albert wrote:I imagine that bird wings are concave on the bottom of the wing and that , that might make a forward pulling vacume to create the negative drag???
The wing shape you describe (concave on the bottom) is called an "undercambered" wing and this shape creates a lot of lift but also creates a lot of drag. In fact when airliners land they extend slats on the front of the wing and flaps on the back which change the shape of the underside of the wing to increase it's camber (makes it concave in shape). This is pretty important because it allows the airplane to have more lift at lower speeds safe for landing, while at the same time creating drag to slow the airplane down.
Several of my RC airplanes have undercambered wings which can lift a great deal of weight but not at any great speeds because of their drag.
So for jetliners, during take-off they extend slats and flaps slightly to create more lift, but not to the same degree as in landing. And soon after takeoff, once the landing gear are retracted, the slats and flaps are retracted as well to make the underside of the wing clean (that's the actual technical term) and reduce drag. Since the aircraft is already going fast by this point, the lift produced by the clean wing is enough to carry the airplane to full altitude. And of course at altitude the drag is reduced considerably because the air is thinner.
Oh and the reason undercambered wings create more drag is because the downward underside of the trailing edge causes the air mass to curl under and forward a bit. And Newton's third law tells us since the wing is causing the air mass to be pushed forward ever so slightly, this pushes back on the plane. Hence the drag that must be overcome.
If you want to explore quite a deep question, you can ask, how is lift created. And as long as you don't hold to the equal transit idea you'll be fine.