Thursday, December 21, 2017

Airports a Common Landing Pad for Snowy Owls During Influx

Airside Manager Steve Wabrowetz and a snowy owl at Duluth International Airport.

Some recent inbound traffic at Minnesota airports hasn't been showing up on the radar, but air traffic controllers are on the lookout anyway.

The increase of the snowy owl population of late – known as an irruption – has created a buzz among everyone from birders to wildlife professionals to people who just appreciate cute. 

The birds have recently made their way into a biomass chip lot at a Grand Rapids energy plant, a coffee roastery in Duluth and onto a Twin Cities interstate, among other places, in search of food in what experts say is the most significant irruption in recent memory. Most of the owls are juveniles – hatched this past spring.

Perhaps the greatest number of snowy owl sightings have come at airports, where the treeless landscape most resembles the birds' native Arctic tundra habitat. 

Snowy owls before being released near Grand Rapids.

The owls' presence at airports presents a significant hazard, according to federal Wildlife Biologist Pete Sahr, who's based in Grand Rapids. Sahr contracts to do wildlife work with the Air National Guard's 148th Fighter Wing, and by extension the Duluth International Airport. 

"At Duluth, they had a couple airplanes that had to do go-rounds when the tower identified (snowy owls) on the runway," Sahr said of a couple recent aborted landings. "Definitely, at big airports, controllers are keeping an eye out."

Sahr has made the trip from Grand Rapids to Duluth to trap 11 snowy owls this season, by far the most he's recovered by this point in any given year. He generally relocates two or three each year, he says, and some years none.

"They have a bad habit of sitting on and around runways, runway lights, runway markers," Sahr said. "And the reason is the exposed edge of runways caused by plowing and brushing" which churns up grass, which attracts rodents.

On Nov. 10, a Delta MD 90 struck a snowy owl during departure on a runway at Minneapolis-St. Paul International Airport. The aircraft made flight but returned to the airport so staff could check for damage, airport spokesman Patrick Hogan said. 

The owl had caused a broken hydraulic line in the right landing gear, and the plane – on a scheduled flight with passengers aboard – was towed to the gate. 

MSP has captured and relocated nine snowy owls since Nov. 7, Hogan said, and two have been struck by planes. He said the birds typically hang out on snow piles or large snow-covered areas, but with the relative lack of snow this year, they've been drawn more and more to the white markings on runways.

Like Duluth, MSP contracts with USDA wildlife biologists for hazard assessments, mitigation and wildlife management planning. The USDA's wildlife services office in St. Paul handles that work for MSP, the St. Paul Downtown Airport, and six other regional Twin Cities airports.

The airports use noise cannons, stuffed predators placed around the airfields and other measures, Hogan said. Sahr's office has provided the Duluth airport with radio controlled propane cannons that maintenance teams can move around the airfield and detonate remotely. The noise is intended to scare off the owls.

Sahr, who's also a certified airport biologist and has been based in Grand Rapids more than 20 years, takes the birds he traps back to the Grand Rapids area, where he tags them and releases them in large agricultural areas. 

This snowy owl, trapped at the Duluth International Airport, was released near Grand Rapids.

That's because the birds, typically nomadic, generally fly north-south, rather than east-west. Sahr said releasing them 70-80 miles from the Duluth airport helps assure they don't make their way back to the space.

Sahr said the snowy owls he's encountered this season have generally been healthy juveniles. But that hasn't been the case for many of the birds brought to the University of Minnesota's Raptor Center. 

Executive Director Julia Ponder says the irruption comes during what is typically a slow season for the center, which relies on philanthropic dollars and is generally less staffed during the winter. 

The Raptor Center has admitted 28 snowy owls from all parts of the state already this season, Ponder said. Most of which haven't or won't survive. Another seven have been dead on arrival. 

A French Bal-Chatri trap used for capturing the snowy owls at the Duluth airport. It's a mesh-wire cage with an animal bait inside and covered in a monofilament material that entraps the bird's legs.

"For many of these youngsters, this is a one-way trip," she said of the owls' flight from the native arctic. 

Irruptions occur every five or 10 years, Ponder said, and not like clockwork. She, like Sahr, said this year's influx is the most significant in recent memory. 

The owls are typically mostly white with some dark feathers, bright yellow eyes and a short beak. Ponder says they're amazing creatures that capture the attention of birders and the general public alike, but they're likely stressed and should not be approached.

"Don't intervene and cause stress," she said. "The birds are already fairly stressed, being in a non-native habitat, so, great to see a bird like this in the wild, but we really ask that people keep their distance and don't harass the bird or stress it in any way."

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