"Lawrence" writes:

On Feb 19, 10:26 am, Dan Espen dan
The number of birds in an area is directly related to the amount of
food and shelter. In areas where there is shelter but not enough
food, a feeder will increase the bird population and when the feeding
is stopped, the birds have to starve.

Yes populations are directly related to the resources available. That
is NATURAL RESOURCES, not feeders. Natural sources of food and
shelter are far, far in excess of that provided with birdhouses and
feeders. Birds have adapted for thousands of years to these
natural resources and are genetically programmed to seek them. It is
these natural resources that dominate the birds feeding and
reproduction.

Studies of banded birds

I'm not finding these studies.

Any suggestion on keywords or even a link?

Ok, I tried adding "banded" and hit these:

http://www.birdwatching.com/tips/birdfeedingwinter.html

http://www.hiltonpond.org/ThisWeek030101.html

Neither is a study.
I remain unconvinced.

A large, unlimited supply of food is unlike anything else
in these birds environment.