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A Q&A with biologist Gordon Orians
Gordon Orians is a professor emeritus of biology at the University of Washington and served as a science advisor for BirdNote for many years. He spoke to BirdNote Daily’s Managing Producer, Conor Gearin, about what makes grasslands valuable, why they're so important to birds, why they're at risk, and how we can take action to protect them.
Grasslands are ecosystems dominated by grasses that also typically host a diverse community of wildflowers. Factors such as low precipitation, grazing mammals, and fire help prevent grasslands from becoming overgrown with shrubs or trees. Grasslands are the most at-risk ecosystem type in the world due to large amounts of habitat loss, posing a serious challenge to the many birds, mammals, insects, reptiles and more that call grasslands home.
Conor Gearin: How do grasslands differ from ecosystems dominated by trees and shrubs? Why are they valuable to birds and to people?
Gordon Orians: Grasslands are absolutely fascinating, and they’re rather new in the evolution of life on Earth. About 66 million years ago, a massive asteroid crashed into Earth just off the Yucatan Peninsula. It caused the extinction of the dinosaurs and an awful lot of birds and mammals. Who survived? Among the birds, it was the species that ate seeds, because even if you have a nuclear winter and all the plants die, seeds still last a long time. And the others that survived were the ones that fed on food in the sea, which could still be found after the asteroid.
So this reset things. We ended up with birds and mammals that were dependent upon new kinds of food resources. The evolution of birds and mammals, since 66 million years ago, has been intimately tied with the evolution of grasses, which proliferated after the age of the dinosaurs.
Grasslands occur in many places all over the world, but what characterizes the areas where grasslands persist is that the precipitation is low enough that disturbance can prevent woody plants from taking over. Historically, there have been two major kinds of disturbance: fire and big mammals. In the northern Great Plains, bison are what we call ‘ecosystem engineers’. Bison will graze some areas heavily, especially recently burned areas with lots of new growth, and leave other areas untouched. The result is a mosaic of grassland habitat with different vegetation heights. This combination of low precipitation, mammals, and fire, all working together, can hold back the invasion of woody plants.
Historically in North America, Native Americans managed vegetation by burning it, and that allowed them to open up forested areas, keep grasslands and decide where the new growth was going to be. Fire was the management tool in North America before Europeans came — Native Americans were very good at it.
Trees store carbon in wood, but grasses put it underground, in their roots and the soil. So when fire goes through, you don't get rid of the grassland, you just open it up. And because grassland plants store their carbon underground, that also creates rich prairie soil. Where I grew up in southern Wisconsin, there was historically a combination of oak woodland and prairie. And it's all farms now, but when I drive around, I can tell that it was oak woodland where there are brown soils and it was prairie where there are black soils.
And that's also why prairies are in big trouble now, because it's the world's best agricultural soil. For a long time, we couldn’t plow through prairie sod. It was too tough. And so early agriculture and civilization depended on river floodplains, where you get nutrients coming in from floods and there isn’t tough prairie sod. The problem is that now we know how to destroy grasslands with plowing.
CG: Can you introduce us to the bird community that lives in grasslands? What makes them special?
GO: Grasslands are great places for birds whose babies hatch and start running around right away, because they can find cover in the grass. Grasslands are full of grouse as well as shorebirds that have babies able to run around. What better place to raise them than in grasslands? In the northern Great Plains, there are big shorebirds such as Long-billed Curlews and Marbled Godwits, as well as smaller sandpipers. A lot of birds that you think of as shorebirds that are on the beaches in the winter actually go into grasslands to breed, because there are good places for their young to hide.
And then there are the songbirds such as meadowlarks and Grasshopper Sparrows that have babies that grow up in a nest and have to be fed by their parents. To find a good place to hide a nest, they depend on the vegetation structure of the grassland. This can be hard for us to see, because we’re a big mammal looking down at the grass. That's not how songbirds see it. I've tried to get down on the ground and look around between the grasses, but I'm not a very good sparrow. Very slight differences in the structure of that vegetation influence which birds are there. That's why, when you have grazing by big mammals that leads to a variety of heavily grazed spots, lightly grazed spots and un-grazed spots, it creates a mosaic with habitat for a lot of different species of birds.
The other thing that's interesting is that a grassland is a wonderful place to be a hawk, because there's not a lot of tree cover — so grasslands are favored by hawks, eagles and owls. There are plenty of rodents and other small animals they can hunt there.
Grasslands have a rich bird community that is quite varied depending on the structure of that vegetation. There are many more species of birds breeding in the grassland than you might think, and they have very special requirements. And we really don't understand them too well, because it's hard to see a grassland the way a sparrow does.
CG: What do people tend to misunderstand about grasslands?
GO: People often don't understand that grassland productivity increases when they are grazed. Grasses grow from the bottom, rather than from the top like trees and shrubs, so grazing grasses doesn’t kill them, it just makes them grow faster. Now, there are some problems with the way we raise cows and all the beef we eat — that's true. Grasslands that are grazed heavily all over become uniform and less diverse in structure, and there are far fewer species of birds there than in the natural grassland where you get this incredible mosaic.
Still, you want grazing animals in grasslands. We want to get bison in as much land as we can, but we want to keep cows on the rest. I'm working with the World Wildlife Fund in the Northern Great Plains, and we have a sustainable beef program that tries to encourage the ranchers out there to use their cows to create that habitat variability.
If you can't make money raising cows out there, you’re going to have cornfields and an ethanol factory, and you're going to produce vegetation to feed cars, and that's not a nice alternative for grasslands. I've been working with ranchers out in the prairie that think we're out to put them out of business because they perceive environmentalists as trying to get rid of cows. Well, cows can be bad, and they can be mismanaged, but large grazing mammals that graze heavily is what makes grasslands what they are, and there's a lot of misconception about that.
CG: What are some of the main threats currently facing grasslands?
GO: The biggest threat is plowing up grasslands for agriculture. It was rather recently in history that we developed the ability to bust the sod with a plow. And that created the biggest problem in grassland conservation.
We have to learn to appreciate that grasslands have these other values — their beauty, the variety of species that live there — and decide we don’t want to plow up all of them and raise food on all of them. But this is a hard thing, because we have a lot of people we're trying to feed. I've talked to ranchers who say, you want to set aside some grassland, and all these people are starving? Why do you want to do that when you could raise more food on them? That's a legitimate question.
However, the vast majority of the grasslands in the American Midwest are growing corn and soybeans, very little of which we eat. Mostly it's going to become feed for livestock raised in feed lots, or to produce ethanol. Part of the problem is that cows aren't adapted to eating corn kernels. They evolved to eat grass. And you have a lot of trouble with cows getting sick because their digestive system is not set up to eat corn.
This is why reducing beef in our diets is very important for the maintenance of grasslands. If the demand for beef stays high worldwide, you're going to use grasslands to raise crops that feed cows, rather than raising cattle on the grasslands themselves. So eating less meat globally, but not zero. I lived for a while in Argentina where all the beef was grass-raised. It’s lower productivity than raising cattle on corn, so there's a sacrifice there, but the answer to this relates to how we manage our diets worldwide. That’s why I’ve been working on the sustainable beef program, which gives special prices for beef for ranchers who are raising them in ecologically sensitive ways, and making it profitable to stay on the land and have the cows there.
CG: What are some of the good strategies you've seen for protecting grassland habitat? Are there developments that have given you some hope that more grasslands will be protected in the future?
GO: One thing I’ve seen that’s provided hope is people developing an appreciation for the aesthetics of grasslands — that they're beautiful and dynamic places. I've been working with the World Wildlife Fund program in the Northern Great Plains, where we are having some success in bringing back bison in places so we have natural grassland ecosystems. And that depends upon tourism. People want to see the bison herds, the pronghorns, the wolves and the bears chasing them. Similarly, it's tourism that keeps the Serengeti going in Africa. Millions of people will spend a lot of money to come to see those big herds, the grassland landscape, the birds and all the wonderful things there. We have to develop an appreciation among people about how grasslands are wonderful places to visit. You get to see stuff you don't see anywhere else.
CG: How can BirdNote listeners get involved in supporting and conserving grassland habitat?
GO: I think it's so important to get people out so they can develop an emotional appreciation for grasslands. You can't mourn the loss of something you didn't even know you had. If you've developed some appreciation for grasslands and other ecosystems, then take people out and show them, because there's nothing like the real experience.
Vote for the people who care about this. The simple act of voting is important because as long as we vote for people who are devoted to growing corn to make ethanol for cars, that's what we're going to get. And support the organizations that are working for the things that you care about.
We’re all different, we have different needs and different opportunities, so there's no one right way to take action, but you look for the opportunities that come your way, due to the way you live and the values you have, and you find out what works for you. But do it!
CG: Do you have a favorite memory of the grasslands that you've spent time in?
GO: I have a number of memories that are really powerful. One was in Montana, in the tent in the prairie at night, listening to the coyotes and the Great Horned Owls calling, listening to the nighthawks booming and the frogs calling — just lying there and listening to nature. Many of my really interesting experiences have been at night when I turn everything off and just listen. Nature's sounds are so wonderful. I cherish those experiences. I don't get enough of them now, because I'm a city guy now, and my mobility is not such that I go tromping around like I used to, but I've had marvelous experiences in grasslands, and I hope there’ll be grasslands around for a lot of people to have those experiences too.
Gordon Orians is a professor emeritus of biology at the University of Washington, served as a science advisor for BirdNote for many years, and has contributed to a number of BirdNote shows. In addition to his research in behavioral ecology, he devoted much effort to the interface between science and public policy. He was director of the University of Washington's Institute for Environmental Studies for 11 years, served two terms on the board of directors of the World Wildlife Fund-US, and is currently a member of the board of directors of Audubon Alaska.