ANCHORAGE (AP) Alaska meteorologists are tracking more than the weather these days.
Longtime Alaska meteorologist Ted Fathauer with the National Weather Service has documented at least 100 episodes of high-flying nocturnal bird migrations using advanced Doppler radar. He's conducted the research over the past three years.
The weather service uses Doppler radar on Pedro Dome, north of Fairbanks, to track the speed and density of precipitation. The radar perpetually scans the horizon and has tracked birds as high as 11,000 feet.
Fathauer, lead forecaster with the Fairbanks office, worked with University of Alaska Fairbanks wildlife biology major Nora Kohlenberg, who helped research and interpret the results. In September, the two presented a report on the phenomenon at the meeting of the Arctic division of the American Association for the Advancement of Science in Fairbanks.
''I've looked up at the sky at night when you know these guys are up there, and unless you have special optics and a full moon, there's no other way to see what's going on,'' Fauthauer said. ''This is our X-ray machine. Without it, this whole process is invisible.''
Tracking birds with radar isn't new and scientists have used Doppler radar to follow East Coast migrations, but no one has gathered readings before from weather radar in Alaska or at such high altitudes, according to Fauthaur and Kohlenberg.
Birds might be flying so high in the dark to seek out cool air, Kohlenberg said.
''Birds are amazingly warm creatures, as they have a very high metabolic rate,'' she said. ''Thus birds tend to fly at times and altitudes that are cool so they can save energy by cooling themselves with the cool evening air.''
In the late 1980s, the weather service began replacing old-style radars with sensitive Doppler systems that had the ability to detect wind speed and direction when signals bounced off rain and snow. In the 1990s, seven systems were installed in the state.
The radar beams scan an enormous swath of sky, Fathauer said, producing the vivid images of approaching weather that most people have watched on television or Internet sites. But the system also has the capacity to return images of relatively slow-moving objects like birds, bats or even insects. It ignores faster objects like aircraft.
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