S1 E4: Ecosystem Engineers with Laura Prugh

Laura Prugh is a wildlife community ecologist with the School of Environmental and Forest Sciences. Research in her lab use a combination of intensive fieldwork, modeling, meta-analyses, and interdisciplinary approaches to study the response of wildlife communities to global change.

Recently, Prugh was lead author on a study published in the journal Science. Researchers at the University of Washington, the Washington Department of Fish and Wildlife and the Spokane Tribe of Indians found that bobcats and coyotes were more than three times likely to die from human activity than from the claws and jaws of cougars and wolves, illustrating how humankind’s growing footprint is changing interactions among other species.

On this episode of FieldSound, Prugh discusses her pursuit to understand connections in the environment, and highlights her work with the critically endangered Kangaroo Rats - the “ecosystem engineers” of the Carrizo Plain National Monument in Southern California.

Laura Prugh is the current holder of the John C. Garcia Term Professorship. Prugh Lab research is supported by the Wildlife Dynamics and Conservation Research Fund.

http://prughlab.com

https://environment.uw.edu/podcast

Transcript

00;00;00;17 - 00;00;14;16
Laura Prugh
I’ve always been really interested in how one species might have a whole variety of surprising effects on other species through these food web interactions.

00;00;16;02 - 00;01;06;00
Sarah Smith
From the University of Washington College of the Environment, this is FieldSound. We've all heard the phrase everything's connected. But what does that really mean? Community ecology looks at how communities essentially organisms like plants, animals, insects, even bacteria, function together in time and place. Scientists study the interactions of these organisms, and by understanding how organisms interact and function in a community, they can assess and monitor environmental conditions in a place.

00;01;06;18 - 00;01;13;04
Sarah Smith
The research can then inform policy on how to protect at risk environments and help save species from extinction.

00;01;15;13 - 00;01;20;07
Sarah Smith
Working in community ecology has sparked some interesting scientific questions for Laura Prugh.

00;01;22;14 - 00;02;01;09
Laura Prugh
So my name is Laura Prugh and I'm an Associate Professor of Quantitative Wildlife Sciences in the School of Environmental and Forest Sciences. And the main focus of my research lab is looking at how species interact with each other. So really, we look at often the whole wildlife community and try to understand how these species are interacting with each other through predator prey interactions or competition, and how that is embedded in a context of a changing world.

00;02;01;09 - 00;02;28;11
Laura Prugh
So human influences and climate change. I've always been really interested in how one species might have a whole variety of surprising effects on other species through these food web interactions. And I am kind of a quintessential generalist. That's kind of why community ecology suits me, because you can look at so many different things.

00;02;29;28 - 00;02;41;02
Sarah Smith
So how does she come up with questions? The first answer pretty simple. Reading the literature, looking at what other scientists have learned about species and how they interact with each other.

00;02;42;00 - 00;02;55;08
Laura Prugh
That often spur some additional questions that I have or highlight some things that we don't really know. And then also, just by spending a lot of time in the field.

00;02;58;20 - 00;03;07;00
Sarah Smith
Getting out in the field is where the magic really starts to happen and the dots begin to connect. But then more questions arise.

00;03;08;04 - 00;03;38;01
Laura Prugh
So a lot of the research we do in my lab is very field intensive. So just spending a lot of time out in the systems that you're working in just gives you a good sense for that system. And what factors might be important. Like in the study we did in California, focusing on kangaroo rats and their role in the system.

00;03;39;16 - 00;03;49;28
Laura Prugh
Over the years, it became really clear that rainfall levels were just a huge influence on everything else in the system.

00;03;54;23 - 00;04;14;27
Laura Prugh
And so we ended up incorporating that into our study by building some rain shelters and irrigation systems and adding rainfall manipulation to our study.

00;04;14;27 - 00;04;19;13
Sarah Smith
Prugh and her team were essentially in tune with the ebb and flow of nature.

00;04;21;01 - 00;04;46;25
Laura Prugh
You also see beautiful stars. We start to see, understand, like the moon rise and set times and the different phases of the moon and the experience of being out there starts cluing you in to some of the things that might be important. So we started to look at moonlight effects on kangaroo rat activity in a day. It's scorching hot.

00;04;46;28 - 00;04;59;28
Laura Prugh
There's really not much around, but at night it pulls off and kind of comes to light and we basically be out all night. So we knew we had to become nocturnal.

00;05;02;13 - 00;05;34;14
Sarah Smith
Kangaroo rats live throughout the southwestern United States. Recently, Laura Prugh selected a little known hotspot for endangered species, including the kangaroo rat called the Carrizo Plain National Monument in Southern California. The hope was to study species interactions for 30 or so endangered species, including plants, herbivores and predators. So critically endangered kangaroo rat is considered a keystone species in the Carrizo plain, where it fills a crucial ecological role.

00;05;35;25 - 00;06;05;22
Sarah Smith
Kangaroo rats build extensive burrow systems in the plains that are utilized by multiple species. They also eat and disperse seeds and aerate the soil. Without kangaroo rats and their intricate burrow systems. The entire ecosystem of the Carrizo plain would radically change or cease to exist altogether. Prugh and her team honed in on the impact of these tiny but mighty rodents as keystone species and ecosystem engineers of their environment.

00;06;06;28 - 00;06;35;14
Laura Prugh
For the kangaroo rats, we had a lot of different plots. So this was a very intensive activity. We did it twice a year and it would take basically a whole month to trap all of our plots. We would trap for three nights on each plot, set up 60 traps in these little metal boxes. When they happen after the bait, then they step on something that closes the door behind them.

00;06;35;29 - 00;06;59;28
Laura Prugh
And since they were nocturnal, we would set these at sunset and then come back 3 hours later and check the traps. One of the ways they communicate is by foot drumming. They they have these big time feet like kangaroos. And so they dump them really quickly on the ground. They would do this in the traps, and it was really loud, so it was funny.

00;07;00;06 - 00;07;24;27
Laura Prugh
Come to your trapping grate and there'd be this kind of loud clanging in the metal traps from all around, but we would just kind of get them into a cannabis spot and put a microchip in them. The same as your pet gets microchipped at the vet, weigh them, take some measurements, and then we release them and they would hop around and go down into their burrow holes.

00;07;26;25 - 00;07;38;01
Sarah Smith
Kangaroo rats are perfectly adapted to their arid environment. They have massive hind legs. That's the name Kangaroo Rat and the ability to jump huge distances.

00;07;38;10 - 00;07;41;29
Laura Prugh
Sometimes you see them kickboxing with each other.

00;07;42;10 - 00;08;07;01
Sarah Smith
And escape predators fast. They're also super adorable, if you can imagine. They're kind of a Miyazaki style gerbil with giant cheek patches and big black eyes. It's just so, so cute. Prue in her team, also looked at the question of how species management might be good for one endangered species. But then harm another.

00;08;07;19 - 00;08;26;00
Laura Prugh
And so with all these endangered species interacting with each other, you might come up with a management strategy to conserve one species. And by doing so, maybe you would inadvertently be harming another endangered species.

00;08;26;15 - 00;08;38;25
Sarah Smith
Cattle grazing is a controversial approach to managing the spread of invasive plants in the environment. This approach can sometimes do more harm than good, leading to habitat loss and drastic negative effects to the ecosystem.

00;08;39;11 - 00;09;07;04
Laura Prugh
So one of the goals was to really understand the interactions among all these species in the system. So we took a big experimental approach where we built these cattle exclusion laws and also kangaroo rat exclusions, because often the best way to understand how a species affects the system is to exclude it from an area and then see how that area changes.

00;09;07;15 - 00;09;33;28
Laura Prugh
Then we did as many surveys as we could in that system. So we did plant surveys. We were also looking at ground squirrel abundance using the same thing. We did the lizard surveys for reptiles. At night we would do spotlight surveys to count predators like foxes for the kangaroo rats. We did mark recapture surveys to estimate their population sizes.

00;09;34;18 - 00;10;10;19
Laura Prugh
The one interesting thing we found in terms of the invasive grasses is that the invasive grasses really like to grow on their burrow mounds because invasive plants often like disturbed soil and disturbed areas and fertilized areas, you're see just mound after mound of bright green vegetation that's taller than the surrounding areas. There's this really good soil that's been churned up and aerated and they're whooping and paying so it's fertilized.

00;10;10;28 - 00;10;23;29
Laura Prugh
In the summer they will mow it all down and dry it in these piles. And sometimes these piles are huge like like big grocery bags full of seeds.

00;10;24;17 - 00;10;33;07
Sarah Smith
Kangaroo rats are like little farmers. They mow down the invasive grasses on their burrow mounds. They help remove these invasive seeds from the ecosystem.

00;10;33;23 - 00;11;04;26
Laura Prugh
So that was sort of a kind of interesting situation where it looks like you have the endangered species that's kind of promoting an invasive species because the kangaroo rats are endangered because of habitat loss in that system. But the kangaroo rats kind of keep those invasive grasses from taking over the entire ecosystem because they prefer to eat those invasive grasses because they have bigger seed heads.

00;11;05;12 - 00;11;33;26
Laura Prugh
And so they are removing a lot of the invasive grass seeds from the system. And so where we in the areas where we excluded the kangaroo rats, those invasive grasses just spread off of the burrow mounds and took over the entire areas, whereas in areas where the kangaroo rats are still present, the invasive grasses are kind of restricted to just being on the burrow mound.

00;11;34;09 - 00;11;46;26
Laura Prugh
And then you get native bunched grasses and other native species that grow like around in between the kangaroo rat burrows. There are fascinating little creatures.

00;11;47;22 - 00;12;19;02
Sarah Smith
That it's a special thanks to our guest, Laura Prugh. You can learn more about peruse research at the University of Washington College of the Environment by clicking the link in this episode description or by visiting our Web site. Environment dot UW dot edu. From all of us at FieldSound, thanks for listening to the.