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Transcribed using AI. May contain errors.

Amy Quinton If you like listening to Unfold, please subscribe and follow us on your device. That way you'll never miss an episode. You can do this on Apple, Spotify, or wherever you get your podcasts. Go ahead, make your listening easier. 

Amy Quinton: Listen closely. Kat. 

Kat Kerlin You're playing me something again. Is this like that episode I co-hosted when you played the whale sounds? 

Amy Quinton Yeah, But this time it's a tiny sound from a tiny bird. 

(Phoebe sound)

Kat Kerlin What bird is that?

Amy Quinton That's a black phoebe. 

Kat Kerlin Those are like tiny black songbirds, right? They only grow about six inches tall. Maybe they're flycatchers or flying insect eaters. 

Amy Quinton Yeah. I first learned about black phoebes when I started observing one in our backyard in Sacramento. It perched right in front of me on a lower tree branch. Didn't know what kind of bird it was so I looked it up and it still comes by occasionally. It's really cute.

Kat Kerlin Well, they live all over cities, backyards, urban parks, sometimes under bridges. It seems like they're everywhere, if you look closely enough. 

Amy Quinton Well, three аÄÃÅÁùºÏ²ÊÄÚÄ»ÐÅÏ¢ Davis researchers are studying how phoebes are responding to increased urbanization and environmental change. It's a research project aptly named Project Phoebe. 

Kat Kerlin Little bird. You'd think it'd be difficult for them in the big city? 

Amy Quinton Well, they do face a lot of challenges, but they're also pretty resilient. And ecology. PhD student Sage Madden, the project lead, wants to find out just how these phoebes are coping. 

Sage Madden Our world is becoming increasingly urbanized. So, larger and larger proportions of habitat for birds are in cities. And actually cities can be spots where we can conserve species, including rare and endangered ones, if we know how. And so I think learning how to make our cities friendlier to birds, and what strategies birds can use to cope with them, is going to be really important as we continue to urbanize. 

Kat Kerlin Birds also make people happy. That's important too. Science shows that people who listen to birds have a better sense of well-being. 

Amy Quinton True, but these little phoebes have a tough future in the big city. Different types and numbers of predators, for example, potentially more or higher concentrations of chemical pollutants. 

Kat Kerlin Don't forget hotter temperatures from climate change causing cities to become heat islands. 

Amy Quinton So in this episode of Unfold, we're going to find out more about just how these little phoebes are adapting to the big city compared to a more natural habitat. 

Kat Kerlin Are we telling this episode Little bird. Big city? 

Amy Quinton Sounds perfect. Coming to you from аÄÃÅÁùºÏ²ÊÄÚÄ»ÐÅÏ¢ Davis. This is Unfold. I'm Amy Quinton. 

Kat Kerlin And I'm Kat Kerlin. So let me guess, Amy, did you go birdwatching? 

Amy Quinton I did, and I look for birds in a lot of places where you wouldn't think to look for a bird. But we start our adventure in a city park. I'm with Sage and Jacob Johnson, who's also a researcher with Project Phoebe. 

Jacob Johnson We are at Chestnut Park, a very quiet little park in the middle of Davis. 

Amy Quinton And we're next to a tennis court, a children's play structure and what looks like a small beige maintenance building. 

Jacob Johnson And in the eaves of this building, there is a mud cup nest that two birds, two black phoebes, have painstakingly constructed over weeks and weeks of effort out of mud. 

Kat Kerlin They make their nests out of mud. That must take forever. 

Amy Quinton Exactly. Jacob and Sage have watched this mud nest all year, and know that these two phoebes have already had chicks, but they'll have more. Sage says right now they're renovating. 

Sage Madden They line these mud cup nests with grass, and they'll pull out the old dirty grass and then put a fresh lining in for their new chicks. Otherwise, they reuse the same mud cup because it is an immense amount of work to build. It's like thousands of individual globs of mud that the parents like, deliver and put on the wall. 

Kat Kerlin So it's like they're renovating their nursery, getting ready for new chicks. Cute, but a maintenance building? That's a strange place for a nest. 

Amy Quinton Sage says buildings provide just what they need for their mud nests: shelter. 

Sage Madden They need a really specific geometry, where they need a vertical wall that has some sort of overhang covering it. And that's hard to find in the natural world, but pretty abundant in cities. So they seem to be moving into our cities and expanding their range in this way. 

Amy Quinton In their natural habitat, they'd look for cliff rocks with large overhangs or protected pockets and old trees or even caves. 

Kat Kerlin And they'd obviously need a river or creek to make mud. 

Amy Quinton Right? So Sage and Jacob are at this particular nest to observe the bird's behavior, and to compare how the birds behave in an urban environment versus a more natural environment. 

Kat Kerlin So what kind of behavior do they look for?

Amy Quinton Well, what do songbirds do Kat? 

Kat Kerlin Well, they sing and they fly. They mate. They eat. They poop. What else? 

Amy Quinton Well, all of that is true. But a bird song is very important. Jacob says they sing for two reasons. One, to attract a mate and two to defend their territory. 

Jacob Johnson Birds will go around their territory and they will sing at different spots. And that will mean, "This is mine. This is where I live." And so a big no-no in the bird world is singing in another bird's territory. This causes the birds typically living in that territory to see a challenge. 

Amy Quinton So in order to observe these birds behaviors in the big city, Jacob is going to challenge them. 

Kat Kerlin How? 

Amy Quinton By playing another Phoebe call from a recording. Jacob, who is getting his PhD in animal behavior, wants to find out how these phoebes respond when trying to defend what's theirs. Jacob lays down a small speaker on the ground next to a jungle gym. It's several feet away from the bird's nest, but he cleverly disguises it under some leaves. 

Sage Madden Are you covering your speaker? 

Jacob Johnson Yeah. They'll never know. They'll never know. It's so disguised. But this will be our arena. This will be how we see how intensely the birds respond. 

Amy Quinton He stands about 50ft away from the speaker and is looking at the nest through binoculars. 

Jacob Johnson I'll be using playback file one starting in three, two, one. 

Amy Quinton The recording starts and within seconds the female bird responds. 

Sage Madden Mom has gotten out of her nest and she's calling right now from the top of the building. 

Amy Quinton And then something happens. Jacob's never seen before. 

Jacob Johnson Song. Song. Was that mom singing? 

Sage Madden Yeah, that was the female singing. Oh, it's really rare. 

Jacob Johnson Oh my goodness. And here comes the male. Flight two two. 

Amy Quinton The male flies toward the sound to a nearby tree. Then he begins to sing.

Jacob Johnson Song. Song. 

Amy Quinton The pair take turns flying to different perches, from trees to the top of the jungle gym to a park bench. For three minutes, they look for the other phoebe intruder. Then the playback stops. Jacob is amazed by the female singing. It's not unheard of for a female to sing, but very rare. 

Jacob Johnson Not nearly enough research has been done on it because there's, in the olden days, been this assumption that, oh, it's going to be the males that are the aggressive ones, the ones that defend, but the females also defend their territories and they also can sing, which is so cool that we saw that in this, in this individual right now. 

Amy Quinton He says these playbacks are a way to observe the birds aggressiveness in defending their territory. 

Jacob Johnson My guess at the start of this was that, resources in cities, you know, in more urbanized places are going to be more limited for these birds. So I was expecting to see birds have higher aggression. You know, adapt to the city in a way by becoming more territorial, fight for the territory they can hold on to. 

Amy Quinton But he says that's not what he's observed so far. 

Jacob Johnson I've actually seen the opposite. The birds that live in more naturalized places seem to be responding more strongly to play back. 

Amy Quinton We then head out of the city into farmland and pull up next to an irrigation canals, where water is flowing fast. We've come here to visit another Phoebe nest. But first Jacob notices a Phoebe making a racket on utility wire above us. 

Jacob Johnson So did you see that? That male was singing and he just chased another. What I think is another male off of his territory. Did you hear that sharp little peep call he made? Yeah, yeah, that was, territorial aggression in action right there. 

Amy Quinton Jacob won't be playing a Phoebe recording here, but the little bird is clearly demonstrating that this is his territory. 

Jacob Johnson He's fired up. So this male is giving kind of a repeated bout, you know, doo doo doo doo doo doo doo doo. When they get really incensed. Yeah, they can sing louder or they will sing kind of more rapidly. 

Amy Quinton Jacob says he's hoping to determine how their aggressiveness in different environments, whether urban or natural, could affect their ability to reproduce. 

Jacob Johnson I think the most prominent, most impactful, most important challenge of the 21st century is reconciling the needs of our human communities with the needs of the wildlife around us. The challenge of preserving wildlife in this century is, is, to me, the most important and one of the most important things we can think about. 

Kat Kerlin That's so interesting that Jacob is finding that these black phoebes are more aggressive at defending their territory in more natural environments, rather than in the city. Yeah, we mentioned other challenges phoebes face, including chemical pollution. If these phoebes are making their nest out of mud, then they could be exposed to soil and water pollution. 

Amy Quinton And air pollution is everywhere. 

Kat Kerlin So what is the Project Phoebe team finding? 

Amy Quinton That's the next part of our story. So we're going to head back to that irrigation canal. Researchers came to the spot because a pair of phoebes have made their nest in the oddest of places under a metal bridge going over the canal. But Ian Halliburton, a аÄÃÅÁùºÏ²ÊÄÚÄ»ÐÅÏ¢ Davis master's candidate in animal behavior, says that's not unusual at all. He has a rule of thumb about finding phoebe nests. 

Ian Haliburton What is the most ridiculous possible site in the area. Generally, that leads me to where they nest. 

Amy Quinton They found these little birds before and drainpipes, sewer grates, under highways and behind restaurants. Ian is wearing waders to get to this nest. Today he, Sage and other researchers will band, measure and take blood samples from five 13-day old chicks. 

Sage Madden Ian is going to take the nestlings out of the nest now. 

Ian Haliburton Start the timer. 

Amy Quinton Ian carefully grabs the pinkie sized birds and puts them in a soft cloth bag to carry them out of the canal. The research team, now joined by two more students, immediately huddle over the chicks and get to work like a medical team in an evening. 

Sage Madden Can you do glucose strips for me? 

Speakers 231. 

Ian Haliburton Can you hold this little guy? 

Amy Quinton Okay. Ian hopes to understand how chemical pollution in different environments can affect the phoebe's ability to survive and raise their young. 

Ian Haliburton We know that urban spaces can be polluted, but unfortunately, our natural spaces can be polluted as well. And the different types of pollution vary across that gradient. 

Amy Quinton He's using California EPA data that ranked census tracts based on potential exposure to pollution. Ian then relates this pollution burden information to where phoebes nest and to the number of chicks. 

Ian Haliburton We found that the probability of fledging anything, whether that's one or two or three chicks, drops off as you get into higher and higher values of this overall pollution burden. 

Amy Quinton That's not to say that pollution is causing fewer chicks to survive, but Ian says it may just be adding another layer of pressure to what may be one of the Phoebe's biggest challenges: rising temperatures from climate change. 

Kat Kerlin Okay, Amy. We've now visited a park in Davis and agricultural land outside the city. Just how many nest sites do these researchers visit? 

Amy Quinton They visit more than 30 sites in Davis, West Sacramento, Sacramento and Woodland. And some of the places they'll visit have more than one nest as well. 

Kat Kerlin It sounds like a huge project. 

Amy Quinton It's definitely a lot of data .And Sage Madden is gathering another important piece of data from these nests: temperature. She wants to learn how nest temperature affects the chicks growth.

Kat Kerlin Well, cities in general are hotter environments. There's more pavement and asphalt, which makes everything hotter.

Amy Quinton Yeah. And in this final chapter of their research, we're going to talk more about temperature and go to where you'd expect to find a bird at a nature preserve. Sage and аÄÃÅÁùºÏ²ÊÄÚÄ»ÐÅÏ¢ Davis student Ji-Heng Huang are walking into South Fork Nature Preserve, a 120 acre grassland and oak tree habitat along a creek. 

Sage Madden We're going to walk down to a dock. 

Amy Quinton This tree covered wood dock is the only manmade structure in this preserve, and the phoebes have made their nest underneath it. We listen for them. 

Sage Madden You hear that? That squeaking noise. That's the nestlings. 

Amy Quinton Okay, I didn't hear it. Perhaps my ears are not tuned into phoebe sounds like these birders with bionic hearing. But Sage sent me a recording from the camera they place at the nest. When Mom and Dad deliver food, the nestlings sound like this. So we head underneath the dock, where Sage explains to Jih-Heng how to take the little birds out of the nest. 

Sage Madden You're going to gently work them out and, like, get a grab on their feet. 

Amy Quinton Sage also grabs temperature data here, both in the nest and near the nest. At this point, the nestlings parents are keeping an eye on us from a distance. So they're watching us? 

Sage Madden Yeah, they definitely watch. They'll go right back as soon as we put their chicks back, but they definitely know what we're up to. 

Amy Quinton I, however, was completely caught off guard by what Sage and Jiyoung then began to do next. Paint the little bird's toenails. 

Sage Madden So I'll give you red, okay, to paint and measure. And they're going to get their little dabs of nail polish so we can track who they are. Four very cute little nuggets. 

Amy Quinton She then drops a little chick into a metal cup to weigh it. 

Sage Madden All right, little nugget into the cup. 

Amy Quinton It squirms around. 

Sage Madden Yeah. No, honey. Settle. So these guys are already heavier than the last nest. 

Amy Quinton And that's significant because the birds here at the preserve are younger than the birds under the canal bridge. She says these birds are in a better environment and a cooler one. 

Sage Madden The nest that we went to this morning, the highest temperature it reached over the last seven days was 104°F, gets really hot because it's under that, dark colored metal bridge. This one got to 89°F. 

Amy Quinton And for reference, the high temperature on this day was just 82. Sage says nest location can make a big difference in whether the chicks survive, nest near heat absorbing pavement or concrete experience more extremes, both hotter and colder temperatures. She says she's not seen a chick survive above 113 degrees. 

Sage Madden This work can be really, really emotionally taxing because I obviously love these birds and spend a lot of time with them, and then I spend a lot of time watching them die in really horrific ways. We've seen nestlings that have cooked in their nests and like, they're all dried out and crispy and like, that's a terrible way to die. So not only is it a conservation concern, but it's a welfare concern, which is why I'm so motivated to understand how we can help them. 

Amy Quinton She says based on preliminary data, it's hotter near the phoebe's nest in urban environments, and hotter temperatures are linked to slower chick growth. But sage hopes to learn more about what's most important for the chicks survival. 

Sage Madden If it's hot, are you dying because you got hot? Or are you dying because your mom got hot and stopped delivering you food? And so by understanding that we can understand what sorts of changes need to happen to protect these birds so that we have more biodiverse city parks that we can enjoy. 

Amy Quinton She says the big city for this little bird doesn't have to be a deadly one. 

Kat Kerlin Amy, do we know any steps we can take now that could make it easier for the phoebe's survival? 

Amy Quinton Well, there's so much more to learn about that. And researchers hope to share whatever they learn with the parks departments that they're working with. Some suggestions might be things like painting roofs and overhangs of buildings white instead of black. 

Kat Kerlin To reduce the radiant heat. 

Amy Quinton Yeah. And Ian Haliburton started a program to put up supplemental nest sites, basically shelves that Phoebes can use to build a nest along the American River in Sacramento. 

Kat Kerlin That would be a good spot, since they need a source of water to make their mud nests. 

Amy Quinton Right. Sage says these birds were traveling long distances from neighborhoods and backyards to get to the river. 

Kat Kerlin Making a tiny birds commute a little tinier. 

Amy Quinton Exactly. And you can read more about Project Phoebe at our website www.ucdavis.edu/unfold.

Kat Kerlin And there you'll also find a link to an in-depth multimedia feature story on Project Phoebe by our wonderful science news intern, Malia Reiss, who just graduated and is flying off herself. 

Amy Quinton And we could not have done this podcast without her. She's good at finding stories. 

Kat Kerlin She is. I'm Kat Karlin. 

Amy Quinton And I'm Amy Quinton. Thanks for listening. 

Andy Fell Unfold is a production of аÄÃÅÁùºÏ²ÊÄÚÄ»ÐÅÏ¢ Davis. Original music for Unfold comes from Damian Verrett and Curtis Jerome Haynes. Additional music comes from Blue Dot sessions.