I blogged about Aquileia a couple of weeks back.
When Attila and the Huns tried to take the city in 452, it was a long entrenchment on both sides, though Aquileia eventually fell. At dawn one day, so the story went, Attila saw a stork leaving the city with its young. He took this avian departure as a sign that he was going to capture the city.
The story, originally in Procopius' History of the Wars is an image that was much used by medieval scribes and appears in numerous manuscripts.
Here is an example from the Basel printing of Sebastian Münster’s Cosmographia from 1561. As always, click to enlarge.