The Science of Birds - Bird Habitat: Temperate Grasslands and Prairies

Episode Date: November 22, 2022

This episode—which is Number 64—is all about the importance of temperate grasslands as habitat for birds.When we say “temperate grasslands,” we mean those generally occurring in the middle latitudes.Temperate grasslands exist in several parts of the world. Some of them cover vast areas. Here in North America, we have the Great Plains as a “great” example.The steppes of Mongolia and the Pampas of South America are similarly vast temperate grasslands.Many, many bird species around the world depend on such grasslands for food and breeding habitat. Among them are raptors, sparrows, blackbirds, larks, pipits, a bunch of South American species in the ovenbird family, Furnariidae… and the list goes on. But, unfortunately, temperate grasslands are also among the most threatened ecosystems on the planet. Many of the bird species that call them home are, not surprisingly, also in trouble.Today, we’re going to dive into what makes temperate grasslands special, and why they’re so important to birds. I’ll give you several examples of bird species that depend on grassland habitats. And we’ll also talk a bit about grassland conservation. Because you know we can’t get through this without a little gloom and doom.Links of InterestLittle Bustard [VIDEO]Grassland Bird TrustAmerican Prairie ReserveThe North American Grasslands Conservation Act~~ Leave me a review using Podchaser ~~Link to this episode on the Science of Birds websiteSupport the show

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 64, is all about the importance of temperate grasslands as habitat for birds. When we say temperate grasslands, we mean those generally occurring in the middle latitudes. You know, the Goldilocks zone that lies between the tropics and the polar regions,

not too hot, not too cold? Temperate grassland is one type of biome. Examples of other biomes include tropical rainforest, tundra, and desert. Remember learning about biomes? If you're like me, you learned about them in elementary school. We made diaramas of biomes in my class. Do kids still make diaramas? Glue together some styrofoam, popsicle sticks, and construction paper to make a little 3D model in a cardboard box?

Anyway, I chose to make a diorama of a boreal forest. There was a moose in there and a grizzly bear both made out of Play-Doh. And a bunch of spruce trees, of course. It was pretty dope. In fact, I'm pretty sure it was the best diorama ever seen at that school, before or since. Not that I'm biased or anything, but forget about boreal forests. The biome of interest today is temperate grassland. Temperate grasslands exist in several parts of the world. Some of them cover vast areas.

Here in North America, we have the Great Plains as a great example. This enormous region covers about 500,000 square miles, or 1.3 million square kilometers. The steps of Mongolia and the Pampas of South America are similarly vast temperate grasslands. Many, many bird species around the world depend on such grasslands for food and breeding habitat. Among them are raptors, sparrows, blackbirds, larks, pippets, a bunch of South American species in the oven bird family, for nariadi, and the list goes on. But unfortunately, temperate grasslands are also among the most threatened ecosystems on the planet. Many of the bird species that call them home are not surprisingly also in trouble. Today, we're going to dive into what makes temperate grasslands special and why they're so important to birds.

I'll give you several examples of bird species that depend on grassland habitats. And we'll also talk a bit about grassland conservation. Because you know we can't get through this without a little gloom and doom, Sound good? No? Well, too bad. This is happening. Let's start by getting on the same page about the definition of grassland. We'll get to the birds, I promise, but first we have to cover the basics. So what exactly is? is a grassland, in general terms.

It's simple, right? You get a bunch of land and you toss some grass on there. Bam! Congratulations! You've got a grassland! Or maybe, bam, you've got a golf course. Or if you bury some human corpses in there, you've got a cemetery? Hooray! But seriously, one way biologists define grassland is simply an ecosystem with a continuous blanket of grasses, where trees and shrubs are rare. Basically, wherever grasses and similar non-woody vegetation are dominant. So the vegetation of a grassland can also include things like sedges,

rushes, and other herbaceous plants like wildflowers. Under the banner of the name grassland are some other familiar words we use in English. Plain, field, meadow, savannah, Prairie and Step. That's S-T-E-P-E, right? These words have some subtle differences in their meanings, but most are pretty much just synonyms for grassland. Like that popular TV show back in the 70s could just as easily have been called

Little House on the Grassland. Whatever you call, them, grasslands exist only where certain aspects of the physical environment, such as climate and topography, are just so. Precipitation is the biggest factor. Grassland vegetation is found in parts of the world where the amount of annual precipitation from rain or snow is too low to grow full-on forests, but it is high enough to prevent a desert from forming. Too dry to be a forest, too wet to be a desert. Grass-dominated ecosystems like this cover about 20 to 40% of the planet.

The percentage you get varies depending on how you define grassland. In any case, that's an enormous part of Earth's land surface. 20 to 40%. Wow. But not all grasslands are the same. There are several primary types. The two most widespread types, of grassland are temperate and tropical.

Tropical grasslands cover large parts of sub-Saharan Africa, South America, Southern Asia, and Australia. At some point, I'll do another podcast episode on tropical grasslands. But today, it's all about temperate grasslands. Perhaps the most important thing that distinguishes temperate from tropical grasslands is the range of temperatures they experience across the seasons. Temperate grasslands cover about 8 to 10% of the planet. They exist where winters are cold, but summers are hot, often hot and dry.

So plant and animal species in this ecosystem regularly have to deal with harsh weather, ice and snow in the winter, baking sun in the summer. But the rich, deep soils of temperate, grasslands allow for insane amounts of plant growth when it's rainy and warm, like in the spring. And much like the universal law of mo money, mo problems, one rule of thumb in nature is mo plants, mo animals. More plant biomass and diversity can usually support more animal biomass and diversity. So despite the annual extremes in temperature, this ecosystem can support an incredibly rich and complex diversity of animal life. Temperate grasslands are crawling with many

species of birds, reptiles, burrowing mammals, grazing mammals, predatory mammals, and of course invertebrates, worms, spiders, grasshoppers, beetles, bees, butterflies, and so on. Within this category of temperate grassland, there are further subdivisions we can make. For example, where the climate tends toward being more arid, we get ecosystems like short grass prairie and steppe. In other warmer regions with more rainfall, taller grass species can grow. Here in North America, our best examples of vast temperate grasslands include the California grasslands, Chihuahuan Desert Grasslands, and the short grass and tall grass prairies of the Great Plains. Any patch of grassland habitat in one of these ecosystems also exists on a spectrum

of disturbance. In other words, how messed up it is or isn't. At one end of this spectrum, a grassland is 100% natural, having never been defiled by the grubby hand of man. At the other end of the spectrum, a patch of grassland is classified as 100% agricultural, 100% messed up, completely transformed into crop land or whatever. In between these two extremes are semi-natural grasslands. We silly humans have sometimes labeled natural grasslands as quote-unquote unimproved land. Because clearly we improve the land when we come in and rip out the native plants, kill or scare off the animals, and then plant monocultures of our most profitable food crops. Nice try, nature, but let us show you how it's really done. We're going to get rid of

all those useless wildflowers, prairie dogs, and metal larks. What you really need here are some endless rows of corn. Maybe the slogan for our species should be humans. We make everything better. But anyway, these temperate grasslands, they cover about 8 to 10% of the Earth's land surface, right? That includes everything across the spectrum, from natural to agricultural. Besides North America, this ecosystem exists on all the other continents. Well, I mean, all of them except, you know, that one that's way down there, it's all chilly and whatnot. Yes, I'm talking about good old Antarctica. always the exception to the rule.

There are no grasslands in Antarctica. But there are temperate grasslands across large parts of South America and Eurasia. Africa too has them in the far southeast. And parts of both Australia and New Zealand have temperate grasslands. All of these ecosystems fall within the temperate latitudes. From one continent to the next,

grassland ecosystems contain very, different groups of plant and animal species. But these ecosystems are all dominated by grasses because they share a similar climate. Each temperate grassland gets too much rain to qualify as a desert and not enough rain to support the growth of forests. In general, they have cold winters and warm, dry summers. As plants go, it seems we often take grasses for granted. Most of us don't get too excited about them. I mean, I've got a field guide to the grass species of the Pacific Northwest on my bookshelf.

Collecting dust on my bookshelf, because have I ever gone out into the field to try to identify different species of grass? That, my friend, is a big fat, no. Grass is treated as a sort of filler. It's the blurry background for the things we're really interested in. Trees and other more charismatic plants, especially those with pretty flowers. And, of course, animals, including birds. But hear me when I say that grasses are amazing. As a group, they are a force of nature, one that has shaped the evolution of life across the planet.

Grasses are the species in the plant family, Poaceae. This is one of the largest and most successful plant families, containing about 12,000 species. Grasses have been around since at least the Cretaceous period, but grassland ecosystems are a relatively recent phenomenon when you look at the entire history of life. Grasslands first appeared roughly 30 million years ago during the oligocene epic, but they really got ripping during the Miocene, starting about 18 million years ago. Grasslands spread more rapidly at that time and kept on spreading well after the last glacial period ended about 10,000 years ago. Why did they spread? Well, remember that grasslands dominate in places where it's too dry for a forest but too wet for a desert. The global climate

has become progressively drier over the millions of years since grasslands first appeared. Dryer conditions have opened up more land area for grasses to take over. Massive mountain ranges like the Rockies and the Himalayas have grown up in that time. Mountains like these create dry regions called rain shadows, and then deserts and grasslands spread into those arid places. As grasslands expanded, many animals evolved to fill new niches out there on the plains. For example, grazing ungulates like horses, sheep, wildebeest, and bison evolved. Creatures like these form massive wandering herds that mow down the grass. But they also fertilize the grass. So grasslands co-evolved with such grazers in many parts of the world. It's the give and take of plants and animals interacting that

helps to maintain these ecosystems. Oh, and I should add that wildfire too is an important factor in maintaining grasslands. But there's another reason we got to show some respect to grasses, because they might be responsible for our very existence as human beings. Many anthropologists think grasslands played a role in the evolution of Homo sapiens. As forests in Africa gave way to more open grassy habitats like savannah, our ancestors moved from the trees out into the open. It's possible that one reason our ancestors evolved an upright posture was to peer over the tops of tall grasses to survey their surroundings. So if you've ever picked apples from a tree, thrown a basketball, or used a standing desk, you can thank grasses for your ability to walk on two legs.

Thanks, grass! birds too adapted to grasslands as these habitats opened up birds that moved into grasslands faced some new challenges compared to their ancestors who lived in woodlands and forests because if there's one thing that's conspicuously absent from grasslands it's trees well trees and shrubs and roller coasters I guess. There aren't really that many roller coasters out there. Several things are conspicuously absent from grasslands. The point is, there aren't tall objects where a bird can build a nest or perch while

singing. So some birds evolved to build their nests on the ground among the grasses. The pitch, tamber, and patterns of their songs changed too, so they could be heard over long distances in windy open landscapes. The song of the Western Meadowlark, for example, is an iconic sound in the grasslands of Western North America. One classic image of a singing metal arc is the bird perched on a weathered old fence post. Metal arks and other grassland birds like to get a little elevation above the grass to let their voices carry farther. Well, lucky for them that people came along to improve the land by putting up a bunch of fences everywhere. You're welcome, metal larks. Look at all the perches we made for you. But for real, though, grassland birds eventually evolved

new courtship behaviors in response to the scarcity of elevated perches. For example, males of some species, such as the skylarks, sing and display while in flight high over the grass. singing while flying takes an enormous amount of energy compared to just sitting on a perch but in the grasslands male songbirds may not have a choice if they want to be heard and seen by potential mates but why go through all the trouble of adapting to a life out there in the grass what was the original appeal of grasslands to birds

most likely it was food lots of food. The rise of grasslands around the world made available some new and plentiful food resources for birds. Insects like grasshoppers evolved and became super abundant in grasslands. For example, tall grass prairie in North America today can have over 3 million individual insects per acre. There was no way birds weren't going to notice all those insects. They swooped in to take advantage of this bounty of invertebrate prey. Grass seeds themselves

became a nutritious and abundant food for birds. These grains contain fiber, protein, fats, and important vitamins and minerals. Which is why we use grass seeds like oats, rice, and corn

as ingredients in the highly nutritious breakfast cereals we feed our kids. You know, nutritious and delicious selections like cap and crunch, cocoa puffs, and marshmallow fruity pebbles? My understanding is that these cereals are fortified with essential vitamins and minerals, and they're part of a complete breakfast. So we've been talking about the evolution of grasslands and grassland birds over millions of years.

Let's return to the present. Today, many bird species depend on grassland ecosystems, in one way or another. Some use grasslands for just part of the year, as a place to rest and refuel during migration, for example. Other bird species are more specialized, living in grasslands all year long. But just because a bird depends on temperate grassland habitat, that doesn't mean it sees all such habitats as being equally attractive, equally groovy. These habitats are more complex than they appear at first glance. You or I might look out at a vast, grassy plain and think it's pretty much uniform, monotonous, even boring. But to a bird, that same plane might be anything but uniform. More likely, the bird sees it as an elaborate tapestry, with lots of

variety in physical structure and biological resources. For example, there can easily be hundreds of plant and invertebrate species living in just a few acres of grassland. On top of that, there can be small and large-scale differences among patches of grassland, in terms of their moisture, vegetation density, vegetation height, litter density, and number of woody plants, and so on. Not so monotonous, it turns out. Such differences among habitat patches, even if they seem subtle to us,

can be very important to birds. For example, the upland sandpiper, Bartramia-Longicouda, seeks out grasslands of a particular flavor. This species breeds in North America. It requires dry grasslands or agricultural fields with only short grasses. The Upland Sandpiper also doesn't like there to be

too much woody vegetation like shrubs or too much bare ground. In contrast, Henslow's Sparrow, Centronics Hensloiye, is a North American species that needs large fields of tall, dense grasses for its breeding habitat. And this sparrow prefers there to be a deep layer of litter and lots of standing dead vegetation. Oh, and no woody vegetation, thank you very much.

Everything has to be just right for these finicky little buggers. I'm guessing a Henslow's sparrow will throw a tantrum if you don't cut off all the bread crust from its peanut butter and jelly sandwich. To be fair, though, there are lots of other grassland birds around the world with similarly narrow habitat requirements. But some species are just easier to please. Birds like the Vesper Sparrow, Savannah Sparrow, and Bobbolink, for example, all breed in a wider variety of grasslands and open habitats in North America.

And if you didn't already know, yes, there's a bird called the Bobolink. Some human modified grasslands can work well enough as habitat for Bobolinks and a number of other bird species. These agricultural fields may not be 100% natural, or even 50% natural, but they are still way better for birds than places like strip malls, industrial wastelands, or amusement parks. Now I'd like to give you the profiles of three grassland bird species. We'll spend a few moments looking at how each of these birds uses its habitat. First up is a North American species, the chestnut collared long spur, calcareous ornatus. This is a sparrow-like songbird in the family calcareidi.

The male chestnut collared long spur is a good-looking little dude. He's got a black and white head, a black breast and belly, and surprise, surprise, a chestnut patch of feathers on the back of his neck. For a grassland bird, that's a lot of contrasting bold color. The female is much more camouflaged, with an overall streaky brown plumage. She needs to stay hidden from predators while tending to her nest. Chestnut collared long spurs are birds of the short grass prairie in North America. Before Europeans showed up on the continent and started making improvements, these birds nested

at sites that had been swept by wildfire recently, or grazed by bison. Fire and grazing kept the grass short and sparse, just how the birds like it. Chestnut-collared long spurs eat grasshoppers, caterpillars, and grass seeds in the summer months, and nothing but seeds in the winter. During the breeding season, male longspurs establish territories in the grassland. A male makes an aerial song display. to mark and defend his territory. He flies up about 30 feet,

then flies around in undulating circles while spreading his tail and singing. His tail is boldly marked with black and white. After this impressive performance, the male long spur flutters back down a bit, then, without landing, he shoots back up to repeat the whole thing. He does this a few times. So here's another example of a grassland bird

that takes to the air to sing and display. This is the way to do it when there are no trees or other high perches around. When fall arrives, chestnut collard long spurs head south to spend the winter in prairies and desert grasslands in the southwest of the U.S. and in northern Mexico. The current estimate for the total number of chestnut collard long spurs on the planet is about three million. That might sound like a lot, but there used to be way way. more. This species has actually lost over 80% of its population since the 1960s. There are multiple

reasons for this precipitous decline, but the biggest one is loss of habitat. Across the Great Plains, enormous amounts of native grassland habitats have been converted to agricultural land. Chestnut-collared longspers can and do breed in some semi-natural cultivated fields. But research has shown that the birds nesting at those sites produce significantly fewer young compared to birds nesting in natural grasslands. So for the conservation of this species, protecting the remaining natural grasslands is critical, as well as habitat restoration. The chestnut collared long spurs status at the global level is currently near threatened, as determined by the IUCN. But it's listed in,

as an endangered species in Canada. Other North American birds that similarly depend on grasslands include the lesser prairie chicken, mountain plover, long-billed curlew, sprague, sprague, and baird's sparrow. Let's zip over to Eurasia to look at our next species, the little bustard, Tetrax, Tetrax. In case you misheard me, I said Little Bustard, you know, like when you catch your dog in the act of digging up your flower garden and you say, you little Bustard, it's a euphemistic term of endearment, let's say, or something like that. Bustards are birds in the family Otidity. They're heavy-bodied groundbirds that look to me sort of like a cross between a crane and a pheasant. But Bustards aren't closely related to cranes or pheasants. The closest relatives of Bustards are actually the cuckoos.

That's right, cuckoos. Pretty wild, right? The little Bustard is approximately chicken-sized. The breeding male is mostly white with a mottled brown back. His face is blue-gray and his long neck is decorated with a few bold black bands. Here's one sound made by the male little buster. It's a short staccato sound he makes with his bill. This species breeds in parts of western and central Asia and in southern Europe. One of its primary strongholds is the Iberian Peninsula in Spain and Portugal.

These busters need open grasslands and pastoral land, where the vegetation is high enough to provide some cover, but not too high. They can do okay in some agricultural areas, as long as the farming is low intensity. But Little Bustard Habitat is disappearing in Europe and elsewhere. Natural grasslands, already rare in Europe, are still being converted to agricultural land. And there's also a massive trend toward intensive industrial cultivation. That is no bueno for our little Bustard friends. This species, too, is in decline. Other Eurasian species dependent on grassland and pastoral farmlands include

black-tailed godwit, common snipe, black-bellied sand grouse, great-bustard, Calandra lark, Eurasian skylark, and corn bunting. The third and final species I want to tell you about today is a South American bird, the chocolate-vented tyrant, neoxal miss Rufaventress. This is a member of the family Tyrannity, the tyrant flycatchers. The chocolate-vented tyrant is about the size of an American robin. thrush-sized. It's a beautiful bird with its gray head and breast and that signature

chocolatey cinnamon-colored belly and vent. In flight, the wings show a bold pattern of black, cinnamon, and white. This bird spends most of its time walking around on the ground, among short grasses on the Patagonian steppe. This vast ecosystem, the Patagonian Steppe, is in southern Argentina and Chile. It's a dry, dry, windy, and often cold place. Large beetles, other insects, and lizards make up the diet of the chocolate-vented tyrant. The male makes an aerial display in the breeding season. He shows off the beautiful pattern in his wings.

Here's the subtle song of the male chocolate-vented tyrant. Grassland habitats in the pattern. Patagonia step have suffered from destruction by grazing sheep. The chocolate-vented tyrant isn't currently considered a threatened species, but it seems to be thriving only where native grasslands are protected from grazing. The temperate grasslands of South America are home to many other bird species, such as the lesser Rhea, tawny-throated dodderal, black-faced ibis, and band-tailed earth creeper, to name a few.

Temperate grasslands are one of the most endangered types of ecosystem on Earth. By one account, over 300 million acres of grasslands in North America have been converted to agricultural lands. That's about 1.2 million square kilometers, which is the size of the country of Peru, or more than seven times the size of Florida. We've converted about 50 million acres of grasslands in North America in just the last 10 years. Converted, destroyed, improved, however you want to say it, we've lost that natural habitat, quite possibly forever. Massive industrial-scale agriculture in the United States and Canada is the worst offender. Giant fields of monoculture crops, sprayed with pesticides, these.

are pretty much wastelands for birds and other wild animals. This kind of agriculture is less common in other parts of the world, but it's on the rise. The opposite, traditional small-scale farms and pastures, can still support a lot of birds and other wildlife. This kind of agriculture is still the norm in some regions, even today. But hey, the global human population just hit 8 billion. Eight billion people. That's a lot of mouths to feed. And the population just keeps growing. So it should

come as no surprise that we've destroyed so much of the world's grassland for food production. This includes conversion to both crop lands and grazing lands for cattle or whatever. Where grasses grow naturally on flat or rolling land, the soil is often deep and fertile. These are the places where our domesticated crops grow best. In fact, many of our most important crops are themselves grass species. Corn, wheat, rice, and barley are all grasses. Our beloved amber waves of grain. America, America. You know all that. We got to grow those grains. so our factories can keep cranking out boxes of cocoa puffs and fruity pebbles. Unlike a bowl of breakfast cereal, I'm not going to sugarcoat the situation as it stands for birds.

Grassland birds have been and continue to be hammered by habitat loss around the world. Long-term population studies of North American birds have revealed that grassland species have had the most dramatic losses since 1970. That's compared to all other groups, forest birds, desert birds, wetland birds, grassland birds have suffered the most. But this isn't just something happening here in North America. The biggest losses of birds in Europe, for example, are among those species that depend on grasslands and traditionally cultivated fields.

As industrial farming is taking over there, the birds are disappearing fast. Humans, we make everything better. Besides the threats of expanding agriculture and overgrazing, some grasslands have been lost because of changing fire regimes. Either there are now too many fires or too few. Grasslands can disappear when fires are suppressed. Without a natural fire regime, trees and shrubs can encroach on a grassland, converting it to a woodland or forest.

Periodic fires can keep these woody plants from invading. You can see that the situation for grassland birds is dire. You would probably agree that we need to make major efforts to conserve them. Thankfully, there are conservation organizations out there fighting hard to save grasslands and the birds that depend on them. For example, there's the Grassland Bird Trust and the American Prairie Reserve. I'll put links to these in the show notes

if you want to check them out. There might also be some conservation programs like these near where you live. Here's a quote from the recent State of the Birds report put out by the Cornell Lab of Ornithology. Quote, massive losses of birds can be reversed with voluntary incentive-based programs powered by partnerships, landowners, and indigenous nations

to restore grasslands using the successful North American Wetlands Conservation Act as a model. End quote. Since 1989, the North American Wetlands Conservation Act has helped to protect about 30 million acres of wetland habitats. The populations of ducks and other waterbird populations, have rebounded enormously, in large part, because of this program. This is a conservation success story. So it was good news to hear that some legislation has been introduced recently

to help grasslands using a similar strategy. The North American Grasslands Conservation Act of 2022 was introduced by a congressman right here in my home state of Oregon, Senator Ron Wyden. Hey, thanks, Ron. Good on you. The North American Grasslands Conservation Act is intended to work similarly to the Wetlands Conservation Act. It's an incentive-based program aimed at working with landowners to conserve and restore habitat. This is super important because, according to some sources, about 85% of America's grasslands are privately owned. I really hope this legislation

makes it through Congress and gets passed. And I hope that similar efforts are being made to protect grasslands in other parts of the world. Our meadows, prairies, and steps, and the wonderful grassland birds that call these places home need all the help they can get. Thanks for learning about grasslands with me today. I hope you feel inspired to go see some grassland birds. in their natural habitat. I sure am.

I can't wait to get back out there to see some bobbolinks, sparrows, pippets, metal larks, and all those little buggers. Or should I say all those little bastards? Huh?

I want to give a big thank you to all my supporters on Patreon. And hello to my newest patrons. Emily Claire Barlow, Roy Smith, Paul C, Matt Miller, Max Roth,

Shindy Yang, Annika Vaughal, and Randy Countryman. Thanks so much to each of you for supporting my work. You're helping me share the love of birds with people all around the world. If you, highly intelligent bird-loving person who is listening right now, have some interest in supporting this podcast, you can check out my Patreon page at patreon.com slash science of birds. You can reach me by email if you have something you'd like to share with me. Perhaps you have some thoughtful comments about the podcast.

Or you want to share with me what your favorite breakfast cereal is. Mine is probably Honeynut Cheerios. Or maybe Flaming O's. Remember Flaming O's? Let's not forget about them. In any case, my email address is Ivan at Scienceof Birds.com. You can check out the show notes for this episode, which is number 64, on the Science of Birds website, scienceofbirds.com.

This is Ivan Philipson, wishing you a great day. Peace.