1578: Rain of 'Big Yellow Mice' (aka Lemmings?)
In 1578, in the area of Bergen, Norway, 'big yellow mice' rained down and swam ashore when they fell in water. Another such fall occurred in the autumn of the next year. It was theorized in 1957 that this story explained where lemmings came from.
This account is given in an article by Leonard W. Wing on lemmings in the Journal of Cycle Research, 1957; but the author doesn't tell us where he got the account from. Wing only presents it as an example of how folklore and folk tales have gotten mixed with the history of lemmings, and there is very little reason to think he believes this tale describes any sort of actual event. I have been unable to track an earlier account of the story.