UNR Scientist Looks At Impact of Urban Sprawl On Wildlife

Oct 25, 2017

As northern Nevada continues to grow and expand its urban core, one local scientist is looking to see what impacts that could have on wildlife.

Reno Public Radio’s Noah Glick sat down with Jenny Ouyang, an assistant professor of biology at the University of Nevada, Reno to learn more about her research into how local bird populations are being affected by urban sprawl.

KUNR: Tell me about your research. What are you studying and what do you hope to find out?

Ouyang: So my lab is really interested in how animals physiologically adapt to changing environments. And the environment that I’m really interested in is this gradient between the urban environment and the rural environment.

I’m really interested because certain individuals seem to have a specific phenotype if they are urban-avoiders, or if they like to be in urban areas. So I’d really like to figure out what makes individuals really adapted towards urbanization.

As our areas get more and more urban, you tend to find certain species are displaced. So trying to find the physiological traits or behavioral traits that underlie this sort of preference will really help us try to figure out diversity and “greenifying” our cities.

What are you finding? How does wildlife adapt to manmade urban ecosystems?

It depends on where you are, which city you’re studying, which species you’re looking at. So I’m going to talk about Reno and I’m going to talk about the House Wrens in Reno. So House Wrens are these little birds that nest in both downtown Reno, so very urban environments, all the way to rural areas. They’re all over, and they’re on this gradient. And we’re finding that the urban House Wrens, they have a higher stress hormone level, called corticosterone. So this glucocorticoid level is higher in urban animals than in rural ones.

We ran this experiment last year with an honors student, Nicole Haddad, and her experiment was looking at whether traffic noise in urban areas would increase this sort of stress response. The fascinating thing was that the birds were responding to traffic noise in particular, and not just noise. Because we played both traffic noise and ambient noise. And we also played them for both rural and urban individuals. And the urban individuals did not elevate the response, whereas the rural ones, after they heard this traffic noise, they had higher levels of circulating glucocorticoids.

If we just played pink noise, which is this "bzzz" sound, that actually didn’t change their before and after treatment levels.

The urban environment isn’t just noise. It’s also higher light levels, perhaps higher heavy metal contamination. So we’ve been looking at lead levels across Reno and Sparks as well.

Stressful city sounds: glucocorticoid responses to experimental traffic noise are environmentally dependent... by KUNR Reno Public Radio on Scribd

Is that some of the next steps then for this research, to maybe look at the light, look at the lead levels?

Yeah, so with a collaborator, we’ve already mapped out urban factors at a very, very fine scale. Reno in particular is really interesting because we can find areas where there’s high noise and light levels. But we can also have areas across the interstate where you have very high noise, but low light levels. And then casinos with very high light levels but low noise levels.

And at least with some path analysis diagrams that we’re working on right now, it seems like the birds are more responding to noise in particular than to light.

Why should the everyday Average Joe care about the House Wren and whether or not they’re stressed out?

All of us, as vertebrates, we have the same hormone levels. So having a model species in which we can do experiments or to observe them in the wild doesn’t just conserve this species, it conserves all songbirds or helps us understand how hormones react from all vertebrates, that kind of general point of view.

So by understanding how hormones and hormone levels work in a House Wren, we can in a way learn how hormones work in us?

Absolutely. This is why a lot of animal research, penicillin, all of the drugs we’ve developed, were developed on animal models. And trying to find research-friendly ways in which we can help us as humans, and also help these animals, is a goal in my life.