USE OF AMPHIBIANS AS ECOSYSTEM INDICATOR SPECIES

110 Pages·2006·0.51 MB·English

USE OF AMPHIBIANS AS ECOSYSTEM INDICATOR SPECIES

By

JAMES HARDIN WADDLE

A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY

UNIVERSITY OF FLORIDA

2006
1
Copyright 2006

by

James Hardin Waddle

2
This dissertation is dedicated to my parents, Chris and Sherrell Waddle, who have always
supported me and encouraged me to do what I love, and to Amanda, the love of my life.

3
ACKNOWLEDGMENTS
I would first like to thank the members of my committee. Ken Rice has been a great
mentor and friend over the last six years. His guidance has helped prepare me to be a better
scientist. Franklin Percival has truly taken me “under his wing” and taught me about philosophy.
Jim Nichols was always available for help when I needed it and has consistently provided me
with insightful feedback on my work. Frank Mazzotti was always supportive of me during my
time as a student. Harvey Lillywhite has been a valuable member of the committee, and forced
me to think more about what I think I know.
I would also like to thank the people who assisted me in the field. Brian Jeffery, Andy
Maskell, Chris Bugbee, Meghan Riley, and Debbie Kramp all spent many long hours with me
slogging through swamps. Many members of the Ft. Lauderdale REC Mazzotti and Rice lab and
the Florida Alligator and Amphibian Research Team (FAART) volunteered for the sampling
experiment in Chapter 2. Other volunteers from the Big Cypress National Preserve Student
Conservation Association provided valuable help. All of the FAART people have also provided
useful feedback on my work and great friendship.
The staff of Big Cypress National Preserve was very helpful in all stages of this work. Big
Cypress provided an office and housing for this project, and granted access and permits for the
research. Deb Jansen and Ron Clark engaged me in many good conversations about
management and wildlife in the Preserve. Jim Burch shared plant knowledge, Bob Sobczack
helped with hydrologic questions, and Frank Partridge provided maps and GIS data. Jim Snyder
of the USGS allowed me to share equipment and space and helped watch out for me.
Finally I would like to thank my family for all of their love and support. My new wife,
Amanda is always my biggest supporter. My parents, and my sister Virginia and her husband
Brian Lott all deserve thanks for supporting me through my graduate career.
4
TABLE OF CONTENTS

page
ACKNOWLEDGMENTS...............................................................................................................4
LIST OF TABLES...........................................................................................................................7
LIST OF FIGURES.........................................................................................................................9
ABSTRACT...................................................................................................................................11
CHAPTER
1 INTRODUCTION..................................................................................................................13
Characteristics of Indicator Species........................................................................................13
Suitability of Amphibians as Indicator Species......................................................................14
Outline of the Dissertation......................................................................................................15
2 SAMPLING METHODS FOR AMPHIBIAN MONITORING............................................19
Introduction.............................................................................................................................19
Methods..................................................................................................................................20
Sampling Experiment......................................................................................................20
Double Observer Analysis...............................................................................................22
Distance Analysis............................................................................................................23
Results.....................................................................................................................................23
Double Observer..............................................................................................................24
Distance Analysis............................................................................................................24
Discussion...............................................................................................................................25
3 USING SITE OCCUPANCY MODELING TO DETERMINE THE EFFECT OF OFF-
ROAD VEHICLE USE ON GROUND-DWELLING ANURANS.......................................41
Introduction.............................................................................................................................41
Methods..................................................................................................................................42
Study Area.......................................................................................................................42
Sampling..........................................................................................................................43
Data Analysis...................................................................................................................45
Results.....................................................................................................................................45
Discussion...............................................................................................................................46
4 THE EFFECT OF TOE-CLIPPING ON TWO SPECIES OF TREEFROGS.......................63
5
Introduction.............................................................................................................................63
Methods..................................................................................................................................64
Study Site.........................................................................................................................64
Capture Recapture...........................................................................................................65
Survival Analysis.............................................................................................................66
Results.....................................................................................................................................66
Discussion...............................................................................................................................68
5 INFLUENCE OF HYDROLOGY ON SURVIVAL AND RECRUITMENT OF
GREEN TREEFROGS...........................................................................................................77
Methods..................................................................................................................................78
Results.....................................................................................................................................82
Discussion...............................................................................................................................83
6 CONCLUSION.......................................................................................................................97
Introduction.............................................................................................................................97
Characteristics of Indicators...................................................................................................97
Abundant and Efficient to Sample..................................................................................97
Sensitive to Stresses on the System.................................................................................98
Responses to Stress Should Be Anticipatory...................................................................99
Integrate a Response across the Whole System..............................................................99
Known Response to Anthropogenic Stresses and Natural Disturbances........................99
Conclusion............................................................................................................................100
LIST OF REFERENCES.............................................................................................................102
BIOGRAPHICAL SKETCH.......................................................................................................110

6
LIST OF TABLES
Table page

2-1 Number of artificial frogs observed by each team in prairie and pineland habitats.........29
2-2 Actual detection rates of a known population of artificial frogs within 30 cm, within
50 cm, beyond 50 cm, and overall for teams searching in prairie and pineland habitat....30
2-3 Model selection for the three double-observer models analyzed in Program SURVIV
with the model log-likelihood, number of parameters (K), quasi-likelihood Akaike’s
information criterion adjusted for small sample sizes (QAIC ).........................................31
c
2-4 Estimates from program SURVIV of individual detection probabilities of artificial
frogs for each observer in prairie and pineland habitat with standard error (S.E.) and
95% confidence intervals (C.I.) taken from the double observer method.........................32
2-5 Abundance estimates of artificial treefrogs for each team in prairie and pineland
habitat with standard error (S.E.) and upper and lower 95% confidence intervals (C.
I.) based on Chaos’s estimatorfrom the double observer data...........................................33
2-6 Model selection for detection functions in Program DISTANCE showing number of
parameters (K), Akaike’s Information Criterion (AIC), the difference between each
AIC and the minimum (Delta AIC), and the AIC Weight of each model.........................34
2-7 Abundance estimates of artificial frogs by team for transects in the prairie and
pineland habitats with coefficient of variation (CV) and 95% confidence interval (CI)
from the distance sampling approach................................................................................35
3-1 Combinations of the 3 site covariates and 4 sampling covariates that were used in the
occupancy analysis for each species. Each set of site covariates was modeled along
with each set of sampling covariates for a total of 80 unique models for each species.....50
3-2 Number of sampling sites and total number of site visits by habitat.................................51
3-3 Number of detections by species, and proportion of sites at which a detection
occurred (naive occupancy) during amphibian surveys across all habitat types...............52
3-4 Model selection results for the oak toad (Bufo quercicus), including Akaike’s
Information Criterion (AIC) and the delta AIC and AIC weight (Burnham and
Anderson 1998) for all models with any AIC weight........................................................53
3-5 Model selection results for the southern toad (Bufo terrestris), including Akaike’s
Information Criterion (AIC) and the delta AIC and AIC weight (Burnham and
Anderson 1998) for all models with any AIC weight........................................................54
7
3-6 Model selection results for the greenhouse frog (Eleutherodactylus planirostris),
including Akaike’s Information Criterion (AIC) and the delta AIC and AIC weight
(Burnham and Anderson 1998) for all models with any AIC weight................................56
3-7 Model selection results for the eastern narrow-mouthed toad (Gastrophryne
carolinensis), including Akaike’s Information Criterion (AIC) and the delta AIC and
AIC weight (Burnham and Anderson 1998) for all models with any AIC weight............57
3-8 Sums of Akaike’s Information Criterion (AIC) weights for all models including the
ORV index, habitat type, or hydrologic index covariates for each of the four focal
anuran species....................................................................................................................59
3-9 Beta estimates, standard errors (S.E.), and lower and upper 95% confidence intervals
(C.I.) for the ORV use index covariate from the best model for each of the four focal
anuran species....................................................................................................................60
4-1 List of 23 models analyzed in Program MARK for captures of both Green Treefrogs
and Squirrel Treefrogs in Big Cypress National Preserve during 2004-2005. ................70
4-2 The number of green treefrogs and squirrel treefrogs marked by removing 2, 3, or 4
toes in Big Cypress National Preserve, Collier County, FL, Nov. 2004-June 2005 and
the return rate (proportion of marked individuals recaptured at least once)......................71
4-3 Model selection table for Cormack-Jolly-Seber open population mark-recapture
model of Green Treefrogs including Quasi-likelihood Akaike’s Information Criterion
for small sample sizes (QAIC ).........................................................................................72
c
4-4 Estimates, standard error (SE), and the 95% confidence interval of the beta values for
the toe-clip effect on apparent survival and recapture probability....................................73
4-5 Model selection table for Cormack-Jolly-Seber open population mark-recapture
model of Squirrel Treefrogs including Quasi-likelihood Akaike’s Information
Criterion for small sample sizes (QAIC )..........................................................................74
c
5-1 Dates of each sample of the PVC pipe refugia and the season to which each sample
was assigned for mark-recapture analysis..........................................................................86
5-2 Model selection results for all models analyzed in Program MARK. Model describes
the covariates and groups associated with survival, capture probability, and seniority....87
5-3 Estimates of the population growth rate, the contribution of survival and the
contribution of recruitment to growth for each sampling interval.....................................88

8
LIST OF FIGURES
Figure page

2-1 Histograms of the frequency of perpendicular distances in cm of actual artificial frog
placements along the 2 transect lines in the prairie and pineland habitat..........................36
2-2 Histograms of the frequency of detections of artificial frogs by each team at
perpendicular distances in cm along the 2 transect lines in the prairie habitat..................37
2-3 Histograms of the frequency of detections of artificial frogs by each team at
perpendicular distances in cm along the 2 transect lines in the pineland habitat..............38
2-4 Histograms of the frequency of detections of artificial frogs at perpendicular
distances along the transect lines for teams in the prairie habitat and pineland habitat....39
2-5 Abundance estimates with standard error for each team from prairie (A) and pineland
habitat (B) using the double observer and distance methods.............................................40
3-1 An aerial photograph depicting off-road vehicle damage in marl prairie habitat in Big
Cypress National Preserve.................................................................................................61
3-2 Map of amphibian occupancy sampling locations within BCNP during 2002-2003........62
4-1 Numbers of individuals of green treefrogs and squirrel treefrogs captured and
released in each of the three toe removal groups during the first 7 sampling
occasions............................................................................................................................75
4-2 Apparent survival and 95% confidence interval of green treefrogs and squirrel
treefrogs in each toe removal group category across the first 6 monthly sampling
intervals..............................................................................................................................76
5-1 Mean water depth across the 3 sampling locations in BCNP in the cypress strand,
broadleaf marsh, and prairie habitats from April 2004-August 2005................................89
5-2 Number of captures of Green Treefrogs during each of the 25 samples from April
2004 to August 2005 and mean water depth (in cm) of marsh plots across all 3 sites......90
5-3 Mean snout-to-urostyle (SUL) in mm of Green Treefrogs captured in all habitats at
the three sites at each sampling occasion in BCNP...........................................................91
5-4 Number of captures by sample of Green Treefrogs in cypress, marsh, and prairie
habitats at the three sites in BCNP.....................................................................................92
5-5 Estimates with 95% confidence intervals of apparent survival of Green Treefrogs for
each sampling interval for cypress, marsh, and prairie habitat in BCNP..........................93
9
5-6 Estimates with 95% confidence intervals of seniority of Green Treefrogs for each
sampling interval for cypress, marsh, and prairie habitat in BCNP...................................94
5-7 Estimates with 95% confidence intervals of capture probability of Green Treefrogs at
each sampling occasion for cypress, marsh, and prairie habitat in BCNP........................95
5-8 Derived estimates of population growth of Green Treefrogs for each sampling
interval for cypress, marsh, and prairie habitat in BCNP..................................................96

10