A crow funeral can happen at any time. Farmers bear witness after shooting unwanted crows in their fields. Powerline workers see them should an unlucky bird zap itself and drop. Occasionally, the funerals occur in a city park. All it takes is one dead American crow plus one fellow crow to spot it and release an alert, harsh and urgent — Caw! Caw! Within moments, a mob of crows arrives. Sometimes it’s only a handful, other times up to 60 or 70 birds settle onto branches or whatever aerial perch allows good viewing of the corpse and the surrounding scene.
For a short time, the birds remain quiet and still, only to break into a chorus of shrill calls. Back and forth, silence and aggravation for about 15 to 20 minutes until nearly all at once the ink-black birds launch and disperse, leaving branches to quiver.
Crow populations have ballooned in many urban areas including the Bay Area in the last 40 years. Annual bird counts conducted by the Golden Gate Audubon Society used to turn up a couple dozen crows in the 1980s. In 2018, the count estimated 2,500 crows in the Oakland skies and 900 in San Francisco. It’s common to see the birds exploiting the habitat we’ve created, like picking through food in a Berkeley dumpster or congregating at a large community garden near the Albany Bulb or enjoying the twilight near Lake Merritt. Crow funerals, though, that’s a rare sight.
Kaeli Swift, an avian behavioral ecologist, has watched hundreds of them. About seven years ago, as a graduate student at the University of Washington, Swift started manufacturing the events. With a taxidermied crow in her backpack, and a clipboard for notetaking, she set out to find out if the birds internalized a dead crow as a danger cue. Perhaps, she thought, the funerals functioned as a mass gathering of evidence, the attending crows seeking out clues for what killed the ill-fated bird before them.
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That wasn’t Swift’s only quest. She’s drawn to comparative thanatology, a relatively new area of science that navigates how non-human species respond to death, and how it may parallel or even help explain the human experience. “We are definitely in this period of time where it has become accepted and really exciting within the wildlife scientific community to really break down what have been rigorous barriers between ourselves and animals,” Swift says. “One of the ways we’re seeing that manifest is paying more and more attention to how non-human animals attend to their dead.”
Our human response to death started somewhere, Swift says. Early hominids — the taxonomic family of primates that includes Homo sapiens — devised simple rituals for their dead for some reason. “Animals might provide a window into understanding,” she says.
Both scripture and folklore connect corvids, the family that includes crows, ravens and jays, to human life and death. God sent a raven to instruct Cain how to bury his brother, Abel. A group of crows is known as a “murder,” a label dating back to medieval times when crows feasted on slain soldiers lying in battlefields. In some North American indigenous cultural traditions ravens facilitate the origin of human life.
Swift recognizes that linking crows to humans might sound like a stretch. The American crow is evolutionarily leaps and bounds away from people. How could we learn about us from them? There are similarities, though. Like humans, they’re very social creatures. Crows roost in large groups and choose a mate for life.
Crows also exist in community much like mammals do. “We live in a so-called fission-fusion society,” Swift says. “There are groups that come together, we interact, we go our separate ways for a little while then we come back. We’re constantly seeing people, saying goodbye and then seeing them again and there’s a lot to track there cognitively.”
Such complex thinking comes naturally to crows. While their brain measures about the size of a human thumb, relative to body size corvid brains are more in line with a mammal, even a primate, according to John Marzluff, a corvid cognition researcher at University of Washington. “There are a couple ways to solve the problems the environment throws at you,” he says. “You can reproduce like crazy and basically try to flood the market with your progeny and hope that you do well, or you can evolve with the strategy of being thoughtful and smart. Crows have that second strategy.”
A sampling of crows’ clever ways: in 2002, a New Caledonian crow named Betty wowed Oxford University researchers by bending a wire to make a hook so she could grab food at the end of a tube. A neurobiologist in Germany recently trained two crows — Glenn and Ozzy — to peck at either a “yes” or “no” target to indicate whether they had detected a faint light, a proof of analytical thought more associated with monkeys. Fourteen years ago, Marzluff caught and tagged crows on the University of Washington campus as part of a study. He wore a caveman mask while doing it, since he knew the crows might recognize him from his regular presence in the area. To this day, when Marzluff wears that mask and walks on campus, crows scream at him. Some of the birds weren’t even alive 14 years ago. “They have to spread that information culturally by social learning,” Marzluff says, sort of like the don’t-talk-to-strangers lesson human parents pass to their young. “To learn from one another, to take things at face value like that, that isn’t something that happens with all species.”
For Swift’s arranged crow funerals, after feeding crows peanuts for three days in a particular location, on the fourth day, a masked volunteer would hold the taxidermied crow out, much like a waiter with an hors d’oeurve platter. Though the dead bird was unfamiliar to the territory, it didn’t matter. When one crow spotted the deceased, the alarm call would erupt and a crowd reliably gathered. When presented with a dead song sparrow, no funeral commenced. For the next six weeks, Swift observed as crows screeched and dive-bombed the masked volunteer who’d arrive without a dead crow in hand, proving they recognized that face as a potential enemy. When Swift returned to feed the birds where the funeral took place, “they were definitely wary,” she says.
As part of her many experiments related to crow funerals, Swift
would sometimes leave a taxidermied crow on the ground. In one video that made
it into news reports, a crow pair had sex with the dummy crow. “It’s
interesting to think about and talk about,” Swift says. “But if our goal is to
understand how crows interact with their dead we have to know if this is
representative.” Turns out it happens, but not often. After doing hundreds of
these trials, Swift says a “necrophiliac three-way” only happened four percent
of the time, and primarily only during early breeding season.
Still, such varied behaviors stoked Swift’s curiosity. It wasn’t enough to observe crow funerals. She wanted inside the crow mind. Swift and Marzluff teamed up to image the brains of seven crows using positron emission tomography, or PET. During imaging, a gloved researcher would reach into a covered cage, gently strap the bird into place and perform a “control” scan and a scan right after showing the subject a stuffed crow, in hopes of capturing how the birds process this information. Marzluff and Swift focused their imaging on areas in the brain that process emotion, spatial learning and decision-making.
“The part of the brain that we found that lit up was the analog to our prefrontal cortex, which is the decision-making part of our brain,” Swift says. Swift and Marzluff published their findings in the journal Behavioural Brain Research earlier this year and concluded the way crows process the sight of their dead suggests that the birds learn from past negative experiences.
“I think the biggest takeaway for me is that they’re really thinking about this stuff,” Swift says. “It’s not a super automatic basal brain behavior. It’s really something they are thinking through.”