16 October 2024

Did you know that ravens have paranoid, abstract thoughts about other minds?

A new(*) study has found that ravens are able to imagine being spied upon — a level of abstraction that was previously thought to be unique to humans.

— WIRED, 3 Feb 2016(*)

Ravens are well known to cache food but who owns the stash operates on the principle: “Unless another raven is actively guarding it, whatever food I see is mine.” The finder eats or re-hides the cache. We would call this thievery.

To prevent thieves, a raven with lots of food waits until all the other ravens leave before caching his treasure. He’ll even go to a place where no one can see him hiding it.

Scientists thought that a raven had to see another raven before he went to all this trouble. Then a study in 2016 tested whether ravens can imagine potential thieves they cannot see.

The study, published in Nature Communications, found that if a nearby peephole was open, ravens guarded pockets of food against discovery in response to the sound of other birds — even if they didn’t see another bird. This was not replicated when the peephole was closed, despite hearing the same auditory clues.

Ravens are so smart that they can imagine thieves, just like we can. Is it a blessing or a curse to be this intelligent?

Watch how ravens imagine what another raven is thinking in this video from BBC Earth.

19 November 2023

As I wrote in Trying To Move The Crows last Thursday, Pittsburgh’s winter crow flock now numbers 6,000 to 10,000 and will build to 20,000 by the end of December. Their final flight to the roost every evening is so impressive that I included a video taken from my apartment window. Annie commented, “Your video is incredible! But where do the crows go during the day? And does morning look the same as they leave?”

In the morning crows leave the roost before sunrise but not nearly in the numbers I see at dusk, probably because most of them leave when it’s too dark to see Black Birds in a Black Sky. They are tiny silhouettes in this sunrise photo.

The crows fan out in all directions and travel 6 to 50 miles one way — in stages — to find food. Flocks of 10 to 50 go to neighborhoods on trash day.

Photographer Sue Thompson said these crows were a day too early. It wasn’t Garbage Day yet.

Some groups visit restaurants and shopping centers to explore the dumpsters.

But for a really big feast crows go to landfills. There are at least seven large landfills within 30 miles of Pittsburgh’s crow roost. The nearest are 8-15 miles “as the crow flies.”

In mid-afternoon they start to head back in stages. At first there are just a few crows per flock.

They pause along the way in ever greater numbers as they combine into boisterous, noisy flocks. At the staging areas they meet new friends, greet neighbors, and exchange information about their day. It’s “The Bar Scene For Crows.”

The last stage is a only few blocks from the roost. Often they fly in after dark.

And the next morning they start all over again. If people rousted them from the prior night’s roost they’ll pick a new one and change the final staging area close to the new location. Crows can be flexible.

p.s. If you did not see the video taken from my apartment window at Trying To Move The Crows, check it out here:

16 November 2023

Crow news this week! from Phillip Rogers:

Hi all! There are hundreds (probably thousands?) of crows that roost every night outside the Cathedral of Learning at Pitt. Coming in at sunrise it feels like a scene straight out of Hitchcock’s The Birds movie. This evening I saw a man (facilities or groundskeeping employee?) using loud clapping and flashing lights to try to get the birds to leave (short video below). The sidewalks all around are littered with droppings, which is presumably why they want the birds gone.

— Phillip Rogers comment to PittsBirder Chat

I remembered a similar episode 10 years ago when Pitt used bird distress sounds to scare the crows. Back then it worked …

… but crows are really smart. They soon figured out the recordings are fake and promptly ignored them.

By 2020 Pitt had to change tactics. Crows don’t like sudden loud noises and flashing lights when they’re trying to sleep so they made hinged wooden clappers to scare the crows.

The clappers worked for a while … but crows are persistent so this week Pitt had to add flashing lights.

This tug of war with winter crows happens every year when thousands come to Pittsburgh to spend the winter. By mid-November the crows wear out their welcome in Oakland and are “encouraged” to move to other locations.

By the end of the year the crow flock will number 20,000 and the roost will have moved at least once or twice. Where will they be on 30 December when I have to count crows for the Pittsburgh Christmas Bird Count? I’ll need to find out.

(credits are in the captions)