Bald Eagle Population Soars Past 170 Nests

Bald Eagles have enjoyed tremendous support from the public in recent decades.Not only are they the national symbol but also represent good stream quality, the concept of wildness, and the idea that we can recover our diminished natural resources. Eagles often nest in Important Bird Areas and can be viewed from considerable distances. These facts make them an ideal target species for bird expeditions. Places where we can find eagles are generally great for other birds, too. If you go out to view eagles, please share your results with others by contributing your trip data to eBird. 

The 2009 Bald Eagle nest totals continue the steady population increase of approximately 15% per year for the last two decades. Bald Eagle nesting population is expanding not only in numbers but in geographical distribution with nesting pairs now in 48 of the state’s 67 counties.  Four more counties were added to the list of Pennsylvania counties with eagle nests: Beaver, Bedford, Clinton, and Mifflin. New nesting territories were found in 20 different counties in 2009, 5 counties with multiple new nesting territories. The counties with the most eagle nests in 2009 were Crawford (17), Pike (14), Lancaster (12), York (12), and Mercer (11). 

The 2009 nests produced a record number of eaglets, a total of at least 244 young.  This was the first time the state’s nests produced more than 200 eaglets. This represents the sixth consecutive year that more than 100 eaglets were produced from Pennsylvania nests. Amazingly, Pennsylvania bald eagle nests have produced over 1,500 eaglets in the last two decades. For nests with known results in 2009, there were 1.6 eaglets produced per nest. For those nests known to be successful, there was a productivity of 1.8 eaglets per nest. The Pennsylvania nesting success is similar to neighboring states in the Northeast and exceeding the mark of 50% nest success and 0.7 young per nest used as the measuring stick for stable populations. Success rates were high for all regions of the state, even in the Northwest and extreme Northeast where snowfall has been a factor affecting nest success in many years.   .   

Bald eagles continue to expand their range into areas where they are encountering humans and their activities with greater regularity. Bald eagles have even colonized the City of Philadelphia where pairs have had successful nests for at least three years.  Each pair may not succeed in nesting each year in this landscape, but the overall pattern of success by eagles is unprecedented and remarkable.  According to historic records, there are no records of Bald Eagles nesting in Philadelphia for over 200 years although a pair apparently nested in Delaware County in the 1940’s.  Some nesting pairs are in suburbs or the edges of municipalities, often in areas with minimal human activity.  Other pairs are demonstrating remarkable tolerance of human activities including boat and aircraft traffic, earth moving, and road-construction near their nest, but seem sensitive to other human activities or to activities within about 1000 feet.  Eagles tend to tolerate human activities that do not seem to threaten their nest or on-going before the nesting season began. 

By occupying the green zones of such urban and suburban areas, these Bald Eagles are acting as “ambassadors for wildlife” to the urban human population in the state who normally consider wildlife either as being pests or a novelty to be enjoyed after a long trip out of town.   The Game Commission suggests a 1000 foot buffer around each active nest with limited human visitation and activities within that circle that would cause the eagles to flush from or abandon the nest.  More activities are allowed outside the nesting season within the buffer area.  With more eagles nesting in suburban and agricultural areas, eagles have become increasingly tolerant of many human activities, automobile traffic, and farm animals near their nest as long as those conditions existed before the nest was built or are perceived as non-threatening by the eagles.  

In addition to the official count of active Bald Eagle nests, we had reports of at least three sets of eagle adults with young where we do not have a documented nest.  Reports like these are frustrating because they probably represent a nest for which we lack location information.  The Game Commission cannot protect a nest that it does not know about.   We also believe that we had partial nest-building or attempted nest building at sites in Bucks County and Lawrence County near human activity centers.  Adult eagles are also seen in suburban counties such as Chester and Lancaster where there are wooded areas along quality streams.  We anxiously await news of whether these pairs return to these locations and try again.  

The return of Bald Eagles in Pennsylvania is a success on many levels.  Eagles have larger territories, often flying a mile or two from their nest, but usually forage within a half-mile of it.  They require a healthy fish population because that is their principal diet during nesting season.  So, a healthy watershed is critical for eagle occupation of an area.  They need many good perching sites, usually trees or snags within a short glide of the water where they go fishing.  Bald eagles also nest in some of our larger wetlands, riparian forest corridors, and drinking water reservoirs.  As such, they may act as “umbrella species” for protection of habitat for many other species of conservation concern that do not have the charisma or the protections given the popular and well-known eagle.  This extends to wildlife without feathers as well.  

Bald Eagles like quiet areas, but they can be remarkably tolerant of human “background noise” of highways or air traffic in urban areas.   So, even in the urban landscape they can serve as indicators of where certain habitat qualities exist in sufficient quality to support eagles and perhaps some other species. 

What can birders do to help with Bald Eagle nest surveys and protection?  Some suggestions:

• Report any new Bald Eagle nests and results of those nests to PGC (see my contact information below).
• Make a trip report for all the birds you observe while watching eagles.  Enter your trip data into eBird so others can benefit from your good day afield. Many of our Bald Eagle nests and congregation areas are in Important Bird Areas or popular birding spots. 
•   Avoid disturbing eagle nests by getting too close (1000 feet is a good rule of thumb) or advancing directly toward a nest.   Over-eager photographers are often the cause of eagles flushing from nests.  Gently let others know that they should not frighten the eagles away from nesting areas (see Eagle Etiquette notes sent out previously). 
• From a proper distance, show eagle nests or foraging eagles to people who have not experienced the excitement of watching eagles.  This is a great way to introduce birds to youngsters and beginners.
• Advocate for Bald Eagle conservation locally.  Eagles need clean water, open space, good forest along streams.  That sounds like good habitat for humans, too.

• Many Bald Eagles nest, migrate through, or spend the winter in the state’s Important Bird Areas (IBA).  This is a partial list of IBAs where you might find eagles and your observations of all species found would be very valuable:

  • Presque Isle State Park
  • Roderick Wildlife Reserve, SGL 314
  • Pymatuning / Hartstown Complex
  • Conneaut Marsh / Geneva Marsh complex
  • The Glades, SGL 95
  • Pine Creek Gorge area
  • Promised Land State Park
  • Shohola Falls Waterfowl Management Area, SGL 180
  • Upper Delaware Scenic River area
  • Codorus State Park
  • Sheets Island Archipelago in Susquehanna River
  • Conjehela Flats in Susquehanna River
  • Conowingo Reservoir, Muddy Run
  • Octoraro Reservoir
  • Green Lane Reservoir
  • Peace Valley Park

  Send in your observations of Bald Eagle nests, especially of new nests, to:

  Douglas A. Gross, Endangered Bird Specialist, Pennsylvania Game Commission

  E-mail: dogross@state.pa.us

   

  The picture of Bald Eagle adult with eaglet in Northeast Pennsylvania nest was kindly provided by volunteer eagle-watcher and wildlife photographer, Scott Rando.