Let’s talk about birds. One certain species of birds, for that matter: desert purple martins. They nest in saguaro cacti and, as climate change threatens the health of those behemoths of the Sonoran desert, one researcher is working to make sure these little birds survive.
Victoria Wiley is a Ph.D. student at Northern Arizona University, and she’s spent the last several years putting tiny backpacks on desert purple martins and tracking them on their yearly migration.
The Show spoke with her more about it.
Full conversation
VICTORIA WILEY: So I actually grew up in the Sonoran Desert, kind of near Phoenix, and I had never noticed a purple martin once until I started studying them. But once you kind of recognize them and notice them, you see them everywhere. So, these birds like to perch on saguaros and all the males are all dark. So if you see them from far away, they look like smaller black birds, but when you see them in the sunlight, they are iridescent blue, absolutely beautiful. They like to be in flight and they eat insects only. So you'll see them flying a lot, and then they'll perch on a saguaro for a little while and then take off in flight again.
LAUREN GILGER: Okay, okay. So the saguaro is their nesting place essentially, right? What got you interested in studying them?
WILEY: I have always been really, really fascinated by migration and just the thought of animals being able to migrate thousands of miles, whether it's sea animals, birds, insects, it's just fascinating. And so when I started at NAU, I had this project in mind where these purple martins are migratory birds that migrate from all over North America, in our case, the desert purple martins, they are exclusively in the Sonoran Desert, and they fly thousands of miles to Brazil every year to spend the winter. And then they fly all the way back to the desert and breed in the saguaros.
GILGER: Interesting. Okay. And they're threatened because of this, right? Because of that saguaro kind of landing spot for them. Right?
WILEY: Yeah. And so the desert purple martins are really unique because they use that saguaro to build their nest. So those are subjected to wildfires in the Sonoran Desert with climate change and habitat destruction. And then on their wintering grounds, they also have threats, unfortunately. So in Brazil, it's a hotspot for mercury contamination due to illegal gold mining, hydroelectric dams, all of these different reasons. And so the desert purple martins are especially threatened and are in a unique position because they have threats both on their breeding and wintering grounds.
GILGER: Oh, wow. Okay. So your work is focused on figuring out their migration patterns, right? And is the goal to help them in this process and help them survive going forward?
WILEY: Yeah, definitely. So with migratory animals, any species, you can't just protect their breeding grounds or their wintering grounds. It really has to be both. And that's what's so special about working in this field and conservation is that you have the opportunity to have international collaborations. It takes transhemispheric, transcontinental efforts to conserve animals like this. So migratory species are kind of complicated to conserve, but also really rewarding.
GILGER: So let's talk about how you do this work because it's really, really interesting and kind of cute too, right? Like what you're putting on in order to study the migration patterns of these birds, you actually put trackers on them that kind of like tiny little backpacks, right? Tell us about those. How do they work?
WILEY: So, the backpacks that we've used in the past, there's a few different kinds, but the kinds that we've used for purple martins are — one is called a dial locator. So those are kind of more primitive technology. It uses— well primitive now, I mean they've only been around for about 15 years, but they basically track when the sun is rising and when the sun is setting, and based off of those data, you can tell where the animal is on the globe. So we've used geolocators — they are a little bit less expensive than the other type we've used, which are GPS trackers. And so GPS kind of works like how you would pull up GPS on your phone. You can tell the exact tree that that bird was in with GPS trackers. They're more expensive, but when we found out that we were successful with geolocators, we thought, let's spend the extra money and let's get a really precise reading so we can protect this wintering grounds and find out where they're going and try to move conservation forward in that way.
GILGER: Okay. So how do you do this? Like, how do you get these trackers or tiny backpacks on the birds themselves? And you have to get them back at the end, right?
WILEY: Yeah. So the desert purple martins, like I said, they're really unique. Purple martins are pretty much all throughout the East Coast. There's a population in California, but these desert birds that we have in Arizona are really, really unique because they nest in the saguaros other parts of the country, purple martins, nest and nest boxes. So it's a lot easier to take the nest box down and do what you need to with the bird. These birds are wild, so they do not take to nest boxes. They are nesting in — you know you've seen saguaros. They are 40 feet up in the air sometimes, the cavities. And so we use what are called mist nets. It's kind of like a volleyball net, and we're out there sometimes for hours and hours and hours and we do not catch any birds. And then the next day we'll be out there for hours and hours and hours and we'll catch two birds. And so we'll do this for weeks on end to try to get as many as we can, because like you mentioned, you have to get the bird back. So we put on these little backpacks, send them on their way, and we wait a year, and then we return the next year to the same saguaro and hope that the bird is there. And so last year, we were so excited to get basically the very first record of the desert purple martin migration path. We deployed eight geolocators and we had a male that came back to the same saguaro. We recaptured him, got his little tag off. He was probably happy to have the backpack off — felt light as a feather. And it was really exciting.
GILGER: So what did you find?
WILEY: We found that the desert purple martins actually winter in a separate location of Brazil. So not only do they breed in a unique location in the Sonoran Desert, they're isolated in their breeding grounds. They're also isolated on their wintering grounds. And what this could mean is when species or subspecies are isolated for thousands and thousands of years, they can eventually evolve into their own species. And so that's a new part of this project that we're looking into is their genetics. To see whether or not the desert purple martin could, in fact, become their own species.
GILGER: Okay. So you're continuing this work, right? Like this summer, you're going to be collecting tracker tags from another round of desert purple martins. Are you hoping you'll get more than one this time?
WILEY: Oh, definitely. Yeah. So we'll be out there again this summer collecting the ones from last year. And what's very exciting about this year is we've upgraded, yet again, to a different type of tracker. These ones are called satellite trackers. And this is basically — it's the best of the best right now. With the satellite tags, we do not have to retrieve the bird again. So we'll send out — we got about eight of those — and so we'll deploy those this summer, and we will not have to collect that tag in hopes of having way more data. So right now we have data for one individual. We will, after this summer, hopefully have data for several. And it's just a lot more informative when you have more data points.
GILGER: Yeah. Makes sense okay. So what is your goal here? Like what do you hope this data leads you to in terms of helping to, as you said, sort of preserve this species in a climate change era?
WILEY: Our main goal here is figuring out where these birds spend the winter so that we can actually go to that area, speak with the community, ask about what problems they're facing and figure out what's going on with these birds, because it really goes beyond the birds in a sense. You know, the issues that the birds are facing can affect tons of other animals. It can affect humans, for example. The mercury exposure goes beyond the birds. So if we could figure out where they're migrating to and quantify the mercury in their feathers, figure out maybe what they're exposed to, we can help a larger audience, basically, of animals as well as people.
GILGER: Yeah. All right. That is Victoria Wiley, a Ph.D. student at NAU, joining us to talk more about her research into desert purple martins. Victoria, thank you so much for coming on. I really appreciate it
WILEY: Oh, thank you I appreciate it.
