Our greatest effect on crows is on their survivorship, not on their reproduction…if an adult crow lives near people it is likely to survive, but if it lives more than three miles from people, it will likely die. Mortality over a two-year period was 2.3 percent near people and 38.9 percent far from people…Populations in remote wildlands are not likely to be self-sustaining…
If urban crow populations are simply self-sustaining, why are so many exploding in size? Immigration is the answer, we suggest…young crows are moving to the cities to exploit their riches.
That is from In the Company of Crows and Ravens, a fascinating book. Most of all this volume stresses how much crows have co-evolved with humankind.
The same day, Michael Vassar wrote me: "One problem I have with
Greg Clark’s thesis is that I don’t understand how a Malthusian Earth
could have left so much land forested and unproductive. If food was
the limiting factor in population why didn’t people clear more land for
farms?" And here’s Nick Szabo’s challenge to Greg Clark.