Five A.M., sound asleep, and suddenly all Hell breaks loose,
cats screaming hysterically!  I was halfway to the source of
the racket before I'd even opened my eyes.  There were my
two girls, tails bushed to full capacity, confronting a
strange cat through the patio door!  This really surprised
me, because I had no idea they could display that kind of
aggression!  When I acquired Cendrillon, she and Melisande
accepted each other with only cautious avoidance for the
first day or two - no screams, no hisses, not even a warning
growl between them.

I live in a very large apartment complex (over 100
buildings, 1220 units).  The terms of our leases require
people to keep their pets confined, but of course not
everyone complies.  The patio walls are only four or five
feet high - you can put a dog out there and it stays
(although it may bark all day and night) - cats don't even
regard a wall that high as a challenge!  Unfortunately,
however, I think most of the wandering cats on the property
are "throw aways" - people move out (or get tired of the
responsiblilty) and just leave them to fend for themselves.
 There are decorative pools and waterfalls to drink from
all over the spacious grounds, plenty of nooks and crannies
for creatures their size to find shade or shelter, and lots
of birds and small prey to hunt.... A cat on its own could
do a lot worse, so I'm sure we have quite a sizeable colony
of ferals.

Those I occasionally catch sight of appear reasonably
well-fed, so either hunting is very good, or some of the
tenants put food out for them.  (Or they have homes, but are
allowed outside, despite the rules.)  Occasionally I've seen
an Animal Control truck on the premises, but these cats are
pretty wary of being approached, so I doubt they are often
successfully captured.  Judging from the episodes I've seen
on Animal Planet, Phoenix has a fairly enlightened humane
society - I'm not sure how they deal with colonies of feral
cats on private property, but hopefully the strays that get
picked up are the lucky ones.