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High-tech trackers give scientists better eagle data

The eagle know as NX will “phone home” using the latest in wildlife tracking technology.

Instead of satellites, the system uses cell phone towers to relay data back to researchers.

The shorter signaling distance extends operating life. Transmitter batteries last longer and antennas can be eliminated – a protrusion that can break off or cause an animal to become hopelessly snagged.

Cellular Tracking Technologies supplies the transmitters – each about the size of a deck of playing cards – for around $3,000 each. Michael Lanzone, a biologist who co-founded the Pennsylvania company, says Virginia game officials have 19 of the systems deployed.

Most are on the backs of golden eagles, members of a small eastern population that breeds in Canada and winters in Virginia.

Baited with road-killed deer and captured with rocket nets, the golden eagles are monitored to learn more about their habits and migration routes, insight that could shape the future of wind farming in the region. Wind turbines are a top cause of raptor mortality in western states.

But even with their cell tower advantage – and solar recharging – the transmitters only work for about two years.

“It’s kind of like the battery in your phone,” Lanzone said. “After awhile, it just wears out and won’t hold a charge anymore.”

Five bald eagles have been part of Virginia’s tracking program, but only three of those units are still working. According to their signals, one of the bald eagles is currently in Canada and the other two are near tidal rivers in eastern Virginia.

Like the other birds wearing cellular transmitters, NX will carry her backpack long after its last signal fades. Its tiny Teflon harness is designed to last 25-plus years, the average life span of an eagle in the wild.

Lanzone says permanent harnesses are safer than break-away versions, which could snare birds with their fraying straps.

“And the bird gets used to wearing it,” Lanzone said. “It’s like a dog with a collar or a ring on your finger. After a few months, you forget it’s even there.”

The weight of NX’s unit was trimmed to ease the load on the young, inexperienced bird. Instead of the usual 100 grams, she’ll be toting 80 – the weight of about 16 nickels versus 20.

The compromise shrank battery power even further. To make up for it, the unit will only mark NX’s position every 15 minutes – it can record in 30-second intervals – and will send its data just once every two days.

If NX flies out of cell tower range, the unit will store its map until she returns. Once downloaded, the data transmits to a server, which researchers – armed with a smart phone and the proper code – can tap into from just about anywhere.

“We’ve never had this kind of continuous information,” said Stephen Living, a biologist with the state game department, the agency behind the tracking project. “In the past, our only tool has been banding, and that doesn’t tell you much about a bird’s life except the beginning and the end.”

NX’s data will also be fed into a project that analyzes avian activity around airports. The hope is to reduce the kind of bird-airplane collisions that killed her mother near the Norfolk airport in April.

“It’s kind of neat,” Lanzone said, “that this eagle could help us do that.”