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Stevens Point biology professor continues to gather data on Cooper’s Hawks

One of the Cooper's Hawk's Professor Rosenfield collected data on in Stevens Point, Wis.
One of the Cooper's Hawk's Professor Rosenfield collected data on in Stevens Point, Wis.(WSAW)
Published: Jun. 20, 2022 at 9:06 AM CDT
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STEVENS POINT, Wis. (WSAW) - Robert Rosenfield has been studying and collecting data on Cooper’s hawks for more than 40 years. He is a biology professor at the University of Wisconsin-Stevens Point. He started conducting his research on the birds when they were listed as threatened.

Cooper’s hawks are native to North America. It was named after the naturalist William Cooper, one of the founders of the New York Academy of Sciences. The medium-size hawk is sometimes called a big blue darter, chicken hawk, hen hawk, Mexican hawk, quail hawk, striker and swift hawk.

Since then, his focus has been on gathering information on the reproductive biology and success of the birds. He’s found nests around the city, rural areas, and most recently a nest on campus outside of Old Main.

“The more nests I find the more data I can actually contribute to my understanding of what’s going on with the birds... So the birth might respond differently to a variety of ecological factors if they’re in a city versus some part of the city versus maybe out in a rural surrounding,” Rosenfield said.

In more than four decades of research, he said the most surprising find was how they’ve adapted to an environment outside of a forest.

“Lo and behold, they have adapted remarkably well to fragmented landscapes, where trees have been cut down at a market rate. And of course, what would be a good index that would be a city setting, and they now attain their highest densities, and their highest reproductive successes occur in cities,” Rosenfield said. “Now, here in Wisconsin, what I’ve discovered is actually the city really doesn’t appear to be any better than a rural environment. So generally, Wisconsin overall is a good place for Cooper’s Hawks. And their populations are just there. They occupy virtually every habitat that humans occupy or have altered inadvertently, so to speak to the betterment of Cooper’s Hawks.”

He said the birds are also occupying every possible breeding site that could be occupied in Northern America.

Rosenfield collected data on the birds he found in the nest next to Old Main. He used his owl to distract the male and female in order to climb the tree to get to the chicks. He said the information and data he collects on the birds are used to determine how they are reacting to climate change.

“Climate change is one of the biggest environmental concerns by many ecologists and societies around the planet... And if I wasn’t able to conduct the study, for whatever reason, and gather data across these four decades, plus, I would not have been able to combine my data with the population biology of penguins, seabirds, sparrows and warblers, and grouse across the planet Earth to find out how birds writ large are doing. And I can tell you that that analysis is done and their projection for Cooper’s Hawks, at least for the state of Wisconsin, may be benefiting from climate change,” he explained.

He said that’s because summers are getting longer which leads to a longer breeding season.

“So it’s a rather surprising find, I’m sure for a lot of folks. So it’s neat to be able to contribute to a long-term global view rather than just the Wisconsin perspective. That’s neat.”

He said his favorite part of conducting the research is working with the students.

“I’ve worked with hundreds of students over the years, I couldn’t possibly have gotten done what I have gotten done without students and without the support of the administration at this campus. Because no one’s going to fund a study for 43 years and find people... I love trapping Hawks. I love trapping birds, and I love climbing trees. Ever since I was a little kid I’d always thought it’d be kind of cool to get a job or I could do a lot of things I liked as a kid. And so I get to do them now and I really like that.”

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