Abundance Study of the Great
Blue Heron (Ardea herodias
herodias) on Center Hill Lake
Research presented by
Kevin W. Pitts & Jason R. L. Holcomb
Introduction
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The Great Blue Heron is protected under the Federal
Migratory Bird Act and is considered to be of special
concern
The Great Blue Heron is approximately 135 cm tall
with a wingspan of 175 cm with a body color of mostly
gray with white, black and brown on the neck.
The top of the head is white and the bill is yellow.
Introduction
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Breeding season for the heron is March to June. They
nest in colonies (rookeries) and are seasonally
monogamous. Most rookeries are found near rivers in
old growth forests. Most rookeries are about 20m off
of the ground.
When the Great Blue Heron is not in breeding season
they tend to be very territorial and are very defensive of
their feeding territory.
The Heron is most active early morning and late
evening.
Objective
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The objective of this study was to gain
perspective of the Great Blue Heron on Center
Hill Lake:
Abundance of the Great Blue Heron during the day
and night.
 territory of the Great Blue Heron during the day
and night.
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Materials and Methods
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This abundance study was conducted on Center
Hill Lake in Dekalb and Putnam counties in
Tennessee.
Center Hill Lake was surveyed for the Great
Blue Heron from the dam (N3605.973,
W8550.292) to the headwaters of the reservoir
(N3553.402, W8539.698).
The distance of the survey was 31.4 nm. and
62.8 nm. of shoreline.
Materials and Methods
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This survey was done on six different days,
spaced a week apart.
After surveying the lake, it was discover that a
large number of herons gathered at Hurricane
Landing at dusk and the largest numbers of
heron were regularly recorded at this location.
Materials and Methods
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A nineteen-foot pro-line bay boat equipped with
a Garmin® GPS/chart plotter was used to
survey the lake and mark the locations of heron
sighted.
This GPS information was downloaded to a PC
with Garmin® BlueChart™.
Results
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Two separate bird counts were made, one during the
day and one during the night.
During the day we counted: five on 2/21/05, one on
2/28/05, seven on 3/14/05, five on 3/21/05, three on
3/28/05, and six on 4/4/05.
During the night, the birds were exclusively located at
the hurricane marina, and we counted: 12 on 2/21/05,
6 on 2/28/05, 16 on 3/14/05, 23 on 3/21/05, 17 on
3/28/05, and 19 on 4/4/05.
Results
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These separate counts yielded two averages, one
for the day and one for the night.
The day average was 4.5.
The night average was 16.2.
The average size of territoriality found was .79
nm in circumference.
Results
Date
Location/heron present
2/21/05
678/yes
679/yes
680/no
681/yes
682/no
683/yes
684/yes
685/no
2/28/05
678/no
679/no
680/no
681/no
682/no
683/yes
684/no
685/no
3/14/05
678/no
679/yes
680/yes
681/yes
682/yes
683/yes
684/yes
685/yes
3/21/05
678/yes
679/yes
680/yes
681/yes
682/no
683/no
684/yes
685/no
3/28/05
678/no
679/yes
680/no
681/no
682/yes
683/yes
684/no
685/no
4/4/05
678/yes
679/yes
680/no
681/yes
682/no
683/yes
684/yes
685/yes
Results
Data From Hurricane Landing (table 3)
Date
Heron Count
2/21/05
12
2/28/05
6
3/14/05
16
3/21/05
23
3/28/05
17
4/4/05
19
Results
Day Abundance of Blue Heron
Hurricane Abundance
7
25
5
4
3
Series2
2
Number of Birds
Number of Birds
6
20
15
10
Series1
5
1
0
0
1
2
3
4
Day
5
6
1
2
3
Day
4
5
Discussion
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The Great Blue Heron of the Center Hill Lake area
were found to be territorial. However, they also had a
tendency to gather in Hurricane Landing.
There was little heron activity on Center Hill Lake in
the daytime.
The heron that were sighted, on the shoreline, were
found in the same locations.
The early evening abundance count was low, on average
< 6.
Discussion
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In the late evening to dark, heron were observed
flying into Hurricane Landing and the greatest
numbers of heron were observed here.
After surveying all of the marinas on Center Hill
Lake it was discovered that Hurricane Landing
was unique.
the largest rookery on the lake was discovered
on the southeast hillside of the marina.
Discussion
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Apparently the heron are considered a nuisance
at Hurricane Landing.
They can be found at the end of almost every
dock, after sunset.
Boat owners at the Marina have hung up the
bird eye predator balloons over their vessels and
hung old CD’s on strings along the docks as a
deterrent to the heron.
Conclusion
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Average abundance of the Great Blue Heron on
Center Hill Lake was found to be greater in the
night than in the day.
The average abundance during the day was 4.5
The average abundance during the night was
16.2
Great Blue Heron were found to hold territories
The average circumference of their territories
was .79 nm.
Questions?