Multiple responses by Cerulean Warblers to experimental forest disturbance in the Appalachian ...

221 Pages·2016·2.2 MB·English

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Doctoral Dissertations Graduate School
12-2011
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Than James Boves
University of Tennessee - Knoxville, [email protected]
Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss
Part of the Behavior and Ethology Commons, Forest Management Commons, Population Biology
Commons, and the Terrestrial and Aquatic Ecology Commons
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Boves, Than James, "Multiple responses by Cerulean Warblers to experimental forest disturbance in the
Appalachian Mountains. " PhD diss., University of Tennessee, 2011.
https://trace.tennessee.edu/utk_graddiss/1169
This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee
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[email protected].
To the Graduate Council:
I am submitting herewith a dissertation written by Than James Boves entitled "Multiple
responses by Cerulean Warblers to experimental forest disturbance in the Appalachian
Mountains." I have examined the final electronic copy of this dissertation for form and content
and recommend that it be accepted in partial fulfillment of the requirements for the degree of
Doctor of Philosophy, with a major in Natural Resources.
David A. Buehler, Major Professor
We have read this dissertation and recommend its acceptance:
Patrick D. Keyser, David S. Buckley, Todd M. Freeberg
Accepted for the Council:
Carolyn R. Hodges
Vice Provost and Dean of the Graduate School
(Original signatures are on file with official student records.)
Multiple responses by Cerulean Warblers to experimental forest
disturbance in the Appalachian Mountains

A Dissertation Presented for the
Doctor of Philosophy
Degree
The University of Tennessee, Knoxville

Than James Boves
December 2011
ACKNOWLEDGEMENTS

I would like to thank many people for their valuable help and support on this project; without
these individuals this research and this amazing experience, would not have been possible. First,
I‘d like to thank my advisor and mentor, David Buehler, for his guidance, advice, and
exceptional support. Dave was ideal for me at this point in my educational career: very
optimistic, encouraging, and willing to give me the freedom to explore my personal interests
within the confines of this project. I will be forever grateful that he talked me into coming to
Tennessee when I was initially hesitant! I‘d also like to thank my graduate committee members,
David Buckley, Patrick Keyser, Todd Freeberg, and Lynn Siefferman for their comments, useful
discussions, and constructive critiques of my research. I would particularly like to thank Lynn for
providing me with her expertise and positive outlook (not to mention lab equipment) regarding
my plumage color work.
I greatly appreciate the hard work of the professors and graduate students (from multiple
universities) that conceived, implemented, and collected data for this study including: Amanda
Rodewald, Jeff Larkin, Petra Wood, Ben Wigley, Tiffany Beachy, Greg George, Jim Sheehan,
Felicity Newell, Marja Bakermans, Andrea Evans, and Matt Woods (as well as Dave Buehler
and Pat Keyser).
I‘d like to thank my friends and labmates at the University of Tennessee; without their
camaraderie it would have been nearly impossible to complete this work. I‘d also like to thank
the fantastic work of many field assistants that (a) collected data for me, and (b) became great
friends: Phill Massey, Doug Raybuck, Angie Langevin, Jen Glagowski, Jess Piispanen, Peter
Capobianco, David Rankin, Evan Pannkuk, Richard Gaillard, Evan DeHamer, Matt Horton, and
Will Collier.
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I owe many thanks to my parents for allowing me to follow my passions, instilling in me a
great appreciation for learning and supporting my seemingly never-ending education. Most of
all, I‘d like to thank my wife Emily for her constant encouragement, patience, and devotion to
me and the Cerulean Warbler project. It is difficult to express in words how much she has helped
me. Not only was Emily there for me emotionally when I had doubts about my ability to
complete this work, but she was also the greatest field assistant I could ever imagine; she was
personally responsible for finding over 100 Cerulean Warbler nests, and I could not have done
this without her.
Last, but by no means least, I‘d like to (insufficiently) express my gratitude to the ceruleans
and the rugged Cumberland Mountains. Before I started this project, I had only seen a couple of
Cerulean Warblers in my life, and I had never heard of the Cumberlands. Four years later, I now
know that both will always be a part of who I am. For the rest of my life, I will smile whenever I
think of DB Cooper, with his pink and black band, bouncing out of the net on the heavy
treatment and Moe singing to one of his females on the intermediate. Someday, I hope that my
son and I can walk up plot three at Royal Blue, stand together on the rocky outcrop, and hear the
beautiful sound of seven Cerulean Warblers singing simultaneously. And maybe even see Moe
again.

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ABSTRACT

The Cerulean Warbler (Setophaga cerulea) is a mature forest obligate and one of the fastest
declining songbird species in the United States. This decline may be related to a lack of
disturbance within contemporary forests; however, the consequences of disturbance on the
species have not been rigorously evaluated. Thus, we assessed multiple responses by Cerulean
Warblers to a range of experimental forest disturbances across the core of their breeding range in
the Appalachian Mountains. We quantified individual and population responses to these
manipulations, and assessed the potential consequences of disturbance on the sexual signaling
system. Male ceruleans were strongly attracted to intermediate and heavy disturbances at the
stand scale. Despite attraction to disturbed habitats, nest success declined in these conditions,
particularly in the highly productive Cumberland Mountains of northern Tennessee. Taken
together, these opposing responses suggest that anthropogenically-disturbed forests may act as
local ecological traps, but the impact of these local traps on the global population is dependent
on several unestimated parameters. At a finer scale, selection for habitat features varied spatially.
Males consistently selected for territories near canopy gaps and on productive slopes, but they
displayed inconsistent territory selection in regards to tree diameter, basal area, overstory canopy
cover, and canopy height. Females were more consistent in their selection of features within
territories, selecting nest patches with large, well-spaced trees near disturbances. Floristically,
female ceruleans consistently selected for sugar maples (Acer saccharum), white oaks (Quercus
alba), and cucumber magnolias (Magnolia acuminata) as nest trees and they selected against red
maples (A. rubrum) and red oaks (Q. rubra). Disturbances had little effect on male age structure,
but males that occupied disturbed forest habitat were in better condition than those in
undisturbed habitat. Parental behavior differed among disturbances, with birds in more highly
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disturbed habitats provisioning their young at greater rates, but bringing smaller food loads,
potentially helping to explain the decrease in nest survival in disturbances. Finally, we found that
male ceruleans displayed various plumage ornaments that signaled individual quality. However,
the relationship between breast band width and body mass was contingent on habitat, and only
existed in intermediate disturbances.
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TABLE OF CONTENTS

INTRODUCTION .......................................................................................................................... 1
LITERATURE CITED ............................................................................................................... 6
CHAPTER 1: BRINGING DISTURBANCE BACK TO THE FOREST: AN EXPERIMENTAL
TEST OF THE IMPACTS OF EMULATING NATURAL DISTURBANCES ON A MATURE
FOREST OBLIGATE ................................................................................................................... 13
INTRODUCTION .................................................................................................................... 15
METHODS ............................................................................................................................... 19
RESULTS ................................................................................................................................. 27
DISCUSSION ........................................................................................................................... 30
LITERATURE CITED ............................................................................................................. 41
APPENDIX ............................................................................................................................... 55
CHAPTER 2: SPATIAL VARIATION OF MULTI-SCALE HABITAT SELECTION AND
ADAPTIVENESS OF HABITAT DECISIONS MADE BY CERULEAN WARBLERS
ACROSS A DISTURBANCE CONTINUUM ............................................................................. 68
INTRODUCTION .................................................................................................................... 70
METHODS ............................................................................................................................... 73
RESULTS ................................................................................................................................. 83
DISCUSSION ........................................................................................................................... 88
LITERATURE CITED ............................................................................................................. 96
APPENDIX ............................................................................................................................. 105
CHAPTER 3: INFORMATION CONTENT AND HABITAT CONTINGENCY OF MULTIPLE
PLUMAGE ORNAMENTS IN A CANOPY-DWELLING SONGBIRD, THE CERULEAN
WARBLER ................................................................................................................................. 116
INTRODUCTION .................................................................................................................. 118
METHODS ............................................................................................................................. 123
RESULTS ............................................................................................................................... 131
DISCUSSION ......................................................................................................................... 133
LITERATURE CITED ........................................................................................................... 140
APPENDIX ............................................................................................................................. 149
CHAPTER 4: INFLUENCE OF HABITAT AND OTHER PROXIMATE FACTORS ON
PARENTAL CARE BY CERULEAN WARBLERS ................................................................ 163
INTRODUCTION .................................................................................................................. 165
METHODS ............................................................................................................................. 168
RESULTS ............................................................................................................................... 175
DISCUSSION ......................................................................................................................... 178
LITERATURE CITED ........................................................................................................... 184
APPENDIX ............................................................................................................................. 191
CONCLUSIONS......................................................................................................................... 207
VITA ........................................................................................................................................... 210

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LIST OF TABLES
Table 1.1. Summary of model selection results for factors influencing daily survival of Cerulean
Warbler nests ........................................................................................................................ 55
Table 2.1. Cerulean Warbler habitat measurements at random (R), territory (T) and nest patch
(N) points pooled across six study areas in the Appalachian Mountains, 2008–2010 ....... 105
Table 2.2. Cerulean Warbler habitat measurements at random (R), territory (T), and nest (N)
points at six study areas in the Appalachians, 2008–2010.................................................. 106
Table 2.3. Meta-analysis results of Cerulean Warbler habitat selection at six study areas in the
Appalachian Mountains, 2008–2010 .................................................................................. 108
Table 2.4. Cerulean Warbler nest-site characteristics at six study areas in the Appalachian
Mountains, 2008–2010 ....................................................................................................... 109
Table 2.5. Multi-scale habitat selection in relation to floristic composition by Cerulean Warblers
at six study areas in the Appalachian Mountains, 2008–10 ................................................ 110
Table 2.6. Final candidate models from Cerulean Warbler nest survival analysis at individual
study areas in the Appalachian Mountains, 2008–2010 ..................................................... 113
Table 3.1. Pairwise correlations (estimated using REML method) between six plumage
measurements for age classes pooled and within-age classes ............................................ 149
Table 3.2. Plumage measurements of breast band width, tail white, rump blue-green (BG)
chroma (435–534 nm) and hue, and crown BG chroma and hue for second-year (SY) and
adult (ASY) male cerulean warblers in the Cumberland Mountains, 2009–10 .................. 150
Table 4.1. Pairwise correlations (estimated using REML method) for 8 continuous predictor
variables of measures of parental care by Cerulean Warblers ............................................ 191
Table 4.2. Environmental and ecological factors included in model selection process, listed
hierarchically in the order we performed the analyses. ...................................................... 192
Table 4.3. Summary of gender-specific parental care behaviors. ............................................... 193
Table 4.4a-b. Final models (and null) using full nest set (n = 56) with strong support explaining
variation in feeding rates for (a) males and (b) females ..................................................... 194
Table 4.5. Summary of partial regression coefficients (β estimates) and 95% CI for key predictor
variables included in final models that garnered strong support. ....................................... 195
Table 4.6a-b. Final models (and null) using full nest set (n = 56) with strong support explaining
variation in nest attendance time (log-transformed) for (a) males and (b) females ............ 197
Table 4.7a-b. Final models (and null) using reduced data set (n = 22) and including data on male
characteristics (age and mass) as predictors, with most support explaining variation nest
attendance time (log-transformed) for (a) males and (b) females. ...................................... 198
Table 4.8a-b. Final models (and null) using full nest set (n = 50) with most support explaining
variation in average food load size for (a) males (log-transformed) and (b) females. ........ 199
Table 4.9a-b. Final models (and null) using full nest set (n = 50) with most support explaining
variation in total food delivered/hr (feeding rate/hr * average food load size) for (a) males
and (b) females. ................................................................................................................... 200

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LIST OF FIGURES
Figure 1. Conceptual flowchart illustrating the relationships between habitat disturbance and
various measured responses .................................................................................................... 5
Figure 1.1. Map displaying locations of seven study sites in the Appalachian Mountains .......... 56
Figure 1.2. Mean densities ± 1 SE of Cerulean Warbler territories on disturbed treatments,
controls, and buffers from pre-disturbance years (mean of 2005–06) to four years post-
disturbance. ........................................................................................................................... 57
Figure 1.3. Mean density ratio of male Cerulean Warblers (calculated as post-disturbance
density/pre-disturbance density) in various treatments. ........................................................ 58
Figure 1.4. Age structure of male Cerulean Warblers on various treatments expressed as the
proportion of second-year (SY) males captured. .................................................................. 59
Figure 1.5. Body condition (via body mass) of male Cerulean Warblers by treatment, 2008–10.
............................................................................................................................................... 60
Figure 1.6. Cerulean Warbler nest success by site, all treatments combined, 2008–10. .............. 61
Figure 1.7. Cerulean Warbler nest success by year, all treatments combined .............................. 62
Figure 1.8. Cerulean Warbler nest success by treatment, all post-disturbance years combined. . 63
Figure 1.9a-b. Cerulean Warbler nest success by treatment and year at (a) southern sites (RB and
SQ) and (b) northern sites (REMA, DB, LW, WYO). ......................................................... 64
Figure 1.10. Source-sink graphical model using point estimates of nest success rates and mean
number of young fledged/successful nest on various treatments at both southern (S) and
northern (N) sites, 2008–10 .................................................................................................. 66
Figure 1.11. Causes of nest failure for Cerulean Warblers in the Appalachian Mountains from
2008–2010............................................................................................................................. 67
Figure 2.1. Locations of study areas across the Appalachian Mountains, all within the core of the
Cerulean Warbler range ...................................................................................................... 114
Figure 2.2. Multi-scale selection for tree species by Cerulean Warblers at all study areas (pooled)
in the Appalachian Mountains, 2008–10. ........................................................................... 115
Figure 3.1a-d. Photographs depicting Cerulean Warbler ornaments evaluated .......................... 151
Figure 3.2. Example of the use of ptilochronology to infer body condition at the time of tail molt
............................................................................................................................................. 152
Figure 3.3. Crown reflectance spectrum from second-year (SY) and after-second-year (ASY)
Cerulean Warblers captured in the Cumberland Mountains, TN, 2009–10 ....................... 153
Figure 3.4. Rump reflectance spectrum from second-year (SY) and after-second-year (ASY)
Cerulean Warblers captured in the Cumberland Mountains, TN, 2009–10 ....................... 154
Figure 3.5a. Partial regression leverage plot indicating relationship between achromatic tail white
and condition at molt (via tail growth bars) for male Cerulean Warblers after controlling for
age and year ........................................................................................................................ 155
Figure 3.5b. Partial regression leverage plot indicating relationship between structural rump
blue-green (BG; 435–534 nm) hue and provisioning rate for male Cerulean Warblers after
controlling for age and year ................................................................................................ 156
Figure 3.5c. Partial regression leverage plot indicating relationship between structural rump blue-
green (BG; 435–534 nm) chroma and body mass for male Cerulean Warblers after
controlling for age and year. ............................................................................................... 157
Figure 3.6. Relationships between melanin-based breast band (BB) width and body condition at
time of capture (body mass) in different habitat conditions. .............................................. 158
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