Abundance Study of the Abundance Study of the Great Blue Heron (Great Blue Heron (Ardea Ardea

herodias herodias) herodias herodias) on on Center Hill LakeCenter Hill Lake

Research presented byResearch presented by

Kevin W. Pitts & Jason R. L. Kevin W. Pitts & Jason R. L. HolcombHolcomb

IntroductionIntroduction

The Great Blue Heron is protected under The Great Blue Heron is protected under the Federal Migratory Bird Act and is the Federal Migratory Bird Act and is considered to be of special concernconsidered to be of special concern

The Great Blue Heron is approximately The Great Blue Heron is approximately 135 cm tall with a wingspan of 175 cm135 cm tall with a wingspan of 175 cm with a with a body color of mostly gray with body color of mostly gray with white, black and brown on the neck. white, black and brown on the neck.

The top of the head is white and the bill is The top of the head is white and the bill is yellow.yellow.

IntroductionIntroduction Breeding season for the heron is March to Breeding season for the heron is March to

June. They nest in colonies (rookeries) and June. They nest in colonies (rookeries) and are seasonally monogamous. Most rookeries are seasonally monogamous. Most rookeries are found near rivers in old growth forests. are found near rivers in old growth forests. Most rookeries are about 20m off of the Most rookeries are about 20m off of the ground.ground.

When the Great Blue Heron is not in When the Great Blue Heron is not in breeding season they tend to be very breeding season they tend to be very territorial and are very defensive of their territorial and are very defensive of their feeding territory.feeding territory.

The Heron is most active early morning and The Heron is most active early morning and late evening.late evening.

ObjectiveObjective

The objective of this study was to The objective of this study was to gain perspective of the Great Blue gain perspective of the Great Blue Heron on Center Hill Lake: Heron on Center Hill Lake: Abundance of the Great Blue Heron Abundance of the Great Blue Heron

during the day and night.during the day and night. territoryterritory of the Great Blue Heron during of the Great Blue Heron during

the day and night.the day and night.

Materials and MethodsMaterials and Methods

This abundance study was conducted This abundance study was conducted on Center Hill Lake in Dekalb and on Center Hill Lake in Dekalb and Putnam counties in Tennessee. Putnam counties in Tennessee.

Center Hill Lake was surveyed for the Center Hill Lake was surveyed for the Great Blue Heron from the dam Great Blue Heron from the dam (N36(N3605.973, W8505.973, W8550.292) to the 50.292) to the headwaters of the reservoir headwaters of the reservoir (N35(N3553.402, W8553.402, W8539.698). 39.698).

The distance of the survey was 31.4 The distance of the survey was 31.4 nm. and 62.8 nm. of shoreline. nm. and 62.8 nm. of shoreline.

Materials and MethodsMaterials and Methods

This survey was done on six different This survey was done on six different days, spaced a week apart.days, spaced a week apart.

After surveying the lake, it was After surveying the lake, it was discover that a large number of discover that a large number of herons gathered at Hurricane herons gathered at Hurricane Landing at dusk and the largest Landing at dusk and the largest numbers of heron were regularly numbers of heron were regularly recorded at this location.recorded at this location.

Materials and MethodsMaterials and Methods

A nineteen-foot pro-line bay boat A nineteen-foot pro-line bay boat equipped with a Garmin® GPS/chart equipped with a Garmin® GPS/chart plotter was used to survey the lake plotter was used to survey the lake and mark the locations of heron and mark the locations of heron sighted.sighted.

This GPS information was This GPS information was downloaded to a PC with Garmin® downloaded to a PC with Garmin® BlueChart™.BlueChart™.

ResultsResults

Two separate bird counts were made, one Two separate bird counts were made, one during the day and one during the night. during the day and one during the night.

During the day we counted: five on 2/21/05, During the day we counted: five on 2/21/05, one on 2/28/05, seven on 3/14/05, five on 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. 3/21/05, three on 3/28/05, and six on 4/4/05.

During the night, the birds were exclusively During the night, the birds were exclusively located at the hurricane marina, and we located at the hurricane marina, and we counted: 12 on 2/21/05, 6 on 2/28/05, 16 on 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 3/14/05, 23 on 3/21/05, 17 on 3/28/05, and 19 on 4/4/05.19 on 4/4/05.

ResultsResults

These separate counts yielded two These separate counts yielded two averages, one for the day and one averages, one for the day and one for the night. for the night.

The day average was 4.5. The day average was 4.5. The night average was 16.2. The night average was 16.2. The average size of territoriality The average size of territoriality

found was .79 nm in circumference.found was .79 nm in circumference.

ResultsResultsDate 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

ResultsResultsData 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

ResultsResults

0

1

2

3

4

5

6

7

Nu

mb

er o

f B

ird

s

1 2 3 4 5 6

Day

Day Abundance of Blue Heron

Series2

0

5

10

15

20

25

Nu

mb

er o

f B

ird

s

1 2 3 4 5

Day

Hurricane Abundance

Series1

DiscussionDiscussion

The Great Blue Heron of the Center Hill The Great Blue Heron of the Center Hill Lake area were found to be territorial. Lake area were found to be territorial. However, they also had a tendency to However, they also had a tendency to gather in Hurricane Landing. gather in Hurricane Landing.

There was little heron activity on Center There was little heron activity on Center Hill Lake in the daytime. Hill Lake in the daytime.

The heron that were sighted, on the The heron that were sighted, on the shoreline, were found in the same locations. shoreline, were found in the same locations.

The early evening abundance count was The early evening abundance count was low, on average < 6.low, on average < 6.

DiscussionDiscussion

In the late evening to dark, heron were In the late evening to dark, heron were observed flying into Hurricane Landing observed flying into Hurricane Landing and the greatest numbers of heron were and the greatest numbers of heron were observed here.observed here.

After surveying all of the marinas on After surveying all of the marinas on Center Hill Lake it was discovered that Center Hill Lake it was discovered that Hurricane Landing was unique. Hurricane Landing was unique.

the largest rookery on the lake was the largest rookery on the lake was discovered on the southeast hillside of discovered on the southeast hillside of the marina.the marina.

DiscussionDiscussion

Apparently the heron are considered Apparently the heron are considered a nuisance at Hurricane Landing. a nuisance at Hurricane Landing.

They can be found at the end of They can be found at the end of almost every dock, after sunset. almost every dock, after sunset.

Boat owners at the Marina have Boat owners at the Marina have hung up the bird eye predator hung up the bird eye predator balloons over their vessels and hung balloons over their vessels and hung old CD’s on strings along the docks old CD’s on strings along the docks as a deterrent to the heron.as a deterrent to the heron.

ConclusionConclusion Average abundance of the Great Blue Average abundance of the Great Blue

Heron on Center Hill Lake was found to be Heron on Center Hill Lake was found to be greater in the night than in the day.greater in the night than in the day.

The average abundance during the day The average abundance during the day was was 4.54.5

The average abundance during the night The average abundance during the night was was 16.216.2

Great Blue Heron were found to hold Great Blue Heron were found to hold territoriesterritories

The average circumference of their The average circumference of their territories was territories was .79 nm..79 nm.

Questions?Questions?