Well, we are trying to reduce the other numbers. 10 million in the US is still a big number. We are 4% of the world population. As per capita energy use increases throughout the world, we're going to generate a lot more clean energy.

http://world.bymap.org/ElectricityProduction.html

Is there a reason we need to kill tens of millions of additional birds every year so we can have "clean" energy?

10 million in the US is not a big number, relative to other sources of bird deaths. As long as it's insignificant, you'll have a hard time convincing people that it's significant, and should stand in the way of saving the planet.