Crow

The Crow is a creature first appears in Luigi's Mansion, and also reappears in Luigi's Mansion 2 as an enemy.

Luigi's Mansion
The crows in Luigi's Mansion are black with white eyes, and sound more like ducks than real crows. The crows only appear in the opening scene of the game, and do not harm Luigi.

Luigi's Mansion 2
The crows in Luigi's Mansion 2 are purple with white eyes, but have the noise that actual crows make.

They appear as ambient enemies or hazards and will actively fly towards Luigi and deal 5 HP of damage, fly away, then return and attack again and they will repeat this until they fly away for real of until they are defeated. They can be defeated by blinding them with the Strobulb or by rudely sucking them up into the Poltergust 5000.

Trivia

 * Crows in Paper Mario: The Thousand Year Door mention the game Luigi's Mansion if the player hides from them while using Vivian.