Science Talk

Singing New Songs: Urban Birds Vocalize Differently; Insurance Industry Worries About Warming

In this episode, Leiden University bird song expert Hans Slabbekorrn notes the changes in bird vocalizations when they move from the forest to the city. And we wrap up our series on Scientific American magazine's "SA 50" citations with Ivo Menzinger, managing director of sustainability and emerging risk management for the reinsurance company Swiss Re. Plus we'll test your knowledge of some recent science in the news. Websites mentioned on this episode include;

Science Talk December 6, 2006 -- Singing New Songs: Urban Birds Vocalize Differently; and Insurance Industry Worries About Warming

Welcome to the Science Talk, the weekly podcast of Scientific American for the seven days starting December 6th. I am Steve Mirsky. This week on the podcast, you know how city guys make talk differently from country folk, well new research from Hans Slabbekoorn finds that when birds move from the forest to the city, their songs change too. We will talk to him about that in our respective accents and we will finish up our look at the Scientific American 50 with Ivo Menzinger from the company Swiss Re. Plus, we will test your knowledge about some recent science in the news. First up, the difference in song stylings between city birds,—"I am a chicken hawk" and country birds—"now, I say cut that out, what's it all about boy, elucidate." Hans Slabbekoorn will indeed elucidate. He is one of the world's foremost experts on bird song, which is often used as a model for behavior neurobiology in general. Slabbekoorn and his colleague Ardie den Boer-Visser has a new study in this week's issue of the journal Current Biology. They found that the song of at least one species of bird—Parus major, common[ly known as the]in Great Tit—significantly changes in the city. Here is one of the real birds in the study that lives in the Belgian forest of Riviera (bird chirping). Now, listen to another bird, same species, that has made its way in the big city Brussels (bird chirping)—very different song. To find out why, I called Slabbekoorn at his office at Leiden University in the Netherlands.

Steve: Dr. Slabbekoorn, nice to talk to you today.

Dr. Slabbekoorn: How are you doing?

Steve: Good, tell me about this bird song study, very interesting. What did you actually do and what were you looking for?

Dr. Slabbekoorn: Well, what I did is I traveled Europe, went to 10 different city types, recorded the Great Tit birds over there and also went to 10 forest sites nearby those 10 cities to get me 10 independent comparisons between city and forest habitat. And together with Ardie den Boer-Visser, we analyzed the songs, inspected on tempo features, and we found a very consistent divergence between city and forest birds of the same species.

Steve: And talk about the nature of that divergence between the urban birds and the forest birds.

Dr. Slabbekoorn: So, first of all we were interested in the frequencies, because in the cities we have very low frequencies because of all the traffic noise over there. We expected in the cities that the birds may use the low frequencies less for their songs and that will lead to a peace sound. Like in 10/10[10 out of 10] comparisons, we found that the minimal frequency was a[o]n average higher in the cities. So, they kind of avoid those low frequencies, which would otherwise be masked by the traffic noise.

Steve: And [10 out of 10], that is pretty statistically significant there.

Dr. Slabbekoorn: Yeah, there was no problem in that respect and it's quite unique, I think, for a few studies like this, because noise is not likely to be the only factor determining song characteristics. I mean, there will be many factors, environmental factors, physical factors, and so it's quite surprising to get such a consistent outcome.

Steve: And the song in addition to getting higher, got faster.

Dr. Slabbekoorn: Yeah, another difference was that the city birds sang their songs faster and especially the duration of their first note, the note that they start off, the repeated phrases with that were shorter in the cities than in the forest, then again in [10 out of 10] comparisons. So, it was a kind of a notable finding. Nobody has ever found such a thing, that a particular part of the song show[s] more divergence than another part. but more of the explanation I have at the moment is that the first part of the song is perceptually very important; it is the most salient part of a song. I mean, if you do not detect or recognize another bird is of your own speed that is singing, then you of course may miss a more detailed information that is coming afterwards. So, the first part is really important and that is kind of an alerting component. And I think that's why also selection may be working strongest on that first part.

Steve: Well, you know, it's really not a surprise that[to] those of us who live in big cities because if you go to Vermont in the United States people might talk like this, and then if you are in New York you are going to be talking like this because if you have to get by.

Dr. Slabbekoorn: Yes, you need to be louder. Yeah, that's correct. The People haven't looked at the human languages as well and that's on a larger scale even; people have found that languages that have evolved in areas where people live and are usually talking to each other in an indoor environment and being much closer, the synergy level is lower than in areas where languages have evolved where people are typically outside and maybe talking to each other at larger distances, and so then synergy levels or the carrying capacity like how far sound would transmit independent of the amplitude—that is longer, that is louder for the ones the languages that are used for outside use.

Steve: Very interesting. Now, one of the really interesting things you talk about in your paper is that it may not just be that the birds change their song in the cities; it may be that the birds that we see succeeding in cities are the species that have the capacity to change their song in response to all the background noise.

Dr. Slabbekoorn: Yeah, I think, I have been—in Europe, people have studied the birds communities and that the pattern that emerges is that you get a few species that are quite successful and that those are the same species everywhere irrespective of the original habitat that is urbanized; that that's your location, which means that only a few species may be really able to adjust; and all the other types of bird there before, well they may have disappeared because of their vegetation or the food is gone, but at the same time, it may be the ability to adjust to, well, the noise pollution that may make these birds survivors and made other birds disappear.

Steve: Talk for just a moment about the fact that although you cannot of course say whether this species is in the act of diverging into multiple species—however, this change in the vocalization could be an important step in that process if it is indeed going on.

Dr. Slabbekoorn: Yes, I mean, I think the behavioral flexibility of Great Tits helps them to survive in urban cities at the moment. And that's on an ecological time scale, but at the same time that means that some learning may help them in adjustment; but it means that some learning also accelerates the divergence between populations that are in a different habitat, and I think that is a requirement for maybe indeed a next step on evolutionary time scale in the direction of reproductive divergence. Because if different environment leaves the different selection pressures to all sorts of fitness-related traits—such as morphology or life history characteristics—birds may start breeding earlier or later, may have larger broods or smaller broods. And at the same time, if they diverge in the sexual trait like deplemish or what we study in this[these] song characteristics, then those accelerated the divergence[es] in sexual trait[s] that may help females to find males that are adapted to the local environment. And if that's the case, then of course you may accelerate assortative mating. Folk females may have a preference for folk males that they pick out based on the song; and in the same way urban females may pick out urban males, and they recognize those based on the song. We don't know yet and we probably will not find out because that's, as I said, the evolutionary time scale. But a first step towards the process may haven’t been tak[ing]en place.

Steve: It's very interesting. I think most people probably think of speciation as a physical thing, but here you might have birds that are still for the most part physically identical, but because they can't communicate with each other anymore, that may be a barrier as fundamentalism[as a] mountain between two populations.

Dr. Slabbekoorn: Yes, and I don't think at the moment that Great Tits [from the forest] are unable to communicate with forest birds like in urban areas or vice versa; but, I mean, we definitely may have a small look at the start of such a divergence.

Steve: What's the big thing about this study? The bird business is fascinating, but what's the bigger lesson about urbanization and wild populations?

Dr. Slabbekoorn: Well, that’s may be a difficult one because urbanization of course is not just the noise. There are many differences between the original habitat and the new habitat; and also people are living in there and animals are living in there, and we know that not only birds may be bothered by the noise, but also people are bothered by the noise. We know that there is a relationship with noise levels in cities and the risk of heart attacks. We know that with noisy airplanes nearby the cognitive development slows down for kids at schools. So, the reading skills are behind if you compare it to schools which are not nearby an airport. So, I think the problem of noise pollution is a big one, not only for birds, but also for people. And I think if you compare to other pollutants in cities, I think, noises may be a tricky one because the prognosis is that while chemical pollutions or light pollutions—those maybe brought down in the future, but the prognosis for noise pollution is that it's still going up. There is no strong lobby to get those cars out of cities.

Steve: Dr. Slabbekoorn, thank you very much.

Dr. Slabbekoorn: Thank you for your interest.

Steve: Slabbekoorn is the coauthor of the book Nature's Music: The Science of Bird Song. For more info, just Google "bird song" and "Hans". He comes up multiple times on the first page of results— and you didn't even have to spell Slabbekoorn.

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: Cross-cultural studies show that people worldwide all hear a ticking clock ias going "tick-tock".

Story number 2: A new pit detector should keep your prunes more pit-free in the future.

Story number 3: Lamas have unusual antibodies that stay intact at high temperatures, making them good materials for us to use as biosensors.

Story number 4: Livestock worldwide are responsible for about one fifth of all greenhouse gases.

We will be back with the answer. But first—the last two weeks we have been talking about the SA 50, the yearend Scientific American list of 50 individuals and organizations helping technology develop for the benefit of society. To end the series, I spoke with Ivo Menzinger, managing director of sustainability and emerging risk management for the insurance company Swiss Re. Scientific American names Swiss Re our SA 50 business leader of the year. To find out how an insurance company made the list, I spoke with Menzinger at his office in Zurich.

Steve: Mr. Menzinger, good to talk to you today.

Mr. Menzinger: Good to talk to you.

Steve: Tell me about Swiss Re. First of all, what kind of company is it? All I know is it's an insurance company.

Mr. Menzinger: This is actually a reinsurance company, i.e., our main business is insuring insurance companies. So, any what we call primary or direct insurers need protection [themselves from], for instance, large catastrophe events; themselves and that's what they approach us with.

Steve: I see. And in 2005 I know that the company was one of the developers of a big report on the economic consequences of global warming. Can you tell me about that?

Mr. Menzinger: Yeah, this report was actually [a] collaboration with Harvard Medical School and UNDP.

Steve: UNDP, United Nations…

Mr. Menzinger: United Nations Development Program.

Steve: Okay.

Mr. Menzinger: And in this collaboration we tried to—come as comprehensively as possible—to describe what the consequences of climate change could be, especially under a life and health aspect and in terms of ecosystem.

Steve: And conclusions were?

Mr. Menzinger: Well, I think the conclusions were that the phenomenon of global warming has such wide implications—on not just in terms of extreme events, but also in terms of gradual changes—that, you know, consequences are significant going forward in a very wide range of a variance.

Steve: It's interesting that, from an economic point of view, your company has decided that it makes good economic sense to try to deal with this issue now.

Mr. Menzinger: Absolutely. The climate change is going to stay with us, and the issue is that if we act today, it will economically make much more sense than wait[ing] for another decade or so and then, hav[ing] to act under more pressure and take even more serious, you know, undertake more serious changes.

Steve: Do you find it ironic [that] most of the global warming deniers seem to point to economic arguments to not do anything about global warming—well first of all though[they] often say that global warming isn't really happening—but they now argue that the steps that would be needed to deal with global warming are just too expensive. But it seems like it's too expensive really not to do anything about global warming.

Mr. Menzinger: Absolutely. I think it's a myth to think that, you know, the economic consequences today would be so severe. If you take a look at a recent study of Sir Nicholas Stern—he wrote a report on the economic consequences of climate change, and his conclusion is actually that in terms of economic cause to mitigate the most severe consequences, it would cost about one percent of GDP; which basically translates into—if you take a look at the year 2050, at an average annual growth rate of GDP of currently 3.2 percent; if we have, you know, one percent of lower GDP growth, that translates into: The wealth level that we would have achieved on the 1st of January 2050, will actually be achieved, let's say, in the order of May 2050. So, from the macroeconomic point of view, consequences are not very severe.

Steve: Tell me about—I know the Swiss Re has taken steps internally to try to diminish its own environmental footprint.

Mr. Menzinger: I mean, first of all, we need to acknowledge that we are—as a financial services company, we do not have a very large footprint. But since we are so vocal on the subject, to us it's a matter of credibility to also try to minimize our own covering footprint. And we have actually started very early on to develop policies, for instance, internal policies to reduce our energy consumption. We invest, for instance, in our real estates, only in energy efficient buildings. We have In 2003 [we became] as the first major financial services company [to] pledged to become greenhouse neutral by the year 2013 by further reducing our own energy consumption by 15 percent and then by offsetting the remainder through an investment into the World Bank Community Development [Carbon]Common Fund.

Steve: What's been the reaction within your industry to the steps that your company has taken?

Mr. Menzinger: First, in terms of our own common footprint, it has become more common than other financial services industry players actually have taken the same steps. So, if you look for instance at HSBC or if you look at Swiss Operations of Credit Suisse Bank, they have in the meantime also pledged to become greenhouse neutral. So, it has become much more common, and I am sure we will see more companies following, actually, that example. And then, with respect to the wider engagement on climate change, there are other players in the reinsurance industry and the insurance industry who have also been very vocal; and we are seeing more of this all the time actually.

Steve: So, within the industry the science has been considered to be a mature science.

Mr. Menzinger: Absolutely, absolutely. I mean, we have been following this[these] scientific developments for many years. And of course, it is wise from our perspective to follow the majority, the consensus view, which in terms of no global warming happening, I think has been established for quite a while now; and from our perspective there is no doubt about, you know, climate change and the underlying reasons for it.

Steve: And so, dealing with it is just good business.

Mr. Menzinger: Absolutely.

Steve: Mr. Menzinger, good to talk to you. Thank you very much.

Mr. Menzinger: You're welcome.

Steve: The entire SA 50 list is in the December issue of Scientific American and is available on the Web site,

Now, it's time to see which story was TOTALL.......Y BOGUS. Let's review the four stories.

Story number 1: Everyone hears "tick-tock".

Story number 2: Better prune pit detector.

Story number 3: Lama antibodies’ unusual stability makes them good candidates for biosensors.

Story number 4: Livestock behind one fifth of greenhouse emissions.

Time's up.

Story number 4 is true. A report by the UN's Food and Agricultural Organization says that the worldwide livestock industry produces a fifth of all greenhouse emissions. Some of that is the livestock themselves. (All the time putttt putttt puttttt.) And some is the result of emissions produced for creating and using the lamb[land] that livestock live on.

Story number 2 is true. Department of Agriculture scientists have come up with a better prune pit detector. Prunes on a conveyor belt get gently pressed by a roller; a force transducer under the belt measures the resistance the roller encounters. A pit piece causes more resistance than the fruit flesh signaling us[an] order to punt [pit] the prune. That is still rather badly wrinkled, you know.

Story number 3 is true. Most antibodies are two stranded and fall apart at high temperatures, but llamas and camels have one-stranded antibodies, which are more stable. Researchers are looking at the llama antibodies—which react with specific molecules—for possible use in biosensors. For more, see the news story "Llamas Recruited to Fight Against Biological Threats" at

All of which means that story number 1, about everyone hearing a ticking clock as "tick-tock" is TOTALL.......Y BOGUS; because Japanese people, for example, interpret the ticking clock as going "tock-tick". (This is going to cause a small confusion in a mouse in a burlesque show.)" What you hear turns out to be related to the natural rhythms of one's native language. For more, listen to the Tuesday, December 5th episode of the daily Scientific American podcast 60-Second Science titled, "Tick, Tock, Tock". Well that's it for this edition of the weekly Scientific American podcast. (Well, when you say when you got to go, you got to go.) You can write to us at Check out news articles and science video news at our Web site,; and the daily Scientific American podcast 60-Second Science is at the Web site and at iTunes. For Science Talk, the weekly podcast of Scientific American, I am Steve Mirsky. Thanks for clicking on us.

Web sites mentioned on this episode include;

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