Short Stuff: Brown-Headed Cowbird

Summary

Stuff You Should Know – Short Stuff: Brown-Headed Cowbird

Podcast: Stuff You Should Know
Hosts: Josh and Chuck
Episode Date: April 22, 2026

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Overview

In this "Short Stuff" episode, Josh and Chuck take a fascinating look at the brown-headed cowbird—a bird native to North America with a controversial reproductive habit: brood parasitism. The hosts unravel how this adaptation evolved, its consequences for other bird species, and some of the unique quirks and characteristics of the cowbird.

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Key Discussion Points & Insights

What is a Brown-Headed Cowbird?

• Brood Parasitism Explained:

  • Brown-headed cowbirds do not raise their own young. Instead, they lay their eggs in the nests of other bird species and let those birds rear their young for them.
  • Chuck: “A brood parasite is a bird that will be like, you know what? I don't want to build my own nest and go through all that whole process of raising these babies that I egg out of my body. So I'm just going to go lay those eggs in some other bird's nest and then go away and shirk parenthood.” (02:00)

• Evolutionary Adaptation:

  • Brood parasitism was an adaptation to their nomadic lifestyle as they followed bison herds on the Great Plains, feeding on insects disturbed by the bison.
  • Because the bison moved frequently, cowbirds could not stay in one place long enough to raise their own young.

From Bison Birds to Cowbirds

• History & Name Change:
  • Originally referred to as “bison birds” or “buffalo birds,” cowbirds shifted their alliance to cattle after bison nearly went extinct.
  • This environmental shift didn’t change their reproductive strategy.
  • Josh: “Cowbird was rolling stone.” (03:59)
  • Chuck: “They said, we love these cows, but we also kind of like this adaptation...who really wants to parent their young.” (07:58)

Cowbird Eggs and Their Impact

• Egg Placement:

  • Brown-headed cowbirds are not picky about which nests they choose. They have been known to lay their eggs even in nests of birds much larger (like ducks), leading to comically unmatched clutch sizes.
  • Some species, like the finch and catbird, have developed strategies to reject or destroy cowbird eggs; finches are particularly poor at raising cowbird chicks, often leading to the latter’s death.
  • Chuck: “I think the finch is notorious for not liking these eggs in their nest...catbirds do that. And then the yellow warbler...will just nest a new nest on top of those poor little eggs. Sometimes several new nests, like up to five new nests on top...” (08:57)

• Survival Tactics:

  • Cowbird hatchlings often outcompete native chicks because:
    • They hatch earlier (shorter incubation, up to 3-4 days ahead)
    • They’re often larger and more aggressive in seeking food.
    • Sometimes, cowbird chicks will push other eggs or hatchlings out of the nest.
  • Josh: “That cowbird is probably going to be the only hatchling that survives because it has adaptations to out compete other birds in the nest...” (09:45)
  • Chuck: “You can’t get mad at nature for being nature. But then you get to this part and you’re kind of like, oh man, that really kind of sucks.” (10:32)

Cowbird Identity & Behavior

• Imprinting Mystery:
  • Despite being raised by other species, young cowbirds don’t “imprint” on their foster parents.
  • Researchers believe cowbird chicks may be attuned to the sounds of adult cowbirds and seek out their own kind once they’re mobile. They may also take “nighttime excursions” away from their foster nest, possibly to learn essential cowbird behaviors.
  • Chuck: “How in the world does the cowbird not start to take on traits of the bird that raised them? How do they remain cowbirds?” (11:08)
  • Josh: “We don’t really know, Chuck. ...They think that cowbirds hatchlings are attuned to the sound of adult cowbirds in the area and that they're naturally attracted to it...Also there's they do some weird nighttime excursions out of the nest while they're being raised.” (11:27)

Identification & Range

• What They Look Like:
  • Males: Distinctive shiny brown head with iridescent green-blue body plumage
  • Females: Duller, less remarkable coloring (common in bird sexual dimorphism)
• Where to Find Them:
  • Range across North America—rural, suburban, and urban environments
  • Josh: "They are adapted to all over North America, rural, suburban, urban. You can find them everywhere." (12:41)

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Notable Quotes & Memorable Moments

• On evolutionary "jerks":

  • Josh: “A lot of people think of cowbirds as kind of jerk birds just for doing that. But from their point of view, this is just an adaptation that made a lot of sense to how they evolved originally.” (02:20)

• On cowbirds' parental outlook:

  • Chuck: “We love these cows, but we also kind of like this adaptation because, you know, who really wants to parent their young.” (07:58)

• On cowbird chicks outcompeting others:

  • Josh: “That cowbird is probably going to be the only hatchling that survives because it has adaptations to out compete other birds in the nest that it's laid in.” (09:45)
  • Chuck: “You can’t get mad at nature for being nature. But then you get to this part and you’re kind of like, oh man, that really kind of sucks.” (10:32)

• On the mystery of self-identification:

  • Chuck: “How in the world does the cowbird not start to take on traits of the bird that raised them? How do they remain cowbirds?” (11:08)
  • Josh: “...Some sort of mechanism that prevents cowbirds from imprinting onto their adopted or foster parent from the other species...they do some weird nighttime excursions out of the nest while they're being raised…” (11:27)

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Timestamps for Important Segments

• 01:22: Episode start and sources
• 02:00: Explanation of brood parasitism
• 03:15: Cowbirds’ relationship to bison
• 06:36: Discussion of cowbirds shifting from bison to cows
• 07:58: Modern cowbird behavior and adaptation
• 08:57: Strategies of other birds to reject cowbird eggs
• 10:08: Cowbird chick survival strategies
• 11:08: The mystery of cowbird identity
• 12:41: How to identify and spot cowbirds

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Tone & Final Thoughts

The episode is conversational, playful, and curious, with Josh and Chuck expressing a mixture of amusement and sympathy for the quirks and controversies of the brown-headed cowbird. They offer insight into evolutionary biology, adaptation, and the ethics of judging animal behaviors by human standards, all while providing accessible science grounded in nature’s weirdest corners.

If you want to spot a brown-headed cowbird, just check your backyard or local feeder—they’re everywhere!

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End of Summary

Transcript

[A]

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[D]

Hey, and welcome to the podcast. I'm Josh, and there's Chuck. And Jerry's here too. And this is a short stuff, which is why I realize now that I started this off incorrectly. Short stuff. Let's go.

[E]

That's right. Big thanks to Britannica, Yellowstone Wild Tours, California Department of Fish Wildlife, New Hampshire Audubon and Autobahn for information about the ground headed brown. Ground brown headed cowbird.

[D]

Thanks to Yumi too. She brought this bird to my attention.

[E]

Oh, I forgot.

[D]

Yumi.org so, Chuck, we're talking today about cowbirds, and really in particular the brown headed cowbird. You ever heard of them before?

[E]

Had never heard of them.

[D]

I had neither. But if you want to know about a brown headed cowbird, the first thing you need to know about it is that it's a brood parasite. What does that mean, Chuck? What does that mean?

[E]

Well, I had never heard of this trait in a bird either. So a brood parasite is a bird that will be like, you know what? I don't want to build my own nest and go through all that whole process of raising these babies that I egg out of my body. So I'm just going to go lay those eggs in some other bird's nest and then go away and shirk parenthood.

[D]

Yeah, you do it for me. How about that? Yeah, that's exactly what they do. And you're like, why would you do that? You have to be a jerk bird. And yeah, I think a lot of people think of cowbirds as kind of jerk birds just for doing that. But from Their point of view, this is just an adaptation that made a lot of sense to how they evolved originally. And they're from North America, and they were, I think, indigenous to the Great Plains of North America. And the reason why is because there's another animal that was indigenous to the Great Plains of North America and they had a commensal. Commensal?

[E]

Is it commensal?

[D]

I don't know. I don't think so. I feel like there's a U in there. Anyway, they had the kind of relationship where they benefited but didn't harm the other animal. And I feel like it's high time we tell everybody what the other animal was. Chuck.

[E]

That's right. Drumroll, everybody. It is the bison. They would follow these bison across the plains sometimes. They were initially they were called bison birds or maybe buffalo birds, even though that's wrong. And they would follow these guys across the plains and they would feed on the insects that the bison would kick up, and they would sometimes ride along on their backs. And this led to why they would not birth their own little eggs in their own little nest and raise them. Because they went where the bison went, and they were always on the move. And bison can travel, buddy. So if they're moving 10, 20 miles a day and they're catching a ride on a bison's back, or at the very least flying around with the bison, they're not staying there long enough to set up their own home.

[D]

Yeah. Cowbird was rolling stone.

[E]

That's right. Well, bison bird at the time, I guess.

[D]

Oh, yeah, that's right. So, yeah, it totally made sense that, like, they still need to reproduce, so they would just find a nest somewhere along the bison route and leave their egg and then fly back to the bison and be like, wait, wait, wait for me, everybody. And I feel like that's a pretty good place to take our break. What do you think?

[E]

I totally agree.

[D]

Okay. All right, we're taking our break, everybody.

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[D]

So Chuck, sadly, as probably most people know, the American bison was over hunted almost to extinction. We can seriously legitimately thank Ted Turner for almost single handedly bringing the American bison back.

[E]

That's right.

[D]

And so while in between that period between over hunting and Ted Turner, the bison bird was like, I don't have my niche anymore. I need to figure out what's going on here. I got to start looking elsewhere. And they basically spread outside of their ecological niche in the Great Plains to look for other things they could do to replace their bison friends, which they must have just been horrified by all the massacres they witnessed.

[E]

Yeah, I bet. Probably very sad times for the bison bird. But eventually one of them would land on a cow and say, hey, these guys aren't so bad to ride around on. But here's the thing is cows don't move around like the bison did. They're not traveling, you know, 20 miles a day. So you might think, all right, they're leading a more sedentary life. These birds are now cowbirds. And so maybe they will change their behavior now that they're not. They don't need to do this. But they didn't. They said, we love these cows, but we also kind of like this adaptation because, you know, who really wants to parent their young.

[D]

Yeah, right, exactly. We're not gonna, we're not gonna change anything. We're just gonna stop, you know, wasting so much effort flying around all the time. I think there's, I don't remember. Oh, there's five species of cowbirds at least the parasitic versions and the brown headed cowbird. The reason we're talking about the brownhead is because it is by far the least picky about what nest it lays its eggs in. Yeah, so these are, you know, they're not large eggs, they're much smaller than like a chicken's egg, but they're probably not as tiny as like say a robin's egg. They're middling size eggs. Brown headed cowbirds will lay their eggs in like a duck's nest. So this little egg is like five times smaller than the other eggs around it. Obviously the ducks are like, what is this crud? And there are other bird species too that are kind of onto them. But a lot of times the birds will just, you know, play along or else just be fooled.

[E]

Yeah. I think the finch is notorious for not liking these eggs in their nest. They're not good host to these, these intruding eggs. So apparently they will, you know, they will, they will die if they are left in charge of a finch. Other birds will, will get mad and puncture holes in the eggs or just, you know, beak them out of their nests. I think the catbirds do that. And then the yellow warbler has a strategy where they build nest. They'll just nest a new nest on top of those poor little eggs. Sometimes several new nests, like up to five new nests on top to really bury those guys.

[D]

I know there's some like Tom and Jerry scene that makes me think of, but it happens really, really fast.

[E]

Right, Right.

[D]

So if however, the cowbird happens to lay their egg in a nest that the bird is like just too lazy to do anything about, that cowbird is probably going to be the only hatchling that survives because it has adaptations to out compete other birds in the nest that it's laid in.

[E]

Yeah, one of them is they have a shorter incubation period. So they're born first, I think sometimes up to three or four days before the other eggs might hatch. And so they got a little bit of a head start where they might take care of those extra eggs themselves. These baby birds might nudge those things out. So earlier you were saying there are some bird enthusiasts that kind of think these are jerk birds. And in my mind I was like, yeah, but you know, these birds are doing their thing. You can't get mad at nature for being nature. But then you get to this part and you're kind of like, oh man, that really kind of sucks.

[D]

Yeah. Yeah. So even if they're like, I'll let you guys stay, and the cowbird doesn't push the other hatchlings out just from being a couple days older, they'll be able to muscle the other birds out of the way to get the food and they'll just continue to outpace them in their growth. And it might be so bad that the other hatchlings starve because the cowbird doesn't let them get any of the food from the mother.

[E]

Yeah, so I get it now, bird enthusiast. I have a question for you though, Joshua, which is, with all this going on, not being raised by their parents, how in the world does the cowbird not start to take on traits of the bird that raised them? How do they remain cowbirds?

[D]

I'm glad you asked that. We don't really know, Chuck. As a matter of fact, there seems to be some sort of mechanism that prevents cowbirds from imprinting onto their adopted or foster parent from the other species. They're not exactly sure how this happens, but they think that cowbirds hatchlings are attuned to the sound of adult cowbirds in the area and that they're naturally attracted to it. Once they learn to fly, they'll go seek out other cowbirds. And I guess there they learn all of the cowbird habits like playing craps and smoking cigarettes and all that stuff. And then also there's they do some weird nighttime excursions out of the nest while they're being raised. And I guess no one knows where they go, but that's something that they're like. That probably has something to go learn actual cowbird behavior too.

[E]

Yeah. I wonder if when they are attuned to the sound of their own, if they eventually fly out when they're big enough to find them. If they're like, mama. And the birds are like, don't look at me, buddy.

[D]

Right, exactly. Even if it was their mom, they wouldn't take credit because it's a brown headed cowbird.

[E]

Yeah, that's right.

[D]

So if you want to find one of these, you might see them in your feeder. They are adapted to all over North America, rural, suburban, urban. You can find them everywhere. They're a smallish, a medium sized, smallish bird, whatever that means. But the males have a brown head that shines and shimmers almost like a deep red in the sunlight. And they also have iridescent greenish blue plumage on their body. The females, you're not gonna really notice that much. They're much less showy. But that's pretty standard for birds anyway, for sure.

[E]

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[D]

Oh, nice.

[E]

And it is fantastic stuff, as always. Exactly what you would expect out of the BBC nature series. And Sir Attenborough is 99 years old. He's gonna be 100 in May, and he's still doing it. And it's just some really amazing, striking stuff.

[D]

Did they spell it like Steely Dan

[C]

spelled?

[E]

What? Like Steely Dan. Oh, no, no, no, no, no.

[D]

They spelled it normally A S, I, A. Okay, gotcha.

[E]

Not A J, A.

[D]

Well, there you go. You're welcome. BBC Chuck just hooked you guys up with some viewers. I'm going to go check that out myself.

[E]

It's great. You guys would love it.

[D]

Cool. Well, then I think now, Chuck, Short Stuff is out.

[A]

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