ABERDEEN PROVING GROUND, Md. - During the most recent count of Aberdeen Proving Ground bald eagles in early January, 177 were spotted along the installation shorelines; indicating a thriving eagle population on post.For nearly 30 years, APG personnel have monitored, tracked and protected the lively -- and growing -- population of bald eagles who call the installation home.Lynda Hartzell, a Directorate of Public Works Natural Resources Branch employee, has served as one of APG's eagle gurus, formally known as an eagle compliance manager, for the past six years, during which time she says the eagle population has "really just exploded."While the count is slightly lower than the five-year average of 206, Hartzell says it still indicates "a robust eagle population."On a second aerial survey in late January, 10 new eagle nests were identified, in addition to the 75 nests Hartzell and other environmental personnel are already tracking.These aerial surveys are just a fraction of the work done by Hartzell, her coworker Jessica Baylor, and many of the installation's tenants to monitor the APG's bald eagle population.From workforce education, to population and nest tracking, to protection and responding to downed eagles, installation personnel work diligently to protect the nation's symbol of freedom right here on APG.Monitoring the population In the 1970s, the APG bald eagle population wasn't monitored or tracked with much detail, mainly due to its small numbers. There was just one documented nest on post in 1977."When we started seeing the birds reappear and come back to the Chesapeake Bay Area in the 1980s, we began more intensive surveys in consultation with the U.S. Fish and Wildlife Service," Hartzell said.By the mid-1980s, a database of eagle population information was created, keeping tabs on where the birds were nesting and, unfortunately, how many were found injured or deceased."We have miles and miles and miles of power lines to support our mission and support our infrastructure," she said. "These are big birds; they're not terribly maneuverable with their long wings, and unfortunately they tend to hit the power lines."By 2002, a spike in eagle fatalities initiated a need to call in the U.S. Fish and Wildlife Service (FWS). At that time, the bald eagle was still listed as an endangered species and while it was de-listed in 2007, it still remains federally protected."As a federal agency, we have to consult with the [Fish and Wildlife] service any time there's an activity we think could impact the species, so we did," Hartzell said.After analyzing information about APG's eagle population and mission activities, the FWS provided APG with a biological opinion, a legally-binding document, which outlined risks to eagles and requirements for monitoring and protecting the eagle population on post, at which point the data collection and monitoring of the eagle population was standardized across the board. As part of the installation's agreement with the FWS, APG agreed to bury power lines in select areas."It's extremely expensive to bury power lines, but we have done so on some really hot areas for line strikes. Spesutie Island's power lines are almost entirely underground now," Hartzell said.Reflective "flappers" that swivel in the wind were installed on many power lines that that remain above ground to make the lines more visible to the birds. According to Hartzell, the combination of line burials and line markers has "reduced the number of line strikes" significantly.Population growth and territory With countless miles of relatively undisturbed shoreline along the Chesapeake Bay, Gunpowder River and Bush River, APG is an ideal habitat for bald eagles.The birds normally nest no more than a quarter mile from a large body of water, preferably right along the shoreline so they have access to their prey of choice: fish.Between a species-wide population growth and efforts to minimize power line strikes on the installation, APG's bald eagle population began to grow considerably."It really took off in 2005 and 2006. And then it increased again around 2011," Hartzell said. "By 2014, last year, we had 50 active nests."Since 2011, the population growth has slowed but Hartzell says this is not worrisome."We think, and we hope, that we've hit our carrying capacity for eagles and we're not going to see a huge increase again, in the number of nests at least," she said. There are only so many trees and so much land for eagles to claim as their territory.According to Hartzell, habitat availability remains the biggest threat to the species."The availability of habitat will always be the limiting factor for their growth and expansion," she said. "You'll see on the eastern shore of Maryland particularly, and north and south of us, a lot of shoreline development and that's what will limit the number of eagles that we have [in the region.]"Limiting habitat means eagles lay claim to territory, which can turn violent."As with many animal species, the more individuals you pack into a small area, the more they're going to fight," Hartzell said. "We get a lot of observations of eagles tangling, dropping to the ground almost. We've picked up injured birds that have obviously been in fights with other eagles. They have punctures on their heads that can only come from another talon."Hartzell said the uptick in fighting and documented injuries as a result also indicates APG's bald eagle population has reached its upper limits."We've seen a lot of [fighting] the past four or five years, so we know we're reaching our carrying capacity. They will level themselves out. There's only so much room and so many trees."Injured birds When the DPW Natural Resources Branch receives a report of an injured eagle, they capture the bird - if it is safe to do so. They then personally transport the bird an hour north to Tristate Bird Rescue in Newark, Delaware.Once at the rescue, the bird's injuries and overall health are assessed and it receives treatment and rehabilitation. Tristate is also equipped to euthanize birds that cannot recover from their injuries."I think it [the ability to euthanize] is very important," Hartzell said. "Personally, I like to know that if nature can't take its course, then we can at least humanely put down a bird that is suffering. To take an adult bird, who has been flying around the bay its entire lifetime and to throw it into a cage….there are enough in captivity for educational purposes. We just like to know they'll be treated humanely."Eagles that can be rehabilitated are released back into the wild at APG whenever possible."We've had several cases where they've rehabbed the bird and given it back to us to release. That's always a good story," she said. "We go pick it up, drive it back here and release it."Most recently, in 2011, an eagle was found on the ground with an electrical burn, an obvious marker of a power-line strike, Hartzell said. The bird was transported to Tristate where its burns and irregular heart beat were tended to. It was then transported back to APG South and released on one of the ranges.Balancing Army missions with bald eagle protection While APG is home to shoreline that serves as ideal habitat for bald eagles, it is also home to unique -- and noisy -- activities that one could assume to be bothersome to nesting eagles.The U.S. Army Test and Evaluation Command's Aberdeen Test Center operates on the vast majority of the installation's acreage, conducting countless testing operations simultaneously. Many of APG's 50+ active eagle nests reside on active ATC test ranges."You go right down the end of a firing range and you don't even need a telescope; the nest is that close," Hartzell said. According to ATC Environmental Engineer David Goad, who monitors the nests on ATC test ranges, the noise isn't disruptive to the nesting eagles."From watching how the birds react, the noise itself doesn't seem to bother them as much as you or I walking nearby, because they would think we're there to harm them, versus just a sound they hear," Goad said."It's like anything else -- you get acclimated to it over time. Some of the birds have been here for 15, 20 years; if you've heard booms for 15 to 20 years you're probably used to it."Because the eagles have adjusted to the noise level on APG, successful nesting occurs concurrently with the successful execution of APG's test and evaluation missions."We are still able to successfully protect the species and do what we need to do as an Army installation. That's evidenced by not only the numbers we're seeing, but the locations we're seeing the nests, right off the test ranges," Hartzell said.Goad said test schedules aren't greatly impacted by bald eagle nesting season. If a situation arises in which it's believed testing might be disruptive to the birds, Goad and Hartzell monitor the eagles closely."A high percentage of APG's eagle nests are in our range areas, so we have a vested interest in protecting the nests and maintaining our operations," Goad said. "We keep an eye on all of the tests we're doing that might have any sort of interaction with birds or nests, but for the most part, we can do everything we'd normally do and not bother them."Goad said he and other members of the ATC Environmental Division have used cameras to monitor nests particularly close to active testing to ensure testing is in fact not bothering the birds. He said it also provides an opportunity to educate the ATC workforce about the birds ATC goes to such lengths to protect."The success of the eagle program at APG is due in large part to the cooperation and commitment of the tenants" Hartzell said. "Stewardship is a shared responsibility. The folks that work on the ranges are particularly helpful with reporting downed birds and anecdotal observations."Impact beyond APG As a result of a positive working relationship with the FWS and extensive historical data outlining the eagle population and the impact -- or lack thereof -- of APG activities on the nesting birds, APG has some flexibility in terms of managing and protecting the eagles, Hartzell said.It's that flexibility that has helped to maintain and nurture a successful population alongside APG's many missions, and that impact is being felt beyond the gate."What we're doing on the installation to protect the eagles is impacting birds as far north as Labrador, Canada and as far south as Florida," Hartzell said. "We're having birds come to us from such great distances to either spend the winter or the summer. That's pretty wild to see."Over the course of the next few months, Hartzell and Goad will continue to monitor APG's bald eagles during the current nesting and egg-laying season. By early April, they will have an idea of how many of the 85 identified nests will produce eggs and how many of those eggs will hatch successfully.Check back with the APG News and on the APG Facebook page at www.facebook.com/APGMD for updates on this year's bald eagle nesting season.