High-tech radar helps OU doctoral student study bird migration

A University of Oklahoma doctoral student is using radar to track the migration of birds across Oklahoma and how the wind affects their nighttime flights.

With dual polarization radar introduced in 2013, researcher Kyle Horton can see the orientation and direction of migrating birds.

“We are sort of at the cutting edge in terms of understanding migratory behavior, especially on a large scale,” Horton said.

With the radar system known also known as Next Gen, Horton said, he can see hundreds of thousands of birds flying every night and details about their flights.

“The videos that are being produced by radar technology … can really help visualize what is going on outside of everybody’s front door,” said Dan Reinking, a senior biologist at the Sutton Avian Research Center in Bartlesville.

Most birds fly eight to 10 hours a night, Horton said, but some can fly 30 hours when traveling over the Gulf of Mexico.

Oklahoma is home to more than 400 species of birds, and three-fourths of them migrate into the state, Reinking said.

Horton tracks about 125 species that pass through the Central Fly Zone, or the Midwest region.

“Historically we have found that many migratory birds are declining,” Horton said, with research showing changes in landscape and habitat causing different migration patterns.

Many birds, including the American tree sparrow, are becoming less visible in Oklahoma, Reinking said. As the climate changes, he said, certain birds will either adapt or no longer fly to Oklahoma.

“The winters have been warming over the past 40 to 50 years here in Oklahoma,” said Gary McManus, state climatologist for the Oklahoma Mesonet.

Without the wind, many birds could not go to their winter and summer grounds, Horton said.

“For a long time, you were able to use the weather radar to understand the direction,” said Jeff Kelly, director of the Oklahoma Biological Survey and adviser to Horton in his research.

“We could never understand the way the birds were oriented in the wind and where they wanted to go,” he said.

Tracking the birds opens up questions for future researchers on how the birds could deal with changes in the wind and climate, Kelly said.

Wind is dominant factor

“Winds are a dominant factor that drives migration, there is no question about that,” Horton said. Some of his research has already appeared in peer-reviewed journals.

The new radar system sends out a horizontal and vertical burst of energy, which provides a two-dimensional view of what is in the air, something older radars could not do.

“We see a large migration through the plains, and the wind in Oklahoma … is a huge factor in migration biology,” Kelly said.

Many birds begin their journeys in Texas and make their way to the Canadian border, Horton said.

“I am a pretty avid bird-watcher,” said Horton, who was wearing socks decorated with bird images.

Many of the birds Horton studies fly across the Midwest during the night, when conditions are favorable are there are fewer predators. He occasionally travels to Texas to observe and gain a deeper understanding of avian behavior.

By varying the altitude at which they fly, Horton said, migrating birds can catch tail winds that allow them to drift to their destinations, which can be seen with the new radar.

In Horton’s research he has found that birds will change their altitudes to avoid too much wind. He said a songbird has problems flying in 70 mph winds.

“Often these birds will go back to within meters of the place they spent last summer,” Kelly said.

“Try to think about finding your way through that atmosphere when that wind is blowing 30 mph,” he said.

CAPTION: Kyle Horton stands in front of dual polarization radar in Norman. [Photo by Eriech Tapia]

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