Initially this was supposed to be an evening scene shoot with some glowing sunset colours.
However, it partially turned out to be something to do with birds.
When I got home and uploaded my shots on to the mac, I noticed that I had shot more than I originally planned. In this first image below, if you examine the top left quarter and middle left area of the image you can just make out some small dark spots. They are not dust spots on the sensor of the camera, but migrating birds flying South. I had observed some whilst out there, but didn't appreciate I would get any in the frame. Many species migrate at night and often together. I read somewhere that they prefer clear skies for navigation purposes.
In this second image below you can see in the centre, the profile of a light aircraft. If you look to the left of that aircraft you will notice a line of birds spreading nearly all the way across the image.
Anyway here are some more images below that I shot that evening as intended.