Time for some more horizontality:
Click on that to get the 1000×750 original bigger picture, which I found here.
Notice the title of the posting. Hartley really is fascinated by colour, whether present, as here (in the sky), or absent, as is the case for the black and white birds here.
Interesting that stripping out the context, which makes it that bit clearer that these are birds, makes these birds that little bit harder to see clearly, as birds.