Crows and their relatives engage in distinctive, sometimes eerie, reactions to encountering dead animals, particularly other members of their own species. For the first time we know which parts of the brain are responsible for this, the closest we have yet come to understanding their thinking, and perhaps the origins of our own responses to the deaths of others.
To find this out, Dr Kaeli Swift of the University of Washington injected crows with a radioactive sugar that gets drawn to the most active parts of the brain and showed them images of either dead crows or dead sparrows, and played them various sounds. She then anesthetized them and placed them in a PET scanner where the radioactive material indicates which parts of the brain have been most used since the injection. All the crows made full recoveries.
“In response to observations of a dead crow, crows show significant activity in areas associated with higher-order decision-making, but not in areas associated with social behaviors or fear learning,” Swift reports in Behavioural Brain Research.
On her blog, Swift explains the work. She starts by pointing out crows’ reactions to the deaths of their fellows is different from most other animals, and often very complex. “Crows don’t ignore their dead, they don’t reflexively flee from their dead and they don’t just go about carrying out undertaking behaviors without a second thought.”
Instead, on finding an unfamiliar dead crow, a live one might sound an alarm call, bringing a mob of others who make a lot of noise for 15-30 minutes before dispersing. On other occasions, that look identical to the human eye, the same crow will behave quite differently. We have no idea of the reasons for these varying reactions, but Swift has previously indicated she thinks the crows are using the death as an opportunity to learn about threats.
Swift’s investigation of the funerals performed by the far more intelligent crows began even earlier. She attracted some fame thanks to the extraordinary masks she wore so she could see crows’ reactions, and for revealing that when crows witness a person handling a dead crow they treat them as a threat for weeks afterwards.
Swift has in the past shown that crows do everything from shouting at deceased members of their species to engaging in necrophilia, sometimes collectively. Even more oddly, some of this behaviour is restricted to springtime.
If you’re puzzled as to why anyone would conduct positron emission tomography (PET) tests on birds to view their brains’ response to seeing death, we refer you to this. The haunting video of turkeys walking around a dead cat left millions asking, “What are they thinking?”
The scans Swift performed don’t explain the diversity of responses, but they do show that for the crows, the sight of a dead member of their species stimulates the part of the brain used in making complex decisions, rather than instinctive reactions. We don’t know what the crows are thinking, but at least we know they are thinking.