A study of painted turtle nest predation and inter-pond migration at a study site in Pennsylvania.

1. The painted turtle (Chrysemys picta) is a common sight in many ponds and waterways
across the United States--however, because of anthropogenic changes in landscape, many of these
turtles face new challenges in survival. This project aimed to better understand the spatial ecology
of painted turtles at the Lehigh Gap Nature Center, Carbon County; these populations exist in three
separate, but geographically close, ponds: Mallard, Kingfisher, and Wood Duck. The painted turtle
is useful to use in studies aimed at conservation, as they have been extensively researched across
their vast range—C. picta is the only turtle with a range that spans the entire North American
continent—and their behavior and physiology is generally well-understood (1). They act as
indicator species--the health of a turtle population can be used to gauge environmental health and
suitability for the survival of other aquatic and amphibious species (2). Turtles also perform vital
services within their ecosystem. Because they feed heavily on aquatic plant material, turtles help
keep waterways clean and clear of large amounts of growth and their movement between land and
water also helps to disperse nutrients, (1).
In understanding the best practices to use when focusing on local turtle conservation, it is
first immeasurably useful to identify the geographical areas inhabited and used by these turtles. For
many local populations, growing urban areas encroach on critical habitat on which turtles rely for
their hunting and nesting grounds. With evolving technologies, the ability to understand the spatial
distribution of creatures has advanced as a niche field referred to as spatial ecology. By utilizing
techniques important to spatial ecology, important information about this population can be
gathered to aid in conservation efforts.
Data from trapping reveals that, of 220 individual turtles that had been caught and
marked, 28 (12.73%) had migrated between ponds at least once, with 27 of the 28
Migrant turtles having moved once between ponds, and one moving twice between
ponds. The shortest period between observed was one day, the longest period was 1391
days, and the median time between captures in different ponds being 633 days. Table 1
details the population demographics of migrant turtles, the majority of which were adult
and female. It is important to note that juveniles cannot be accurately sexed, thus their
categorization reflects their age and non-sexed status. Table 2 demonstrates the timing
and location of the captures of migrant turtles. It shows the majority of captures
occurring in the summer months (75%), and the majority of captures being turtles that
had migrated from other ponds into Kingfisher Pond (48%).
Telemetry data reveals that there was no inter-pond migration documented through
radio tracking. All subjects remained in Mallard Pond for the duration of observation.
Within this pond, favored locations appeared to be those that were relatively deep and
wide in area. Fewer turtles were tracked to locations were the water was more shallow,
or in which there was an observably thick layer of algal growth along the bottom of the
pond. Figure 3 details the frequency of turtles being tracked to each pond zone.
Nest Predation data shows that two of 12 simulated nests (17%) were predated within
one week, both at distances of 50 meters, and one (8.3%) was predated after two weeks
at a distance of 150 meters. These sites are mapped in Figure 2. None we predated
during the third week. Of the nests placed at 3, 5, and 10 meters, none were predated
during the entire three-week observational period, though this could be attributed to a
strong influx of snowy weather. Overall, this site had a 100% success rate at distances
of 3, 5, 10, and 100 meters, a 50% success rate at 50 meters, and a 75% success rate at
150 meters. Predators caught on cameras include feral dogs and coyotes. It is also of
note that several deer were captured on film, which could be responsible for nest
disturbance, even though they do not consume eggs from the nest.
Turtle Nest Predation and Inter-Pond Migration
Shelby Does
Advisor: Dr. Frank Kuserk
Liaison: Dr. Christopher Jones
Table 1. Population Demographics of Migrant Turtles
Figure 1.
Painted Turtles
with radio
transmitters
adhered to the
carapace
Introduction
Trapping: Inter-pond migration data used in this experiment was collected beginning in 2012 by
Moravian College Students under the supervision of Dr. Frank Kuserk. Trapping was conducted at
least once a year by baiting three-foot diameter hoop traps with sardines. The traps were then left in
one of the three ponds overnight, after which time the nets would be removed from the water.
Turtles captured in the net were marked using an alphabetic code corresponding to notches placed
in the marginal scutes of each turtle. The nets were then reset, and the same procedure followed the
next day. Data including lengths of carapace, plastron, foreclaw, and pre-cloacal tail, as well as
approximate age and sex, was compiled and analyzed, with particular attention paid to turtles that
had been captured in different ponds, indicating inter-pond migration.
Telemetry: Five turtles captured in Mallard Pond in the fall of 2016 were outfitted with radio
transmitters (Telonics LB-65 VHF) and released back into the same pond.. The turtles were then
individually tracked every other week for the duration of the 16-week study period, from late
September, 2016 to January, 2017. To facilitate mapping the location of turtles in the water, the
pond was divided into eight zones based on the physical features of the pond, and turtle locations
were designated by the zone in which they spent the majority of a five-minute observational period.
This data was mapped using ArcMap 10.3 for Desktop (ESRI) in order to determine hotspots of
turtle activity.
Nest Predation: To study the predation of turtle nests, simulated nesting sites were created at
distances of 3, 5, 10, 50, 100, and 150 meters away from the edge of each of the three ponds. These
simulated nests were 10cm deep and 5cm wide. The nests were sprayed with water in which a turtle
had been living in order to scent the hole, after which two bobwhite quail eggs were placed in the
hole and covered loosely with soil. The nest was again sprayed with turtle-scented water. GPS
locations were taken for each experimental site using a Trimble Geo7x handheld unit, and mapped.
The sites were then checked weekly for three weeks, and were also monitored by trail cameras
(Moultrie P150 and P150i). The sites were then mapped in ArcMap 10.3 and color-coded to reflect
their predation status after three weeks, in order to identify nests that had been deemed successful
in this trial.
Experimental Method
Figure 2. Map of simulated nesting site predation at 50, 100, and 150 meters at
the three ponds (Left to Right: Mallard, Kingfisher, and Wood Duck)
I would like to sincerely thank my Advisor Dr. Kuserk, and my Liaison Dr. Jones, Dr. David Bowne
and his research students Jennah Krause and Alyssa Taylor, the staff at the Lehigh Gap Nature Center,
Lehigh University, and Cardinal Directions for sharing their GIS information and knowledge, and my
Turtle Squad: Nathan Jordan, Rob McKinley, Matt Kukla, Mitchell Lapka, Luke Peterson, and
Brooke Santy
Acknowledgements
1. Ernst CH, Barbour RW, Lovich JE. (1994). Turtles of the United States and Canada. Washington,
vvvDC: Smithsonian Press.
2. Dodd, Jr. CJ. (2016). Reptile Ecology and Conservation. New York: Oxford University Press.
3. GIS Data Sourced By: Carbon County, Cardinal Directions LLC, Lehigh County, Lehigh
GapNature Center, Lehigh University, Northampton County.
4. ESRI (2017). ArcGIS Desktop: Release 10.3. Redlands, CA: Environmental Systems Research
Institute
References
Results and Discussion
Migrant Female Migrant Male Migrant Adults Migrant Juveniles
Number of
Turtles
11 4 15 13
Percentage of
Migrant Turtles
39.29% 14.29% 53.57% 46.43%
Table 2. Timing and Location of Capture of Migrant Turtles
Caught in
June/July
Caught
in April
Caught in
Sept
Migrating To
Wood Duck
Migrating to
Kingfisher
Migrating to
Mallard
Number of
Turtles
22 2 5 8 14 7
Percentage
of Migrant
Turtles
75.86% 6.90% 17.24% 27.59% 48.28% 24.14%
Figure 3. Map of turtle locations determined during radio tracking