From Alley Cat Allies website ay
http://www.alleycat.org/NetCommunity/Page.aspx?pid=402
What’s Best for Cats: Being Alive or Dead?
Many animal control pounds and shelters operate on the notion that if a cat can’t live in a human home, it’s best to kill her. They use individual anecdotes of sick and abused stray cats to extrapolate that millions of these animals are better off dead than alive. But research shows otherwise. The bottom line is: being killed is not in cats’ best interests.
• Veterinary studies show that stray cats’ incidence of trauma and disease is low, and their infection rate—4%—is the same or lower than in house cats.
• Evolutionary research shows that the natural habitat of cats is outdoors in close proximity to humans. The species Felis catus came into existence 8,000 to 10,000 years ago when humans shifted from hunting and gathering to farming. Initially attracted by grain stores with plentiful rodent populations, cats have been living side by side with humans ever since.
• A recent national public opinion poll shows that 81% of Americans believe it is more humane to leave a stray cat outside to live out her life than to have her caught and killed.
Intentionally killing a cat is a criminal offense in all 50 states and the District of Columbia, regardless of ownership. Anti-cruelty laws apply to all cats—companion, abandoned, lost, and feral.