19 December 2022

Pittsburgh’s Christmas Bird Count is only 12 days away on 31 December 2022 so my search for Pittsburgh’s winter crow roost has taken on some urgency. I need to find their roost and a good vantage point for counting them, all before New Year’s Eve. Please let me know where you see crows overnight or after sunset, especially next week (after Christmas)!

Several of you responded to my 5 December blog, Help Me Find Pittsburgh’s Winter Crows, with these helpful dates and locations.

• mid-November: On the Cardello Building near the West End Bridge
• Dec 8 & 9: Flying over Mt. Oliver/Allentown just before dawn
• Dec 11 and 14: roosting at City View, PPG Paints Arena and Cambria Hotel area
• Dec 14: Big flocks flying east to west over Kennard Playground as viewed from Elmore St

I’ve checked from City View to the Hill District but haven’t made it to Mt. Oliver/Allentown yet. This map includes your sightings in orange and mine in yellow.

If I’ve learned anything it’s that the crows keep moving their roost, sometimes rather far. They’ve already abandoned the PPG Paints Arena area and have nudged their Hill District roost further north. Where will they be 12 days from now?

The other mystery is that I’ve only seen 5,000 of them. Does Pittsburgh have 10,000 to 20,000 crows as we did in years past? Where are the other 5,000 to 15,000?

Please let me know where you see crows overnight or after sunset. I’ll be out of town over Christmas and am going to miss the next crow move (they will change location when it’s only 7 degrees on Fri & Sat nights). Your help is really crucial.

I hope to count 10,000 to 20,000 crows on New Year’s Eve.

(and yes, I need to check Mt. Oliver/Allentown!)

(photo by Kate St. John, annotated map screenshot from Google Maps, click on the caption to see the original)

6 December 2022

We humans used to think we were very special and very smart because we had language while other species did not. When we learned that other animals had language too our hubris diminished slightly but we still believed in our uniqueness: We were the only species that could think recursively.

In The Recursive Mind (Princeton University Press, 2011) Michael C. Corballis describes “a groundbreaking theory of what makes the human mind unique.”

The Recursive Mind challenges the commonly held notion that language is what makes us uniquely human. In this compelling book, Michael Corballis argues that what distinguishes us in the animal kingdom is our capacity for recursion: the ability to embed our thoughts within other thoughts. “I think, therefore I am,” is an example of recursive thought, because the thinker has inserted himself into his thought. Recursion enables us to conceive of our own minds and the minds of others. It also gives us the power of mental “time travel”—the ability to insert past experiences, or imagined future ones, into present consciousness.

— Princeton University Press Book description: The Recursive Mind

Our uniqueness suffered another blow last month when a study published in Science Advances revealed that crows can think recursively, too.

What is recursive thinking and how did crows prove they can do it?

Recursive thinking means “embedding thoughts within other thoughts” like nested Russian dolls.

For instance, my sentences are often recursive. If you put parentheses around the complete embedded thoughts they can be thrown away without hurting the sentence. As in: “Our uniqueness suffered another blow last month when a study (published in Science Advances) revealed that crows can think recursively, too.”

To test the birds researchers trained two crows to peck pairs of brackets in a center-embedded recursive sequence. They used differently shaped brackets, some in proper order, some not. Like this:

[ { () } ] or { ( [ ) } ]

The brackets make my head hurt. It’s easier to see in this diagram.

If you put brackets around the starting and ending “thoughts” you’ll see a pattern. The brackets fail in the non-recursive example.

According to Scientific American, after the crows were trained to peck bracket pairs, the researchers tested the birds’ ability to spontaneously generate recursive sequences on a new set of symbols. The birds were successful about 40 percent of the time, on par with 3 to 4 year olds in a 2020 study. The crows were better than monkeys who needed extra training to reach that level.

So another unique human trait is toppled by Corvids.

Hooray for crows and ravens!

p.s. Not all the scientists agreed with the study’s conclusions. Read more at Scientific American: Crows Perform Yet Another Skill Once Thought Distinctively Human.

(photos from Wikimedia Commons, diagrams by Kate St. John. Click on the caption links to see the originals)

26 October 2022

During the summer corvids stay home to raise their families but as soon as the breeding season is over they move around. In autumn large flocks of American crows return to Pittsburgh to join the winter roost while a few common ravens show up, alone or in pairs.

This month the crows and ravens are back in town. Since August their populations have gone through several phases.

Late August: On 30 August a surprising count of 380 fish crows gathered on rooftops at Fifth & Craig while only 12 American crows were present that evening.

September: By 6 September fish crow numbers dropped from 30 to zero. American crow numbers rose through the hundreds. No ravens.

October so far: On 10 October a high count 620 American crows flew past “the doorknob” water tower at dusk. By late October no crows were counted because they changed their route. However we now see and hear ravens!

Ravens in town?

Crows migrate. Adult ravens stay home year round. However, young ravens go wandering until they reach sexual maturity at three years old. From fall through early spring a handful of these ravens visit Pittsburgh.

Last Sunday 23 October Andrea Lavin Kossis saw two ravens on Dawson Street dining on some “delicious roadkill.” The pair even had something to say about it.

Brock! Brock!

p.s. In December I’ll enlist your help to find the crow roost in time for the Pittsburgh Christmas Bird Count.

(photos by Andrea Lavin Kossis and Kate St. John)

6 March 2022

Sometimes an experiment doesn’t work as planned but the results are far better than expected.

Researchers wanted to track Australian magpies (Gymnorhina tibicen), a very social species that lives in groups of 2-12 individuals on permanent territories. Rather than use the typical long-lasting harness that requires recapturing the bird to collect the datapack, they designed a harness that would release when exposed to a magnet placed at a feeding station. Would the new harness design work? The first step was to try it on a few magpies and see.

Researchers led by Joel Crampton captured five magpies at Pacific Paradise, Queensland, banded them and fitted each one with a GPS harness. Then they followed the birds to see the harness release at the feeding station.

Each banded bird immediately tried to remove the harness but it was too well designed for that to work. Instead the unexpected occurred. Unbanded magpies came to the rescue.

On the day of trapping, one individual was observed attempting to remove its own tracker but was then approached and aided by another juvenile (without a tracker or coloured leg-band) once again pecking the harness part of the tracker. The tracker remained but, within the next 10 minutes, an adult female (also without a tracker or leg-band) proceeded to approach and successfully pecked the harness at various points such that the tracker came off the fitted juvenile within c. 10 minutes. This first Magpie that had been tagged had its GPS device removed within 1 h.

— Australian Field Ornithology: Australian Magpies Gymnorhina tibicen cooperate to remove tracking devices

This happened over and over again until none of the banded birds had trackers. Here’s a video of the magpies helping each other.

This finding was unexpected but far better than the original experiment. It was the first time anyone had seen rescue behaviour among Australian magpies.

To our knowledge, this is the first study to report the conspecific removal of GPS trackers, and should be considered when planning future tracking studies especially on highly social species.

— Australian Field Ornithology: Australian Magpies Gymnorhina tibicen cooperate to remove tracking devices

“Here,” say the magpies to each other. “Let me help you out of that.”

p.s. A tip of the hat to Michelle Kienholz for pointing out this study.

(photo from Wikimedia Commons, diagram and video from Australian Field Ornithology: Australian Magpies Gymnorhina tibicen cooperate to remove tracking devices; click on the captions to see the originals)

24 February 2022

Corvids [crows, jays, magpies] occupy virtually every terrestrial habitat on Earth, including Arctic tundra, arid deserts, urban streets, and tropical rainforest. Having likely dispersed around the world over millions of years from an Australasian core, it is odd that they never reached New Zealand or Patagonia or disappeared from them both.

— Birds of the World: Corvidae account

It’s hard to imagine a place without any crows or jays but it is true of the southern end of South America, New Zealand and quite a few Caribbean and Pacific islands. I learned this seven years ago when I visited a place that has none of them: St. John, U.S. Virgin Islands.

In the absence of intelligent omnivorous corvids, other birds fill their niche. The all-purpose crow/jay/predator at St. John is the pearly-eyed thrasher (Margarops fuscatus) …

… an aggressive, opportunistic omnivore that feeds primarily on large insects, but also feeds on fruits and berries, and will occasionally eat lizards, frogs, small crabs and other bird’s eggs and nestlings.

— Wikipedia: Pearly-eyed Thrasher account

He acts like a jay, hunts like a corvid, and eats like a crow. I think he looks more aggressive than a blue jay. Maybe it’s the pearly eye.

On Throw Back Thursday, learn about this thrasher in the corvid niche in this 2015 article: