By Amy Eldredge, 2014 BHI Conservancy Intern

1. The
Effectiveness
of
BHIC’s
Sea
Turtle
Nest
Relocation
Practices
Amy
Eldredge

2. Overview
Ê The
Bald
Head
Island
Conservancy’s
efforts
since
1983
Ê The
sea
turtle
monitoring
program
involved
nightly
monitoring
of
nesting
sea
turtles
Ê Involving
tagging,
implementing
conservation
techniques
of
caging
and
relocation,
and
recording
nests’
location,
hatching
and
emergence
success
rates,
and
incubation
period
Ê Study’s
Objective:
To
examine
the
relocation
practice
as
a
sea
turtle
nest
management
tool
on
the
Bald
Head
Island
beaches
Ê Study’s
Findings:
The
BHIC’s
use
of
relocation
is
an
important
nest
management
tool

3. Background
&
Significance
Ê There
are
seven
species
of
sea
turtle
of
which
three
have
nested
on
Bald
Head
Island:
Loggerhead
Green
Leatherback
Ê
It
is
difficult
to
find
population
numbers
for
sea
turtles
Ê Observing
hatchlings
and
females
that
leave
the
water
to
lay
eggs
is
key

4. Nesting
Behavior
Ê Sea
turtles
tend
to
build
nests
in
the
general
region
where
they
were
born.
Cues
that
influence
this
behavior
include:
• scent
• surf
noise
• magnetic
fields
• offshore
currents
• reefs
and
rocks
• beach
slope
and
width
• sand
texture
• dune
vegetation
• lighting

5. Nesting
Behavior
(continued)
Ê When
females
come
to
the
shore
they
dig
out
a
nest
in
the
ground
with
their
back
flippers,
bury
their
clutch
of
eggs
and
return
to
the
ocean
Ê Sea
turtle
eggs’
incubation
period:
50-­‐70
days
Ê Hatch
at
night
to
reduce
the
risk
of
predation

6. Major
Population
Declines
Ê Overall
reduction
in
all
sea
turtle
populations
Ê All
seven
species
of
sea
turtles
are
endangered
and
several
factors
have
contributed
to
their
decline
Ê Heavy
predation
on
young
Ê Poaching
of
eggs
and
adults
Ê Pollution
Ê Unsound
fishing
practices

7. Conservation
Efforts
Ê Conservation
efforts
focused
on
sea
turtle
reproduction
since
hatchlings
are
vulnerable
and
nests
are
accessible
Ê Three
most
common
conservation
techniques:
Ê Fencing
Ê Screening/caging
Ê Relocating
Ê All
significantly
increase
hatchling
success
rate
–
Georgia
Study

8. Background
on
Relocation
Practices
Ê Relocating
involves
excavating
the
nest
that
is
at
risk
of:
Ê Tidal
inundation
Ê Erosion
Ê Eggs
are
carefully
placed
into
a
cooler
for
transport
Ê An
egg
chamber
is
then
dug
out
using
a
cockle
shell
Ê Eggs
are
placed
into
a
new/safe
nest
and
covered
up

9. Risks
with
Relocation
Practices
Ê Intense
patrolling
allows
nests
to
be
found
and
relocated
within
the
six
hour
window
before
development
starts
Ê
Risks:
Ê Embryo
mortality
Ê Sex
ratio
Ê Hatchling
fitness

10. Relocation’s
Effect
on
Nest’s
Temperature
Ê Relocations
generally
occur
further
from
the
water
Ê Sand
temperature
increases
with
distance
from
the
water
Ê Temperature
impacts
sea
turtle
eggs
Ê Affects
sex
ratio
Ê Incubation
periods
decreases
with
increasing
temperature
Ê Hatching
success
may
decrease
for
nests
in
which
sand
temperatures
exceed
33C

11. Hypotheses
&
Predictions
Ê H:
The
application
of
the
relocation
technique
would
affect
the
hatching
success
rate,
emergence
success
rate
and
the
incubation
period
in
comparison
to
in
situ
nests.
Ê P1:
Relocated
nests
will
have
a
lower
hatching
success
rate
Ê P2:
Relocated
nests
will
have
a
lower
emergence
success
rate
Ê P3:
Relocated
nests
will
have
a
shorter
incubation
period

12. Methods
Ê Sea
turtle
nesting
data
collected
from
the
nesting
and
hatching
seasons
for
2003-­‐2013
were
analyzed
Ê A
comparison
between
the
in
situ
and
relocated
nests
for:
Ê Hatching
Success
Rate
HS
=
#
Hatched
/
Total
#
Eggs
Ê Emergence
Success
Rate
ES
=
(#
Hatched
–
(#
Live
+
#
Dead))
/
Total
#
Eggs
Ê Incubation
Period
#
of
Days
between
Date
Laid
&
Date
Hatched

13. Statistical
Analysis
Ê Comparison
between
In
Situ
and
Relocated
Nests
Ê Normality
Test
(Kolmogorov–Smirnov
test:
p<0.05)
Ê Nonparametric
version
of
Independent
T-­‐Test
Ê Mann-­‐Whitney
U
Test

14. Results:
Hatching
Success
Not
Significant
Ê Mann-­‐Whitney
U
Test:
U=44083.500,
df=603,
df=154,
p=0.33

15. Results:
Emergence
Success
Not
Significant
Ê Mann-­‐Whitney
U
Test:
U=45621.500,
df=603,
df=154,
p=0.737

16. Results:
Incubation
Period
Significant
Ê Mann-­‐Whitney
U
Test:
U=16868.000,
df=438,
df=130,
p<0.001

17. Discussion
Ê For
Relocated
vs.
In
Situ
Nests:
Ê Hatching
Success
did
not
change
Ê Emergence
Success
did
not
change
Ê Incubation
Period
was
shortened
Ê For
Hatching
&
Emergence
Success
this
is
good
news!
Ê Consider
implications
of
a
shorter
incubation
period:
Ê Used
to
predict
sex
ratio
Ê Area
of
future
research

18. Relocation
Study
in
St.
Croix
Ê Sandy
Point
National
Wildlife
Refuge,
St
Croix,
US
Virgin
Islands
Ê Natural
beach
erosion:
Ê loss
of
45–60%
leatherback
sea
turtle
eggs
per
year
Ê 31·∙4–68·∙1%
of
the
nests
were
relocated
Ê Overall
hatch
success
of
relocated
clutches
compared
to
in
situ
clutches
decreased
(53·∙7%
vs
64·∙1%)
Ê Relocation
of
“doomed
eggs”
resulted
in
a
net
gain
of
6650
hatchlings
over
4
years

19. Conclusion
Ê Relocation
is
a
successful
tool
to
continue
to
use!
Ê Bald
Head
Island
seeing
better
results
Ê Compare
to
study
of
1997-­‐2001
data
Ê Still
be
cautious
Ê Strive
to
improve
technique
Ê Continue
research
and
investigate
consequences
of
a
short
incubation
period
period

20. Future
Research
Ê Expand
analysis
to
include
earlier
years
of
data
collection
Ê Next
Questions:
Why
do
we
need
to
relocate?
Ê Do
we
have
bad
beaches
or
bad
mothers?
Ê Examine
where
relocation
more
frequently
occurs
Ê Per
individual,
how
has
the
percentage
of
relocations
changed
over
time?

21. References
Ê Baskale,
E.,
Kaska,
Y.
(2005)
Sea
turtle
nest
conservation
techniques
on
southwestern
beaches
in
Turkey.
Israel
Journal
of
Zoology.
51:13–26.
Ê Broderick,
A.
C.,
Glen,
F.,
Godley,
B.
J.,
Hays,
G.
C.
(2002)
Estimating
the
size
of
nesting
populations
of
green
and
loggerhead
turtles
in
the
Mediterranean.
Oryx.
36:
227–236.
Ê Davenport,
J.,
Davenport,
J.L.
(2006)
The
impact
of
tourism
and
personal
leisure
transport
on
coastal
environments:
A
review.
Estuarine,
Coastal
and
Shelf
Science.
67(1-­‐2):280-­‐292.
Ê Davidson,
O.
G.
(1998)
The
Enchanted
Braid.
John
Wiley
&
Sons,
Inc:
New
York.
Ê Eckert,
K.L.,
Eckert,
S.A.
(1990)
Embryo
mortality
and
hatch
success
in
In
Situ
and
translocated
leatherback
sea
turtle
Dermochelys
coriacea
eggs.
Biological
conservation.
53(1):37-­‐46.

22. References
(continued)
Ê Matsuzawa,
Y.,
Sato,
K.,
Sakamoto,
W.,
Bjorndal,
K.
(2002)
Seasonal
fluctuations
in
sand
temperature:
effects
on
the
incubation
period
and
mortality
of
loggerhead
sea
turtle
(Caretta
caretta)
pre-­‐emergent
hatchings
in
Minabe,Japan.
Marine
Biology.
140
(3):639-­‐646.
Ê Pike,
D.A.
(2008)
Environmental
correlates
of
nesting
in
loggerhead
turtles,
Caretta
caretta.
Animal
Behaviour.
76:
603-­‐610.
Ê Pinedo,
M.C.,
Polacheck.
T.
(2004)
Sea
turtle
bycatch
in
pelagic
longline
sets
off
southern
Brazil.
Biological
Conservation.
119:
335–339.
Ê Weishampel,
J.F.,
Bagley,
D.A.,
Ehrhart,
L.M.,
Rodenbeack,
B.L.
(2003)
Spatiotemporal
patterns
of
annual
sea
turtle
nesting
behaviors
along
an
East
Central
Florida
beach.
Biological
Conservation.
110(2):295-­‐303.
Ê Wyneken,
J.,
Burke,
T.
J.,
Salmon,
M.,
Pedersn,
D.
K.
(1988)
Egg
Failure
in
Natural
and
Relocated
Sea
Turtle
Nests.
Journal
of
Herpetology.
22(1):88-­‐96.

23. Thank
You!

24. Questions?