I would like to add some thoughts to the discussion. I think that
sometimes WE tend to look at the MICRO view of our world, and forget that
the world is a much larger place. Assuming that there is a relatively
stable bird population several factors would have effect on a local general
population. These include more people feeding and gardening to attract
hummingbirds. Result hummingbirds spread out along the migration route and
in a local area. It appears that those who watch the migration further
south did not notice any such decline in numbers. It is OK to ask the
question, but I think that the trend is to try to place the finger of blame
on development, environmental catastrophies, the weather; without thinking
about the other possible factors that can affect the equation.
Scott