Why do birds usually take flight against the wind?

The experts we contacted point out that, birds wings are structured like an airfoil and work best with air flowing from front to back. Feathers are arranged to overlap like shingles to aid in smooth air flow--taking off with the wind ruffling up the feathers from behind creates a lot of useless turbulence.
Also, birds with disporportionately heavy bodies for the size of their wings would probably take off against the wind more consistently--they can use all the lift they can get.
http://www.earthlife.net/birds/flight.html