C., Canada
Date: Mon, 28 Dec 1992 18:20:21 GMT


C.  THE ENVIRONMENTAL IMPACT OF CATS (are our pets also pests?)

Should we have laws to ensure owners stop their cats from killing
their prey?  This seems too absurd to entertain, but you know how
fussy people can be.  Here I can do no better than do as May
(1988) suggested, namely that we consider the words of Adlai
Stevenson when he was Governor to the Illinois State Legislature:

     "The problem of the cat vs the bird is as old as time.  If
     we attempt to resolve it by legislation, who knows but what
     we may be called upon to take sides as well in the age-old
     problems of dog vs cat, bird vs bird, or even bird vs worm.
     In my opinion, the State of Illinois and its local governing
     bodies already has enough to do without trying to control
     for feline delinquency"
          (May (1988).  Control of feline delinquency.
              NATURE, 332:392-3.)

What about the environmental impact, you might ask?  Well, it
turns out that the actual environmental impact upon, say the bird
population, has been documented to be minimal or nonexistent.

In one study it was found that House Sparrows formed about 44% of
the birds killed by cats (Churcher & Lawton, 1987).  There is in
fact an overpopulation of urban and suburban House Sparrows and
Starlings.   Now, to be fair to our cats it should be kept in
mind that for small urban wildlife cats are probably substitutes
for other predators and other mortality factors.  For instance,
they may substitute for Weasels, which in woodlands kill up to
2/3 of the young tits (Perrins, 1979).  We should also remember
that adult urban House Sparrows, for instance, have an annual
survival rate of only 56%-62% and cats are not the major cause of
death (Summers-Smith, 1963).  Robins, which my cat seems not able
to catch, have a 60% adult annual mortality, food shortage being
the key factor.  The annual mortality of Starlings is over 50%
(Freare, 1984).  Yes, it is true (except for my congenitally
runty cat) that cats are a major cause of mortality of Starlings
in towns, but this is probably a desirable result.

People who have serious studied this question about the impact of
cats upon wildlife have generally concluded:

     "Cats have little or no long-term impact on urban wildlife.
     They may transmit disease, toxoplasmosis is the most
     devastating and rabies the most potentially serious, but
     overall incidence is slight.  Feral Cats may become local
     nuisances; their control may be best effected by a programme
     of castration.  Cats provide many benefits as pets, and
     retain some value in controlling rodent pests.  The pest
     status of any animal depends on its activities and numbers,
     but whether pest status has been achieved is often a matter
     of perception.  On balance, I do not consider that the case
     for the urban cat as a serious pest rather than a pet has
     been satisfactory made."
         (Jarvis, 1990)

					Happy Vegetarian New Year,
						ted

Newsgroups: rec.food.veg