I think it should be mentioned that crows (ravens/crows: Corvus genus) have been viewed as intelligent tricksters in literature worldwide, from ancient times. The oldest one I can think of is the Epic of Gilgamesh. In this story, a dove is send out to search for land, but it merely circle around the boat and returns. Then a raven/crow is released, but it doesn't return. The main character, Utnapishtim, concludes from this, that the raven has found land (and is smart and selfish enough to not return). A similar story can be found in the book of Genesis.
In norse and native american mythology, the raven is seen as a trickster too. In norse mythology, Loki, son of Odin, is the worst trickster of them all, and one of his tricks is to turn into a raven/crow.
In native american folklore, the raven is seen as a trickster as well. I remember a specific example in the mythology of the Nuxalk people from the Bella Coola area, where the raven is a no-good trickster. See the raven masks here:
The 6th one is a Bella Coola mask.
If I saw ravens/crows more than normal, then I would probably consider if someone was playing tricks on me. Just a thought :)