Roadside mortality in Terrapene carolina and T. ornata ... Roadside mort… · F=4). Using p = 0.05...
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(a) identify landscape features associated with travel corridors. (b) examine differences between routes on a National Wildlife Refuge and routes off of a refuge. (c) examine differences in the sex ratio of turtles found. Roadside mortality in Terrapene carolina and T. ornata: are females more at risk? A comparison between urban and non-urban sites 1 Ariel Richter 2 Eric Johansen 1 Tim O’Connell 2 Stanley F. Fox 1 Natural Resource Ecology and Management 2 Department of Zoology, Oklahoma State University •Many turtle species make periodic and extended overland migrations. These migrations can result in individuals being struck and killed by automobiles as the turtles cross roads (5, 1). While both sexes regularly migrate, females may be more susceptible to collisions because they tend to move farther than males and may seek out roadside ditches for nesting (6). This puts not only themselves at risk, but also their future offspring, when they hatch near high traffic roadways. •Turtle road mortality can have negative effects on local populations (3, 5) and reduce local biodiversity (4). Human development is a major influence on turtle mortality because it reduces the amount of suitable habitat overall and the number of safe passages for migrating turtles. This is especially true in areas with high road densities that would otherwise support healthy populations of turtles and other wildlife (2). Human development is especially important in Oklahoma due to rapid urbanization of areas supporting local populations of turtles and rapid conversion of habitat from suitable to unsuitable. •One way to reduce road mortality in turtles is to identify specific routes and conditions that promote seasonal movements. Figure 1. Comparison of total turtles found at each site. Introduction Methods •2 routes in the Norman/Noble area and 2 routes in the Sequoyah National Wildlife Refuge (SNWR) were surveyed. The 2 Norman/Noble routes were between 20-25 miles long and the 2 SNWR routes were 10-15 miles long. •Each route was driven twice daily (before 8:00 am and after 5:00 pm) for a total of 17 days for the Norman/Noble routes over a 12 week period and a total of 25 days for the SNWR routes over a 9 week period. •Turtles encountered along select roads were also counted. •Biotic data included, but were not limited to: nearest water type, age, sex, MCL (mm), MCW (mm), MCH (mm), mass (g), and GPS coordinates. •Abiotic data included, but were not limited to: precipitation (for the past 24 hours), cloud cover, road type, % tree cover, and placement in road. •We used systematic sampling points to select for habitat availability. Objectives Acknowledgments •The Lew Wentz Foundation and Oklahoma State University. •The Sequoyah National Wildlife Refuge. Results Figure 2. Total number of turtles found at each site. AOR = Alive on road. DOR = Dead on road. •More female turtles of both species were found ( T. carolina: M=8, F=28 and T. ornata: M=3, F=4). Using p = 0.05 and CV = 3.84, we calculated a X 2 = 1.311.This supports our hypothesis that there is a female bias. •Juvenile turtles of both species were found (2 T. ornata and 7 T. carolina) and one hatchling T. carolina was found supporting the hypothesis that not only are adult turtles at risk of being killed by automobiles, but juveniles and hatchlings are as well. •More total turtles were found in the SNWR (n=38) than in the Norman/Noble areas (n=16) with the total route length for each area as 19.4 miles and 41.6 miles respectively. This leads to the conclusion that the population density of the SNWR (mean = 0.078 turtles/mi) is greater than the population in the Norman/Noble areas (mean = 0.023 turtles/mile). •Due to the fact that more turtles were found in the SNWR and that only 3 of the 38 (0.08) individuals were dead, as compared to 11 DOR of the 16 (0.69) in the Norman/Noble areas, it can be concluded that the population outside of the refuge is greatly impacted by road mortality. •Large bodies of water and expanses of grasslands were disproportionately selected by box turtles. See Figure 3. •Further study is needed to determine the role road mortality plays on the overall population structure and recruitment numbers of both species. Conclusions • Turtles had the strongest IEI score in association with water. • Turtle IEI scores were all greater than the systematic sampling IEI scores except the Forest habitat. Figure 3. Ivlev’s Electivity Index Scores for the different habitat types. Terrapene ornata and T. carolina were grouped together. All routes for the Norman and Noble areas and the Sequoyah NWR have been grouped together for the systematic sampling scores. 0 5 10 15 20 25 30 35 40 Refuge Norman/Noble Total Turtles Males Females Juveniles 0 20 40 Refuge Norman/Noble Total Turtles AOR DOR 0.00 0.10 0.20 0.30 0.40 0.50 0.60 Refuge Norman/Noble Mean number of turtles per mile
Transcript of Roadside mortality in Terrapene carolina and T. ornata ... Roadside mort… · F=4). Using p = 0.05...
(a) identify landscape features associated with travel corridors.
(b) examine differences between routes on a National Wildlife Refuge and routes off of a
refuge.
(c) examine differences in the sex ratio of turtles found.
Roadside mortality in Terrapene carolina and T. ornata: are females more at risk?
A comparison between urban and non-urban sites
1 Ariel Richter 2 Eric Johansen 1 Tim O’Connell 2 Stanley F. Fox
1Natural Resource Ecology and Management 2Department of Zoology, Oklahoma State University
•Many turtle species make periodic and extended overland migrations. These migrations can
result in individuals being struck and killed by automobiles as the turtles cross roads (5, 1).
While both sexes regularly migrate, females may be more susceptible to collisions because
they tend to move farther than males and may seek out roadside ditches for nesting (6). This
puts not only themselves at risk, but also their future offspring, when they hatch near high
traffic roadways.
•Turtle road mortality can have negative effects on local populations (3, 5) and reduce local
biodiversity (4). Human development is a major influence on turtle mortality because it reduces
the amount of suitable habitat overall and the number of safe passages for migrating turtles.
This is especially true in areas with high road densities that would otherwise support healthy
populations of turtles and other wildlife (2). Human development is especially important in
Oklahoma due to rapid urbanization of areas supporting local populations of turtles and rapid
conversion of habitat from suitable to unsuitable.
•One way to reduce road mortality in turtles is to identify specific routes and conditions that
promote seasonal movements.
Figure 1. Comparison of total turtles found at each site.
Introduction Results Continued
Methods
•2 routes in the Norman/Noble area and 2 routes in the Sequoyah National Wildlife Refuge
(SNWR) were surveyed. The 2 Norman/Noble routes were between 20-25 miles long and the 2
SNWR routes were 10-15 miles long.
•Each route was driven twice daily (before 8:00 am and after 5:00 pm) for a total of 17 days for
the Norman/Noble routes over a 12 week period and a total of 25 days for the SNWR routes
over a 9 week period.
•Turtles encountered along select roads were also counted.
•Biotic data included, but were not limited to: nearest water type, age, sex, MCL (mm), MCW
(mm), MCH (mm), mass (g), and GPS coordinates.
•Abiotic data included, but were not limited to: precipitation (for the past 24 hours), cloud cover,
road type, % tree cover, and placement in road.
•We used systematic sampling points to select for habitat availability.
Objectives
Figure 4. The mean
number of turtles per mile
for each sample site.
Acknowledgments
•The Lew Wentz Foundation and Oklahoma State University.
•The Sequoyah National Wildlife Refuge.
Results
Figure 2. Total number of turtles found at each site.
AOR = Alive on road. DOR = Dead on road.
•More female turtles of both species were found (T. carolina: M=8, F=28 and T. ornata: M=3,
F=4). Using p = 0.05 and CV = 3.84, we calculated a X2 = 1.311.This supports our hypothesis
that there is a female bias.
•Juvenile turtles of both species were found (2 T. ornata and 7 T. carolina) and one hatchling T.
carolina was found supporting the hypothesis that not only are adult turtles at risk of being killed
by automobiles, but juveniles and hatchlings are as well.
•More total turtles were found in the SNWR (n=38) than in the Norman/Noble areas (n=16) with
the total route length for each area as 19.4 miles and 41.6 miles respectively. This leads to the
conclusion that the population density of the SNWR (mean = 0.078 turtles/mi) is greater than the
population in the Norman/Noble areas (mean = 0.023 turtles/mile).
•Due to the fact that more turtles were found in the SNWR and that only 3 of the 38 (0.08)
individuals were dead, as compared to 11 DOR of the 16 (0.69) in the Norman/Noble areas, it
can be concluded that the population outside of the refuge is greatly impacted by road mortality.
•Large bodies of water and expanses of grasslands were disproportionately selected by box
turtles. See Figure 3.
•Further study is needed to determine the role road mortality plays on the overall population
structure and recruitment numbers of both species.
Conclusions
• Turtles had the strongest IEI score in association with water.
• Turtle IEI scores were all greater than the systematic sampling IEI
scores except the Forest habitat.
Figure 3. Ivlev’s
Electivity Index
Scores for the
different habitat
types. Terrapene
ornata and T.
carolina were
grouped
together. All
routes for the
Norman and
Noble areas and
the Sequoyah
NWR have been
grouped
together for the
systematic
sampling scores.
0
5
10
15
20
25
30
35
40
Refuge Norman/Noble
Tota
l Tu
rtle
s
Males Females Juveniles
0
20
40
Refuge Norman/NobleTota
l Tu
rtle
sAOR DOR
0.00
0.10
0.20
0.30
0.40
0.50
0.60
Refuge Norman/Noble
Me
an n
um
be
r o
f tu
rtle
s p
er
mile
Literature Cited
1) Andrews, K. M., J. W. Gibbons, and D. M. Jochimsen. 2008. Ecological effects of roads on amphibians and reptiles, a literature review. In Urban Herpetology, J. C. Mitchell, R. E. Jung Brown, and B. Bartholomew (eds). Herpetological Conservation 3: 121–43.
2) Ashley, E. P. and J. T. Robinson. 1996. Road mortality of amphibians, reptiles and other wildlife on the Long Point causeway, Lake Erie, Ontario. Canadian Field-Naturalist 110: 403-412.
3) Findlay, C. S. and J. Bourdages. 2000. Response time of wetland biodiversity to road construction on adjacent lands. Conservation Biology 14: 86–94.
4) Iverson, J. B. 1982. Biomass in turtle populations: a neglected subject. Oecologia 55: 69–76.
5) Marchland, M. N. and J. A. Litvaitis. 2004. Effects of habitat features and landscape composition on the population structure of a common aquatic turtle in a region undergoing rapid development. Conservation Biology 18: 758–67.
6) Steen, D. A., M. J. Aresco, S. G. Beilke, B. W. Compton, E. P. Condon, C. Kenneth Dodd Jr., H. Forrester, J. W. Gibbons, J. L. Greene, G. Johnson, T. A. Langen, M. J. Oldham, D. N. Oxier, R. A. Saumure, F. W. Schueler, J. M. Sleeman, L. L. Smith, J. K. Tucker, and J. P. Gibbs. 2006. Relative vulnerability of female turtles to road mortality. Animal Conservation 9: 269–273.
