The way I use the meter (other methods are available):
It doesn't matter what mode you use, you need to understand what you're measuring. The meter sees an average of 18% reflectance. If you point it at a black wall it sees mid grey, if you point it at a white wall it sees mid grey.
So you need to either, set the meter on mid grey, or use exp compensation to make your subject correctly exposed. So use 1 - 2 stops + compensation when measuring the sky, or use a spot meter on your bird and try to adjust comp to suit. To me that's a harder one, but some people do choose that method.