Crow

The sacred animal of Death, they are a very complicated omen to see.
Most interpret their presence as Death watching over you. However, that has wildly different connotations for different people. On one hand, perhaps she is watching you to protect you from meeting her too soon, telling you to be cautious and careful. On the other hand, perhaps she is telling you that she is coming for either you or someone in your circle.
To kill a crow for any reason aside from necessity is believed to bring Death's wrath in quick succession, as the crow's spirit will fly twice as swiftly as it could in life, to either her or her twin flame, lord of the wildlife, The Blood God.