Storm-Watching Radar Systems Find Another Use: Bat-Tracking
In the realm of meteorology, bats, birds, and insects are usually considered “animalas non grata,” since they create unwanted noise in the Doppler radar readouts used to study storms. But now, thanks to better radar station networking and the sharing of unfiltered data, ecologists have realized that these radar systems can be used as powerful animal tracking tools.
At last week’s American Association for the Advancement of Science meeting, researchers Thomas Kunz, Winifred Frick, and Phillip Chilson explained how Dopplar data can be used by ecologists. They call their new discipline aeroecology.
This melding of meteorology and ecology started with an “Aha!” moment:
“Dr Kunz and I were meeting Dr Chilson about a year ago over breakfast and they kept talking about the ‘QPE’, and finally I asked what it is,” Dr Frick told the meeting. It stands for quantitative precipitation estimator — a numerical method to measure how much rain there is in a storm front. “I paused and said, ‘you can estimate the number of raindrops in a raincloud? Do you think we could estimate the number of bats in a bat cloud?’” To calibrate their experiment, the team took a bat into a chamber where the degree to which it reflects radio waves could be measured. “From those measurements and using radar, we’ve been able to adapt those QPE measurements to a ‘QBE’ – a quantitative bat estimator,” Dr Frick said. [BBC News]
In the past, animals like bats have been tough to track due to the size of radio transmitters: these tracking devices work well on large animals, but they’re too large for many kinds of birds, not to mention bats and insects. But a radar system removes the need for transmitters, and can allow researchers to examine the under-explored ecology of the air.
In one new initiative from the National Severe Storms Laboratory in Norman, Oklahoma, meteorologists put the data from 156 NEXRAD radars across the United States on to a map; now all that data is available to biologists in a project called Surveillance of Aeroecology. The map is updated 12 times every hour, and the researchers hope to improve the resolution to get better images of insect swarms and flocks of birds.
The use of meteorological data saves ecologists from having to invest money in equipment, and they’re already reaping the benefits:
At the meeting, Frick described how, in a radar sequence from southern Texas, she had seen something she had never imagined: swarms of bats following an evening weather front. â€œRadar is like a really fancy pair of binoculars,â€ Frick said. In the radar view of a storm front rolling over Texas, Frick pointed out a frayed tan bar indicating insect swarms moving with the air mass. The radar doesnâ€™t reveal much about the identity of species in a cloud, but Frick knew that the front was passing over a bat cave. A yellow burst on the radar showed what Frick identified as dense crowds of Brazilian free-tailed bats speeding out of their cave at sunset to hunt for insects. The burst bloomed into a cloud of bats, with an elongated mass sliding west along with the bugs. â€œItâ€™s a big aerial buffet line,â€ Frick said. [Science News]
Better tracking of animal behavior can also aid conservation efforts for various bats, birds, and insects. Researchers hope the field will grow quickly, because they’re not building their data banks from scratch: Radar stations have decades of data just waiting for the sharp eye of an aeroecologist.
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