Tumbleweed wrote:
[...]
how come a doubling of the sparrow hawk population over the same
period isnt mentioned as a potential contributory factor?
http://www.bto.org/birdtrends2004/wcrsparr.htm

or wouldnt that lead to any interesting & grant-funded research?

I don't know; but I think it's been conventional, and therefore
probably grant-funded or university-salaried, research which has led
to the conventional wisdom that predators are actually the vulnerable
ones in terms of numbers. I could be wrong, of course, but I think it
takes a certain population size of prey species to maintain a healthy
population of predators: below that critical size, the prey may be
viable, but the predators aren't. (The cat factor skews it all for
the suburbs, of course, just as the human factor skews it for the
sea.)

If TV coverage is anything to go by, there's never been any shortage
of research on predators -- sharks, crocs, killer whales, lions,
tigers, birds of prey, you name it. They're the glamorous species,
not the sparrows.

--
Mike.