The Science of Birds - Red-winged Blackbird

Episode Date: June 21, 2026

👕 Bird Merch —  Get yourself some bird shirts!~~~Episode 135 takes on one of North America's most recognizable birds: the Red-winged Blackbird, Agelaius phoeniceus. With a population possibly approaching 200 million, this species is a fixture of wetlands and marshes across the continent, and one of the most intensively studied birds in ornithology.Ivan explores the biology and behavior that make this bird so compelling: its striking sexual dimorphism, the surprisingly complex story behind those iconic red epaulets, and a breeding system that turns out to be far messier than it first appears. Territorial wars, interspecies conflict, and the occasional human casualty are all part of the picture.The episode also digs into the Red-winged Blackbird's fraught relationship with agriculture—from the enormous crop damage these birds can cause to the high-tech and sometimes controversial methods farmers use to manage them. And despite being among the most abundant birds on the continent, the species has seen a significant population decline over recent decades.Link to this episode on the Science of Birds website🔥 Bird Merch - 20 New Shirt Designs!Support the show

I'm super excited to announce that I've got a bunch of new t-shirt designs available now on birdmerch.com. Birdmerch is my online store where I've got bird-related t-shirts. Maybe someday I'll have more stuff, but for now it's all t-shirts. So for this spring, 26, I've got 20 new designs for you that I've been working on for the last six months or so. These feature species like the American Dipper, Piliated Woodpecker, Ready Duck, Northern Flickr, American Woodcock, Northern Mockingbird, and more. These are designs made by me, and I'm excited for you to check them out. See if anything catches your eye.

Maybe grab yourself a shirt and wear it while you're out birding this spring and summer, showing everybody how much you love birds, and how cool you are. It's been really fun to create these. When I started bird merch, it was partly because I've always loved wearing graphic teas, and I love making them. So at this point, my drawers are basically full of bird merch t-shirts, and that's it. That's all I wear. And pants.

I also wear pants. Just to be clear. The point is, I am a customer of my own product. I dig these shirts. They're comfortable, they've got nice colors. And of course, yes, I am super biased because I made the designs, but I really like them. And I hope you will too. Check everything out at birdmerch.com, and I'll put a link in the show notes.

Cool. Now let's get on with the show. Ah, the familiar and comforting sound of a North American wetland in spring. Those bird sounds are coming from a dense stand of cattail plants growing along the margin of a large pond with their iconic hot dog-shaped flower spikes. Cavorting in the cat tails are some cheeky blackbirds. Red-winged blackbirds, to be exact. The males are deep black with red and yellow shoulder patches

and the females are streaky brown all over. These blackbirds are so noisy and active that no matter how hard you try, you just can't ignore them. The red-winged blackbird is actually one of the most common bird species in North America. As we'll see in today's episode, there are reasons both good and bad

for why the red-winged blackbird is so well-known to birders, ornithologists, and farmers. Hello and welcome. This is the Science of Birds. I am your host, Ivan Philipson. The Science of Birds podcast is a lighthearted exploration of bird biology for lifelong learners. This episode, which is number 135, is, of course, all about the red-winged blackbird, Ageleus Phenicius.

This is one of the most abundant bird species in North America, with a total population possibly approaching 200 million individuals. The red-winged blackbird is so widespread and easily observable that it's also one of the most well-studied birds on the continent. For many decades, scientists have been interested in understanding the behavior and ecology of red-winged blackbirds in the noble pursuit of pure knowledge. However, another reason researchers have been studying these birds is to understand their negative effects on human crops

and to devise ever more sophisticated ways to thwart the birds from devouring colossal numbers of commercially grown sunflower seeds, corn, rice, and so on. So in the eyes of some farmers, a swarm of red-winged blackbirds descending on their fields is sort of like a biblical plague. I mean, isn't that the quote from Exodus 42 or whatever.

And lo, never before had there been such a plague of red-winged blackbirds. Nor will there ever be again. They covered all the ground until it was black. The black birds were fruitful, and they multiplied, and filled the earth, and ate

all the sunflower seeds. Yeah, I'm pretty sure that's the exact quote. Anyway, the species for today's episode of the Science of Birds podcast was the winner of a poll that I ran. There were two choices in said poll, the red-winged blackbird and the black-crowned knight-heron. The poll was neck-and-neck for a while, but the red-wing blackbird pulled ahead and

ended up with 53% of the votes, and the black-crowned knight-heron got the rest at 47%. The lucky people who got to cast their votes in this poll were my supporters on Patreon. Because one perk of being a paying supporter is that you get to help me decide on some of the podcast episode topics. So please consider becoming a member of my Patreon community if you'd like to support my work here and to get some fun perks like voting in polls. Okay, it's time to dive headlong into the cat tails to get our feet wet and figure out what the deal is with Agulaeus Phenicius. Let's begin with the appearance of this species, and then we'll listen to some of its vocal sounds.

This is a medium-sized New World Blackbird, measuring 6.7 to 9.4 inches, which is about 17 to 24 centimeters, and that's the length, and the wingspan is about 12 to 16 inches, or approximately 31 to 40 centimeters. Across the red-winged blackbird's vast geographic range, there's a fair amount of geographic variation in overall size and bill shape among populations. For example, the bill varies from long and stout in central Canada to short and slender in the short grass prairie of the U.S. When ornithologists or other biologists see this kind of geographic variation within a species, one question they often ask is, are these physical differences we observe from one region to the next the result of underlying genetic differences across the populations? Or are they the direct result of

environmental factors like climate? Well, a series of experiments several decades ago helped answer this question for the red-winged blackbird. In these experiments, researchers moved eggs between geographically distinct populations, such as from northern Florida to southern Florida and from Colorado to Minnesota. It's like the old old switched at birth cliché. What the researchers discovered was that the shape of a nestling, specifically bill to tarsis ratios in Florida and wing to tarsis ratios in the Colorado-Minnesota group,

well, those shapes shifted to resemble the foster population rather than the biological parents. And the tarsis, in case you're wondering, is the lower leg bone just above the toes. The results of these egg-swapping experiments, showed that a significant portion of the geographic variation we see in the size and shape of redwing blackbirds is induced by the environment, the environment in which a nestling grows up. So this variation is not purely genetic. There is sexual dimorphism in this species. Males are quite a bit larger

than their lady friends, being approximately 50% heavier and 20% larger in linear dimensions. than females. The tail of a red-winged blackbird is rounded at the tip and it has a medium length. These birds have an undulating or bounding flight style, characterized by rapid, shallow wing beats interspersed with brief glides, sort of like a woodpecker. The bill or beak of a red-winged blackbird has the typical shape seen in many members of its family, ecturidie.

The bill is slender, medium, medium length and oh so pointy at the tip. Okay, so let's now get into plumage coloration and plumage patterns. Adult males are a uniform glossy black with black bills, black eyes, and black legs. And of course they have those distinctive red shoulder patches, each bordered by a yellow bar on the lower edge. The red feathers correspond to the lesser coverts, while the yellow ones are the median coverts. A word we use for color patches in this part of the wing is epaulettes, spelled E-P-A-U-L-E-T for the singular epaulet in American English anyway. This word comes from the

world of us silly humans where an epaulet is an ornamental shoulderpiece or decoration, often used on military uniforms to display the wearer's rank. Dictators who wear military get-ups seem to be fond of sporting big flashy epaulettes on their shoulders. I mean, I'm definitely going to have some big old epaulettes on my outfit when I finally become a dictator. And to be honest, the only reason I even want to become an authoritarian tyrant is so I can get away with wearing epaulettes out in public. Oh, and I should point out that epaulettes on birds aren't really on the shoulder region, even though we call them shoulder patches informally, because actually that part of the wing is the bird's wrist. Anyway, the red color is produced by carotenoid pigments, which come from the

blackbird's diet. The black and yellow areas, on the other hand, contain high concentrations of the pigment melanin. Males actively show off their colorful epaulettes, flaring them out, mostly to threaten rival males and protect their turf, but perhaps to impress some females as well. I'll talk more about that later. The singing male also leans forward, droops his wings, and spreads his tail feathers. When he wants to, he can also tuck his epaulets away to keep a low profile when trespassing on another male's territory. So he can go into a sort of stealth mode. In the non-breeding season, males aren't quite as uniformly black.

Their plumage looks more scaly, and their shoulder patches aren't as brightly colored. Female red-wing blackbirds look quite different. They are cryptically colored, in other words, camouflaged. Females are brownish with lots of heavy streaks below, and they have a prominent pale eyebrow stripe. At first glance, you might mistake a female red-wing blackbird for a large sparrow. I've been confused more than once by a female red-wing blackbird, thinking I'm looking at something like a sparrow.

I started off this episode with some red-winged blackbird vocalizations. The male's song is easy to recognize, and it's well known by many North American birders and nature lovers. The male's advertisement song is iconic, with a strident, liquidy sound that people describe as Ocali or Concleri. The male flashes his epaulets and sings this song from a high perch like a cat. bat-tail stock sticking out from the surrounding wetland vegetation, or on a branch on a shrub or a tree. Here's a great example of the Concla Re advertisement song, recorded in Minnesota. And here's another example of this song, this time recorded in Toronto, Canada.

Male vocal activity peaks during the early morning and near dusk. Each male has a repertoire of up to nine distinct song types. Female Red Wing Blackbirds sing as well. Her song is more of a scolding chatter, rendered sometimes as chit, chit, chit, chit, chir, tear, tear, something like that. A female will sometimes perform a sort of duet with a male. She sings three to five chit notes right after a male belts out his advertisement song, or at the same time.

Both sexes use a variety of calls. Some calls are shared by males and females. Others are used only by males or only by females. These sounds function as contact or alarm calls. One researcher distilled these calls into seven types. They're all single note sounds and their names are Pete, cheer, check, chuck, chick, chunk, and chink. Okay, you got that?

Pete, cheer, check, chunk, chick. Wait, no, no. Here we go, let's do it again. Pete, cheer, check, chuck, chick, chunk, and chink. Sorry. Yeah, I'm not joking. These are the real types. But hey, blackbirds, I mean, why stop with just those seven calls? You could say so much more by expanding your repertoire with more sounds. Might I suggest chak, chunk, chork, chilk or chusk? In any case, one of the most common sounds you'll hear these birds make is the check call. Both sexes make the check call in a bunch of different situations, feeding, flying, battling with their enemies, and as an alarm if predators are nearby.

Researchers have found evidence that red-winged blackbirds communicate mainly by switching between different calls, rather than by using specific calls that each means something particular. So just as a hypothetical example, a male might be making the check call repeatedly and then something happens like a predator comes on the scene and he switches to the chunk call. And it's that switch that communicates information to his neighbors. Okay, I have one more recording to play for you. And I believe we're hearing the Pete call here, which is often used as an alarm or distress call. Red-winged blackbirds can also understand some of the calls of other bird species. In one study, when researchers played a yellow warbler warning call,

one used to signal a nearby brown-headed cowbird, which is a brood parasite, the Red Wings responded defensively. They even seemed to understand the specific meaning of the call, since they didn't react to other less frantic yellow warbler sounds. In this next section, we'll cover the root meanings of the Red-Winged Blackbird's scientific name, then we'll talk about this species' family and its genus,

subspecies distribution, and all that fun stuff. Again, the scientific name is Agileus Phoenisius. Agileus comes from the ancient Greek word, Agileos, which means gregarious, or flocking. And that is a fitting name because red wings gather in enormous winter flocks. Some of the largest gatherings have millions of birds in them. They roost together at night, sometimes with other blackbirds, species, as well as grackles, cowbirds, and starlings. This communal roosting behavior is seen

all year long, but the biggest crowds are the ones that gather in winter. These masses of blackbirds spread out across the land every morning, and they might find food 50 miles from where they roost at night. Agileas means gregarious or flocking. The specific epithet, the second part of the name, is Phoenius, and that's spelled P-H-O-E-N-I-C-E-U-S. That is Latin for crimson or deep red, which again is a fitting name. As I mentioned earlier, the red-winged blackbird is in the avian family, Icturidi. This family belongs to the order Pasariformis, which is known as the order of the perching birds. Ecturity is the New World Blackbird family, or another name for this group is the troop eels and allies.

I have not yet done a full episode on the family Icturity, but I will, and I think it'll be a really good one, because this is a really interesting family with 105 species. Five of those species, including our red-winged friend, are in the genus Agileus. The closest relative of the red-winged blackbird is the red-shouldered blackbird, Ageleus Asimulus, a bird that's endemic to Cuba. In other words, it's found only in Cuba. The next closest relative of Ageleus Phoenius is the tricolored blackbird, Ageleus tricolor.

That species is found mostly in the state of California. The red-winged and tricolored blackbirds can be seen in the same wetlands sometimes. and they look superficially very similar. But the male tricolored blackbird has red epaulettes bordered by white, not by yellow. It seems that ornithologists have designated as many as 20 to 24 subspecies within the red-winged blackbird. That's a lot of subspecies, yo! But I have to wonder how many of them are distinct at the genetic level. Or do some of these so-called subspecies just reflect those.

environmental effects we talked about earlier. Unfortunately, I couldn't find any published research on red-winged blackbirds that used genetic data from DNA to sort out what's going on with all those subspecies. Hopefully, some brave researcher will take on that task someday. Now, I'll only highlight one subspecies here, and that is Adjoleus Phoenician, Californicus. This subspecies has a name. It's the California bicolored blackbird. That's right, bicolored, not to be confused with the tricolored blackbird, which is that other species, right? Well, the range of this bicolored blackbird subspecies in California overlaps the range of the tricolored

blackbird. The bicolords want to be able to recognize and mate with their own species, not with those pesky tricolored. Like I said, bi-colored, not to be confused with the tricolored. They don't want to be confused. Well, evolution might have provided the solution here, because the key trait of the bicolored blackbird is that its median wing coverts are black, not yellow like they are in other regions. Without that yellow margin, the bicoloreds look a lot less like the tricolards that they're rubbing elbows with, or rubbing epaulets with, in the same wetlands. Scientists have hypothesized that the lack of yellow might help the bicolored recognize each other more easily. And remember here that the California bicolored blackbird is just a

named subspecies of the red-winged blackbird. Let's look more closely now at the red-winged blackbirds distribution and its habitat. These birds breed from Alaska and Central Canada, South to Costa Rica and the Bahamas. Their populations are more scattered in the relatively dry country west of the Rocky Mountains. They're at their densest and most common in the Great Plains, the Midwest, and the Mississippi floodplain. Most red wings in the U.S. and Central America stay put year-round. Their residents. But the populations living in the northern states and Canada heads south for the winter. They migrate during the day, and males are the first to leave in spring. Some of them start moving north as early as January to claim the best territories before the competition arrives.

Females, on the other hand, show up a month or so later and pick their mates based on who has scored the sickest crib. And just what makes for a sick crib? a dope pad, if you will? In other words, what qualities does a good red-winged blackbird territory have? Well, we'll talk more about that a little later. But as for this species' habitat preferences in general, they live in primarily freshwater and saltwater marshes. But they're also highly adaptable birds,

so they can thrive in some upland habitats like hay fields, alfalfa fields, prairies, and old fields. You frequently find Red Wing Blackbirds in human altered landscapes like this, including urban parks. One of the key features of Red Wing habitat is plants in the genus Typha, T-Y-P-H-A. These are the cat-tails, and there are a handful of species in North America. For example, there's the narrow-leaved cat-tail and broad-leaved cat-tail. Red-winged blackbirds have a very strong connection to cat-tails, because these plants are perfect for nesting and roosting.

While these birds are flexible and can live in many places, as I mentioned, they usually prefer freshwater marshes with plenty of cat tails. The thick, sturdy stems of a cat tail provide excellent support for a red-wing's nest, making it much safer and more stable than a nest built in other flimsy marsh plants. Because of this, blackbirds that build their homes in cattails often have better luck raising their chicks successfully. Beyond nesting, cat-tailed marses also act as a haven where those massive flocks huddled together to sleep at night. As mentioned, the Red Wing Blackbird is one of North America's most abundant bird species, with the population estimated between 150 and 180 million

breeding individuals in the U.S. and Canada. So not surprisingly, the status of this species on the international red list of the IUCN, on that list this bird is categorized as least concern in terms of its conservation. But given all that, what you might find surprising is that red-winged blackbird populations declined by approximately 36 percent between 1970 and 2014. That is a massive decline. The overall continental population in the United States and Canada for the red-wing blackbird has experienced a steady decline of approximately 0.93% every year since 1966. So even this superabundant, widespread species isn't safe from the threats that humans pose. And what threats exactly have been causing the decline in red-winged blackbirds?

Well, one major factor is the conversion of preferred breeding habitats, such as wetlands and grasslands, to agricultural use that requires intensive tillage. This includes wetland drainage, grassland conversion, and urbanization, all of which reduce suitable nesting and foraging areas. Other threats include pesticides and climate change. For instance, warmer but stormier winters have been responsible for low winter survival in some populations. And these birds are outright targeted and killed by some.

humans. Lethal management techniques intended to reduce crop damage and manage large winter roosts may also be a significant factor in the blackbird declines. Or maybe not. I'll talk more about that in a moment. But first, let's move on now to learn more about what red-wing blackbirds eat. In simple terms, red-winged blackbirds eat insects and seeds. During the breeding season, between 70 and 100% of their diet is insects like grasshoppers, caterpillars, beetles, and flies. Other invertebrates like spiders and earthworms are also on the menu. Animal material like this provides lots of protein, which is essential for egg production and for feeding the fast-growing ravenous nestlings. But once the parents have kicked their

youngsters to the curb, so to speak, when autumn and winter roll around and the family members go their separate ways, red-winged blackbirds, switch to eating plant material, mostly seeds but also small fruit like blueberries. Seeds eaten include agricultural crops like sunflower, corn, and rice, but also grass and weed seeds and waste grains like oats, wheat, and millet. So if we look at the entire annual cycle, the diet of red-winged blackbirds is mostly plant material at about 75%. Male and female red-winged blackbirds, birds have different eating habits because of their physical size differences and the types of food that they can easily handle. Males eat more farm crops like corn and sunflower, while females eat a

much higher percentage of weed seeds. For example, studies have found that males may eat nearly three times as much corn as females, who instead fill their little bellies with smaller seeds. This dietary difference is mainly because females are at least 20% smaller than males, and they have shorter bills. So females aren't as good at cracking open tough grain kernels once those kernels harden. In general, though, the sharply pointed bill of the Red Winged Blackbird is ideal for both cracking seeds and probing for insects. Like many other species in the family Icturidie, Red Winged Blackbirds use a foraging technique called gaping. This is where the bird forcibly opens the bill against some substrate to expose hidden goodies like insects. The bird jams its pointy, tightly closed beak into a hiding spot,

like a patch of dirt, a curled up dead leaf, or a crack in a piece of wood. And then once the beak is buried or wedged inside, the bird forcefully opens its mouth. This pushes the dirt, wood or plant material apart, creating a small hole so the bird can see what's inside. Now, imagine you are a farmer in North Dakota. You grow sunflowers. There are lots of wetlands in North Dakota, and these are home to thriving populations of red-winged blackbirds. From your perspective as a farmer, this bird might seem sort of like a jekyll and hide species. In spring and summer, when the birds are raising their little blackbird families, they're like the amiable Dr. Jekyll. They're good guys because they eat enormous numbers of crop-damaging insect pests,

insects like seed weevils, corn borers, grasshoppers, and so on. Flocks of Red Wing blackbirds also eat weed seeds by the ton. But after the breeding season, and when the sunflowers mature, from mid-August until harvest in October, your friendly, helpful, local blackbirds transform into the villainous Mr. Hyde. They become a seed-eating swarm that sweeps through your fields, gobbling up a non-trivial proportion of your crop.

Now, while industry-wide damage from red-winged blackbirds is typically low at just 1 to 2 percent, it's unevenly distributed. A small percentage of producers near major red-winged roosts, can suffer significant losses exceeding 5% of their crop, maybe even 20% or more. Now, if these birds are causing trouble on your farm, you could rely on traditional tactics for keeping them away.

You could put up a scarecrow in your field, or a scare blackbird, I guess. Or you could go with the tried and true method of running around in your field, wildly swinging a pitchfork and screaming like a lunatic at any blackbird that dares touch your son. Sunflowers. Admittedly, that approach is a little labor intensive. You got to be in good shape. But hey, this is the 21st century, right? Don't we have more sophisticated tools for keeping the red-winged blackbirds at bay? Well, we do. Farmers today can use propane cannons, pyrotechnics, and electronic

noise-making gizmos to spook birds into staying away. For example, there's the Sonic Net. This is a high-tech tool used to scare birds away without hurting them. It works by playing a special type of background noise at frequencies that overlap with the sounds birds use to communicate. Because this noise masks important alarm calls, like the ones we talked about earlier, the birds feel less safe. As a result, they get all twitchy and much more watchful for danger. So they spend significantly less time eating, and that eventually encourages them to leave the area. One major benefit of the Sonic Net system is that birds are less likely to get used to the noise over time compared to older methods like loud propane cannons, or screaming farmers, I guess.

Another high-tech sci-fi solution is drones. In other words, unmanned aircraft systems. Some research shows that rotary wing drones, flown at low altitudes, like within about 100 feet or 30 meters from the ground, that can work pretty well to encourage blackbird flocks to clear the heck out. Other research is testing the use of drones to both scare birds away and keep an eye on them to prevent crop damage. When these drones fly over fields, they flush red-wing blackbirds out of hiding.

And then cameras on the drone can get a clear view of the birds. The drone images from the cameras are processed with artificial intelligence, and that can automatically identify, count, and track the birds in real time. By connecting these drones to a smart network, the system can automatically decide to use scaring tools only when there are enough birds present to cause a problem. A targeted approach like this could be helpful because it saves on the need for manual labor. As in, the farmer doesn't need to run around screaming and waving a pitchfork anymore. They can just sit on the sofa back at the same.

the farmhouse, put up their feet, and crack an ice-cold beer, or mountain dew, or whatever. Let the robots do all the harassing. This drone AI system also prevents birds from getting used to, or habituated to, the sounds and sites that are used to frighten them. And that makes the protection much more effective over time. Other non-lethal approaches to reducing the damage caused by flocks of red-winged blackbirds include habitat management and chemical repellents. With respect to habitat, reducing the carrying capacity of the surrounding land

by thinning cat tail stands in marshes can disperse the birds across the landscape and away from specific fields. Fewer cattails in the area means fewer blackbirds, usually. And as for chemicals, everybody loves chemicals, right? Well, a chemical called four aminopiridine, commonly known by the brand name avatrol, is used as a chemical frightening agent to keep red-winged blackbirds from damaging crops like corn and sunflower. It's usually applied by spreading corn bait across a field from an airplane with only about one and every hundred seeds or corn kernels that are actually treated with the chemical.

When a bird eats one of the treated kernels, it starts to fly in a wild, erratic way and let out loud, painful-sounding distress calls. This reaction has been described as epileptic-like convulsions. Well, that sounds pleasant and not in any way horrifically cruel. This distress call behavior creates a strong fear response in the rest of the flock, causing the other birds to panic and flee the air. area to find food elsewhere. Now, while this method can be very effective at scaring away large groups, it is no longer used for growing crops in many places because it turns out that avatrol is highly toxic to other birds and mammals. But at least for red-winged blackbirds, the effects of avatrol supposedly wear off after about four hours. And I suppose that is better

than simply killing the birds. Because, so far, we've been talking about. non-lethal ways to keep red wings away. And thank goodness lethal options are off the table, right? Because this is a native species that's fully protected under the Migratory Bird Treaty Act of 1918. That law makes it illegal to kill blackbirds or destroy their nests. But not so fast there, you bird-loving hippie, because there's a loophole. And that loophole's name is the Blackbird Depredation Orr.

which was originally established by the U.S. Fish and Wildlife Service in 1949. And side note, I'm adding the Blackbird Depredation Order to my list of possible band names. The Blackbird Depredation Order would be a good name for like a goth rock or electro-industrial band. Right up my alley. So, anyway, this federal loophole allows individuals and government agents to lethally control, in other words, kill, red-winged blackbirds, along with cowbirds, grackles, and magpies, without a federal permit, as long as the birds are found, quote, committing or about to commit depredations upon ornamental or shade trees,

agricultural crops, livestock, or wildlife, end quote. Hmm, interesting. One question, though, how do I actually know that a bird is about, to commit depredations. No, with such certainty that I feel justified in murdering the bird in question. Is there a particular look on the bird's face? A mischievous gleam of depredation intention in its shiny little eyes? Perhaps not surprisingly, there's some controversy around this depredation order.

Some conservation and animal welfare groups argue that it's overly broad, essentially providing a blanket license to kill a protected native bird without oversight or proof of actual crop damage. Conservationists argue it violates the spirit, if not the letter of the law, that is the Migratory Bird Treaty Act. And it turns out that lethal control is not very effective anyway. Because red-winged blackbirds have massive continental populations and a high rate of natural annual terms, turnover, making it difficult to remove enough individuals to really put a dent in their populations. Even when millions of birds are killed, the impact is often marginal because the survivors experience density compensation, where they have better survival and higher reproductive success

to fill the gap. Also, these birds are extremely mobile. If a group is removed from a specific roost, new birds often quickly move in to take their place, filling the void. Killing large numbers of birds is also expensive and often results in the accidental death of non-target species. Because of these biological and logistical hurdles, many experts have concluded that blackbird culling programs don't really provide an economic benefit to farmers. So the good news for us bird-loving hippies is that non-lethal management strategies are more practical. Red-winged blackbirds have an interesting breeding system called territorial polygyny.

This is where one male establishes a territory, then he mates with two or more females that nest on his territory. A single male might have a so-called harem of up to 15 females, but two to five females per male is more typical. So we have territorial polygyny. At least that's what seems to be going on to the outside observer. It looks like polygyny. But the situation is often more complicated because ornithologists have used genetic data from DNA to test the parentage of red-winged blackbird chicks. And their research has discovered that 25 to 50 percent of the chicks in a male's territory are not his own. So it turns out that the Red Wing Blackbird is actually a Polyginandris species. Polygenandri is the breeding system where both males and females mate with more than one partner.

Females choose their mates based on territory quality. The best territories have great access to resources like food and water, and they're relatively safe from predators. At the beginning of the breeding season, a female prospects for a good territory. And then she settles in without the need for complex courtship interactions with the male holding that territory. But when he realizes he has a new female, he's pretty jazzed, he gets excited and performs his song spread display. If you spend any time around red-winged blackbirds, you'll see males making the song-spread display. While singing, a male fluffs out his epaulet feathers and his body contour feathers, so fluffing up his whole body,

he sticks out his wings and he lets them droop downward, and he spreads and lowers his tail. That's the song spread display. Now there is one form of courtship behavior seen in these birds, and that is sexual chasing, where a male will pursue a female at high speed. You'd think that those bright red and yellow epaulettes would surely have evolved as a signal meant to impress females. You know, as secondary sexual characters driven by sexual selection, I did a whole podcast episode on that topic, this would be where the females choose to mate with males who have the brightest, biggest epaulettes. But as I understand it,

female red-winged blackbirds do not appear to consistently choose males based on the size or color of their epaulets. Instead, it seems the epaulets have evolved as the result of intracultural selection, specifically competition between males for territory, rather than direct female choice based on the qualities of the patches themselves. Research has shown that these feathers are super important to a male for maintaining his status among other males. For example, in experiments where the epaulettes were dyed black, up to 64% of males had their territories taken over, usurped, compared to only 8% of control subjects that had normal red epaulets. And interestingly, males with experimentally blackened epaulets can still successfully attract females and reproduce as long as they have good territories.

So, yeah, territoriality is a big deal to male red-winged blackbirds. After all, a male needs to find and defend a high-quality territory if he has any hope of breeding with even one female. The male defends the boundaries of his little kingdom by regularly performing his song-spread display. He'll perform this display to no one in particular, but he definitely does it for any male flying over his territory or any male perched nearby. And he'll mob and dive-bomb any potential predators near the nests in his territory, because he's all hopped up on hormones. In a fit of roid rage, a male red-winged blackbird will chase and attack

not just interloping birds of his own species, but any other bird. If you do a quick search on the internet, you can find fantastic photos of male red-winged blackbirds seemingly riding on the backs of birds like red-tailed hawks and bald eagles. But the male isn't going for a joyride. No, he's digging his tiny claws into the back of that much-lawful. larger bird to express his white-hot fury, to chase off what he thinks is a threat. But the wrath of the blackbird is not limited to avian foes. Other vertebrates like reptiles and mammals also get swooped upon and attacked. These birds are known to go after dogs, cats,

horses, and yes, people. For example, I found a Reddit post with a comment by a user named Sunsprout. Referring to red-winged blackbirds, the commenter said, They are notorious at my mom's old work. They nested by a bridge that had a ton of foot traffic, so people were always getting attacked. One time a guy got swooped on and fell and broke his arm, and then a lady nearby saw it and fainted.

Two ambulances for one swoop of a bird. Such is the drama that can unfold in the presence of territorial blackbirds. When it comes to the nest, it's the female that chooses the site, though a male might perform a symbolic nest site selection display. He helps a female choose a nesting spot by picking up and shuffling some nesting materials around, and although the female is the only one who actually builds the nest, this symbolic nest site selection display is the male's way of suggesting potential locations for her to consider. There's some interspecies conflict that has to do with nest site selection.

Another species, yellow-headed blackbirds, often live in the same wetlands as red-winged blackbirds. The two species struggle to share space during the nesting season. The yellow-headed blackbird is a habitat specialist, meaning it's strictly limited to building nests in large open marshes with standing water. In contrast, the red-winged blackbird is much. more adaptable and can nest in a wide variety of places, including dry land or even high trees. But both species prefer the deep water at the center of the marsh, because that location offers the best protection from predators and easier access to food like damsel flies.

So the two species fight for control over the deep water habitat. In a head-to-head battle, you're going to want to place your money on the yellow-headed blackbird, because this is a bigger, beefier bird. Almost every time it's going to chase any red-wing blackbirds away, forcing the latter to nest in the mid-locations, the less desirable ones along the edges of the marsh. Timing also plays a key role in this war between the species. Red-wing blackbirds typically arrive at breeding grounds

about two weeks earlier than their yellow-headed rivals. That allows the red wings to claim territories before the other birds show up. Enjoy it while you can, Mr. Red Wing, because your head start is only temporary. Because once the yellow-headed bruisers arrive, they can take over the best nesting spots in as little as six days, quickly displacing the red-winged blackbirds. Ultimately, red-winged blackbirds are able to survive alongside their more aggressive neighbors because they're flexible enough to use many different habitats that the specialized yellow-headed blackbirds just aren't interested in. Female red-winged blackbirds build their nests alone, typically completing the process in three to six

days. The construction occurs in four main stages, starting with the female weaving long, stringy plant fibers around several vertical stems to create a sturdy support, and often those are the vertical stems of cat tails. Then the female makes a base platform using coarse wet grasses or other marsh plants. After the platform is ready, she builds the outer structure of the bulky open cup using wet leaves and maybe some bits of decayed wood. To finish the whole thing off, she adds an internal lining of mud and a final soft layer of fine, dry grasses. She'll lay one pale, bluish-green egg per day until she has a clutch of maybe three or four. Incubation is performed solely by the female, and that process lasts 11 to 13 days.

The hatchlings are altricial, so that means they're blind, naked, and helpless. The female provides most of the feeding and care, but the male might help with feeding, particularly later in the nestling stage and for larger broods. But if you thought that by this stage all that is, interspecies conflict had been resolved, well, think again, because marsh wrens and red-wing blackbirds also compete for the same nesting spaces in wetlands. Unlike the yellow-headed blackbirds, however, marsh-rens are smaller and weaker than the red wings. So wrens have to resort to covert black-ops missions. A marsh-ren will sneak into a blackbird nest to punch holes in the eggs or to

kill the young chicks. But the wren isn't there to eat the eggs or the chicks. It's only there to commit a war crime, to kill the innocent offspring of its enemy. In response to this threat, blackbirds are very aggressive toward wrens and will constantly chase them away from their territories. Because of this ceaseless fighting, both species tend to have less success raising their young when they are forced to nest near each other. Usually the red-winged blackbirds claim the best spots in the deep central parts of the marsh, which forces the wrens into the thicker bushes around the edges. Unless, of course, there are yellow-headed blackbirds in the area. If that's the case, the yellowheads get the very best prima real estate,

red wings get the so-so nesting spots, more towards the margins, and the wrens have to settle for whatever is left. Interestingly, some researchers hypothesize that red-wings Blackbirds began nesting in large groups as a way to better protect their nest from the attacks, the depredations, if you will, of marsh wrens. If the chicks can survive all of that avian drama, then they'll fledge when they're around 10 to 14 days old. Mean life expectancy for wild red-winged blackbirds is only about 2.14 years, and that's because of the high annual mortality rates, which is about 50%. That means that in a given year,

only about 50% of the birds will survive to the next. But the oldest wild red-winged blackbird that we know of lived to be at least 15 years and nine months old. I hope you'll agree that the red-winged blackbird is a fascinating species.

It's a polygenandrous breeder, a territorial maniac that takes on bald eagles and apparently puts humans in ambulances. It's engaged in endless war with yellow-headed blackbirds and marsh wrens, and it's an ecological generalist that has somehow thrived across an entire continent while driving farmers crazy and driving them to lethal retaliation. The fact that red-winged blackbirds' population has declined by more than a third in recent decades is a reminder that abundance is not the same as invincibility, and that even our

most familiar birds deserve our attention and our care. So the next time you're walking past a cat-tailed Martian spring, and you hear that iconic, strident, conclory singing out across the water, take a moment to appreciate it. Because that is one of the defining soundscapes of North America. And there's a whole lot of amazing science and natural history packed into the body of that little black bird making it. Well, that's a wrap on episode 135. If you ever wanted to learn more about the Red Wing Blackbird, I hope you found this episode satisfying.

I certainly enjoyed researching it and writing it. And now I really look forward to spending some quality time observing this species the next time I see it. Maybe I'll see it just as it's swooping in to attack my eyes with its stabby beak and its itsy-bitsy claws. Thank you as always to my wonderful supporters on Patreon. The support I get from my community on Patreon is why I'm able to keep making these episodes. Otherwise, I'd have to quit the podcast and make ends meet some other way, like opening

a hot dog stand or something. So if you would like to keep the podcast rocking and rolling, please consider supporting my work through Patreon. Check it out at patreon.com slash science of birds. And there's also a support the show link in the show notes in your podcast app. I always do my best to answer emails. I've currently got a bit of a backlog, so if you emailed me and I haven't gotten back to you yet, sorry about that. But if you have something you'd like to share with me, your thoughts about the podcast, or you'd like to suggest a particular brand of over-the-top military epaulettes for my consideration, that would be great. In any case, my email address is Ivan at ScienceofBirds.com. Again, this is episode 135.

You can check out the show notes for the episode, along with some curated photos of blackbirds, on the Science of Birds website, Scienceof Birds.com. Don't forget to check out Bird merch, my online store with a bunch of bird-themed shirts. I've actually got a red-winged blackbird design in the store, if you're feeling inspired by today's episode. You can check it all out at birdmerch.com. As always, I'm Ivan Philipson, and A True Fact About Me, I am an only child. And I suppose that's a true fact in itself, but the real story is that when I was between the age of about 7 and 13, I got into some real mischief when I was home alone. My parents always told me not to play with knives or matches.

Well, as soon as they drove off, guess what I did? That's right, I yanked open the kitchen drawers and went straight for the forbidden items. I was practically juggling knives and lighting all sorts of things on fire. Thankfully, I never hurt myself or caused any damage. At least not that I remember. But it's those kinds of memories that are one reason I chose not to have kids of my own. And mom, if you're listening, I'm sorry about the knives and the fire. But hey, I survived.

And with that, I say goodbye, my friends. Talk to you next time. I wish you all the best and all the birds.