1. The Impact of Management on the Movement and Home Range Size of Indiana’s Eastern Hellbender Salamanders
Emily B. McCallen, Bart T. Kraus, Nicholas G. Burgmeier, and Rod N. Williams
Department of Forestry and Natural Resources
GIS Processing
Results
Hellbenders in Indiana
Large, fully aquatic salamanders requiring cool, fast-flowing lotic systems (Fig. 1)
Once found in tributaries throughout the Ohio and Wabash River watersheds
Now restricted to a single river in southern Indiana (Fig. 2)
20 years of monitoring has revealed significant, ongoing declines in the abundance of hellbenders in the Blue River
No evidence of successful recruitment during this time leading to an increasingly geriatric population
All points recorded on Garmin Rino 86 and imported into ESRI ArcGIS 10.2 (Fig. 3)
Distance between points calculated with R package “geosphere”
Linear Home Range (LHR) Calculation
Points snapped to line representing river midpoint
Points connected and distance (m) of line measured (Fig. 3)
Mean Convex Polygon (MCP) Home Range Calculation
Minimum bounding geometry tool with convex hull geometry type
Polygon area (m2) measured (Fig. 3)
Movement Probability
Variable
Estimate SE
P-value
Intercept
-1.840
0.197
<2e-16
Time Since Last Observation
-0.184
0.048
0.0001
Time Since Release
0.338
0.034
Site Density
-0.207
0.082
0.0119
Fall
0.218
0.090
0.0148
Predicted movement probability over time
Distance Moved
Variable
Estimate SE
P-value
Intercept
2.94
0.106
<2e-16
Time Since Last Observation
0.115
0.038
0.0027
Site Density
-0.154
0.070
0.0286
Fall
0.688
0.083
Status
0.698
0.187
0.0002
Predicted movement probability as a function of site density
Home Range-LHR
Movement and Management
Variable
Estimate SE
P-value
Intercept
5.1927
0.1359
<2e-16
Number of Observations
0.2055
0.1137
0.0707
Status
0.599
0.2412
0.0129
Movement tracked 3x weekly during field season (May – November) via radio telemetry
Pre-management
21 resident adult hellbenders tracked at 8 sites
Post-management
42 individuals tracked at 2 sites where translocations were undertaken to increase local densities
Site 1 contained resident adult hellbenders (11) and translocated adult hellbenders (11) from isolated sites across the river
Site 2 contained resident adult hellbenders (10) and translocated captive-reared juvenile hellbenders (10)
Predicted movement distance for resident and translocated hellbenders
Home Range-MCP
Variable
Estimate SE
P-value
Intercept
9.562
0.3901
<2e-16
Age
0.4260
0.016
Predicted
LHR and MCP
home range sizes
for statistically independent groups
Figure 3. Location points, LHR and MCP for an individual hellbender in the study
Figure 1. An eastern hellbender on the banks of the Blue River
Figure 2. The location of the Blue River in southern Indiana
Predicted movement distance as a function of site density
Statistical Models
Model Type
Generalized Linear Mixed Model
Generalized Linear Model
Discussion
Management
Less movement (probability and distance) at higher site densities
Temporal
Initial period of higher movement probability decreases over time
More movement (probability and distance) in the fall which is when breeding occurs
Individual
Translocated hellbenders move more resulting in larger home ranges
Effect more pronounced in juvenile age classes
Random Effects
Animal ID
Site ID
Negative Binomial
Binomial
Research Question
Error Distribution
Are hellbender movement patterns or home range sizes in the Blue River impacted by management actions, temporal patterns, or individual hellbender characteristics?
Response
Movement Probability
Movement Distance
LHR Size
MCP Size
Covariates: Management
Site Density (hellbenders/kilometer)
Management (pre or post)
Acknowledgements
Covariates: Temporal
Time Since Release
Season (summer or fall)
Financial support was provided by the Indiana Department of Natural Resources, Division of Fish and Wildlife, Wildlife Diversity Section, State Wildlife Improvement Grant T07R11 and the Department of Forestry and Natural Resources at Purdue University. Eastern Hellbenders were collected, handled, and processed following standard procedures approved by the Purdue Animal Care and Use Committee (PACUC; ) and in accordance with Indiana Scientific Permit #
Covariates: Individual
Age (juvenile or adult)
Status
(translocated or resident)
Sex (female or male)
Covariates: Control
Time Since Last Observation
Number of Observations