Pretty straightforward. Capture a couple of swans coming in for landing against a cloudy overcast sky. Then convert to b&w. [simage=873,max,n,center,]
Not quite as straightforward. Find a great gray owl. Find one on a lone branch with nothing in the background. Find him while the sky is completely blue behind him. Get close enough to photograph him without spooking him. Make the shot. Then convert to b&w and use a red/orange filter to block all of the blue light, making the blue sky almost black.