ASU researchers study how urbanization affects health of songbirds

Video by Edward James Hernandez | Multimedia Reporter

There's no question that the human presence and urbanization have a profound impact on the environment, but for the first time ASU researchers from the School of Life Sciences have found a direct link between the degree of urbanization and the occurrence of illnesses in songbirds, such as house finches.

A team of professors and graduate and undergraduate students made this discovery while investigating intestinal parasites such as isospora, which causes acute, non-bloody diarrhea in hosts, and the canary pox, which manifests in lesions of the skin and may eventually lead to the loss of digits.

They published their findings in the Feb. 4 issue of the journal, PLOS ONE.

According to the journal, urbanization can strongly impact the physiology, behavior and fitness of animals. Conditions in cities may also contribute to the spread of animal parasites and pathogens.

Biology professor Kevin McGraw said urban areas could foster increases in multiple disease types in wild animals.

McGraw is an integrative behavioral ecologist who was one of the contributors to the journal. His studies focus primarily on the colors of birds to understand the benefits and evolution of visual signals.

"It's that color that makes them 'sexy,'" he said.

McGraw has been part of ASU for 10 years and has been working with finches on campus since the month he arrived.

“Our lab is mostly focused on local opportunistic desert finches called the house finch,” he said. “It’s abundant in this part of the United States.”

The house finch is native to the western part of the U.S. and has recently been introduced into the east. Adult males are identified as having reddish orange markings around their breast and rump.

“It’s a pretty diverse species and one that does pretty well in urban environments,” he said. “They are very abundant, versatile and flexible.”

Biology professor Kevin McGraw recently found that urbanization is a direct cause to illness in songbirds. McGraw is also a director of the School of Life Sciences Undergraduate Research Program. (Photo by Ryan Liu) Biology professor Kevin McGraw recently found that urbanization is a direct cause to illness in songbirds. McGraw is also a director of the School of Life Sciences Undergraduate Research Program. (Photo by Ryan Liu)

McGraw said his team had some hypotheses as to why urbanization might be affecting house finches' health.

“Urban sites impose stressors on the birds,” he said. “Noise pollution and air pollution could lead them to have depressed health. As a result, they are more susceptible to illnesses.”

McGraw also said bird feeders and birdbaths might also be part of the problem. Although they're helpful when the Arizona heat decreases the abundance of food and water, they also act as congregation sites for parasites.

“People don't often clean bird feeders,” McGraw said. “Though we don’t wipe down things in nature either, they also don’t have as high congregation as bird feeders do.”

Another question posed concerning bird feeders is whether or not they are actually good for the birds.

“What are the nutritional foods we are giving them?” he said. “Are they good for the birds, or are they essentially the Skittles of the bird world?”

McGraw said these questions are hard to know and also hard to test. His team runs experiments in the lab, but it’s difficult to run a large-scale ecological system. His team has been continuing to analyze parasites and how they relate to the behavior of the animals.

“We are actually studying things about their immune system to understand how healthy they are,” he said. “We can’t understand what about the city is impacting health, but we can certainly assess if their immune systems are performing differently.”

Bird catching

On Saturday, animal behavior graduate student Melinda Weaver and two student volunteers set out early in the morning to trap and collect house finches to collect more samples for the ongoing study.

Starting at 7:30 a.m. they set up a trap in the life sciences courtyard. Their goal was to catch 30 birds.

The process involved a lot of sitting and waiting. Weaver said their success depended on the whim of the birds.

“Even on the best field day, we will be working until 10:30,” she said. “Usually it takes much much longer.”

Weaver said the hotter it gets, the easier it is to catch birds.

“When it gets hotter, sources of food and water become more limited, drawing them to the traps,” she said. “However, I usually quit when it gets too hot, because the birds could die inside the traps after being exposed to excess heat.”

Unlike most birds, house finches aren’t quite so wary of new environments. Birds will imprint on things, making them very cautious, while house finches have shown to be less afraid.

“We can get 15 birds in one trap," she said. "Since there is food inside, they will go inside the traps and can’t figure out how to get out,” she said.

When the trap starts to get crowded, Weaver and her volunteers collect the birds and store them in separate brown paper bags. They would then evaluate and record each bird and measure factors such as weight, tarsal length, gender and color and later house them in the lab for eight to 10 days.

“Though they are very social animals, we house them in separate cages to eliminate interfering factors,” she said. “We want them all to be under the same conditions.”

Weaver said she has a team of 16 students who help her with these sorts of field studies. Instead of making them get up every morning to help her, she allows them to sign up for certain days of the week.

“Students participate for the research experience,” she said. “I let them dictate how much work they are willing to do.”

Biology senior Emily Boyle was one of the volunteers who helped Weaver. She has been on Weaver’s field team for over a year.

Boyle said these field studies have helped her learn how to handle birds and some of their behavior aspects.

“It’s really great," she said. "You learn a lot of what detailed-oriented research is like."

Biology senior Jeremiah Wetherby was also one of the researchers at the site. He began working with Weaver this semester and has proven to be one of the most dedicated volunteers on her team, volunteering three days a week.

He said ASU offers a lot of research opportunities for different students.

“This research will help us to integrate and co-exist with animals,” he said.

Reach the reporter at or follow her on twitter @kelciegrega

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