TNR in urban areas such as ours (cold city) does not work all of the time and it's so complicated..
We have not seen the vaccum affect at all where jan has rescued 190+ cats from behind the West Lynn Creamery (she was on local news for this) or at the Porthole Resteraunt on the Lynn Harbor where boat owners were throwing cats with their litters overboard into the harbor, AND, buried some alive in the boat yard. No cats have returned to these areas.
I can't even to begin to remember all of the sickly cats that Jan has rescued, eyes falling out, eating dead sticks and leaves, dragging uterus on the ground, busted legs, infected mouths so they couldn't eat at all, and all were luek pos. The immune systems cannot stand even a "cold".
These guys literally starve to death, which, according to a Lithuanian friend of mine who witnessed starvation of jews, is THE most painful way to die.
There are other alternatives not mentioned in above posts!
Moosmom was correct in asking about the kittens. Even though the picture is old- why weren't they socialized then or when first discovered, "the day they were born".