BRI researchers have fitted red color bands to nearly 700 Bald Eagle nestlings throughout the state (Figure 1). This notable effort is a significant investment in our current and future understanding of Maine’s recovering Bald Eagle population. Photographers now encounter our Maine red-banded eagles throughout the Northeastern U.S. regularly – BRI biologists commonly get 1-2 Bald Eagle band ‘encounters’ per week, and the frequency of these observations seems to be increasing! As of summer 2015, BRI has received information on more than 250 Bald Eagles banded as nestlings throughout the northeastern U.S. and Canada.

BRI’s growing database of band encounter information allows us to better understand many aspects of the ecology and recovery of Bald Eagles throughout the New England region. For example, estimates of the age of first breeding are typically determined by observing known-aged individuals banded as nestlings. Observations of banded individuals can also help provide estimates of survival, natal dispersal (the distance from a bird’s natal area that it goes to breed itself), and movement patterns. We aim to use BRI’s extensive banding database to answer some of these critical questions about Eagles that are important in making informed management and conservation decisions.

Figure 2: Encounters with Bald Eagles banded as nestlings in Maine.

In 2005, BRI and its collaborators began tracking Bald Eagles using satellite telemetry. While initial efforts aimed to better understand the habitat use of Bald Eagles on Maine hydroelectric reservoirs, satellite-tagged eagles quickly revealed that they could teach us about a wide range of subjects. From 2005 – 2015, we have fitted 21 fledgling and one adult Bald Eagle with satellite units.  Tracking using telemetry offers researchers the opportunity to document individuals’ daily movements for many consecutive years.

Our satellite-tagged individuals have demonstrated revealing information about Maine’s ‘subadult’ Bald Eagles. They help us determine what habitats are important to them for roosting and feeding during all months of the year, for both adult and subadult eagle age classes (i.e., 1-, 2-, 3-, and 4-year olds). For example, our moderate sample of satellite-tagged eagles is already helping demonstrate the value of seasonally abundant food supplies, such as anadromous fish runs, to Bald Eagle populations. We are excited to track this cohort of eagles for years to come and tell their story to aid in conservation and management decision-making.

Figure 3: Locations throughout Maine where Bald Eagle Fledglings were instrumented with satellite transmitters, 2009-2015. Read the full report here.

Figure 4: Composite Utilization Distributions for Maine Bald Eagles during the second full year (based on 1 May) as revealed by satellite telemetry. Read the full report here.

Figure 5. Annual use areas for Maine Bald Eagles during the first three years of life. Colored polygons reflect “core use areas” (50% Utilization Distributions). Polygon values indicate the number of overlapping composite age class layers present. (i.e., red polygons highlight areas in which eagle year 1, year 2 and year 3 composite use areas overlapped, presumably reflecting areas of higher conservation value/importance). Read the full report here.

Banded eagle, photographed by Wayne Thomson