Anger and memories of the reasons why you feel anger are age-old traits. Once we think that someone has trampled over us in bad ways, we can – and often do – kick into a grudge state. With that, a long period of remembering the event that causes one to remain angry and unforgiving about a wrong gets burned into some of us. Even as we age, if we hold onto such grudges, we can pass them on for others to carry the torch for far longer. It turns out, we’re not the only species with a long memory for wrongs. Crows have been recognized as serious grudge holders and can remember wrongdoing for as long as 17 years.

Crows are found throughout the world and are represented by many species of the Corvidae family. Crows are well-known for their extraordinary intelligence. Crows are considered by the scientific community to be as smart as a 7-year-old child. That’s impressive. They can reason in abstract ways, make and use tools to perform tasks, make decisions that impact not only them but others around them, count, and cooperate socially to help create a societal community. And they have long memory retention.

Crows Never Forget

If a crow is angered or otherwise inconvenienced, chances are strong that the crow in question may not forget it. Once a crow attaches a negative reaction to someone or something, it’s going to become a long-standing problem. This behavior among crows has been studied, and the reality is, don’t make one mad.

John Marzluff, professor emeritus at the University of Washington in Seattle, launched a study to explore how crows display and retain grudges. In 2006, Marzluff captured a group of crows from various sites while wearing different masks (ogre, caveman, etc). His team used a net to capture the crows, and, as masked aggressors, the team caged the crows while allowing the free crows the opportunity to watch. The free crows associated the trapping and caging with the masks. The captured birds were banded and then released. For years after, these crows expressed anger and caution when spotting these masks. To show that it wasn’t the masks, the researchers also wore masks not associated with the captures, all with no ill impact. It was the remembered masks that the crows associated their discomfort with.

After three years, the unhappy, grudge-holding crows had grown to a sizeable number, indicating that the original crows had passed their anger and caution on to others, even to fledglings. To test the longevity of the memory, Professor Marzluff left them alone for a year. After the year, Marzluff donned an offending mask, and the crows immediately went on the defensive, using angry vocal caws to express their concern. This proved to Professor Marzluff that the crows did not forget the incident.

Crows can aggressively and collectively mob and dive-bomb their enemies. They have long been known to mob and attack hawks to keep them away. Now, researchers are studying to determine what happens to crows neurologically when they recognize something associated with a long-held grudge or other dangers. So…don’t make any crows mad. They won’t soon forget it.

What about parrots? Do you think parrots hold grudges, too? Have you ever noticed your bird staying a little salty after something they didn’t like? Do share in the comments!