Last week in Newfoundland our birding tour witnessed an amazing bird interaction when a merlin attacked a big black corvid in the air. It happened so fast that we had to think hard about the birds’ identities.
Yes the attacker was a merlin — a small, streaky dark, very fast falcon that made this sound as it attacked. (Xeno-canto XC332445: alarm calls of merlin pair recorded by Pritam Baruah in Churchill, MB, August 2016)
But was the big black bird a crow or a raven?
Fellow traveler Trina Anderson captured the action with her camera. Before we saw her photos we could only identify the corvid by size and behavior. We decided “raven” based on the relative size of the two birds and the behavior of the raven.
Merlins are 2/3 the size of a crow but less than half the size of a raven. Overhead the merlin was tiny compared to the bird it attacked, so it had to be a raven. Trina’s photos show the size difference.
The black bird barely flapped during the interaction and it flipped upside down in flight (see the last photo). Crows flap hard when they’re under attack and they don’t fly upside down.
During the fight it was hard to see the diagnostic field mark — the tail — but Trina’s next photo shows the corvid has a wedge-shaped tail. That means “raven.”
It’s hard to tell ravens from crows unless you have some practice. Get tips on how to tell them apart in this 3 minute video from The Raven Diaries: Ravens vs Crows, they’re different!
I love ravens, not only because they’re really smart but because they’re great acrobatic fliers. They show off to impress each other.
Ravens live a long time — 30 to 40 years — and don’t breed until they’re 2-4 years old. In their first few years they hang out in flocks, get to know other ravens, and choose a mate for life.
Part of getting to know each other includes playing in the sky. When they’ve chosen a mate they make courtship flights together — swooping and diving, soaring with wingtips touching, locking toes and tumbling in the sky.
Have you ever seen ravens tumble? It’s rare to see in western Pennsylvania because we don’t have big flocks of ravens but they’re easy to find in winter in California.
Is a flock of 15,000 crows a burden or an opportunity? At the University of Washington, Bothell it’s an opportunity for a groundbreaking study on crow communication.
Every year from fall to spring, 15,000 crows gather on campus on the way to their roost in the North Creek Wetlands. These gatherings are their noisiest time of day.
Crows are intelligent so chances are good that they’re saying something meaningful — but no one knows what it is.
Last year UW Bothell biologist Douglas Wacker and acoustics expert Shima Abadi decided to team up and find out. Working with a group of students, they tested audio equipment and the crows’ reactions to it. They also wrote software to find the most interesting parts of the crow conversations so researchers don’t have to wade through hours of recorded caws to find the best parts.
Setting up the equipment was not as simple as you’d think. Crows are wary of changes in their surroundings so audio equipment was introduced carefully on the rooftop of Discovery Hall, a building where the crows congregate. By the time this photo was taken, the crows were cool with four audio rigs on the roof.
This winter Wacker, Abadi and their team of students will learn more about crow communication and pair it with video to determine who’s saying what.
Tonight is the night of the Supermoon, a full moon at perigee that looks 14% bigger and 30% brighter than normal.
What will you see by moonlight on Pitt’s campus tonight, clustered at the treetops like large black leaves?
Thousands of crows.
Despite the weird scarecrow sounds played from the buildings, Pittsburgh’s winter crow flock continues to roost in the mature trees surrounding the Cathedral of Learning and Heinz Chapel.
On Friday I tried to count them by the light of the moon. They were clustered in 30 trees and on the roof of Carnegie Museum. The densest trees held 300 crows.
Could there really be 9,000 crows in the area of Forbes, Fifth, Bellefield and Bigelow Avenues? Maybe I over counted. Last year I estimated 230 crows per tree making this total 6,900 crows on December 1 at 6:15pm.
What is their fascination with the University of Pittsburgh? It isn’t the buildings. It isn’t the lawn. It’s the well lit trees.
Crows prefer to roost where they can see danger coming. The campus is well lit for our protection. The crows like it, too.
Alumni Hall is a good vantage point for watching crows and the moon rise next to Heinz Chapel.
Stop by this evening to see it all by the light of the supermoon.
This week pedestrians near the Cathedral of Learning are hearing weird scary bird sounds after sunset. Yale Cohen recorded them on Wednesday and asked, “What is this?”
The recording sounds like a bird in distress followed by rapid peregrine “kakking.” It’s an audio scarecrow.
Pittsburgh’s winter crow flock has decided to roost in Oakland bringing at least 4,000 crows into the trees on campus. Every morning the sidewalks are a gooey smelly mess. Here’s what the Fifth Avenue sidewalk looked like on November 14 (photo by Claire Staples).
In 2013 the recordings worked, The Crows Moved, but this time they haven’t gone so far. Michelle Kienholz texted me on Wednesday:
Pitt aggressive bird sounds screaming out at different locations in sequence. Crows settling elsewhere but still on campus.
I’ve found crow evidence below the London plane trees by Carnegie Library, the Pittsburgh Public Schools office and St. Nicholas Cathedral. The crows have moved — but only across the street.
They’ve already figured out the scarecrow. It’s annoyingly loud but not scary.
p.s. Why does the flock like to roost at Pitt? Look how well lit the area is at night (photo at top)! Crows like to sleep in tall trees where the lights are on.
(credits: Cathedral of Learning at night from Wikimedia Commons; click on the image to see the original. Messy sidewalk by Claire Staples. Audio recording by Yale Cohen)
The black silhouettes in this tree near the Cathedral of Learning are not leaves. They’re crows.
Pittsburgh’s crow population has swelled since the weather turned cold last weekend. On Monday I counted 4,000 flying into Oakland from the south, pausing on the roof of Carnegie Museum before heading to their final destination.
I couldn’t even see the crows arriving from east, west and north but distant trees at Schenley Farms were coated with crows and hundreds, perhaps thousands, gathered on the rooftops north of Fifth Avenue. My cellphone barely captured a look at them as night was falling.
Where did they roost? I didn’t stay long enough to find out, but they left their evidence behind.
On Tuesday Claire Staples sent me photos from St. Paul’s Cathedral on Fifth Avenue. The crows left a mess on the wall and sidewalk below the stately London plane trees.
For now the crows are roosting near Fifth Ave and Craig Street but that will change. They’re wearing out their welcome.