I like what Rivka has to say on this subject. Rivka makes good sense.
I also like the progression of our conversation from fruit stealing
squirrels to 'junk yard cats' to cats preying on birds to (now) cats filling
the niche of critters that used to prey on birds.
Many areas with a lot of free-roaming cats no longer have most of the
original predators who preyed on birds in that area. I don't know if
anyone has ever done studies correcting for this factor, to try to
determine whether the bird mortality rate from cats is higher than a
natural background rate with no cats, but with other bird predators in
the area.
--Rivka
Finger Lakes NY; zone 5 mostly
[NAFEX] Fruit>squirrels>cats> bird predation,
Jim Fruth, 02/15/2007