Solving the mystery of eagles on Pax River’s runways

With a V-22 Osprey in the background, a bald eagle takes flight on the airfield at NAS Patuxent River. A project will soon be underway to study the habits of a large group of eagles who roost on the runways each September and October, with the goal of altering their behavior so they will not return.

Following a bird strike in 2019, funding has been approved for a project to track the habits of a large group of bald eagles that have been showing up each fall to roost on the runways at NAS Patuxent River.

The Class A mishap, which involved an E-6 aircraft striking a bald eagle during takeoff, resulted in engine damage worth $3.5 million and a vital aircraft downed for an extended period of time. Fortunately, no personnel were injured.

“In a test environment like Pax River, that’s very costly,” explained Jim Swift, the installation’s natural resources specialist. “The eagles are a hazard to aircraft that fly at Pax River as well as the mission Pax has. We need to figure out why they’re coming to our airfield so we can implement some management strategy to discourage them from doing so.”

For the past number of years, each September and October, an influx of bald eagles inexplicably arrive and begin to roost on the runways, said Pax River’s Conservation Director Kyle Rambo.

“We can see as many as 50 eagles lined up on our runways at any one time,” Rambo said. “They’re not here all day; we don’t see them showing up at dusk. They arrive sometime early in the morning hours and they’re there when we do our morning airfield sweeps. They’ll fly off one runway and fly onto another one. They’ll hopscotch around and there’s this mess of bald eagles we have to deal with.”

Rambo, who noted the birds are communal and will travel together when not nesting, thinks that due to cooler autumn nights, the eagles may be taking advantage of the heat the asphalt absorbs each morning to warm themselves before leaving to forage.

“Maybe they’re warming their muscles so they can fly sooner, go further, hunt better and waste less energy,” Rambo said. “They’re usually gone before noon and we don’t see them again until the next morning.”

Capturing the birds and the data

The project, spearheaded by scientists from the College of William and Mary’s Center for Conservation Biology, involves capturing 10 of the transient birds and attaching not only U.S. Geological Survey leg bands, but GPS transmitters that will relay real-time data about the birds’ activities.

Bait will be placed to lure the eagles to specific areas near the airfield where traps are set and the team will use rocket nets to capture a mixture of adults and juveniles, preferably some from the group of birds that arrive earlier in September and others from the birds that show up later in October.

“We want to find out where else they’re roosting while they’re here, what route they’re taking from their roost to the airfield, and what’s their other daily activity,” Swift said. “After they leave the airfield around noon, are they feeding out over the water, or in other parts of the county, and do they come back and eat what they catch at the airfield. We’re trying to get these pieces figured out to see if there’s something we can do to disrupt their pattern and keep them away.”

The transmitters will provide location data as well as other pieces of information, such as time and date, and can download this information every hour, every 24 hours, or whatever specific timeframe is programmed.

“The transmitters have good battery life; two to three years is normal,” Swift said. “We’ll be able to see if these are the same birds coming back each year and where their breeding territory is; whether they’re coming from the area of Maine, New Hampshire, Vermont; or maybe the juveniles are coming up from the south during their fledgling dispersal. It’s going to be very interesting to see, once we begin getting this data back, how these puzzle pieces will fit together.”

When the basic answers to the birds’ lifestyle questions are discovered, they may yield a vulnerability that can be exploited by the team.

“We want to find something in their lifestyle that we can disrupt in an attempt to make them not want to come hang out at Pax River,” Rambo added. “They’re a protected species, but if we can find a quirk about their expected behavior and tweak or manipulate that a little bit, we can make them go somewhere else. We can solve what could be a potentially catastrophic problem.”

Ideally, if everything works out as hoped, scientists will be on the ground setting traps sometime in mid-September, and the process of attempting to avoid further disruption to the mission will be underway.

“Aircraft have to be able to fly to test, not just to get the data they want, but to get those products out to the fleet so they can use them,” Swift said. “If you’re delayed a few months because you’re repairing an aircraft due to a bird strike, you’re ultimately delaying the fleet being able to get the resources they need.”