Sage Hardesty
May/19/2014
GIS in Natural Resource Management
Conservation of the Bald Eagle in
Quabbin Reservoir
Background
The Bald Eagle (Haliaeetus leucocephalu) is a large bird of prey commonly in Canada and the
mainland of the United States, although their range extends from Alaska to Mexico. It is both the
national bird and national animal of the United States of American. Bald Eagles prefer to make their
nests in large trees located in riparian zones along surface waters including estuaries, larger inland lakes
and rivers, since their diets mainly consist of fish. In Massachusetts specifically, bald eagles make use of
the Quabbin Reservoir both as a nesting area and a wintering habitat. This is because the reservoir too
large to freeze over and thus can provide open waters for the eagles to hunt in. Massachusetts Division
of Fisheries & Wildlife state that:
“Bald eagles require a great amount of shoreline habitat containing stands of forest for nesting
and trees projecting above the forest canopy for perching, an adequate supply of moderate-size
to large fish, an unimpeded view, and reasonable freedom from human disturbance. Wintering
eagles require suitable roost trees for night roosting. Some such roosts may be 20km or more
from feeding areas, occurring in favorable thermal environments where root trees are protected
from the wind by topography or other trees.”
(http://www.mass.gov/eea/docs/dfg/nhesp/species-and-conservation/nhfacts/haliaeetusleucocephalus.pdf)
Despite the cultural significance, bald eagle populations were threatened from about 1915 until
the early 2000’s. The major threats to the eagle’s health were man-made chemicals and pollutants like
DDT that diminished the eagle’s reproductivity, as well as more direct eagle hunts in Alaska where
128,000 eagles were believed to have been killed. In 1967 the Eagle was listed federally as an
Endangered Species. However since then, due to declines in human hunting and use of DDT, Bald Eagle
populations have recovered. In 1995 the federal status of the Bald Eagle was changed to Threatened,
before finally being removed from the list in 2007. Despite its absence from the list, Eagle populations
are still not fully recovered in many states like Massachusetts due to prior habitat loss as well as other
disturbances from increasing human population. In 2008 a total of 72 Bald Eagles were counted in
Massachusetts, which 36 of those being at the Quabbin Reservoir, making it an area of significance. Due
to the specific habitat necessities of the Bald Eagle, GIS can be an effective tool to locate potential eagle
habitats and preventing human development from further disturbing those nests.
Literature Review
Due to the cultural significance and the threat of extinction throughout the 1900’s, a large
amount of research effort was place on the Bald Eagle. This data is extensive, especially data involving
population trends of eagles within certain areas of the United States. For example, annual mid-winter
eagle counts were conducted both within the Quabbin Reservoir and statewide between 1986 and 2005.
During this time the Massachusetts Wildlife Service found that the Quabbin accounted for anywhere
between 41% and 97% of the total number of eagles seen during the annual survey in the state. While
long term trends analysis like this is important for gaging a population’s health over time, it does nothing
to help protect the population’s health at the current moment. Without and information regarding the
location of the eagles sighted, land managers cannot appropriately introduce plans to avoid areas where
eagles may be found. This is why GIS incorporation is necessary. It allows for the past tend analysis to be
combined within land use analysis to accurately predict eagle habitats and prevent further disturbances.
Hypotheses
The question this proposal is trying to answer is simple: Where are the Bald Eagles likely to be
located? Furthermore is it possible to avoid developing this land in favor of land less suited Bald Eagle
habitats.
Data
The data that will be needed to accurately predict preferred Bald Eagle habitats are extensive,
although luckily a large portion of this data is already available publically online. It is currently possible
to retrieve land use data, forest type and interior forests, Terrain and Elevation Data, coastlines and
coastal zones, roads, tracks and trails, outstanding resource waters, wind power density, prime forest
land, major ponds and major streams all online from the Massachusetts Office of Geographic
Information (MassGIS) at http://www.mass.gov/anf/research-and-tech/it-serv-and-support/applicationserv/office-of-geographic-information-massgis/. From this data I can also examine other data sets
including: distances from roads, bodies of water, or other land use areas, and the condition and size of
forest. These raster layers can be easily analyzed in Arc GIS.
Methods
The methods in which to utilize this data within Arc GIS are not all too complicated. In order to
create a GIS map visualizing the most suitable habitats for Bald Eagles a few steps must be taken. First
old-growth forest of hardwoods or conifers that are preferred by Eagles would be extracted from forest
type raster layers. Secondly the Distance tool will be used on the major water bodies, land use, tracks
and trails, roads and coastal zones. Thirdly a raster calculator will be used to combine the original raster
layers with the created cost distance layers to determine areas which include none fragmented
hardwood or conifer forests that are at least 500 meters from residential and industrial land use areas,
at least 5km of the Quabbin reservoir or any other major body of water. These preferred areas would
then be cross referenced with the elevation data to identify more elevated habitats. Finally these areas
would be ranked in significance, mainly due to their size and distance from human development and
other nests as Eagles are very territorial.
While these methods have the benefit of being relatively simplistic and logical, the lack depth
may distract from the complex factors that influence where Bald Eagles choose to nest. These GIS
analyses may provide a false sense of validity to the exact location of Bald Eagle nests which could hurt
the population’s health if human infrastructure is incorrectly placed.
Anticipated Results
From the GIS analysis, the potential location of the most suitable Bald Eagle habitats would
likely be determined. One would expect to find clusters of land, varying is location and size, throughout
Massachusetts. These areas would likely be prime densely forested areas located between areas of
human development and surface waters, on higher elevations of land so that the eagles can
appropriately survey the areas around them. The larger and farther of the habitats would be ranked the
highest with the small habitats ranking lower. These rankings would assist in determining how likely it is
that a Bald Eagle nest could be found in that cluster.
Policy Applications
This type of GIS analysis could have a variety of policy application. For instance as mentioned
above, regulations could be put in place where new industrial and residential developments could not
be put within say 100 meters of any of these potential Bald Eagle habitats to protect the integrity of
these areas. Furthermore policy could be put in place to place to encourage forest maturation within
these areas to only increase the suitability and quality of the habitats as a hole. Finally these potential
habitats could be used when Wildlife Services attempt to introduce juvenile eagles, or reintroduce older
eagles to an area to help accelerate the colonization of the suitable habitat.
Budget
Item
GIS Intern
ArcGIS Software and
Extensions
GIS Data Layers
Traveling Surveyor
Traveling Expenses
Overhead Cost
Total
Budget Cost
$50,000 Yearly
Salary
$20,000
Details
GIS analysts to acquire the GIS data layers and perform the
analysis.
Software to perform the analysis.
$2,000
$40,000 Yearly
Salary
$20,000 a Year
+(0.4%)
($52800)
184,800
Purchasing any non-publically available GIS data Layers.
Scientist to travel to potential habitats and to survey for
Eagles and insure habitat quality.
Travel Fees (Flight, Car, Gas, etc)
Institutional Overhead Cost
Per Year
Timeframe
It should take no longer than two months to acquire all the necessary data, fully create the GIS
map, and completely finish the analysis of the Massachusetts area. However the GIS analyst will remain
on staff of the entirety of the year in case new data becomes available, and if it does he will add it to the
analysis in real time. After the analysis is completed, the Traveling Surveyor will begin to visit the
potential Bald Eagle Habitats. It is estimated that this process will take between one and two years to
visit the majority of the areas and to survey the necessary data. Finally the timeframe in which this data
will be included into public policy is unknown as it depends on political parties and public acceptance;
however it should take no longer than 5 years maximum.
References
http://www.mass.gov/eea/docs/dfg/nhesp/species-and-conservation/nhfacts/haliaeetusleucocephalus.pdf
http://www.seafwa.org/resource/dynamic/private/PDF/BUEHLER-292-302.pdf
http://www.baldeagleinfo.com/eagle/eagle11.html
http://www2.ucsc.edu/scpbrg/baearesearch.htm