Crows can remember grievances for a long time and take revenge on their offenders.
Studies have shown that crows can hold a grudge against people for up to 17 years.
Professor John Marzluff from the University of Washington conducted an experiment to study the behavior of crows, writes the Daily Star .
In 2006, he captured several crows and then released them.
Soon after, he noticed that the crows began to react aggressively towards him.
The professor noted that crows can track people's actions and store negative associations.
He also encountered aggressive crows 47 out of 53 times 7 years after the experiment.
The birds continued to respond to him with hostile croaking.
The expert claims that crows are capable of harboring a grudge against people for up to 17 years.
They do not want to forget about the threats and react with hostility to their offenders.
