I don't know about physical environmental changes, but in Avon
a project to encourage Barn Owls which live primarily off field voles
and mice, and which have been declining drastically over the last 50
years (beautiful white cream and gold owls) met with startling success
when buffer strips were used along hedges, river-banks and ditches.
The corridors that were provided were essential for the owls to reach
new hunting grounds, and the Owls are now successfully breeding in the
Bristol ( a city of some 300,000).
Buffer strips of long grass have also been successfully used in agricultural
systems using no pesticides or weedkillers, where natural predators can build
up populations in the buffer strips, and forage in the field strips. Back to
the mediaeval systems of farming(!)