Mass isn't great either, due to scaling laws. Physics simply behaves differently at different scales.
An ant can lift a hundred times its body weight, but if you scale it up to human size it collapses under its own weight and immediately dies.
You can drop an injection moulded plastic toy car a hundred times its height into the ground and it won't even dent. If you make a car frame out of the same materials and with the same techniques it will likely fall apart before it's off the conveyor belt.
If you make a scale model of a planetary, you'll struggle getting it to start spinning around its center of mass through gravitational forces.
This is true, but irrelevant here. The bird is moving much less mass, so it takes less energy per mile traveled. I was trying to point out that if you normalize the energy consumption of a Tesla by the mass it is moving, you get a much more favorable (and sensible) comparison.
An ant can lift a hundred times its body weight, but if you scale it up to human size it collapses under its own weight and immediately dies.
You can drop an injection moulded plastic toy car a hundred times its height into the ground and it won't even dent. If you make a car frame out of the same materials and with the same techniques it will likely fall apart before it's off the conveyor belt.
If you make a scale model of a planetary, you'll struggle getting it to start spinning around its center of mass through gravitational forces.