FROM THE VICE PRESIDENT
This University, amidst this natural laboratory, is a special place.
A rundown of science stories during the past year.
UNLOCKING THE SECRETS OF FLIGHT
UM releases new theory of bird evolution.
ONE HOWL OF A GOOD IDEA
Scientists create innovative listening device to track wolves.
Researcher provides tools to track their habitat.
Young researcher studies raptors impacted by metal contamination.
Wildlife biologists snare two prestigious grants.
HARE TODAY, GONE TOMORROW?
The snowshoe hare may become a climate change poster child.
Projects tackle dams, invaders, hybrids and more.
CRACKING A MYSTERY
Researcher suggests inattentive bird parents may produce larger eggs.
While studying how chukar partridges grow and develop the ability to fly, UM researcher Ken Dial developed an original theory for the evolution of flight.
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Wildlife biologists snare two prestigious grants
By Ginny Merriam
|Creagh Breuner and Vanessa Ezenwa
When mountain white-crowned sparrows leave their breeding grounds high in the Sierra Nevada during an April snowstorm, scientist Creagh Breuner can tell you why — at the biochemical level.
Sure, she says, snow covers the insects and seeds the sparrows are eating, and common sense drives them to fly lower to wait out the weather. But inside the birds, stress hormones called corticosterone are circulating and interacting with proteins to create a complex dance with their body condition, weather and the availability of food to make sure the species goes on.
It’s all food for thought and investigation for Breuner, a field endocrinologist who teaches in UM’s Organismal Biology and Ecology Program, as well as in the Wildlife Biology Program.
“I think about interactions between an animal and its environment,” Breuner says. “What are the behavioral decisions? Then what mechanisms underlie the change in behavior? I put my endocrinology background under this framework.”
For the past 12 springs — with one exception, the April in which her now-4-year-old twin boys were born — Breuner has camped at 7,000 feet and studied white-crowned sparrows at 9,000 to 10,000 feet in the Sierra Nevada near Tioga Pass. Swaddled in fleece and parkas, Breuner and her fellow researchers capture male sparrows in seed traps and place tiny 1-gram radio transmitters on their backs that are held snugly to their bodies with elastic bands around the legs. The transmitters can signal the researchers their locations in an area of 2 to 3 kilometers around the pass. The scientists also use miniature tubes implanted in some of the birds, some loaded with stress hormone doses and some empty.
So far, the intriguing results show that generally the presence of the stress hormone moves the sparrows away from breeding — they leave the breeding grounds more readily in bad weather, and they’re slower to return. The corticosterone is saying to the bird, “Go away from here. Take care of yourself. Don’t worry about breeding.”
“So one of the things I’m thinking about is the conflict of testosterone and corticosterone,” Breuner says. “I think of it as a balance between self-maintenance and breeding.”
The researchers also have found that the magnitude of the corticosterone response is related to the body condition of the birds. The birds with lower fat levels seem to generate more of the stress hormone than birds in better condition, which may motivate them to leave the breeding ground more readily.
But there’s much more work to be done surrounding the relationships among birds’ conditions, weather and how much food is available. The end knowledge will give scientists much information about what determines fitness, or reproductive success and survival, in animals.
“How does this stress response benefit the animal in terms of fitness?” Breuner asks.
The work has implications for humans, too. Biomedical work looks at the ties among the level of stress in an individual’s life, how the individual responds and the level of heart disease, Breuner says. And the work also speaks to conservation biology, where scientists look at hormone levels to read stress responses to changes in the environment.
“So I’m looking at the variations among animals and birds,” she says. “I am absolutely interested in the basic biology. That’s what drives my work and drives my interest.”
At home, it’s no surprise that Breuner’s twin sons read “The Sibley Guide to Birds” and accompany their parents on fieldwork. Breuner’s husband, Art Woods, also is a UM scientist. The couple left the University of Texas at Austin for Missoula two years ago because UM had positions for both of them.
“I’d never really thought about Montana,” Breuner says. “I came up to visit for my interview and loved it. I’m so glad we’re here. I love our neighborhood, I love our house, I love our colleagues. It’s perfect.”
That good experience was rounded out last winter when Breuner won a National Science Foundation Early Career Development Program grant of $800,000. The five-year grant will enable her to pay a full-time postdoctoral student, pay Breuner’s salary during the summer and also support her laboratory.
“I was blown away to get that level of award,” she says. “It’s an honor.”
And UM was doubly blessed. Vanessa Ezenwa, a UM scientist who works in wildlife disease ecology, also recently won an Early Career grant, bringing in $715,000.
The dual honor is astonishing, says Dan Pletscher, UM professor and director of the Wildlife Biology Program.
“I don’t know of any other case anywhere where such a thing has happened,” he says. “I think it’s an example of the incredible quality of people we can attract to this university.”
Ezenwa, who earned her master’s and doctoral degrees at Princeton, is interested in the relationships between levels of parasite infection and infectious disease in wild animals. She looks at the way the social organization of an animal population affects parasitism and the transmission of disease.
“I’m interested in social behavior — why animals are organized in different ways,” Ezenwa says. “What makes animals live singly or in groups? Travel or not? And what are the factors that affect the ways animals behave?”
Ezenwa’s scientific interests are so diverse that she sometimes has to put the brakes on. As an undergraduate biology major at Rice, she took a course in animal behavior and worked in the lab of an animal behavior scientist. That work set her on the path of disease ecology.
“I realized people did that,” she says. “But, you know, you never connected that those people on ‘National Geographic’ do that for a job. We can understand why animals do things. And we can look for underlying mechanisms for why animals do what they do.”
Ezenwa’s work began by studying the benefits and detriments of living in groups, with a focus on ungulates. She says groups can protect themselves from predators and forage for food together, but they also bring a greater risk of disease transmission.
The class of an individual also matters, she says. Some male Grant’s gazelles, for instance, defend a high-quality piece of territory, and once they’ve secured it, they don’t leave. These males have higher levels of parasite infection than females or lesser males. In Ezenwa’s study, she asks what effects the parasites are having on these male gazelles.
“That’s the interesting question,” she says. “What are the lasting effects? How are these parasites affecting their behavior and their fitness?”
Ezenwa has looked at worm infestations in the gazelles in Kenya, where she has worked for the past nine years. Her newly funded research has three parts: observing what the animals do in the field, capturing the animals and treating them for the parasites, and looking at the animals’ hormone levels.
“Then you can answer questions like, ‘When you take these parasites away, do males spend more time mating females and defending their territories?’” she says. “Maybe it’s the high levels of stress hormones that cause the high rate of parasite infection.”
Ezenwa also works in South Africa with the African buffalo, where she looks at the relationship between parasitic infection and bovine tuberculosis. That work has implications for the human population.
In developing countries, HIV tends to progress faster and be more severe among humans. There’s also a high level of parasite infection in people.
“There’s a lot of evidence coming out now that the presence of worms affects the severity of diseases like TB and HIV,” Ezenwa says.
Some of that could be the result of cross-talk between the two branches of the immune system, she says.
“So if your immune system is responding to worms, it’s biased toward that, and it might not respond as well or as quickly to a disease like TB,” she says.
In a changing world, Ezenwa’s research can inform the decisions made in wildlife management. Ezenwa’s new grant will allow that work to continue.
“I am very happy, for sure,” she says. “It will allow the testing of some interesting questions that are really exciting for advancing the fields of ecology and animal behavior.”
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|Research by UM’s Creagh Breuner suggests a stress hormone reduces the chance this mountain white-crowned sparrow will breed.
|UM’s Vanessa Ezenwa studies parasites that afflict social ungulates such as this Grant’s gazelle in Kenya. (Photo by Stefan Ekernas)
|Creepy critter: This strongyle worm is found in the gut of Grant’s gazelles.