It's a little known fact that in WWII there was a secret programme, in which my Dad was involved as a pilot, which tried to exploit pigeons' navigational skills to assist bombers returning to England with either the navigator or his equipment, or both, out of action.
In essence, the trials involved carrying a pigeon and 50m of light but strong string. If lost, the pilot would slow to just above the stall, and launch the pigeon through the DV window, with the string attached to one leg and an eyebolt under the DV window. All that the pilot had to do then was to follow the pigeon until he was visual with the FIDO flarepath (usually Woodbridge) that the pigeon was trained to home to.
The relevance to the thread is that the pigeons proved themselves capable of flying and navigating in cloud, at night.
(The experiment failed, however, when it was found that the pigeons tired very quickly when flying at the stall speed +5Kt of a Lancaster, in order not to be overtaken or run down by it. They were then trained to walk about on the top of the panel, pointing at the FIDO airfield. But since they were not airborne, in the purest sense of the word, they quickly lost interest and went to sleep, so the whole scheme was abandoned in late 1944.)