Why do crows gather around their departed avian brothers and sisters? This was the morbidly fascinating scientific question that was occupying the mind of Kaeli Swift, a Ph.D. student in environmental science at the University of Washington. After extensive research – perhaps using the most inventively sinister experiment in recent memory – she reached an answer. When crows gather around a dead crow, they are actually trying to work out if it died due to a threat in the area. The new study published in the journal Animal Behaviour only serves to underline how cunning a murder of crows can be.
Crows are incredibly intelligent birds. The entire cosmopolitan Corvidae family is considered to be among the smartest of all animals, in fact. They are excellent problem solvers, they are capable of crafting and using their own tools, and they have complex social structures. A study in 2013 revealed that a region of the crow brain comparable to the human prefrontal cortex – the region of the brain where higher thinking takes place – was largely responsible for this high level of intelligence.
Swift naturally wondered how emotionally intelligent an entire murder of crows could be when it came to the notoriously tricky subject of death. Over the course of a two-year experiment, and across more than 100 sites in Washington State, she left food for nesting American crows. Before allowing them to feed, however, she asked 25 human volunteers – who were often interchanged – to wear masks to obscure their facial expressions and stand near the food.
This constantly changing, masked cast meant that the crows could not remember the behavior of specific individuals, with each one representing a new potential threat each time. Crows have an advanced hippocampus – the part of the brain responsible for memory – and can remember a wide range of individuals, both threatening and non-threatening. If they remember a threat, they will likely not forget it if it pops back into their neighborhood.
Now this is where it gets fabulously creepy – if the disturbing masks weren’t already creepy enough. The volunteers were asked to then hold a dead, taxidermied bird, either a crow, pigeon, red-tailed hawk – a predator of crows – or sometimes, a crow while standing next to a red-tailed hawk. As a control, some subjects were instructed to stand there without a dead beast in their hands. Some lucky crows were also allowed to feast on their food without any creepy human or death distractions around.
Whenever a deceased bird was being wielded by a masked man or woman, the crows almost always began to cry out to other crows, essentially putting out an alert that a threat was in the area – this process is known as “scolding.” As you might expect, the hawk-crow combination generated the most intense scolding.
Crows also have far more concern for their own species than they do for their avian cousins. The masked people holding a dead pigeon provoked a less panicked, less vocal form of scolding. So much for setting up a neighborhood watch, then.
As soon as a murder of crows connected the masked humans with any form of dead crow – and particularly when a hawk was standing nearby – the associated human is then considered to be a threat for up to six weeks, even without the dead crow in their hands.
So there you have it: crows learn from deaths within their murder.