A Walk in the Park: Central Park and the Spring Bird Migration.
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Steve: Welcome to Science Talk, the podcast of Scientific American for the seven days starting June 7th. I am Steve Mirsky. On this week's podcast, we are going to go for a walk through the Central Park. Every spring millions of birds fly over New York City on their northern migration. Many of them stop in Central Park for some rest and relaxation. Early on the morning of May 31st, near the end of the spring migration, I met up with Liz Johnson and Felicity Arengo from the American Museum of Natural History. We rendezvoused at the 77th Street entrance to the museum, just a couple of hundred yards west of the park and then took off on our walk. We will hear from Johnson and Arengo about the park and green spaces in general and their roles in the lives of birds and other wildlife and we will talk to Marie Winn, a well-known nature writer we bumped into in the park. We will also hear from a lot of birds, after which we will test your knowledge about some recent science in the news. So, let's go for a walk. It was about 10 minutes before 8 A.M. when we entered the park on 77th Street in Central Park West.
Steve: Tell me again who you are?
Johnson: Liz Johnson.
Steve: And what do you do?
Johnson: I work at the Center for Biodiversity at the American Museum of Natural History in charge of the metropolitan biodiversity program.
Arengo: I am Felicity Arengo. I am the associate director of the Center for Biodiversity and Conservation.
Steve: We headed for a section of the park called the Ramble.
Arengo: The Ramble, very popularly referred to as and it's supposed to be close to within Central Park, probably the more wild area.
Johnson: In the park, there are three woodlands; they consider that there are three woodland chunks of habitat in the park: the north woods, the Ramble, and there is a four-acre piece down in the southern end of the park called, the Hallett Sanctuary. So, of all of them, the north woods is probably about 90 acres and that's the most natural, like more of a typical oak-hickory forests and what might have really been here and then the local central park has been modified a lot. This is about 37 acres, the Ramble, but this seems to be the premier food spot. There are so many little nooks and crannies and good canopy and good understory that this [is] really a spot for all the birds to come in and hang out until the birders come and see them. They are actively restoring the woodlands of the park, so especially in the Ramble area here it's been infested I guess with nonnative plant species and what the Central Park Conservancy folks are doing is removing the nonnative species and then bringing back and planting native herbs and native shrubs so they can sort of maintain a more natural system of woodlands. You can see areas that have been fenced off to keep the public from trampling the vegetation and you see little labels where they are actually putting in some of the plantings so they can remember what they put where and keep track of those. One of the management activities that the park is really focusing on is especially on these woodlands, of restoring the forest floor and make sure that leaves remain, not raking them up and when branches fall, letting them remain in place so that they could decompose, this again because it's going to restore the whole forest system and also it's good foraging habitat for all these wild birds we are seeing here, kicking through the underbrush and kicking through the leaves looking for worms and other insects and other invertebrates. So, they're restoring the forest floor part of the forest. It is also pretty important from a restoration standpoint and for benefitting the birds and other species that can be wildlife.
Steve: Couple of starlings just working their way through the brush right here.
Johnson: It's a contrary—leaving things unmanicured is contrary to traditional park management where you really want to have things neat and tidy and everything or all leaves raked away, so the conservancy has been really good about maintaining the Ramble in the north woods, these forested sections in a more natural state.
Steve: A little later I saw a robin land on a tree limb nearby with a beak full of nest material.
Steve: There is a robin right over here building a nest.
Johnson: Well, yeah, look at that. It has got long pieces of grass, looks like there is some tissue in there, little bit of plastic.
Steve: It's an urban nest.
Arengo: Yeah, and she is very neatly weaving all these things together up there.
Johnson: One of the really nice things about Central Park is even though you do get warbler neck from veering up for some reason, allow the birds come down low so that you can see a whole array of warblers without even getting warbler neck, because they all stay low down in some of these lower shrubs, and the other fun thing is that the birds who do nest here are pretty tolerant of people. So, it's an opportunity for every New York resident to just come into the park and actually see a bird building a nest or raising young at eye level or just above eye level. So, it kind of makes the birds accessible to the public, which is [a] really, really nice thing.
Steve: Once we got deep enough into the park to get away from most of the traffic noise, we talked about how birds use the park and other green spaces.
Steve: Talk about why the park is so important for migratory birds. What this patch of green space represents in the bird world?
Arengo: I can start with a more global reason. When birds are migrating from south to north in the spring, they are roughly. There is a concept of flyway, birds are following some prescribed rules. No two species will follow the same exact line and they are not like marked roadways that are precise, but for the most part they go along topographical features like coasts, rivers, mountains. So in U.S. we have four major flyways that are the Atlantic, the Mississippi, the one along the Rockies, the central flyway and then the Pacific coast flyway, but then these natural flyways have tributaries. So, there's a major flyway coming up the Atlantic coast and there will be little branches off at different points. So, birds are coming up along the Atlantic coast and of course New York is part of that coast and they are coming up and they hit New York that has Long Island heading off in the east and the Hudson River valley going out. So, they are coming up along this area and after a lot of urbanization, they encounter Central Park that has patch of green in their continental migration. So, that's in a global prospective that's right. They are coming up from South America to southern United States, they are coming up the coast and they encounter this wonderful patch of green.
Steve: So, it's an opportunity to take a rest, get something to eat and drink.
Arengo: Yeah, refuel and then continue up north.
Steve: And, in the fall, in the opposite direction same thing happens.
Johnson: Yeah, in the fall, it's a little more diffuse, wouldn't you say, that it's the spring migration in Central Park is much more of a hot spot. In the fall, it seems to be more, you know the birds are collecting at different times, it's a more prolonged run and they seem to be more dispersed.
Steve: When the park was built, it's well over 100 years ago, it couldn’t have been envisioned as—that's not why it was a built—as a stopping place for birds. I mean, there wasn't the same level of urbanization, not even close to. There were plenty of green spaces for wildlife back then all along the eastern seaboard. So, we know what the park has evolved into, but how did the birds figure it out or it's just such a natural thing that after nothing but concrete floor [for a] couple of hundred miles, they didn’t really have any choice.
Johnson: I think it's probably a combination. One, the fact that the park is located on this flyway and that as you are coming up the coast many of the birds, they will veer off to Long Island, they are going veer up the Hudson valley. So, it's right on the route that they would fly and that because of this point, I think, it sort of evolved over time. As the surrounding areas completely suburbanized and urbanized, this is a good-size chunk of habitat. So, it's where these birds can land and they need to land, and some of them will stay maybe just for a night, you know, they get enough rest and they can find enough food; some will stick around for a couple days, maybe for a week, partly depends on how much food they can get and it depends on the weather patterns. But it will allow the birds leave here going far, they are not just going up to Albany and hanging out up there, they'll go to the Atlantic, so go up to the boreal forest in Canada. So, it's pretty critical that they can, you know, build up their fat deposits and their reserves to actually continue to make the flight and also have enough reserves when they reach the breeding ground to actually breed and lay eggs and raise a brood. So, having these stopover spots is pretty critical for the overall breeding success along with these different migratory species.
Steve: Any idea how many species you'll see here overall? How many you have the opportunity to see?
Johnson: I think, over 275 species have been recorded from Central Park, just probably around 190 that regularly occur here as a resident or just show up on a frequent basis.
Steve: So, the other approximately 85 exotics?
Johnson: They show up every once in a while and are basically excited and comes to see them.
Steve: We will return to Central Park right after this.
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Steve: Because you see so many birds in the park, you’ll also often spot Audubon’s binoculars—bird-watchers, also known as birders, a group of about two dozen crossed our path.
Steve: Any idea how many birders who are in the park on any given migration day?
Johnson: I have read hundred, yeah, at least a hundred. You can run into some regulars and then a lot of people from other countries come, specifically to enjoy the migration and will be out here trying to find different spots and see that the things add to their life list.
Arengo: New York City Audubon and the Linnaean Society and the museum [and] a whole host of organizations organize bird walks every spring. They either want to sign up for pulling out every week for the whole season or you could just drop in on some of them. So, it's really fun, another good way to get people out and just learning about the park and feeling comfortable in the park and enjoying nature.
Steve: How come people find out about those?
Johnson: I think more through any of those organizations. They could just contact New York City Audubon or they can contact the American Museum of Natural History and the Linnaean society, all three of them you could find information about it.
Steve: Here's a group of birders.
Arengo: Yeah. And they will be able to tell us.
Steve: Maybe we'll see what they have seen today.
Steve: Now, this particular group was being led by this very animated woman who was talking about birds and turtles and their phylogenetic relationships. Liz Johnson informed me that the woman was in fact writer Marie Winn, perhaps best known for her book about Pale Male, the famous red-tailed hawk, who nests on a very expensive piece of real estate on Fifth Avenue.
Johnson: Marie Winn who is author of red-tailed hawk and many other things, and an expert, naturalist and a whole lot.
Steve: Let's chat for a moment if you don't mind. So, tell me again now that I am sticking the microphone on your face, what you have seen today?
Winn: First of all, I will tell you that today is not as great as yesterday. Yesterday was a really good day, unusually good. We had a cuckoo yesterday and every honey locust turned out to be the tree where there were a lot of birds, something they was just flowering.
Steve: But you are still getting some warblers today.
Winn: Yes we are, but it's the tail end. We are not going to get 24 species today. We would probably end up getting five or six and it's the females. So, it's not that easy to find them because they are not singing. They are lollygaggling their way back up to the breeding ground while the guys have all, you know, zipped up there to get their territories. It's great. The park is beautiful. It's not too hot today.
Steve: And tell me about the turtle you saw again.
Winn: Yes, it was like meeting up with a prehistoric creature. We were at a place called the lower lobe and we were listening to birds and just there was this moment and oh my god, there was this huge snapping turtle. It had excavated a hole in a kind of sandy place where they always lay their eggs and it was laying eggs, even though it wasn't happy we were there, the process had started and it was fantastic and one of our groups took pictures of them. I will probably put it on my Web site.
Steve: What is your Web site?
Winn: It's www.mariewinn.com. Again, there is one page on it which is Central Park: hawk and nature news and it's a blog really that page. The rest of it is just fixed stuff, you know, biography and so on, but that one I really write every day.
Steve: If you add your bird watching, you see a turtle. It almost counts.
Winn: Everything counts. That's the great thing about being a Central Park nature person. Yeah, we look at plants, we look at seed pods, we try to identify the litter on the ground. It's just a very rich little microcosm here.
Steve: Why is identifying the stuff you see interesting and/or important rather than just seeing it?
Winn: That's a big question. As Lewis Armstrong said it does throw some kind of deep human need. I think you [are] kind of organizing the chaos of life in some way and putting things into categories. There are some people who are completely free of an impulse to categorize and to identify. They don’t understand why people do it. Then, there are other people who do it, like me and [the] rest of us and we don’t understand the people who don't. So, it's genetic. It's on the phylogenetic tree.
Steve: We are back to the phylogenetic tree? Well, thank you very much. I appreciate it.
Winn: You are very, very welcome. Thanks for asking me all these things.
Steve: By the way, in addition to her own writing Marie Winn, who was born in Prague, has translated the works of some very well-known Czech writers, including poet Václav Havel, who also served as president of the Czech Republic. As we continued walking, it was obvious that on this day at least the robins were really dominating the landscape.
Steve: How many thousands of robins are there in Central Park? Can you guess?
Johnson: I am willing to. They are following us everywhere. I don’t know if anyone has ever done a census of actual numbers of, you know, breeding pairs of birds in the park. There's lots of long-term data on migration on who is showing up and when, and they have Christmas counts, Christmas bird counts that they do in Central Park and I know there was a breeding bird atlas done as part of the New York State Breeding Bird Atlas. They actually divided Central Park in blocks sort of on paper and then had people go out and just tally away within those blocks what confirmed nesting or possible or probably nesting. So, there's a lot of information, but a complete total census of all the breeding individuals I don't think has ever been done for any species.
Steve: This has got a baseline what we are hearing there are thousands of robins here, right?
Arengo: Yes. One of the interesting things to study, we know Central Park is important for migratory birds and we know that they depend upon the food resources that are here, but no one has ever really done a systematic survey of what actually they are feeding on, like we have never done a canopy study of all the invertebrates up in the trees to see what's coming out when and what is the predominant part of the diet of different birds and sort of quantifying; but what they have done—people have done—with shore birds and sort of gauging, weighing them, you know, catching them, weighing them, seeing how much weight they gain over time while they are rather resting and feeding before they depart on their northern trip. I don't know how you would do it. It would be challenging to do it for all of these different songs that are here, but to get a better hand on what is it that they are really depending and which are the invertebrate food resources or vegetation food resources. How much there do they actually need.
Steve: So, any graduate students who might be listening, if they are looking for a thesis?
Johnson: I will be a good thesis project.
Steve: Well, it's time to get back to the concrete and commotion, but not before we ran into this very nice lady, who spends more time in the park than any birder. She noticed our binoculars and yelled out her compliments on our hobby from her motorized cart.
Female voice: It's good that you have had that hobby, that's nice.
Johnson / Arengo: Yes.
Female voice: The only hobby I got is cleaning Central Park.
Steve: We will be right back.
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Steve: Now it's time to play TOTALL.......Y BOGUS. Here are four science stories. Only three are true. See if you know which story is TOTALL.......Y BOGUS:
Story number 1: A contest will reward the best cartoon satirizing political interference in science.
Story number 2: Road rage, maybe the honking idiot behind you actually has what's now being called intermittent explosive disorder.
Story number 3: Penn State researchers have programmed computers to do a decent job of judging the beauty or blindness of pictures.
Story number 4: In the new X-Men movie one of the mutants is shown eating a copy of Scientific American.
Story number 1 is true. The Union of Concerned Scientists is sponsoring an editorial cartoon contest to draw attention to the political misuse of science. The deadline for getting your cartoons in is July 31st. You can read more about the contest at our blog, blog.sciam.com.
Story number 2 is true. Some cases of road rage may be incidents of a larger syndrome now being called intermittent explosive disorder. A study in the June issue of archives of general psychiatry says that about 16 million Americans may have the condition, in which you don't just fly off the handle; you throw the entire coffee cup up against the wall.
Story number 3 is true. Penn State's James Wang developed what's called computational-aesthetics software that allows a computer to make quick decisions about what's a good picture. The judgment matched though was that [which] humans make about 70 percent of the time. Such software could speed up Web searches for images or even find a home one day in digital cameras to help photographers compose their pictures better, which is pretty much the only thing we humans still need to worry about with a lot of digital cameras.
All of which means that story number 4 about one of mutants in the new X-Men movie eating a copy of Scientific American is TOTALL.......Y BOGUS. Because what is true is that one of the mutants in X-Men, the Last Stand, is show[n] actually reading a copy of Scientific American. When we are first introduced to the blue-furred beast played by Kelsey Grammer, he is hanging upside-down reading the October issue of Scientific American with our article on founder mutations prominently featured on the cover. The article is about how specific genetic changes that either cause disease or protect against disease can help researchers trace human migrations over thousands of years. Here's how the beast in you can access that article:
Rennie: Hi, I am John Rennie, editor-in-chief of Scientific American. Our magazine is now available in a digital edition. Not only does your Scientific American Digital subscription include the full contents of every new printed issue, it also entitles you to access our digital archives from 1993 to the present. For more information, visit www.sciamdigital.com
Steve: Well that's it for this edition of the Scientific American podcast. Our e-mail address is email@example.com and also remember that science news is updated daily on the Scientific American Web site, www.sciam.com. For Science Talk, the podcast of Scientific American, I am Steve Mirsky. Thanks for clicking on us.
Organizations and Web sites mentioned on this podcast include the American Museum of Natural History, www.amnh.org; the Central Park Conservancy, www.centralparknyc.org; the New York City Audubon Society, www.nycaudubon.org; the Linnaean Society, http://linnaeannewyork.org/ [CHANGED FROM LONDON TO NYC LINNAEAN SOCIETY]; Marie Winn, www.mariewinn.com; the Scientific American blog, blog.sciam.com; the Scientific American Digital Archive, www.sciamdigital