IT’S NOT UNCOMMON to see a public-television program or magazine article about the impact human development is having on wildlife, typically set in a national park, or wildlife refuge–an undisturbed and astonishing habitat unlike any you could imagine living in yourself. Though we hear a lot less about urban ecology, it’s not always the case that the least-disturbed places on earth always have the most birds. In fact, says Dr. John Marzluff in his book “Welcome to Subirdia,” the greatest variety of birds is often found in the suburbs, where we humans are in great density, too.
It’s certainly true that not all birds do well living with us—but some species have adapted and actually even thrived. So why is that, and what can we do as human neighbors to foster more such success stories?
Marzluff is a renowned ornithologist and urban ecologist, and professor of wildlife sciences at the University of Washington. “Welcome to Subirdia: Sharing Our Neighborhoods With Wrens, Robins, Woodpeckers and Other Wildlife,” from Yale University Press is his fifth book. In his research, he applies a behavioral approach to conservation issues and has particular expertise in crows, ravens, jays and their relatives, as well as birds of prey, and also in so-called pest species of birds.
He joined me on my public-radio show and podcast to talk about birds that do, and don’t, do well with us, and why. Read along as you listen to the Oct. 26, 2015 edition of my public-radio show and podcast using the player below. You can subscribe to all future editions on iTunes or Stitcher (and browse my archive of podcasts here).
my q&a with dr. john marzluff
Q. As you point out, by 2050, two-thirds of humans are going to live in cities. So we’re moving into greater density, but how are the birds going to do? I suppose what I was most surprised about in your book, John, is how optimistic the tone is. Even though you’re candid about the rate of songbird decline in some environments, there is a lot of enthusiasm and positive thoughts in this book, too.
A. I’m glad you pick up on that. It is an important aspect. There is a great diversity of birds, and plants as well, in urban areas, and to just write that off and not celebrate it I think is a mistake.
Q. You spend a lot of time not just doing your research in the wilderness, but in fact tracking birds in the suburban and even urban environments.
A. I enjoy the wilderness as much as anybody, and get there whenever I can—and certainly as you pointed out, there are some birds and many mammals that absolutely require that. But much of our research has been right here in the kind of urbanizing front of Seattle as it grows east into into the Cascade Mountains, and trying to understand how the bird communities change there and what it means for the people who live there as well.
Q. Maybe midway through the book you write: “Rapid, explosive evolution in response to the novel environments humans create is the new normal.” As a lay person, I think of anything involving evolution as taking centuries or millennia, but you’re talking about something different: about birds demonstrating successful strategies for changing faster.
A. It’s been well documented in insects and fish—rapid evolutionary changes in the matter of a few decades. Now we know that’s also the case for some birds. The places you expect that rapid change are where natural selection is acting strongly, and that’s in our urban places, among others. Here, because of our actions—the pollutants we add, but also the opportunities and changed land covers that we provide—those are strong selective forces on the animals that are able to survive with us, and they change accordingly.
A. An example of each: There are a lot of behavior changes. Those are the first steps in adapting and evolving. One of my favorite behavioral changes involves some of the birds who are taking advantage of some of our new food situations. For example, we have a bird here called the Brewer’s blackbird [above], which lives in open areas. In our part of the world its preferred habitat as far as I can figure is a Costco parking lot.
A. These guys love these parking lots and the little fringe of shrubs around them. I was curious how they didn’t get run over, living in these parking lots as they do, right around your car.
So I went early one morning to study them, and the birds weren’t there. In fact, they didn’t show up till 5 minutes of 10, and the store opens at 10. These birds had learned our schedule and were there just in time to line up with the first shoppers, and sneak into Costco just as the doors opened. They get into the café and eat; they stay warm and dry, and they have behaviorally adapted to this activity of ours and this place of ours.
Q. Wow. So that’s a rapid behavioral change to a new food opportunity and a new situation.
A. A good example of a morphological, or physical, change involves the dark-eyed junco, which many people call the snowbird [below]. As they’ve come in to live more and more in our cities and even breed in a lot of our suburbs, they have a different strategy there. The females are exerting a strong force on the coloration of the males, and in the wild parts of their range, the females prefer males that are very aggressive—and an aggressive one is also one that has a lot of white feathering in its tail.
That pays off in the wild lands, because you want a male that can defend the territory you’re breeding in as a female, so you can raise your one or maybe two broods a summer. But in the suburbs, a female junco can pull off three, four, five broods a year—and the females there are selecting for males that are not so aggressive, but for males that are more mellow, more able to withstand the stress of the urban environment, and more attentive to their young.
These males have less white in their tail—because the males flash the white in their tail when they are aggressive. Over time, in 20 years in San Diego, an awesome study done by Pamela Yeh showed that the amount of white in the junco’s tail has evolved from about three feathers to just over two feathers.
Q. In just 20 years? That’s a fast physiological change.
A. And they’ve changed their ability to respond to stress as well.
Q. A small detour: You were talking about male and female juncos, and I have to admit even though I am surrounded by juncos in large numbers in the wintertime, I don’t really know the males from the females. I just think of the bird as having that white flash in its tail when you see it fly away. Are they easy to tell apart?
A. There are so many different morphs of juncos, they are a little bit confusing. In general, most of them have a sort of dark hood, a lighter underbelly, and a dark back. The contrast with that hood and the underbelly and the rest of the bird is striking in a male, and it’s not as striking in a female—it almost looks like they don’t have a hood.
Q. So it’s the intensity of that compared to the rest of the bird. I’m going to look more closely as everybody settles in for feeder season at my house.
A. And see if you can see how much white they have on their tails when they flick them.
Q. Now again: not to paint too rosy a picture, not every bird is able to do what the Brewer’s blackbird or the dark-eyed junco did in those examples. Some birds have not found this kind of adjustment easy. Are there some examples, by contrast?
A. In general, Rob Blair at the University of Minnesota has called these “avoiders” of urban areas. I think it’s a good way to think about it. They decline in our presence. They include some birds that are fairly common elsewhere—like the hairy woodpecker—but it declines generally around us. A few will live with us, but most don’t.
Another species that’s familiar to most of us in North America is the Wilson’s warbler, a small yellow bird with a nice black cap in the male. It nests on the ground. It migrates down to Central America and Mexico. This bird also declines in our presence.
Cavity nesters—woodpeckers in general—a lot of them have trouble around us because we don’t leave enough dead trees. And ground nesters also like the warbler have trouble because of more predators on the ground.
Q. So there are common factors that explain why certain species become avoiders, or cannot make these quick adjustments—perhaps because of their reproductive habits, as you were just saying.
A. And also they’re just generally less flexible in their behavior. Think about a crow, a bird that really does well with us—extremely flexible and can eat just about anything and nest just about anywhere.
Q. [Laughter.] They can eat anything. My sister loves to call me when she has put out pizza crusts from the night before onto her compost heap, and she’s like, “They’re flying away with the pizza crusts, Margaret.” It has become a family joke, when “her crows” are having pizza. They’re amazing and so talkative.
Some other adaptable birds—are songs sparrows adaptable? That’s a bird that appears in the book a number of times.
We captured and marked thousands of these birds with bands. We found the same bird coming back to the same place year after year, and breeding in people’s backyards. Even in newly developing subdivisions where the land cover had gone from basically forest to a suburban setting in a few years, the song sparrows and towhees stuck right with it, and made use of the new resources that we provide in feeders and things like that, and also of the new juxtaposition of forest and kind of edgy landscaped land cover.
Q. I loved that you opened one section of “Welcome to Subirdia” with a quote from Aldo Leopold—the conservationist who is often called the father of wildlife management. He said: “My land is a community.”
I think over all that’s a great philosophical answer to what can we do as humans to make a more hospitable environment—to think of our land as a community—but there are also practical things we can do that you recommend.
A. I think valuing it as a community and not simply as a commodity, as Leopold said, is the underlying philosophy of a sustainable land ethic that definitely applies in our suburban as well as our agricultural settings, where Leopold was concerned.
In the suburban areas, we can do things to increase the quality of land for birds. The simple thing is to increase that diversity, and make it even more diverse. With respect to the places we live, grass is kind of the enemy of diversity. [Laughter.]
Q. It sure is.
A. It’s a uniform, two-dimensional thing that doesn’t support full life for any particular bird. Some may forage there, but none do everything there.
Q. It doesn’t support insect life, either, and aren’t the majority of birds at least in part insectivorous?
A. Especially in the breeding season, when they are raising young.
Q. If you don’t grow bugs, you can’t grow birds. When I get completely basic, that’s what I say when I am marching around the garden trying to figure out what I can do to make it better for the birds. I think: Grow more bugs.
A. I think that’s absolutely the key, and we know from studies that native vegetation has more bugs that are relevant for birds than non-native vegetation. But even non-native vegetation does produce a lot of good things: berries, nuts, nectar, and some bugs that birds use. So that’s a better step than grass, but the best would be to go to a more native vegetation. It adds structure—places to hide and nest—as well as food.
Q. You talked about the two-dimensionality of grass, and where we have grass meets a 40-foot tree, there is something missing—that ecotone, that edge, is missing, and it’s so important.
A. It’s easy to add, and it’s beautiful when you add it. It takes away from that sort of savannah look that people like, but it adds to the complexity that the rest of nature requires.
Q. As a gardener for many years, I do have many non-native plants in my Northeast landscape. This year a new one on me this year was to watch a native bird interested in a non-native plant I’ve grown for a long time, a large Southeastern U.S. native shrub called Aesculus parviflora, or bottlebrush buckeye.
I watched a group of orioles at its flowering time in July, investigating the flowers, as I see them do at apple blossom time and wild cherry blossom time in spring. As you said, sometimes things aren’t exactly native but there can be wildlife interest.
A. They can provide important resources like that, and it also provides birds the opportunity to adapt to these new food resources. A lot of hummingbirds have adapted to our non-native plants for the same reason that you describe with the oriole, and that has allowed them to shift their range and live more with us.
A. Again, in that same vein of habitat, allowing dead trees or parts of trees to remain. [Above, topped dying birch “snag” in Margaret’s garden.] That’s key for woodpeckers. And woodpeckers are facilitators in their ecosystem—or I should say our ecosystem. In that way, they’re drilling holes or putting sap wells in trees that other animals use, or that things like chickadees or nuthatches and swallow nest in.
So having a more healthy woodpecker population buys you more than just woodpeckers—but they need dead trees.
Q. Even if you don’t have a snag, a standing dead tree, leaving some brush—just not being quite so scrupulously tidy can be helpful, yes?
A. Very, very helpful. I think brush piles are key. The species that we share, the winter wren in your part of the world and the Pacific wren here, requires those brush piles. It’s a small bird with a great song that you can enjoy, but it’s not going to be there if you don’t have some brushy areas.
Q. I look forward to the winter wren every year.
I want to talk about two points that are very important in the book, and they’re really things you recommend to limit the death of birds, as opposed to feeding and so on. It’s hard for people to believe, but give us some of the numbers of the effect on birds of cats and window strikes.
A. Cats that roam outside have been estimated to kill between 1 billion and 4 billion birds per year in the United States. That’s about 1 in every 10 birds killed by a cat. And that’s a preventable death, for sure. And cats also live longer inside than out, so it’s better for the cat. If your cat is an outside cat, you can consider leashes, or catteries [secure outdoor pet enclosures like “catios“] or bibs and things like this that can be put on them to reduce their ability to catch birds.
But even if they’re out and wandering around and not catching them, they’re disturbing nesting birds and that leads to nest failure in a dramatic way. Keeping our cats inside is rule Number 1, if you want to help your local birds.
And the window strikes you mentioned is the second-leading source of mortality for birds in the world. About a half a billion birds per year are killed in the United States by colliding with our residential windows. The typical house might take out two or three birds a year, which I’m sure many listeners might appreciate as, “Yes, that’s about right for what I’ve seen.”
You can reduce that mortality by having screening, or netting on the outside works really well. Or even ultraviolet reflective stickers, which don’t obscure our view too much, but make the window visible to birds because birds see in the ultraviolet spectrum as well as the visible spectrum that we see in.
Q. The netting has to be stretched tight and a little away from the window?
A. What I’ve heard is the most effective: Think about cup hooks on the outside surrounding your window, and take the netting you’d normally put on your shrubs to keep birds out of the berries. You’d stretch it very taut. It’s virtually invisible looking out, and birds either see it or they’re cushioned, like a trampoline. It’s very effective, especially when you have a window that a lot of birds hit or is close to a feeder.
Q. I’ve started putting my feeders in excess of 25 or so feet away from the house, or right next to it—which seems to help.
A. Planting vegetation on the outside, but not having plants on the inside that the birds see will help, too. They’ll land in front of the windows instead of going to what appears to them as a plant that’s right there but is separated by the glass.
enter to win ‘welcome to subirdia’
I’LL BUY one lucky reader a copy of “Welcome to Subirdia: Sharing Our Neighborhoods With Wrens, Robins, Woodpeckers and Other Wildlife,” by John Marzluff. To enter, answer this question in the comment box below, scrolling all the way to the bottom after the last reader comment:
Tell us if your garden is urban, suburban or rural (or however you wish to describe your location), and what your most effective bird-supporting efforts have been so far. It can be a plant, a management tactic, or something else.
For me? Definitely never using any chemicals, synthetic or otherwise; having water gardens that remain unfrozen and available 365 days a year; and many big masses mostly native fruiting shrubs (winterberries, aronias, viburnums, twig dogwoods and the like) seem to be among the keys to success.
No answer or feeling shy? Just say something like “count me in,” and I will but an answer is more fun. I’ll draw a random winner after entries close at midnight Sunday, November 1, and notify them by email. Good luck to all.
prefer the podcast version of the show?
MY WEEKLY public-radio show, rated a “top-5 garden podcast” by “The Guardian” newspaper in the UK, began its seventh year in March 2016. In 2016, the show won three silver medals for excellence from the Garden Writers Association. It’s produced at Robin Hood Radio, the smallest NPR station in the nation. Listen locally in the Hudson Valley (NY)-Berkshires (MA)-Litchfield Hills (CT) Mondays at 8:30 AM Eastern, rerun at 8:30 Saturdays. Or play the Oct. 26, 2015 show using the player near the top of this transcript. You can subscribe to all future editions on iTunes or Stitcher (and browse my archive of podcasts here).
(All illustrations by Jack DeLap, from “Welcome to Subirdia.” Used with permission. Disclosure: Purchases from Amazon links yield a small commission.)