Evolution of Bird Brains

[Recusant]

No, seriously.

A large study (37 authors) of the cranial capacity and brain-to-body size ratio of dinosaurs and birds has given a picture of how bird brains have evolved from before the Cretaceous-Paleogene extinction event to now. A particular favorite family of mine, the Corvidae, gets special mention. 

"How birds evolved big brains" | EurekAlert

Visualizations of brain endocasts (blue) from the skulls of a dinosaur and a modern bird.
Image Credit: WitmerLab at Ohio University

An international team of evolutionary biologists and paleontologists have reconstructed the evolution of the avian brain using a massive dataset of brain volumes from dinosaurs, extinct birds like Archaeopteryx and the Great Auk, and modern birds.

The study, published online today in the journal Current Biology, reveals that prior to the mass extinction at the end of the Cretaceous Period, birds and non-avian dinosaurs had similar relative brain sizes. After the extinction, the brain-body scaling relationship shifted dramatically as some types of birds underwent an explosive radiation to re-occupy ecological space vacated by extinct groups.

"One of the big surprises was that selection for small body size turns out to be a major factor in the evolution of large-brained birds," says Dr. Daniel Ksepka, Curator of Science at the Bruce Museum and lead author of the study. "Many successful bird families evolved proportionally large brains by shrinking down to smaller body sizes while their brain sizes stayed close to those of their larger-bodied ancestors."

In order to understand how bird brains changed, a team of 37 scientists used CT scan data to create endocasts (models of the brain based on the shape of the skull cavity) of hundreds of birds and dinosaurs, which they combined with a large existing database of brain measurements from modern birds. They then analyzed brain-body allometry: the way brain size scales with body size.

[. . .]

"Several groups of birds show above average rates of brain and body size evolution," remarks co-author Dr. N. Adam Smith of the Campbell Geology Museum at Clemson University. "But crows are really off the charts - they outpaced all other birds. Our results suggest that calling someone 'bird-brained' is actually quite a compliment!"

"Crows are the hominins of the bird kingdom," says co-author Dr. Jeroen Smaers of Stony Brook University. "Like our own ancestors, they evolved proportionally massive brains by increasing both their body size and brain size at the same time, with the brain size increase happening even more rapidly."

[Link to full press release]

The full paper appears to be open access. I sometimes put in paragraph breaks when I quote abstracts, but apparently it's the convention in writing papers to make the abstract (called "Summary" here) a single paragraph.

"Tempo and Pattern of Avian Brain Size Evolution" | Current Biology

Summary

Relative brain sizes in birds can rival those of primates, but large-scale patterns and drivers of avian brain evolution remain elusive. Here, we explore the evolution of the fundamental brain-body scaling relationship across the origin and evolution of birds. Using a comprehensive dataset sampling> 2,000 modern birds, fossil birds, and theropod dinosaurs, we infer patterns of brain-body co-variation in deep time. Our study confirms that no significant increase in relative brain size accompanied the trend toward miniaturization or evolution of flight during the theropod-bird transition. Critically, however, theropods and basal birds show weaker integration between brain size and body size, allowing for rapid changes in the brain-body relationship that set the stage for dramatic shifts in early crown birds. We infer that major shifts occurred rapidly in the aftermath of the Cretaceous-Paleogene mass extinction within Neoaves, in which multiple clades achieved higher relative brain sizes because of a reduction in body size. Parrots and corvids achieved the largest brains observed in birds via markedly different patterns. Parrots primarily reduced their body size, whereas corvids increased body and brain size simultaneously (with rates of brain size evolution outpacing rates of body size evolution). Collectively, these patterns suggest that an early adaptive radiation in brain size laid the foundation for subsequent selection and stabilization.

[Dark Lightning]

Corvidae are amazing. I've seen crows do things that some people couldn't figure out. I think with people that the ability is there, but living in a civilized world encourages a lot of lazy behavior, and thinking things through seems to be one of the skills that gets lost. In the case of the birds, there is little safety net if they don't get it going. Darwinian selection is still forming them strongly.

[Icarus]

I recently learned that Blue Jays are corvidae types.  They do appear to be smart birds. I have seen one or more of them use a tool to unclog the aperture on my back yard bird feeder.  The sunflower seeds that they appear to like, sometimes get stuck in the delivery opening of the feeder.

At least one of the regular BJ visitors has a peculiar habit.  He likes to pick at the wooden perch stick.  It is a 6mm diameter wooden rod and he has almost destroyed it.  I will need to replace the perch soon.  I have also seen Jays gang up on a squirrel for whatever reason.  BJs are mostly bullies but I have seen a small female cardinal stand her ground and drive the BJ off the perch.  Neither of them mess with the red headed woodpecker that shows up once in a while.   The woodpecker is gluttonous with the suet slab.  The other birds do not seem to interested in that greasy goop. 

[No one]

What to the BJs do to the Woodpeckers?

[xSilverPhinx]

The New Caledonian Crow is awesome. I did a group project on their tool use (associated with beak shape) when I was an undergrad.

Based on this paper, in case anyone is interested:  https://www.nature.com/articles/srep22776 

[Bluenose]

The Australian magpie, a member of the broader Corvoidea superfamily, are very intelligent birds with a wonderful, melodious song.  They have a reputation for swooping on pedestrians during the breeding season, but contrary to this, those who feed the local magpies in their back yard are rarely if ever swooped. These birds have a very good memory for people and it has been estimated that a magpie can remember up to 50 people.  One male would often fly past my right ear, brushing it with his wing tip, and land in front of me to request fond.  I would go in one entry to the house and he would go to the other side and patiently wait for my to come out with some tid-bits.  If no one was outside he would come up to the back door, under the alfresco area, and squawk at he open door to let us know he was there.  This gave our cat a huge surprise one day when she was sitting with her back to the screen door and the magpie came up and loudly squawked for food.  The cat jumped high in the air and just about turned inside out in surprise.  LOL

[Ecurb Noselrub]

Remember the video of the crow snow skiing down a roof on a lid to a container or something?  That had to demonstrate some thought. Perhaps the crow saw a kid sledding and was able to think 1) that looks like fun; 2) I can use that lid to do the same thing.  The advantage the crow had was that it knew that if it wiped out at the bottom it could fly instead of crashing into the ground, so that may have eliminated a fear factor.  The bird is obviously intelligent.

Here it is:

https://www.youtube.com/watch?v=1WupH8oyrAo

[Icarus]

Crafty crow pisses off kitty cat.

https://www.youtube.com/watch?v=pgz9-gmCAbA

[Tank]

Crafty crow pisses off kitty cat.

https://www.youtube.com/watch?v=pgz9-gmCAbA

Fun to watch. But I think the white cat really needed a good feed.

[Asmodean]

The cat didn't even seem to really try. Them can be way speedier than that one if they choose to, all claws-and-teeth-like. Maybe the fish smelled funny and the crow was big and scary..?

[Dark Lightning]

I don't know. I'm a lot bigger than that cat, and I wouldn't be messing with that crow!

[xSilverPhinx]

Young Ravens Could Have Cognitive Skills That Rival Adult Great Apes, Research Finds

[Icarus]

The crow has a wicked beak that is dangerous. He also has some claws that can inflict damage.  The kitty cat may be smart enough to know that although the crow is pissing him off, there may be some risk in challenging the mean ass bird.


Corvines are remarkable creatures. Crows and Ravens are fascinating birds.  I have been trying to make friends with them for years.  There are plenty of them in my area but they do ignore my back yard bird feeders.  They seem more inclined to scavenge the local supermarket parking lot than to get free stuff from me. 

So alright already I have not yet offered them McDonald burger scraps like those that appear in the parking lot of the stores. (some people are slovenly about disposing of scraps)  The parking lot crows are tame and have no apparent fear of people.  They are also exceptionally clever about avoiding the danger of automobile wheels.

[Randy]

Don't those crows know about the dangers of cholesterol? I saw one once pick up a french fry that was lying on the ground at a McDonald's and flew away with it. I'm pretty certain those things aren't healthy.

[Tank]

Don't those crows know about the dangers of cholesterol? I saw one once pick up a french fry that was lying on the ground at a McDonald's and flew away with it. I'm pretty certain those things aren't healthy.

I gather they are better than starvation