UN1VER:::ITY OF HAWAI'I LIBRARY

HABITAT USE BY THE ENDANGERED

(PSEUDONESTORXAN11l0PRYS) EFFECTS OF PHYSIOGNOMY AND

FLORISTICS

A THESIS SUBMITTED TO THE GRADUATE DIVISION OF THE UNIVERSITY OF HAWAI'I IN PARTIAL FULFILLMENT FOR THE REQUIREMENTS FOR THE DEGREE OF

MASTER OF SCIENCE

IN

BOTANY

DECEMBER 2007

By Valerie K. Stein

Thesis Committee:

David Duffy, Chairperson Kent Bridges Sheila Conant We certify that we have read this thesis and that, in our opinion, it is satisfactory in scope and quality as a thesis for the degree of Master of

Science in Botany.

THESIS COMMITIEE

ii Copyright © by

Valerie Stein

2007

iii DEDICATION

This research is dedicated to all those past and present working to protect and restore the amazing flora and fauna that are Haleakala.

iv ACKNOWLEDGMENTS

This research owes itself in part, to collaboration with many individuals.

Conversations on Parrotbill recovery with Scott Fretz first sparked this particular study and inspired me to pursue funding. The fieldwork component of this project would not have been possible without the tremendous effort put forth by my two field technicians: Laura Arnold and Emily Severson. Laura and Emily assisted me throughout the course of two field seasons, providing humor and encouragement as well as research assistance in conditions that might have deterred the heartiest of souls. The Resources

Management Division at Haleakalii National Park was my 'ohana and home away from home when I had none, providing camaraderie as well as much needed logistical support throughout the course of a difficult and challenging field project. Mahalo nui loa Steve

Anderson, Cathleen Bailey, Timmy Bailey, Sean Birney, Chuck Chimera, lain Emmons,

Ross Hart, Bill Haus, Raina Kaholoa'a, Terry Lind, Ron Nagata, Gale Plana, Regan

Ritchie, Ted Rodrigues, Aloha Smith, Joy Tamayose and Patti Welton for making my time on "the mountain" so memorable. Cathleen Bailey in particular served as a mentor and I am grateful for the latitude she provided me in designing and running my own research project. I thank Windward Aviation and the exceptional helicopter pilots of Jim

Hobbs, Eric Pacheco, Pete Voorhees, and Don Shearer for transporting us and our gear safely to and from the field.

I thank my committee members: Dr. David Duffy, Dr. Sheila Conant and Dr. Kim

Bridges for their encouragement and interest in applied ecological studies. David and

Sheila's enthusiasm for my research kept me motivated during moments of self doubt,

v and Kim enthusiastically stepped in as a late addition on my project. Dr. Joe Fragoso provided helpful comments on study design at earlier stages of my project and Dr. Andy

Taylor provided insightful comments on analyses at different stages of my work.

I thank my officemates: Stephanie Joe, Christina McGuire, Elizabeth Keenan,

Dana Crompton, and Lindsay Young for their support and good humor over the years. I also thank Meghan Dailer, Sheldon Plentovich, Stacy Enoch, and Arlene Sison for their support and friendship during much of my graduate school experience.

I thank my parents for encouraging me to be and do whatever I wanted and for exposing me to the wonders of the natural world as a child. The experiences I had growing up on their dairy farm in rural upstate NY set the course for my future at a young age and I am forever grateful for that time. Finally, it is with much gratitude that I thank

Jeff Foster for his patience, support, and encouragement.

My Master's research was funded by the National Park Service and carried out under a cooperative agreement with the Pacific Cooperative Studies Unit of the

University of Hawai 'i.

vi ABSTRACT

Understanding how affects endangered species can provide critical information to scientists and managers faced with restoring habitat. The Maui Parrotbill, one of the most endangered honeycreepers in Hawai'i, is currently restricted to the bigh elevation rainforests of East Maui. I conducted research on habitat use by this species in

Manawainui, an area of montane rainforest under consideration for release of captive­ reared parrotbill in Haleakalii National Park on Maui. I sought to empirically determine how forest stand structure and composition might influence parrotbill distribution in

Manawainui and how these factors might influence the suitability of this area as a potential release site for captive-reared . My main objectives were to quantify the effects offorest stand structure and plant composition on parrotbill habitat selection at the macrohabitat (home range) and microhabitat (foraging site) scales. I studied habitat suitability for Maui Parrotbill at 21 10-hectare sites (10 used, 11 unused) in mixed

Metrosideros polymorpha- forest in Manawainui from February-August 2005 and January-August 2006. A combination of and vegetation surveys was utilized to compare vegetation parameters between used and unused areas at different spatial scales of macrohabitat and microhabitat. Parrotbill exhibited non-random habitat use at multiple spatial scales. At the macrohabitat scale, vegetation structure and composition differed significantly between used and unused areas. Parrotbill were associated with areas typified by large diameter and bigher densities of understory, subcanopy and canopy vegetation layers. Significant indicator plants of parrotbill habitat use at the macrohabitat scale were Cheirodendron trigynum, Jlex; anomala, and Me/icope spp. At the microhabitat

vii scale, parrotbill selected fomging sites non-randomly and were most influenced by ovemll species composition. Birds selectively fomged on C. trigynum, Me/icope spp.,

Acacia koa, Coprosma spp., and in disproportion to availability.

Ovem1l vegetation structure did not differ significantly between used and unused fomging plots, however parrotbill did selectively fomge on smaller diameter trees and used the subcanopy and canopy more than expected. These data highlight the importance of diverse, well developed forest for this species and have important management and conservation implications.

viii TABLE OF CONTENTS

ACKOWLEDGMENTS ...... v

ABSTRACT ...... •vii

LIST OF TABLES ...... xi

LIST OF FIGURES ...... xii

CHAPTER 1. INTRODUCTION ...... 1

BACKGROUND ...... 1

STUDY SPECIES ...... 3

RESEARCH OBJECTNES ...... 6

CHAPTER 2. HABITAT USE BY MAUl PARROTBILL: A MULTISCALE

APPROACH ...... 11

INTRODUCTION ...... 11

METHODS ...... 14

STUDY SITE •••..•....••....••.....••••••••••••••••••••••••.•••...... ••••...••••••••••••••••••••.••.•...... •.....•..... 14

BIRD SURVEyS •...... •...•••...•••••...•.•..•••..•...... •...•••••...•.•...•.•...•..•...... 16

VEGETATION SAMPLING (MACROHABITAT) •.••.•.••...•.•••.••••••..••...... •.....••..•.••••••••.• 17

DATAANALYSES-MAcROHABITAT ...... ••.•.••.•.•..••..•..••...... •...... •.•...•.•...•.•....•. 18

VEGETATION SAMPLING (MICROHABIT AT) ...... 22

DATA ANALYSES-MICROHABITAT •••.•.••.•..••...•...... •.....•...•..•••••••••••••••••..••..•..•...... 23

RESULTS ...... 24

ix BIRD SURVEYS ...... 24

MACROHABITAT •...••....•...... •.••....•.•...•.•...•.••..•.....•.•....•••...••.••..••.•.. 25

MICROHABITAT ...... 27

DISCUSSION ...... 28

MACROHABITAT ...... 28

MICROHABITAT •..••.•..••...... •...... •...... •.••..•.•.••..•.•.•.•...... •...... 30

CHAPTER 3. MAll PARROTBILL FORAGING HABITAT •....••...... 46

INTRODUCTION ...... 46

METHODS .•...... •.•..••.•...•..••..••••..•.•..•.•...... ••••.....•....•.••..••.•..•...... •..•..•.....•••...•.•...••... 47

BIRD SURVEYS ...... ••...... ••...... 49

FORAGING OBSERVATIONS ...... 50

VEGETATION SURVEYS ...... 50

DATA ANALYSES ...... •.. 51

RESULTS .•..•...... 53

DISCUSSION ...... ••...••.....••...... •.....•.....•.....•.....•...... 55

CHAPTER 4. CONCLUSION ...•..•..•.•...... •...•.....••••...... •.• 69

APPENDIX A ...... 76

APPENDIX B ...... 77

APPENDIX C ...... 80

LITERATURE CITED ...... 84

x LIST OF TABLES

Table 2.1. Description of habitat variables measured for macrohabitat ...... 35

Table 2.2. Summary table for habitat variables measured in 21 ten hectare areas ...... 36

Table 2.3. Summary of habitat variables measured for microhabitat ...... 37

Table 2.4. Summary statistics for vegetation structure and floristics ...... 38

Table 2.5. Canonical discriminant functions for vegetation structure ...... 38

Table 2.6. Summary of indicator species analysis for macrohabitat ...... 39

Table 2.7. Summary statistics for Mann-Whitney analyses of diversity ...... 40

Table 2.8. Summary of indicator species analysis for microhabitat ...... 41

Table 3.1. Regression analyses results for plants ...... 61

Table 3.2. Regression analyses results for vertical height tier ...... 62

Table 3.3. Regression analyses results for tress size class ...... 63

xi LIST OF FIGURES

Figure

Figure 1.1. Current and historic range of Maui Parrotbill on Maui ...... 10

Figure 2.1. HaIeakaIii National Park with Manawainui study site ...... 42

Figure 2.2. Detailed overview ofManawainui study site with vegetation plots...... 43

Figure 2.3. NMS ordination for forest structure by home range use ...... 44

Figure 2.4. NMS ordination for floristics by home range use...... 45

Figure 3.1. Maui parrotbill distribution across the study site ...... 64

Figure 3.2. Mean percent time parrotbill spent fomging on plant type, trees size class, and vertical height tier ...... 65

Figure 3.3. Fomging events for parrotbill broken down by plant type and fomging behavior in Manawainui ...... 67

Figure 3.4. Fomging events for parrotbill broken down by substmte type and fomging behavior in Manawainui ...... 67

Figure 3.5. Foraging events for parrotbill in Hanawi broken down by plant and fomging behavior...... 68

Figure 3.6. Fomging events for parrotbiII in Hanawi broken down by substrate type and foraging behavior...... 68

xii CHAPTER 1. INTRODUCTION

BACKGROUND

Habitat is a driving force behind ecological and evolutionary processes and habitat quality is crucial to the survival of all living organisms (Southwood 1977).

Understanding how and at what scale habitat influences distribution, abundance, and fitness is integral to the conservation and management of any species. The concept of habitat can be used in various contexts (see reviews in Block and Brennan 1993, Jones

2001), but is perhaps most commonly used to relate the presence ofa species with certain characteristics of its physical and biological environment (Morrison et al. 1992, Morrison and Hall 2002). Bird-habitat studies have been a central theme in ecology and evolutionary biology, based on the premise that birds selectively choose in an adaptive manner (Rotenberry 1981). Habitat structure, floristics, competition, predation, food resources, presence of conspecifics, and environmental factors such as climate are some of the most apparent factors which influence an 's choice of suitable habitat

(Hilden 1965, Southwood 1977, Butler 1980, Hutto 1985. Rotenberry 1985, Root 1988,

Muller et al. 1997, Luck 2002) and the resulting differential selection ofa particular habitat type is fundamental to the coexistence of multiple species within a landscape

(Rosenzweig 1981). An organism selects habitat by making a series of hierarchical decisions, first deciding where to live and then how to live there most efficiently. These decisions can be further influenced by both temporal and spatial scale (Johnson 1980,

Orians and Wittenberger 1991). In patchy and disturbed landscapes in particular, selection of sites which are simultaneously advantageous for a variety of activities such

1 as nesting, cover and foraging may prove particularly difficult for an organism to find, and site selection may be ultimately dictated by the most limiting resource (Orians and

Wittenberger 1991).

Habitat modification and degradation is the primary cause of species loss worldwide, and a contributing factor to rising extinction mtes over the course of the last twentY years (Meffe and Carroll 1997, Wilcove et al. 1998, Abbitt and Scott 2001,

Davies 2001, Mace 2001, Johnson 2007). Birds are among the most severely affected taxonomic groups, with approximately II % of all avian species either threatened or

endangered (Smith et al. 1993, Restani and Marz1uff2001). Avian species on oceanic

islands, where extinction can be attributed to human colonization and its associated

impacts, have been particularly affected by habitat altemtion (Blackburn et al. 2004).

Thus, it is not surprising that in Hawai'i has negatively impacted much of the state's native biota (Cuddihy and Stone 1990, Abbitt and Scott 2001).

Conversion of forests to urban and agricultural lands by humans has been further

exacerbated by the introduction of non-native plants and . Grazing and browsing

pressures of human-introduced herbivores have altered understory vegetation and

impeded the natural regenemtion of over-story species (van Riper and Scott 2001). This

dmstic altemtion of vegetation structure and species composition has had negative

ramifications for both flom and fauna, and in some cases has compromised the integrity

of entire ecosystems. Habitat altemtion as a result of anthropogenic change has been cited

as a primary limiting factor affecting the continued survival of the Hawaiian avifauna

(Pmtt 1994, van Riper and Scott 2001). The Hawaiian honeycreepers (Fringillidae:

2 Drepanidinae), one of the most impressive examples of adaptive radiation in the world, are the most heavily affected. The advent of human colonization subjected these birds to novel predators, avian disease, and habitat degradation (James 2001). As a result, many of these species have suffered severe reductions in range, with roughly one-third of the historically known honeycreeper species now extinct (James and Olson 1991). Many more remain vulnerable to the threat of extinction with over two-thirds of the remaining forest birds listed as endangered (Pratt 1994, USFWS 2006).

Conservation and restoration of habitat is specified as a major recovery objective in the current Recovery Plan for Hawaiian Forest Birds (USFWS 2006). Reintroduction of captive-reared birds to augment existing bird populations in the wild is an important objective of recovery efforts in Hawai'i (Banko et al. 2001, Tweed et al. 2003).

Understanding which aspects of habitat are most critical in determining site occupancy and vacancy for forest bird species is imperative if forest restoration and reintroductions are to be effective. In the past, recovery efforts in Hawai'i for many rare birds, such as the Po'ouli (Me/amprosops phaesoma), were initiated when population levels were

already too low to accurately assess and identify limiting factors (Groombridge et al.

2003). Therefore, it is essential to initiate studies on aspects of habitat that may be limiting for endangered birds before they become too rare.

STUDY SPECIES

The Maui Parrotbill (Pseudonestor xanthophrys) (population 500 ± 230, 95% CI

individuals) is among the most threatened of the remaining Hawaiian honeycreepers

(Scott et al. 1986). It reproduces at a rate of only one young/year per pair (Simon et al.

3 2000) and is now restricted to the island ofMaui, where it occupies approximately 5% of its original range (Scott et aI. 1986). Parrotbill maintain year-round all-purpose territories,

.a characteristic common to many insectivorous Hawaiian honeycreepers (Pratt et aI.

2001 b). Recently, this medium-sized (20-25 g) olive-green honeycreeper has become a target for conservation efforts on the island of Maui because it is the only endangered

insectivore that may still benefit from recovery measures. Two other endangered,

insectivorous honeycreepers on Maui that historically had similar habitat requirements,

the Po'oull and the Nukupu'u (Hemignathus lucidus), may be extinct. Both species

foraged on invertebrates from woody trees, shrubs, and/or epiphytic material in habitat

types similar to that of the Maui Parrotbill (Perkins 1903, Scott et aI. 1986, Baker 2001).

Their decline suggests that parrotbill may be subject to the same threats. The Maui

'Alauahio (Pareomyza montana), the only other native insectivore on Maui, is not

endangered and is frequently sympatrlc with Maui Parrotbill (Baker and Baker 2000).

'Alauahio, however, occupy a somewhat different foraging niche which may account for

their more extensive range.

Since the early 1900s, the Maui ParrotbiII has persisted in low numbers in the

upper elevation montane rainforests of the dormant Haleakalii volcano (Scott et aI. 1986,

Simon et al. 1997). However, fossil evidence suggests that parrotbiII existed in the dry

lowland and mesic leeward forests ofMaui prior to human contact (Olson and James

1982a) (Figure 1.1.). A variety of dry and mesic forests once occurred from -line to

sea level on the leeward side of the island ofMaui. By the late 1890s most of these

forests, some composed of the dominant canopy tree Acacia koa, had been destroyed

4 (Scott et aI. 1986). Perkins (1903) and Henshaw (1902) noted that parrotbill frequently fomged in A. !wa. It is widely believed that logging of this valuable wood decreased much of the habitat available for parrotbill (Olson and James 1982b, Scott et aI. 1986,

Simon et aI. 2000). This habitat loss, as well as the introduction of avian disease to which native birds lacked resistance (Atkinson et aI. 1995, van Riper and Scott 2001), may have contributed to the contraction of the parrotbill' s historical range. Parrothill currently persist in upper-elevation minforests at densities of 10 birdslkm2 (Simon et aI. 1997, USFWS 2006). Research in the 1990s indicated this species was at carrying capacity on windward east Maui and further suggested that this habitat was only marginally suitable for the species (Simon et aI. 2000, Pratt et aI. 200 I b).

Ongoing research occurs in Hanawi, a core activity area for Maui Parrotbill, but the

forests ofWaikamoi and Manawainui at the edge of this species' range have been little

explored.

Mountainspring (1987) identified lack of suitable habitat as the primary threat for

Maui Parrotbill. The protection, acquisition, and restomtion of habitat for the Maui

Parrotbill in areas of its historic range are major recovery objectives in the Recovery Plan

for Hawaiian Forest Birds as major objectives. The State ofHawai'i's Division of

Forestry and Wildlife is currently committed to the long-term restomtion of remnant koa

forests that exist in portions of historic parrotbill range, with the ultimate goal of

reintroducing captive-reared birds to the leeward side of Maui (Scott Fretz, pers. comm.).

However, the acquisition and subsequent restomtion of critical habitat is a costly and time

consuming venture. Before new areas can be made usable for parrotbill, it is important to

5 determine which attributes of its habitat in occupied areas are most important. Previous researchers have provided insight into parrotbill breeding biology, morphology, and territoriality (Lockwood et a1. 1994, Simon et a1. 1997, Berlin et a1. 2000, Simon et a1.

2000, Pratt et a1. 2001b); however, its habitat requirements have received little attention.

With the exception ofMountainspring's research, no studies have quantitatively

addressed the relationship between the Maui Parrotbill and its habitat. A quantitative

approach however, may identify limiting factors in habitat that may qualitatively appear

suitable.

RESEARCH OBJECTIVES

The Manawainui forests ofHaleakalii National Park were previously identified by

the Maui Parrotbill Working Group as one of three potential future release sites for future

Maui Parrotbill reintroductions (Figure 1.1.). I initiated this project to assist the National

Park Service with determining the suitability of Manawainui as a release site for captive­

bred parrotbill. Initial bird surveys by Stemmerman (1976) and the Hawai'i Forest Bird

Survey (Scott et a1. 1986) failed to confirm the presence of parrotbill in this area.

However, in the early 1990s following ungulate management efforts by Haleakalii

National Park, biologists started to detect parrotbilllocally in low numbers (Haleakalii

National Park unpubZ. data, Reynolds and Snetsinger 2001). It is uncertain if these

detections were a direct result of management efforts, better census data, or both. Park

biologists, continue to conduct yearly forest bird surveys on U. S. Fish and Wildlife

Service Transect 18 (T-18) which is oriented north to south through the Manawainui area

(Figure 2.2.). Until recently, parrotbill distribution from east to west in this area was not

6 known. Systematic surveys conducted throughout Manawainui in the spring and summers of 2005 and 2006 suggest parrotbill occupy a greater portion ofManawainui than was previously documented (Y. Stein, unpubl. data). However, the relationship between the vegetation community and parrotbill distribution is unknown. To better understand the relationship between parrotbill and its habitat use, my main objectives were to (I) determine which proximate vegetative factors make habitat suitable for Maui Parrotbill,

(2) determine what effect scale may have on habitat selection by this species and (3) use these data to determine if Manawainui should be used as a release site for Maui

Parrotbill.

The identification of habitat variables important to Maui Parrotbill could guide the selection of future release sites and the restoration needs of thes.e areas.

Understanding resource use is necessary to determine the relationship between an organism and its habitat (Heglund 2002). Vegetation structure and composition are the primary proximate factors that determine where and how bird species use resources

(Block and Brennan 1993) and quantifying the relationships between parrotbill and vegetation are critical to its recovery. Vegetation attributes influence the distribution and abundance of birds either directly, such as for nesting sites, or indirectly through the provision offood resources (Wiens and Rotenberry 19818, Rotenberry 1985, Luck 2002).

Thus, understanding how a species uses certain habitat features such as vegetation clarifies the physical significance of these attributes for resource managers and scientists by guiding effective design of natural area reserves and appropriate vegetation components. Animal density can be a misleading indicator of habitat quality, so it is

7 important to reconcile demographics with measurements of habitat to accurately assess habitat quality (Van Home 1983, Johnson 2007).

Because key habitat variables will be most accurately identified when studied at the appropriate scale (Orians and Wittenberger 1991), hierarchical assessments of habitat

variables at different scales have become essential to understanding avian habitat use and

needs (Kristan and Scott 2006). Single-species assessments of habitat use at several

increasing scales of resolution can be especially useful because they may provide more

direct iusight as to why a species is selecting a particular habitat type (Cody 1985, Orians

and Wittenberger 1991, Bergin 1992, Luck 2002, Hobbs 2003). Wiens and Rotenberry

(I98Ib) found that the initial occupation of habitat in shrubsteppe birds was driven by

vegetation structure and that within-site distribution patterns were further refined by their

association with plant species composition. The simultaneous assessment of the relative

importance of gross or "coarse" habitat features, in an area as well as those obtained by

watching specific behavior such as singing or foraging has predictive significance

because it allows us to detennine which habitat variables are most important and at what

scale (Bibby et al. 2000). For example, Luck (2002) studied habitat use by Rufous

Treecreepers (Climacteris rufa) in Australia at four spatial scales and found birds

prefentially selected habitat based on different vegetation variables at each scale. At the

broadest or landscape scale, birds preferred to settle in particular forest-types. They then

selected territories and foraging sites based on the presence of scale-specific habitat

variables.

8 To explore the relationship between vegetation structure and composition and

Maui Parrotbill habitat use, I asked the following questions at three spatial scales of increasing resolution (home range, foraging site, and plant species; see Johnson 1980) in used and unused sites within the same general habitat type: (1) do forest structure and plant composition determine Maui Parrotbill habitat use at the macrohabitat (home range) scale, (2) do forest structure and plant composition determine Maui Parrotbill habitat use at the microhabitat (foraging site) scale, and (3) do parrotbill selectively forage on certain plants, vegetation height tier, and tree size class in proportion to relative abundance?

The following two chapters address these questions and were written as manuscripts for publication in peer-reviewed journals. Chapter 2 entitled "Habitat use by

Maui Parrotbill: "A Multiscale Approach" examines the relationships between parrotbill and habitat use at several scales of resolution. Chapter 3 entitled "Maui Parrotbill

Foraging Habitat" examines the use and availability of vegetation strata, tree size class and plant species, as they relate to foraging Maui Parrotbill. Chapter 4 concludes with a review of my results and management implications. The references for all four chapters are listed in a comprehensive bibliography at the end of this manuscript.

9 Figure 1.1. Current and hi stori cal range ofthe Maui Parrotbill with potential Manawainui release site (adapted from the Pacific Basin lnformation Node website, http://pbin.nbii.gov/aviancon/mau iparrotbill.html, October 2005).

10 CHAPTER 2. HABITAT USE BY MAUl P ARROTBILL: A MULTISCALE APPROACH

INTRODUCTION

Hierarchical assessments of habitat at different scales have become increasingly essential to understanding avian habitat use and needs (Wiens 1989, Kristan and Scott

2006, Kristan 2006). Multi-scale assessments may be less prone to produce misleading results than single scale assessments (Kotlier and Wiens 1990) because different resources may be more or less relevant to the species of interest at different scales. Thus,

accurate identification of key habitat variables and the outcome of habitat studies will be

dramatically influenced by the scale at which they are investigated (Orians and

Wittenberger 1991, Hobbs 2003).

For example, Wiens and Rotenberry (1981b) found that the initial large-scale

(continental) occupation of habitat in sbrubsteppe birds was driven by vegetation

structure and that distribution patterns within regional sites were further refined through

association with plant species composition. Luck (2002) studied habitat use by Rufous

Treecreepers in Australia at four spatial scales, and found that birds preferentially

selected habitat based on different vegetation variables at each scale. At the broadest or

landscape scale, birds preferred to settle in a particular habitat-type, further refining

selection ofterritories within forest types and selection of fomging sites within territories,

based on the presence of specific habitat variables that were unique at each scale.

11 Two common references to scale, macrohabitat and microhabitat, are frequently misinterpreted or loosely identified, thus explicit definitions of scale which are

biologically meaningful to an organism are necessary to remove human imposed bias.

Morris (1987) defined macrohabitat as explicit areas (such as a species' home range)

within a particular habitat type in which an organism carries out most of its daily

activities. He defined microhabitat as smaller subsets or "patches" within these larger

areas, which influence where an organism will allocate most of its time within an area.

This patch preference will be determined by whether or not an animal exhibits a fine

(random) or coarse (non-random) grained response, the latter resulting in preferential

habitat use (Wiens 1976, Kristan 2006).

In the Hawaiian Islands, avian studies incorporating scale and habitat use have

been few (Mountainspring 1987, VanderWerf 1993, Fretz 2002). Multi-scale assessments

of habitat may be particularly beneficial for avian species, which are the focus of many

reintroduction and restoration projects in Hawai'i, by providing a more accurate

measurement of the habitat components necessary for species survival. Drawing spatial

comparisons between habitat variables measured in areas where birds currently persist,

with areas where they do not, could allow more accurate identification of avian habitat

needs, allowing subsequent incorporation of these elements into restoration efforts at

reintroduction sites.

The Maui Parrotbill. an endangered insectivorous honeycreeper endemic to the

island of Maui (Simon et aI. 1997), is one such species which may benefit from this

approach. Mountainspring (1987) found that habitat loss and degradation were among the

12 primary limiting factors affecting the distributional range of Maui Parrotbill. He concluded that parrotbills were more closely associated with sites free from pig damage, having well developed understory and little canopy cover. Feral ungulate removal is a chief component in habitat management efforts of Hawai'i. This involves removal of ungulates, in conjunction with large scale fencing projects to prevent the further ingress of animals, once they have been eradicated from an area. Subsequently, some portions of the upper elevation rainforest on East Maui have been recovering from feral ungulate damage for as long as 20 years (Haleakalii National Park, unpublished data) and are currently being considered as potential release sites for parrotbill. Banko et al. (2001) stressed the importance of developing strategies for reintroduction of avian species in habitat that is recovering from ungulate damage and the supplementation of native bird populations that have reached critically low levels. Little quantitative evidence exists, however, relating the structural and compositional attributes of the vegetation community in these recovering forests to the needs of avian species.

The overriding goal of this study was to provide an empirical assessment of habitat suitability that could guide future management decisions regarding potential reintroductions ofMaui Parrotbill. The main objectives were to determine which

structural and compositional attributes offorest vegetation determine Maui Parrotbill distribution and abundance across an area of Haleakalii National Park being considered

for releases of captive-bred parrotbill, and to determine what effect scale has on the relative importance of these attributes. I conducted this study at a local scale and defined macrohabitat as parrotbill home range and microhabitat as parrotbill foraging sites. I

13 asked the following questions; 1) Do changes in vegetation structure and composition across the forest influence patterns of home range use by parrotbill? 2) Do parrotbill preferentially select foraging sites based on certain structural or compositional aspects of the vegetation?

METHODS

STUDY SITE

This study was conducted in Manawainui (20°41'43" N, 156°7'59" W), a 526-hectare

(1300-acre) parcel ofHaleakala National Park at the southeastern-most edge of the East

Maui rain forest. (Figure 2.1.). Manawainui has been recovering from feral ungulate

damage for approximately 24 years, longer than most other sites on Maui. As a result of

this recovery and its proximity to historic parrotbill range, it is being considered for

reintroductions of captive-reared Maui Parrotbill. Manawainui is an ecotone between wet

and dry forest, dominated by wet Metrosideros po/ymorpha forest, mesic Acacia koa and

mixed Metrosideros-Acacia forest.

Gross vegetation cover classes were documented by Jacobi (1989). The

topography in the area is extreme, divided by gulches and streams with an average slope

> 30%. Environmental and anthropogenic disturbance in the area has included

degradation by feral goats (Capra hircus) and pigs (Sus scro/a), and invasion by weeds

(Peterson 1976, Loope et al. 1992). Interestingly, this forest was isolated by the lava

flows which inundated nearby KaupO Gap and KIpahulu Valley and may be much older

than its surroundings due to this geological isolation (Peterson 1976). The area is

14 characterized by high precipitation (i.e., orographic rains and mist) in excess of 5,000 mm per year. Rainfall tapers off from east to west, marking the transition from the windward to leeward sides of the island. Manawainui is intensively managed to control feral ungulates, and marks the edge of current parrotbill range on southwest Haleakalii.

All work was conducted above 1585m elevation (- 5200 ft). Therefore, the effect of disease, which occurs at lower elevations, as a confounding factor on parrotbill distributions was minimized (van Riper and Scott 2001). Conducting work at this elevation also minimized the chance of spreading invasive weeds that occur at lower

elevations in Manawainui. To assess whether changes in vegetation across the habitat

gradient in Manawainui were affecting parrotbill distribution and use, simultaneous

surveys of vegetation, birds, and bird foraging behavior were conducted over the course

of two field seasons from February 2005 to August of2006. This spans most of the known breeding season for parrotbill (Simon et al. 1997) and should have reflected the

time of year when resources would be most critical for the reproduction and survival of

young.

I selected 10-hectare areas as my study unit for vegetation sampling and foraging

observations as a conservative estimate of home range size for the parrotbill. Home

ranges for Maui Parrotbill average 2.3 hectares (5.7 acres) in size (Simon et al. 2000,

Pratt et al. 200 I b). As the birds in this study were not banded, each IO-hectare home

range (used) or "pseudo home range" (unused) helped to maintain a level of

independence throughout the course of the study, based on the assumption that each bird

or pair of birds would not move beyond each 10-hectare area it was actively using.

15 Using Geographical Information Systems technology, I superimposed a grid partitioned into IO-hectare units across the area, and assigned each IO-hectare survey area a unique letter identifier (Appendix A). The initial survey grid included 27 IO-hectare survey areas. Subsequent vegetation sampling was conducted in 22 of these 10-hectare areas in accessible areas where parrotbill occurred and in areas where they were absent.

BIRD SURVEYS

Spot-mapping techniques (Bibby et aI. 2000) were used to assess the distribution of parrotbill across the study site. I searched 27 10-hectare areas from February 2005-

August 2005, and January 2006-August 2006. Full vegetation and bird surveys were conducted only in 22 of the 27 survey areas because treacherous topography made surveying the remaining areas difficult. To maximize the potential of encountering parrotbill, I attempted to survey each home range for at least four hours each month; however, this was not always possible due to poor weather conditions. Selection of survey areas was arbitrary, but without preconceived bias. Survey times were alternated

(morning vs. afternoon surveys) to increase encountermtes with individuals that might be active at only certain times of the day. Observers were rotated among home ranges to prevent bias in data collection. Audio playback equipment was used to increase the chance of detecting birds in new areas. Observers moved around each 10-hectare area during each 4-hour survey period, as is done in standard spot mapping surveys (Bibby et aI. 2000). If a parrotbill was observed foraging during a survey, the observer stopped to conduct foraging observations and microhabitat analysis. Individual birds were assigned ill numbers which associated them to the nearest survey area in which they were found.

16 In addition to location, individuals were further identified by unique coloration and/or vocalizations. Parrotbill are sexually dimorphic and singing is unique to males (Simon et al. 1997), thus birds were sexed based on vocalization and obvious dimorphisms such as bill size and plumage coloration.

VEGETATION SAMPLING (MACROHABITAT)

As suggested by Noon (1981), I selected a random sample ofO.04-hectare (11.3 m radius) circular plots stratified by each 10-hectare survey area across the Manawainui study site (n = 107, Figure 2.2.). These plots spanned the east to west habitat reflecting the structural and compositional heterogeneity of the area. Due to this habitat heterogeneity, I randomly selected five replicates in each home range using the random

sampling extension in ArcGIS. UTM coordinates of sampling areas were uploaded into

Garrnin GPS units to locate plots in the field. I used the methods of James and Shugart

(1970) as modified by Noon (1981) to sample habitat data at each plot. These variables

were comprised of slope, elevation, percent canopy and ground cover, canopy height,

shrub and tree densities (in 3 different size classes); canopy, sub canopy, and understory

density, and plant species (Table 2.1.).

I identified all woody and herbaceous plants within each O.04-hectare plot and made stem counts to ascertain relative abundance of plants throughout the study area.

Stem counts were made by measuring the diameter at breast height (dbh) for all trees

(dbh size class> 3 ern) within each O.04-hectare plot. I also counted all woody stems < 3

ern dbh that touched two 22 m transects oriented perpendicular to one another across each

circular plot (follows James and Shugart 1970 and Noon 1981). Most woody plants were

17 identified to species. Unidentified specimens were brought back to Haleakalii National

Park (HALE) headquarters for identification by National Park Service botanists.

Specimens were deposited in the HALE herbarium. I attempted to identify all plants to species; however some plants could be identified only to genus due to morphological variability and hybridization (P. Welton, pers. comm.).

DATAANALYSES-MACROHABITAT

All data were entered into Microsoft Access 2000 and proofed for errors. Tree height data were computed from field-based clinometer readings and all heights converted into meters. Plant species stem counts were converted to stems per hectare.

Due to the large amount of data collected, it was necessary to reduce many of the original variables into smaller subsets for further analysis. For example tree size class data were originally collected in nine different dbh size categories but was later condensed into three size classes (small, medium, large) for easier interpretation. The data collected from the original 107 vegetation plots were expressed as mean values for the variables in each of the 22 10-hectare areas sampled (Table 2.2.). Due to missing data, survey area HA (n

= 3) was dropped from further analyses, leaving a final sample of 104 plots in 21 10- hectare areas. A complete list of vegetation plots sampled with UTM coordinates can be found in Appendix B. Data were assessed for strong outliers (cut off of > 3 SO) and nonnality using frequency distributions, nonnal probability plots and the Shapiro-Wilkes test. I did not detect any strong outliers, for structure or floristics; however, the data were non-nonnal and heteroscedastic. I assumed those variables that were univariate nonnal

18 approximated multivariate normality (McGarigal et al. 2000). All descriptive and statistical analyses were performed in Systat 11 and PC-Ord version 5.

I used multi-response permutation procedure (MRPP), a non-parametric multivariate method, to test for significant differences between used and unused areas; n

= 21 (used = 10 vs. unused = 11). MRPP is a distribution-free test similar to discriminant analysis (DA) and multivariate analysis of variance (MANOV A) that tests for differences between groups but with relaxed assumptions. The MRPP t-test statistic is based on numerous permutations of the data itself, instead of a predetermined distribution (Mielke

1984, Mielke and Berry 2001). I used the Sorensen (Bray-Curtis) distance measure with the recommended weighting of nlsum (n), as it is sensitive to heterogeneous data

(McCune and Grace 2002). The data matrices were rank-transformed to account for heterogeneity of the data set. I followed this procedure for both structure and floristics

and ran separate MRPP tests for each.

I used Nonmetric Multidimensional Scaling (NMS), a robust, iterative ordination

technique to graphically represent the degree of dissimilarity between the used and unused areas. NMS avoids the assumptions of linearity used in other ordination methods

(Kruskal 1964, Mather 1976). In addition, NMS differs from other ordination procedures

in that the assignment of axes is arbitrary. I used autopilot mode in PC-Ord with the

Sorensen (Bray-Curtis) distance measure, and ran 250 runs of real data and 250 runs of

random data. Dimensionality of the data set was assessed graphically by a scree plot, by

seeking a low stress solution and by assessing Monte Carlo p-values (p < 0.05) for

significance. I followed this procedure for broad patterns in both vegetation structure and

19 floristics and used the methods below for more detailed analySis of specific variables in each group.

Vegetation structure

The final group of ten habitat variables retained for further analyses of vegetation structure was based on biological relevance and included: percent ground cover, percent canopy cover, mean canopy height, small, medium, and large tree totals, sub-canopy,

canopy, and understory foliage density indices and shrub stem totals. Since the variables were expressed using different units, variables were standardized by column totals.

Because MRPP does not distinguish between those variables contributing most to

group separation, discriminant analysis was used in a descriptive mode to identify what

variables might be driving group differences between used and unused areas. Values

were screened for normality separately for each group of used (n = 10) and unused (n =

11) areas. Medium trees (DBHMED) and canopy densities (CANTOT) were log

transformed to meet assumptions of normality and homogeneity of variance.

Multicollinearity was assessed using scatter plot matrices and tested for significance

using the Pearson correlation coefficient with an r ~ 0.7 as criterion for deleting a

variable (Tabachnick and Fide111996). No variables were detected as highly collinear;

however, ground cover, canopy cover, and canopy height were omitted from the

discriminant analysis to minimize the effects of redundancy with several of the other

variables. The final seven variables included were density of the understory, subcanopy,

and canopy layers, and the number of small, medium, and large trees and shrubs.

20 Floristics

Relative abundance of all woody species was calculated separately for trees and shrubs because I wanted to assess whether or not certain shrubs or tree species might be particularly influential. I considered all woody species with a diameter at breast height

(dbh) less than 3 em to be shrubs and anything over 3 em dbh to be trees. I also estimated the relative abundance of and forbs; however, these data were omitted from further analysis because of their unlikely contribution to parrotbill habitat use. Those other woody species that occurred in < 5% of the sample units were also omitted from this part of the analyses. I retained a total of 10 plants for my final analyses which included:

Melicope spp., arguta,Ilex anomaia, Acacia koa, Myrsine spp., Vaccinium calycinum, Metrosideros polymorpha, Cheirodendron trigynum, and Leptecophylla

tameiameiae, and standing dead trees.

Data were non-nonnal and heteroscedastic. therefore non-parametric analyses

were used. I ran an indicator species analysis (ISA) to identify those species that were most useful in separating used from unused areas (Dufrene and Legendre 1997). This

procedure calculates the proportional abundance of a species in one group versus its

abundance in all groups. An indicator value (INDV AL) is obtained for each species,

ranging from 0 (no indication) to 100 (perfect indication). Statistical significance is

evaluated by a Monte Carlo randomization test for each species (p < 0.05). I used 5000

randomizatious.

21 Diversity

I assessed diversity between all used and unused areas for trees, shrubs, and trees and shrubs combined. Shannon Wiener (H) and Simpson's (D.) diversity indices were calculated for all areas using PC-Ord and tested for significance using separate Mann­

Whitney U tests for those species used in the MRPP analyses. Finally I tested for differences in overall woody species diversity including those plants that occurred in <

5% of the survey areas.

VEGETATION SAMPLING (MICROHABITAT)

Within each 10-hectare survey area that Maui Parrotbill were actively using, I collected vegetation data at fomging microsites and paired random sites. Upon

encountering a parrotbill, bird-centered vegetation plots were selected by marking the first location at which it was seen foraging (Larson and Bock 1986). The first fomging

observation point was identified as the point at which the first fomging maneuver was

observed, after waiting ten seconds to remove any observer imposed bias.

Data on vegetation parameters were collected at several scales of increasing resolution, using the first foraging location as the center reference point from which to

collect additional data. In addition to collecting data at this point, I also collected data at two other scales of I-m and 2-m radii. The 1-m radius might influence parrotbill fomging

at the inner portion of a patch while the 2-m radius might represent the maximum extent

22 of the foraging patch that the bird might spend time in before moving somewhere else in its home range.

I collected information on a series of vegetation variables that may be important to parrotbill foraging needs, based on a review of pertinent literature (Table 2.3.). At the point of initial contact. I identified the plant species or genera and determined plant height, as well as the bird height above ground (using the same height tier classes as for macrohabitat), substrate type (foliage, wood, and berries), tree size class, and branch size

(small, medium, large). In the I-m radius, I collected data on foliage density and surface area, using one of six categories (Remsen 1985), and the number of branches approximating the number of perches parrotbill could have used. At the broadest scale

(Le., the 2-m radius), I recorded data on species and the foliage density of each vertical vegetation class (Le., canopy, sub canopy, understory) according to the Braun-Blanquet cover abundance scale (Braun-Blanquet 1932) and percent canopy and ground cover, using a densitometer. I then measured these same variables (with the exception of bird height and substrate) at the same scales at randomly located plots 20 m away (following methods of Moser et aI. 1990, VanderWerf 1993). Habitat variables were measured in 36 used and 36 random plots at these three different scales of resolution in nine of the home ranges parrotbill were actively using. I also assessed proportional use of plant species, tree size class and vegetation stratum, in used plots only. The results of that analysis are reported in Chapter 3.

DATA ANALYSES-MICROHABITAT

23 Data were screened for nonnality, outliers, and homogeneity of variance using the same criterion as for macrohabitat, for each of the three microhabitat scales (O-m, I-m, and 2-m). The data for structure and floristics at all three scales were non-nonnal and heteroscedastic. Monotonic transfonnation of individual variables had little effect on nonnality; therefore I used utilized non-parametric multivariate methods to test for significant differences in forest structure and floristics between plots. Structural data measured on different scales or units were standardized by column totals. Species data were represented as presence/absence and standardization was unnecessary.

To test the hypothesis of no difference between used and random foraging plots, I

used PerManova, a "distribution free" significance test for balanced study designs

(Anderson 2001). The unit of analysis was the foraging site and not the individual.

PerManova calculates an F test statistic similar to MANOVA; however, the test statistic

is evaluated for significance by running a series of randomized permutations of the data. I

followed Anderson (200t) and ran tOOOpermutations of the data, with a = 0.05.

I assessed differences in diversity between all used and random foraging plots at

the I-m and 2-m scales. Shannon Wiener and Simpson's diversity indices were calculated

for all plots using PC-Ord and tested for significance using a Mann-Whitney test.

RESULTS

BIRD SURVEYS

Surveys suggest parrotbill occupy a greater portion ofManawainui than was

previously documented. I estimated that 16 individuals occupied approximately 100 of

the 270 ha of the forest comprising the study site. Maui Parrotbill occurred at densities of

24 0.06 birdslha over the entire 270 hectare study site or 0.08 birdslha over the 210 ha of forest intensively surveyed for birds and vegetation. I did not detect any juvenile parrothill or nesting attempts in the study area. With the exception of the 'Aki.ap5lii'au

(Hemignathus munroz), parrotbill fledglings have a longer juvenile dependency period than any other honeycreeper for which this period is known, and produce frequent, loud begging calls while following fomging adults (Simon et al. 1997, Simon et al. 2000,

Pejchar 2004). It is therefore unlikely that juvenile birds went undetected.

MACROHABIT AT

Vegetation structure

I found significant differences between used and unused areas (p = 0.004, A =

0.116, T = - 3.92), based on vegetation structure (Table 2.4.). NMS autopilot in PC-ORD selected a 2-dimensional ordination based on a low stress solution (p < 0.05). Most of the difference between used and unused areas was captured by axis 1 (59 %) while axis 2 captured another 30% of the variation between used and unused areas. This result was achieved after 135 iterations and had a final stress of 12.3. Plotting survey areas against axes 1 and 2 clearly segregated used and unused areas, and used areas appeared more similar to each other than unused areas (Figure 2.3.). The number oflarge trees and density of subcanopy were strongly associated with the first axis (59%) while the number of small trees and shrubs were most strongly associated with the second axis (30%). The

follow up discriminant analysis expressed these results in more detail. The standardized discriminant function coefficients associated with each variable suggest that unused areas had higher densities of small (dbh 2: 3-15) sized trees and shrubs. Used areas had more

25 large trees (dbh ?: 54cm) and denser canopy, subcanopy, and understory layers (Table

2.5.).

Floristics

A total of 55 herbaceous and woody plant species were recorded in the understory, subcanopy, and canopy in used and unused areas. A complete list of all species found in the Manawainui area with common names and taxonomic abbreviations can be found in Appendix C. Metrosideros was the most abundant tree comprising nearly half of all tree species (54 %), followed by Leptecophylla (16%), dead trees (11 %),

Cheirodendron (8%), Vaccinium (7%), Myrsine (2%), and [lex (I %). Metrosideros was

also most abundant in the shrub category accounting for 31 % of the shrubs surveyed, followed by Vaccinium (27%), Leptecophylla (26%), Broussaisia (9%) and Melicope

(7%). Acacia koa accounted for less than 1% of the trees surveyed but was included in the analyses because the parrotbill were known to use A. koa in historic times (Perkins

1903). In addition, A. koa is used extensively by the closest extant relative to the

parrotbill, the 'Akiap

I found significant differences between used and unused areas based on floristics

(p = 0.025, A = 0.072, T = -2.45). Areas without parrotbill had higher densities of

Metrosideros trees (INDVAL = 65.5, P < 0.024), while those areas with parrotbill had higher densities of both Cheirodendron trees (INDVAL = 63.8, p =0.027), and [lex trees

(INDVAL = 66.7,p = 0.031). Higher densities of Leptecophylla shrubs (INDVAL = 77.5, p = 0.005) occurred in unused areas and higher densities of Melicope shrubs (INDV AL =

73.6, p = 0.012) occurred in used areas (Table 2.6.). The corresponding NMS ordination

26 selected by PC-Ord had a 2-dimensional solution with a final stress p = 0.004 after 78 iterations of the data. The first axis described 45 % of the variation between used and unused areas, while the second axis described 43%. The ordination graphs showed some clustering between used and unused areas although the graphs were more difficult to interpret than that for structure (Figure 2.4.). Axis 1 was strongly correlated with the density of Metrosideros, Cheirodendron, and Myrsine trees and Broussaisia and

Melicope shrubs. Axis 2 was strongly correlated with the density of Metrosideros trees

and Leptecophy/la shrubs.

Diversitv

Diversity of tree species was significantly higher in used areas than in unused

areas for the Simpson's index only (F= 7.75,p = 0.005, df= 10, 9). There was no

significant difference in species diversity between used and unused areas for trees and

shrubs combined as well as for shrubs alone (p > 0.05) for those plants used in the MRPP

tests. However, overall species diversity was higher in used areas than unused areas for

both the Shannon-Wiener (p = 0.035) and Simpson's diversity indices (p =0.041) when

including all species, not just those used in the MRPP (Table 2.7.).

MrCROHABIT AT

A total of22 woody plant species were recorded in the understory, sub canopy and

canopy strata in 9 different home ranges. Parrotbill exhibited non-random selection. of

foraging habitat at the two finest scales 1 measured (O-m and I-m) based on floristics.

27 Structure was not a significant factor at either scale, and overall species diversity did not differ between used and unused plots (Table 2.4.).

At the 2-m scale, results of the PerManova for structure (F= 1.39,p = 0.239, df=

1,35) and floristics (F= 0.777,p = 0.587, df= I, 35) were non-significant (p > 0.05). At the 1-m scale. significant differences were detected between used and unused, random plots based on plant species only (F = 3.97,p = 0.001, df= 1, 35). The complementary indicator species analysis however, did not detect anyone significant indicator species which contributed to group separation (Table 2.8.). No significant differences for structure were observed at the one-meter scale (F = 1. 56, P = 0.186, df = 1, 35). At the

finest scale, (O-m), I found significant differences between foraging sites and random

sites for floristics only (F = 2.31, P = 0.026, df = I, 35). The results of the corresponding

indicator species analysis were significant for only one species; Metrosideros polymorpha (p = 0.005) which was more abundant in random than used foraging plots.

No significant differences were found for forest structure at the O-m scale (F=2.99, p =

0.065, df= 1,35). No significant differences were detected in diversity between used and

random plots at either the 1-m or 2-m scale for either diversity index using a significance

level of a = 0.05.

DISCUSSION

MACROHABITAT

Maui Parrotbill selected habitat non-randomly for both forest structure and

floristics at the macrohabitat (home range) scale using a subset of habitats available in

Manawainui. Parrotbill showed strong associations with specific floristic and structura1

28 characteristics of wet forest. Used areas contained mature, well developed forest with a higher density of large trees per hectare, and greater densities of canopy, sub canopy, and understory layers compared to unused areas. Floristically, parrotbill preferred areas with higher densities of Cheirodendron, flex, and Melicope. Overall plant diversity also was significantly higher in used areas. Unused areas had higher densities of shrubs particularly Leptecophylla and higher densities of small trees, particularly Metrosideros.

Based on this data set, Acacia was not a significant indicator species of parrotbill use in either used or unused areas at the macrohabitat scale. In fact unused areas had greater densities of A. /roa than did used areas.

These data suggest that at the macrohabitat scale, parrotbill are selecting habitat in well developed forest, with high species diversity and are avoiding areas with dense small-stature trees and shrubs. Diverse forest structure and species composition may serve as proximate cues for home range use. Well developed forest may reflect a need for large mature trees for nesting, singing/song posts, protection from harsh windward showers, as well as serve as a proxy for habitat with ample foraging opportunities.

Previous researchers have noted parrotbill utilize the canopy and sub canopy trees for nesting (Lockwood et al. 1994, Simon et al. 1997) and forage primarily in the understory and sub canopy layers (Mountainspring 1987. Simon et al. 1997). indicating the importance of all three vegetation strata for this species. Parrotbill may assess home range areas indirectly for food and/or nesting resources by using cues such as large trees and dense vegetation as correlates of prey abundance or nesting habitat, a concept known as the structural cues hypothesis (Smith and Shugart 1987).

29 I did not note any breeding activity during the two field seasons I conducted my research. It is unclear however, if inadequate nesting or fomging habitat was a cause.

Counter singing by male parrotbill and territory defense was minimal compared to other areas on east Maui (V. Stein pers. obs.). Lack ofterritorial defense could be indicative of low food resources. Maher and Lott (2000) suggest that highly clumped or evenly distributed resources are not defended because the energetic costs associated with territory defense outweigh the benefits. Although I did not investigate nesting habitat in my study, other researchers have noted nest habitat to be a more critical determinant of habitat use and home range use than are fomging sites (Orians and Wittenberger 1991,

Steele 1993). Many species have broad overlap among fomging behavior and partition food resources through competition (MacArthur 1958), while overlap among nest sites is rarely observed (Martin 1988).

MrCROHABIT AT

Maui Parrotbill preferentially selected foraging sites based on cumulative plant composition at the two smallest scales I measured (O-m and l-m). Structure was not a significant factor at either scale and overall species diversity did not differ between used and unused plots. No significant differences were detected for used and random sites at the 2-m scale.

At the J-m scale, no species was a significant indicator of parrotbill foraging; suggesting birds may be cuing in on a suite of plants, and not just one particular plant.

This may be related to fluctuations in invertebmte abundance throughout fomging sites, as well as temporal changes associated with plant species phenology, which exhibits

30 annual patterns for many species (Swezey 1954). Non-random use offomging sites may be a result of different resource densities in different patches (Morris 1987).

Selection of fomging sites with an assortment of plant species may help offset competition from other native and non-native insectivorous species. In montane rainforest, Maui Parrotbill are frequently sympatric with Maui 'Alauahio, the only other primarily insectivorous honeycreeper endemic to Maui. Although I did not formally

survey for •Alauahio, they were readily observed throughout the study site, as were two

prolific non-native insectivores, the Japanese White-eye (Zosterops japonicus) and

Japanese Bush-Warbler (Cettia diphone). These other insectivores however, primarily

glean. rather than excavate during fomging so their dietary overlap may be minimal.

At the smallest scale (O-m), differences between used and unused plots were

largely driven by the presence of Metrosideros polymorpha, the most abundant species in

our study site, which had much higher densities in random plots than in used plots.

Parrotbill avoided fomging in areas of dense Metrosideros. Maui Parrotbill primarily

fomged on 9 different plants: Rulms hawaiensis, Me/icope spp, Acacia koa, Ilex anomala,

Myrsine lessertiana, Vaccinium calycinum, Cheirodendron trigynum, Coprosma spp.,

and Leptecophylla. Mountainspring (1987) found fomging parrotbill were more active in

areas containing less Metrosideros and Leptecophylla. He found parrotbill made a

majority of prey captures on Cheirodendron, Vaccinium, Coprosma, Melicope, and

Broussaisia in the understory and subcanopy. Perkins (1903) noted high infestations of

wood boring invertebrates on Melicope and saw parrotbill fomging on Acacia. suggesting

the importance of these plants.

31 The combined findings of macro and microhabitat suggest parrotbill respond to habitat at different spatial scales and highlight the importance of hierarchical assessments of habitat use for this species. Incorpomting multiple spatial scales into assessments of habitat use may elucidate limiting factors otherwise unidentified at a single scale (Orians

and Wittenberger 1991). In Hawai'i, at least two other insectivorous species have been shown to exhibit hierarchical habitat use. VanderWerf (1993) found fomging 'Elepaio

(Chasiempis sandWichensis) preferred areas with dense foliage at all but the broadest of

scales measured, possibly signaling more fomging opportunities in this vegetation type.

Similarly, the Hawai'i 'Akepa ( coccineus) has been found to prefer areas with

dense canopy, likely due to higher food availability (Fretz 2002).

In a study on insectivorous bark-gleaning species, Adams and Morrison (1993)

found that Red-breasted Nuthatch (Sitta canadensis) and Brown Creepers (Certhia

americana) needed forest stands diverse in both vegetation structure and plant species

composition. They found both species avoided areas dominated by dense small trees,

open canopy, as well as areas lacking understory and low overall diversity of stand

structure and species composition. As in this study, birds preferred mature forest with

high species diversity and greater structural variation, in order to maintain habitat

requirements throughout the year.

The habitat use patterns in this study mirror those documented by other

researchers (Cody 1985, Rotenberry 1985, Wiens et al. 1987); parrotbill made initial

broad scale decisions based on vegetation structure, and then further refined habitat use at

smaller scales based on plant species composition. Although I found significant

32 associations between parrotbill and vegetation in Manawainui, the patchy distribution of

parrotbill in the area could also be attributed to other factors such as weather, behavior, depredation, and history.

MANAGEMENT IMPLICATIONS

Effective management of avian species depends, in part, on accurate assessments

of habitat quality (Van Home 1983, Walters et al. 2002). Future recovery actions for

Maui Parrotbill should incorporate hierarchical assessments of habitat use prior to and

concurrent with forest restoration and parrotbill reintroductions. The data from this study

indicate that parrotbill are already dispersed throughout the most suitable habitat in

Manawainui. These results support the ideal-free distribution model of Fretwell and

Lucas (1972), which assumes birds will freely select the most suitable habitat for survival

and reproduction. It follows then that the "available" (Le. unoccupied) habitat in

Manawainui may lack the appropriate vegetation conditions necessary for parrotbill

survival. Based on this research, releases of Maui Parrotbill into Manawainui at this time

are not recommended. However, fencing for feral ungulates and restoration of additional

habitat in the recovering Metrosideros-Acacia forests in Manwainui below 1600m in

elevation might provide more suitable habitat for parrotbill in the future. Immediate

recovery efforts might instead focus on alternate areas that possess the characteristics

identified as suitable for parrotbill and additional research on parrotbill habitat use in

areas different from Manawainui in vegetation structure and composition. Out planting of

favored plant species in recovery areas is also encouraged. Further investigation into the

33 availability of nest habitat, invertebrate food resources, territoriality, and predation may shed additional light on the habitat needs of this species. In particular, research on invertebrate food resources and associated plant species for male, female, and juvenile birds is encouraged.

34 Table 2.1. Description of habitat variables measured for each 0.04 hectare plot in used and unused ten hectare areas.

Habitat Variable Abbreviation Description Percent canopy closure CanCo Estimated as the presence or absence of leaves sighted through densitometer along two 22m transects in each plot Percent ground closure GmCo Same as above but for ground cover

Canopy height CanHgt Estimated as the mean canopy height for each plot using a clinometer Density of small trees DBHsmalI Number of trees per home IlIIIge (3-15 em dbh) measured using a forester's diameter tspe. Density of medium trees DBHmed Number of trees per home IlIIIge (16-53 em dbh) Density oflarge trees DBHlarge Number of trees per home IlIIIge ~ 54 em dbh) Density of shrubs Shrubtls Total woody shrub stem count at breast height < 3 cm dbb, estimated for two 22m transects in each plot Canopy density Cantot Index of species abundance ~ 12-m tall according to Braun-Blanquet cover abundances Subcaoopy density Subcan Index of species abundance 5-12-m tall according to Braun-Blanquet cover abundances Understory density Under Index of species abundance O-Sm taU according to Braun-Blanquet Plant Species Counted and identified to genus and species Slope Estimated using a clinometer Elevation Estimated using an altimeter

35 Table 2.2. Summary table for habitat variables measured in 21 ten hectare areas in Manawainui.

Floristics Used (n =10) Unused (n=II) Plant species or genus" Mean StDev SE Mean StDev SE Acakoa 29.5 54.7 17.3 290 493 149 Broarg 3383 2766 875 1309 2708 816 Chetri 1020 418 132 829 683 206 Melspp 3204 2141 677 1177 2005 604 Leptam 3179 2008 635 10321 7758 2339 Copspp 1713 667 211 783 942 284 TIeano 121 100.9 31.9 73.2 121.1 36.5 Myrspp 969 945 299 295 488 147 Metpol 9137 6223 1968 9953 6502 1961 Dead 363 144.6 45.7 366.8 231.8 69.9 Rubhaw 632 1108 350 107.7 199 60 Vaccal 6400 4380 1385 7463 5561 1677 Phl!iol!!!omr Elevation in meters 1850.2 102.6 32.4 1854.8 133.1 40.1 Percent slope 21.26 6.44 2.04 22.09 9.03 2.72 Percent Canopy Cover 70.8 9.33 2.95 67.68 14.22 4.29 Percent Ground Cover 62.9 13.28 4.2 59.73 10.14 3.06 Canopy Height in meters 8.092 2.572 0.813 9.507 3.22 0.971 Medium trees (stems/ha) 388.7 238.8 75.5 590.9 204.6 61.7 Small trees (stems/ha) 2752 777 246 3645 1525 460 Large trees (stems/ha) 62 29.27 9.26 20.91 29.22 8.81 Shrubs (stems/ha) 5660 2586 818 6304 3175 957 Canopy density index 5.56 1.192 0.377 5.136 2.481 0.748 Understory density index 15.34 4.45 1.41 13.182 2.875 0.867 Subcanopy density index 6.62 0.373 1.18 5.52 1.12 0.333 "Density expressed as stemslba. Only those woody plants species thst occurred in > 5% of the sampling units, or thst were likely to be used by Maui Parrothill are shown.

36 Table 2.3. Summary of habitat variables measured for microhabitat at foraging sites and random sites.

Habitat Variable Seale Deseription Plant Species O,I,2m counted as presence/absence Plant Height Om estimated in met"", Canopy Height Om estimated in met"", circumference estimated in em using Maui Parrotbillas a Branch Size (em) Om "ruler" Tree dbh (em) Om estimated using a forester's diameter tape counted all branches in the same plane as first foraging Branch Count 1m maneuver Foliage density index 1m estimated in the same plane as the first foraging maneuver Bark surface area index 1m estimated in the same plane as the first foraging maneuver Vertical Ht tier index 2m estimated for unden!tory, subcanopy, and canopy Canopy Cover (%) 2m estimated using a densitometer Ground Cover (%) 2m estimate using a densitometer Om is the point at which the bird's first foraging maneuver was observed 1m is a 1-m radius extending out from the first point of observation 2m is a 2-m radius extending out from the first point of observation

37 Table 2.4. Swnmary statistics for MRPP and PerManova analyses for forest structure and plant floristics at the macrohabitat and microhabitat scales.

Vegetation Scale Statistic Structure Floristics Macrohabitat 10 ha T -3.92 -2.45 P 0.004 0.025 A 0.116 0.072 Microhabitat 2m F 1.39 0.78 P 0.239 0.587 OF 1,35 1,35 1m F 1.56 3.97 P 0.186 0.001 OF 1,35 1,35 Om F 2.99 2.31 P 0.065 0.026 OF 1,35 1,35

Table 2.5. Canonical discriminant functions of vegetation variables standardized by within group variances.

Group Means 1st Variable axis Unused Used OBHLARGE -0.671 0.84 2.48 CANTOT 0.313 0.619 0.736 UNDER -0.532 13.18 15.34 SHRUBTLS 0.614 252.15 226.42 OBHMEO 0.153 1.35 1.132 OBHSMALL 0.355 145.805 110.06 SUBCAN -0.369 5.52 6.22 CANTOT and DBHMED values are log transfonned

38 Table 2.6. Summary of indicator species analysis results for shrubs and trees in unused (0) and used (1) 10-hectare areas.

% Indicator Species Use abundance value Mean SDev l!. Shrubs Metrosideros poiymorpha 1 31.1 50.9 56.3 4.74 0.912 Vaccinium calycinum 0 27 54 56.3 4.67 0.626 Leptecophylla tomeimnewe 0 25.5 77.5 59.4 6.61 0.005 Broussafsw arguta 8.9 57.5 39.5 9.17 0.052 Meiicope spp. 7.4 73.6 48.6 8.54 0.012 Trees Metrosideros polymorpha 0 54 65.5 56 4.36 0.024 Leptecophylla tomeiamewe 0 16.4 64.1 58.3 5.63 0.165 Dead 0 10.8 50.3 54.5 3.55 0.961 Cheirodendron trigynum 1 8.2 63.8 55.2 3.86 0.027 Vaccinium caiycinum 1 6.7 50.7 57.1 7.04 0.8 flexanomaia 1 1.1 66.7 48.1 8 0.031 Acacwkoa 0 0.8 41.2 35.9 9.92 0.255 Ml.rsine !!I!I!. 1 2 61.9 49.1 8.82 0.096 p-values in bold indicate significance at a = 0.05

39 Table 2.7. Summary statistics for diversity following a Mann-Whitney test at the macrohabitat and microhabitat scales.

Scale Macrohabitat Microhabitat 10 ha 2m 1m p U P U P U Diversity (II) 0.035 25 0.323 562 0.933 641 Diversity (D') 0.041 26 0.323 562 0.933 641 H is Shannon Wiener Index, D' is Simpson Index P-values in bold indicate significance at a = 0.05.

40 Table 2.8. Summary of indicator species analysis results for woody plants at the I-m scale. % Indicator Species Use abundance value Mean SD p Acaciakoa I 3.4% 13.9 6.6 2.45 0.052 Alyxia oliviformis 0 0.7% 2.8 2.8 0.04 I BrollSsaisia arguta 0 2.7% 2.8 5.4 2.58 I Cheirodendron trigynum I 19.2% 32.1 24.4 4.18 0.088 Clermontia grandiflora 0 0.7% 2.8 2.8 0.04 I Coprosma spp. 0 14.4% 16 19.4 3.76 I Dead 0 5.5% 8.7 9.1 3.2 0.713 flex anomala I 4.1% 11.6 7.3 2.88 0.197 Labordia venosa I 0.7% 2.8 2.8 0.04 I Leptecophylla tameiameiae 0 6.8% 6.9 10.7 3.34 I Melicope spp. 0 7.5% 16.2 11.7 3.22 0.185 Metrosideros polymorpha 0 13.7% 27.2 18.6 3.99 0.066 Myrsine lessertiana I 4.1% 7.4 7.4 2.93 0.683 Rubus hawaiensis I 6.2% 11.1 10.1 3.08 0.472 Tetraplasandra oahuensis I 0.7% 2.8 2.8 0.04 I Vaccinium callpinum 0 9.6% 16.1 14 3.69 0.379 Significance was evaluated at a = 0.05.

41 N 1' :66,5001 A

Figure 2.1. Haleakala National Park boundary with inset ofManawainui study area.

42 Figure 2.2. Detai led overview of Manawainui study site with lat-I ong references. Letters denote areas surveyed for Maui Parrotbill and vegetation.

43 '"• Habitat Use 6 Unused • Used

",Ill 6·

H IN H. 6 6 • "' ..'" • HW ...

• • HZ •II< • t+I .., 6 •

'"6 Axis 1 Figure 2.3. Final NMS ordination of21 home ranges and habitat variables grouped by use. Each point represents a 10-hectare survey area, and refers to grid letters in Figure 2.2. The degree of similarity (based on forest structure) between points is represented by the distance between each point. Significant differences between used and unused areas were evaluated using a MRPP test, see Table 2.4.

44 .. Habitat Use .t. 6 Unused .t. Used ... ",.'" 6 6 !IX .t. IL II .. .t. J. OK .t. N .t. A 11M .f!! .. {I .t. III III .. ~ 6 .t. '".t. A .. A ., .. 6 .. 6 6 .. 6 AxIs 1

Figure 2.4. Final NMS ordination of21 home ranges grouped by use. Each point represents a to-hectare survey area and refers to grid letters in Figure 2.2. The degree of similarity (based on floristics) between points is represented by the distance between each point. Significant differences between used and unused areas were evaluated using a MRPP test, see Table 2.4.

45 CHAPTER 3. MAUl PARROTBILL FORAGING HABITAT

INTRODUCTION

Habitat is fundamental to the existence of all species and understanding habitat use is paramount to conservation efforts. Understanding foraging behavior and assessments offoraging habitat can, in particular, provide insight into the habitat needs of avian species (Hutto 1990). Plant species composition and vegetation structure are two proximate factors that greatly influence a bird's ability to successfully exploit certain habitats because they affect search tactics and the availability and/or abundance of prey

(Robinson and Holmes 1982, 1984, Rotenberry 1985). Specific plant species may be critical for food specialists such as insectivores, that have a prey base which may exhibit a high degree of host plant specificity (Swezey 1954, Southwood 1960), while vegetation structure may further influence a bird's ability to successfully exploit prey (Robinson and

Holmes 1984). Assessing foraging habitat at the appropriate spatial scale is essential to accurately determine avian foraging needs. This may be especially critical for territorial species, because appropriate foraging habitat may be limited within individual home ranges. Many animals utilize resources in disproportion to their availability (Olsson et aI.

2001), thus assessments of use and availability of specific vegetation attributes can provide meaningful explanations of specific habitat requirements and selectivity by reconciling use of microhabitats with availability at broader scales (Wiens 1989, Dodge et al. 1990).

I addressed habitat use and availability for an endangered Hawaiian forest bird, the Maui Parrotbill (Pseudonestor xanthophrys). The parrotbill is among the most

46 threatened of the remaining Hawaiian honeycreepers (population 500 ± 230, 95% CI individuals; Olson and James 1981a) and reproduces at a mte of only one young/year

(Simon et a1. 2000). It is restricted to the island of Maui, where it occupies approximately

5% of its original range (Scott et a1. 1986) with habitat loss cited as a primary limiting factor (Mountainspring 1987, Simon et a1. 1997). Parrotbill maintain year round a11- purpose home ranges, a characteristic common to many of the insectivorous honeycreepers in (Pratt et a1. 200Ib). Recently this medium-sized olive-green honeycreeper has become a target for conservation efforts on the island ofMaui because it is the only endangered insectivore that may still benefit from recovery measures. Two

other endangered honeycreepers on Maui that historically had similar habitat requirements, the PO'ouli (Melamprosops phaesoma) and the Nukupu'u (Hemignathus

lucidus), may already be extinct (Maui Forest Bird Recovery Project, unpubl. data). Both these species fomged on invertebmtes from woody trees, shrubs, and/or epiphytic

material in similar habitat types as the parrotbill (Perkins 1903, Baker 2001). Their

disappearance suggests that parrotbill may be subject to the same threats. In Chapter 2, I

showed that Maui Parrotbill fomged non-randomly. In this chapter, I address issues of

selectivity and examine whether parrotbill foraged selectively on certain plant species, at

certain heights, and on certain tree size classes in used home ranges.

METHODS

This study was conducted in Manawainui (20°41'43" N. 156°7'59" W). a 526-

hectare (1300-acre) parcel of Haleakalii National Park at the southeastern-most edge of

the East Maui min forest. Manawainui has been recovering from feral ungulate damage

47 for approximately 24 years, longer than most other sites on MauL As a result of this recovery and its proximity to historic parrotbill range, it is being considered for reintroductions of captive-reared Maui Parrotbill. Manawainui is an ecotone between wet and dry forest, dominated by wet Metrosideros polymorpha forest, mesic Acacia koa and mixed Metrosideros-Acacia forest.

Gross vegetation cover classes were documented by Jacobi (1989). The topography in the area is extreme, divided by gulches and streams with an average slope

> 30%. Environmental and anthropogenic disturbance in the area has included degradation by feral goats (Capra hircus) and pigs (Sus scrofa), and invasion by weeds

(Peterson 1976, Loope et al. 1992). Interestingly, this forest was isolated by the lava flows which inundated nearby Kaupa Gap and Kipahulu Valley and may be much older than its surroundings due to this geological isolation (Peterson 1976). The area is characterized by high precipitation (Le., orographic rains and mist) in excess of 5,000 mm per year. Rainfall tapers off from east to west, marking the transition from the windward to leeward sides of the island. Manawainui is intensively managed to control feral ungulates, and marks the edge of current parrotbill range on southwest Haleakalii.

All work was conducted above 1585m elevation (- 5200 ft). Therefore, the effect of disease, which occurs at lower elevations, as a confounding factor on parrotbill distributions was minimized (van Riper and Scott 200 I). Conducting work at this elevation also minimized the chance of spreading invasive weeds that occur at lower elevations in Manawainui. To assess whether changes in vegetation across the habitat gradient in Manawainui were affecting parrotbill distribution and use, simultaneous

48 surveys of vegetation, birds, and bird foraging behavior were conducted over the course of two field seasons from February 2005 to August of2006. This spans most of the known breeding season for parrotbill (Simon et al. 1997) and should have reflected the time of year when resources would be most critical for the reproduction and survival of young.

BIRD SURVEYS

I identified 10-hectare study areas as the unit of scale through which to conduct additional foraging observations and vegetation surveys, because this is a conservative estimate of the home range size for parrotbill (Simon et al. 2000, Pratt et al. 200 1b). As the birds in this study were not banded, each 100hectare area helped to maintain a level of independence throughout the course of the study because the Maui Parrotbill is a territorial species. Using ArcGIS 9.1, I superimposed a grid partitioned into 100hectare units across the area, and assigned each 10-hectare area a unique letter identifier

(Appendix A). I utilized spot-mapping techniques to assess the distribution of parrotbill across the study site (Bibby et al. 2000). To maximize the potential of encountering parrotbills, I attempted to survey each home range for at least four hours each month; however, this was not always possible due to poor weather conditions. Survey times were alternated (morning vs. afternoon surveys) to increase encounter rates with individuals active at only certain times ofthe day and to prevent bias in data collection.

I moved freely around each 10-hectare plot during each 4-hour survey period. If a parrotbiIl was observed foraging during a survey, I stopped and waited 10 seconds to conduct foraging observations and microhabitat analysis. Individual birds were assigned

49 ID numbers which associated them to the nearest home range in which they were found.

In addition to location, individuals were further identified by unique coloration and/or vocalizations. Birds were individually identified based on age and sexual dimorphisms such as bill size, plumage, and voca1izations (Simon et al. 1997).

FORAGING OBSERVATIONS

Within each occupied 10-hectare home range (Figure 3.1.), detailed foraging observations on individual parrotbill were !lOllected following the standard behavior classification scheme of Remsen and Robinson (1990). I also noted bird age and sex when possible. Since parrotbill are mre and encounters infrequent, I spent as much time watching a foraging bird as possible, recording the total observation time for each individual on each plant species. Only the first observation was used in analyses, however, to promote independence among samples. Upon encountering a parrotbill, bird­ centered vegetation plots were selected by marking the first location at which it was seen, following the methods of Larson and Bock (1986). I waited ten seconds to remove any observer-imposed bias and collected data on plant species, substrate type, tree size class, and percent cover of the understory, subcanopy and canopy vegetation layers.

VEGETATION SURVEYS

I selected a stratified random sample ofO.04-ha (11.3 m radius) circular plots across the Manawainui area, n = 40 in areas parrotbill were actively using. Following the criteria of Noon (1981), these plots spanned the environmental gradient which occurs from east to west, reflecting the structural and compositional heterogeneity of the area.

50 Due to apparent habitat heterogeneity, I randomly selected five replicates in each home range using the random sampling extension in ArcGIS to generate x and y coordinates for each point (Figure 3.1.). UTM coordinates of sampling areas were uploaded into Garmin

GPS units to locate plots in the field. At each plot a series of variables potentially influencing parrotbill habitat use were measured, based on the methods of James and

Shugart (1970), as modified by Noon (1981). Previous research on Maui ParrotbiII life history and behavior (Mountainspring 1987, Simon et aI. 1997) served as a guide for the

selection of these variables. I identified all woody plant species within each O.04-ha plot

concurrent with the stem counts to ascertain relative abundance of plants. Most woody

plants were identified to species while in the field, with the exception of a few genera.

Unidentified specimens were brought back to Haleakalii National Park (HALE) headquarters to be identified by National Park Service botanists. Specimens were

deposited in the HALE herbarium for reference purposes. I attempted to identify all

plants to species; however some plants could be identified only to genus due to

morphological variability and hybridization (p. Welton, pers. comm.).

DATA ANALYSES

To assess whether or not parrotbiII were exhibiting preferential habitat use, I

calculated proportional use of foraging habitat (Dodge et aI. 1990). I summed the total

observation time for each individual on each plant species, tree size class, and vegetation

stratum in each home range and divided by the total observation time for each variable

observed to get relative use. Relative availability of each variable was calculated in a

51 similar manner by summing the availability of each variable in each home range and dividing it by the overall total.

Tree size classes were converted to basal area so that comparisons between plant species were weighted appropriately. I calculated overall availability of woody species only, since parrotbill do not forage on herbaceous vegetation. Percent cover was estimated for each vegetation layer according to the Braun-Blanquet cover abundance scale and I used the midpoints for each cover class (Braun-Blanquet 1932).

Data were initially collected in six different height tiers. but were analyzed based on three layers; canopy, subcanopy, and understory due to statistical considerations. Once relative proportions were calculated for each parameter of use and availability, direct

comparisons were made for each individual bird using a series of simple linear regressions.

Calculating use and availability in this manner is an appropriate method for

territorial species such as parrotbill because comparisons for each individual are made

only across the territory or home range that each individual has access to (Dodge et al.

1990). Each separate regression analysis was then assessed for statistical significance (p

< 0.05). If a regression was significant, proportional use for each vegetation variable was

derived by examining the slope of each regression line. Slopes greater than one signified

use greater than availability while slopes less than one signified availability greater than

use. Non-significant results indicated use was equal to availability. I averaged values for

use and availability across individuals to estimate percent use and availability for each

plant species, height class, and tree size class (VanderWerf 1993, Pejchar 2004).

52 Finally, I assessed foraging behavior with regard to plant and substrate type by calculating the number of time birds exhibited certain behaviors as a proportion of all foraging acts observed, by plant and substrate. This included all secondary foraging observations which were omitted from the analysis of use and availability. I compared these data from the Manawainui study area to foraging observations collected in the

Hanawi Natural Area Reserve from 1997-2002 (Maui Forest Bird Recovery Project, unpublished data) to assess similarities and differences in foraging behaviors and use of plants/substrates. Hanawi is an area of high parrotbill density (Simon et al. 1997) and

comparisons of foraging behavior there with those observed in Manawainui could

provide meaningful information on parrotbill habitat needs.

RESULTS

USE VS. AVAILABILITY IN MANA WAINUI

I collected 32 foraging observations for an estimated 14 individuals in 8 different home ranges with a mean observation time of380.63 seconds ± 301 SO for each

observation. A total of 22 woody plant species was recorded in the understory, subcanopy

and canopy strata. Maui Parrotbill foraged primarily on nine different plants which

included Rubus hawaiensis, Melicope spp.. Acacia !roa. llex anomala, Myrsine

lessertiana, Vaccinium calycinum, Cheirodendron trigynum, Coprosma spp., and

Leptecophylla tameiameiae.

Slopes for the regression analyses were significantly greater than one for five of

the nine plant species that parrotbill foraged on. Parrotbill utilized A. !roa, C. trigynum,

Melicope spp., Coprosma spp., and R. hawaiensis in greater proportion than their

53 availability (Table 3.1.) Parrotbill fomged on C. trigynum (23 % of total observations), followed by Coprosma spp (16%), R. hawaiensis,A. koa (10% each), and Melicope spp

(2%). Parrotbill used L anomala, Coprosma spp., L. tameiameiae, M. lessertiano and V. calycinum, in proportion to their relative abundance. M. po/ymorpha and standing dead trees were not utilized at all despite their abundance throughout the home ranges (Table

3.1., Figure 3.2.).

The regression results for use versus availability of the three main height tier classes (canopy 5-12 m, subcanopy 2-5 m, and understory 0-2 m) were all significant

(Table 3.2.). Parrotbill fomged more in the subcanopy and canopy than expected and less in the understory. Parrotbill selectively foraged in the subcanopy and canopy vegetation layers, spending 41% of the time in the subcanopy layer and 39% of the time in the

canopy. Birds fomged less than expected in the understory layer, spending only 20% of the time in that height class, despite its disproportionately high availability (60%) (Figure

3.2.). Parrotbill fomged at a mean height of 4.6m ± 2.24 SD.

The regression results fOT my analyses of use and availability fOT tree size class

were significant fOT both the small (3-15 dbh) and medium (16-53 dbh) tree size classes

but not fOT large (~ 54 dbh). Parrotbill used small trees more than was expected based on

availability, fomging on them 41 % of the time and used medium trees less than expected,

based on availability, foraging on them 43% of the time. Parrotbill used shrubs (0-2.9

dbh) and large trees ~ 54 dbh) in proportion to their availability (Table 3.3., Figure 3.2.).

54 PLANT AND SUBSTRATE USE BETWEEN SITES

Based on total observations (counts), parrotbill in Manawainui foraged primarily on C. trigynum (28%), R. hawaiensis (15%), Coprosma spp., and V. calycinum (10%).

Birds foraged on woodlbark (48%), dead wood (27%) and epiphytes (10%) and gleaned

(55%), excavated (23%), and split twigs (l0%), with the remaining behaviors (probing

and prying) occurring in less than 10% of observations (Figures 3.3 and 3.4).

In contrast the Hanawi data show much heavier use of M polymorpha (38%),

followed by B. arguta (12%), C. trigynum (II %), R. hawaiensis (8%), Coprosma spp.

(6%), and V. calycinum (3%) (Figure 3.5). Birds foraged on similar substrates as in

Manawainui. and most frequently foraging on bark (26%), wood (22%), ripe fruit (20%)

and live leaves (20%) (Figure 3.6). Birds primarily excavated (47%), gleaned (37%), and

probed (15%), and hawked, wrenched and twig split in less than 10% of observations.

DISCUSSION

Maui Parrotbill selectively foraged on specific plants, tree size class and vertical

height stratum in Manawainui. Preferential use of these vegetation variables may reflect

parrotbill morphology and behavioral ecology, foraging in areas that are energetically

most profitable (MacArthur and Pianka 1966). Other researchers have found that foliar

architecture of certain tree species, as well as foraging height and vegetation density can

strongly influence foraging success in (Robinson and Holmes 1984).

Preferential use of certain plants and foraging substrates in an area may be indicative of

greater food resource availability in that patch type (Hutto 1990). Rosenberg (1990)

demonstrated that birds will allocate their foraging time between different habitat types as

55 resource abundance levels change, selecting the most profitable fomging areas. Thus, birds may select some plants because of the expected quantity of prey, and ignore those sites or species which are less predictable (Sipura 1999, Olsson et al. 2001).

I found preferential use of five plant genem in my study area, A. koa, C. trigynum,

Melicope spp., Coprosma spp., and R. hawaiensis. This corrobomtes the findings of earlier researchers who studied parrotbill on windward east Maui. Mountainspring (1987) found parrotbill fomged extensively in the forest understory and subcanopy and made a majority of prey captures on C. trigynum, V. calycinum, Coprosma spp., Melicope spp., and Broussaisia arguta. Perkins (1903) also noted heavy use ofA. koa and Me/icope spp., suggesting the importance of these plants.

At this level of analysis I found preferential use ofA. koa, not detected at the larger macrohabitat scale (Chapter 2). This corrobomtes the findings of Perkins (1903), who suggested that parrotbill preferred this canopy tree as a fomging substmte. The

'Akiap6lii' au, the closest extant relative of the parrotbill utilizes koa extensively (pmtt et

al. 200111, Pejchar et al. 2005). Pejchar (2004) documented preferential habitat use by

'Akiap6lii'au in which they selectively foraged in young A. koa, despite its low

abundance. Evidence for preferential use of A. koa. however, does not obviate the

significance of other plant species for parrotbill foraging, as preference for fomging

substrates may be seasonal and/or associated with fluctuations of prey biomass (Simon et

al. 1997, Berlin et aI. 2001). Olsson et aI. (2001) found that preferential use of tree

species by Lesser Spotted Woodpeckers (Dendrocopos minor) within territories over the

course of one year was a direct result of prey abundance in those territories. Preferential

56 use of trees species between years, in that study however, was a direct result of the fluctuations of one particular invertebrate which was intricately tied to the phenology of several plant species.

A comparison of these data with foraging data collected from the Hanawi Natural

Area Reserve (Maui Forest Bird Recovery Project, unpubl. data) suggests that M. polymorpha may be a more important plant for parrotbill in some forests. Overall, birds in Hanawi foraged on a more diverse group of plants and substrate types than was observed in Manawainui. This result could be an artifact of larger sample size or more diverse plant composition in Hanawi.

Parrotbill foraged on R. hawaiensis intensively, despite the fact that it had the lowest availability of any of the plants the birds utilized. R. hawaiensis likely provides necessary specific arthropod food resources not sufficiently available in the other plant species. Dying or dead stems of R. hawaiensis are relatively soft, making it easy for parrotbill to excavate wood-boring larvae. Simon et aI. (1997) also noted the importance of this plant to parrotbill, particularly during the fall and winter months, although I noted the birds in this study utilizing R. hawaiensis during the spring and summer as well. R. hawaiensis was distributed scarcely throughout Manawainui and further investigation into the relevance of this plant species is needed.

Maui Parrotbill selectively foraged on small trees more than expected and used medium trees less than expected. Smaller trees may allow parrotbill to rapidly search an area for potential food resources, may harbor higher quantities of invertebrates per area than larger tree size classes, and often are composed of C. trigynum and Coprosmo spp.,

57 favored plants. While smaller trees such as C. trigynum may be important for fomging, as the results of this study suggest, larger trees such as M. polymorpha may fill other necessary roles in the ecological niche of the parrotbill.

I report on the importance oflarger tree size classes in determining suitable home ranges for Maui Parrotbill in Chapter 2. Larger sized trees and old growth forest are known to limit nesting habitat for at least one other forest bird in Hawai'i, the Hawai'i

'Akepa (Loxops coccineus coccineus) (Freed 2001). It is currently unknown what effect, if any, limited availability oflarger trees may have had on the demise of the Maui 'Akepa

(Loxops coccineus ochraceus) another likely extinct insectivore which was once sympatric with Maui Parrotbill (Scott et al. 1986).

Parrotbill used the subcanopy and canopy more than expected based on availability. When foraging in the canopy, parrotbill fomged on Cheirodendron, Acacia and Ilex, and foraged on Melicope, Myrsine, and Coprosma in the subcanopy. Canopy structure can influence availability of prey as well as affect a bird's ability to detect and capture prey and to hide from predators (North et al. 1999). Fretz (2002) found that lower canopy densities resulted in lower food availability for another endangered honeycreeper, the Hawai'i 'Akepa. In contrast, overly dense understory may inhibit movement and prey capture, or may not contain the desired plant species for fomging which could explain why birds foraged in the understory less than expected.

MANAGEMENT IMPLICA nONS

Future recovery efforts for this species should include research in other areas to replicate vegetation measurements and habitat use as detailed in this study. Additional

58 research might also investigate use and availability of nesting habitat, invertebrate food resources and associated plant species, and wood quality of branches. While I did not find significant interactions of parrotbill with dead trees in our study, anecdotal observations of birds foraging on dead limbs of living trees suggest these trees may be an important foraging substrate and could be a crucial component of parrotbill habitat. Mountainspring

(1987) found similar associations. It is possible senescing, rather than dead plants, may provide better conditions for certain wood boring invertebrates.

Since I found some evidence of preferential habitat use ofA. /coa, this is one avenue of research that warrants further investigation. Although koa may be relevant for

Maui Parrotbill. managers should consider additional vegetation parameters, such as

adequate levels of vegetation in the understory, subcanopy, and canopy, and a diversity of

plant species and tree size classes as mentioned above, when assessing potential release

sites or initiating restoration efforts for future reintroductions of this species. Parrotbill

utilize a variety of plant species for foraging which may reflect temporal changes in

invertebrate abundances. Thus maintaining forest diversity may be crucial to supplying

adequate invertebrate food resources throughout the year.

Habitat use and food resource use are important avenues of research which have

been little explored, but are necessary to further understand the limiting factors important

for this species. It is especially critical that food resources be addressed, given the recent

likely extinction of the Po'ouli (Maui Forest Bird Recovery Project, unpubl. data) despite

the active management of habitat for this species. It is shortsighted to think that a species

can be recovered or protected without an understanding of habitat and dietary

59 requirements. Management of habitat in Hawai'i is frequently cited as a primary objective for numerous species, yet in many cases little is known of a species' actual habitat needs. For some birds, effective habitat management of existing areas and effective restoration of new areas may be greatly enhanced by an in-depth understanding of avian habitat requirements.

60 Table 3.1. Results of separate regression analyses of Maui Parrotbill use versus aVailability of different plants used for foraging, n = 14 birds. Metrosideros and Dead were not used for foraging but are included for reference. * denotes significance at a = 0.05.

Sl!ecies or Gencra Use A vailabili!l: Slol!e SE t .e:value Conclusion Cheirodendron trigynum 0.234 0.039 6.51 2.1 3.09 *0.01 U>A Coprosma spp. 0.157 0.01 15 6.793 2.21 *0.05 U=A llex anomala 0.149 0.Q15 3.48 4.749 0.73 0.48 U=A Myrsine lessertiana 0.128 0.013 6.98 5.415 1.29 0.22 U=A 0\ Acacia koa 0.103 0.013 8.27 1.9 4.16 *0.00 U>A - Rubus hawaiensis 0.1 0.001 146 52.39 2.78 *0.02 U>A Vaccinium calycinum 0.086 0.01 7.05 3.877 1.82 0.10 U=A Leptecophylla tameiameiae 0.027 0.023 0.35 1.072 0.33 0.75 U=A Melicope spp. 0.016 0.015 1.65 0.74 2.23 *0.04 U>A Metrosideros polymorpha 0 0.749 Dead 0 0.107 Use (U) and availability (A) are relative proportions; availability is the mean value for basal area of each species, use is the mean value of foraging time. Significant regressions with slopes greater than one signify use greater than availability. Slopes less than one signify use less than expected based on availability. Table 3.2. Results of separate regression analyses of Maui Parrotbill use versus availability of vertical height tier classes, n = 14. • denotes significance at a = 0.05. Vertical Height Tier Use Availability Slope SE t p-value Conclusion Rj Subcanopy 0.4098 0.20886 1.84 0.5312 3.46 ·0.00 U>A Canopy 0.3853 0.13388 2.72 0.5737 4.74 ·0.00 U>A Understory 0.2049 0.59539 0.329 0.1438 2.29 ·0.04 U

Understory = 0-2m, Subcanopy 2-5m, Canopy 5-12m, Upper Canopy 12-25m. Use (U) and availability (A) are relative proportions; availability is the mean value expressed as percent cover, use is the mean value of foraging time. Significant regressions with slopes greater than one signify use greater tban availability. Slopes less than one signify use less than expected based on availability. Table 3.3. Results of separate regression analyses ofMaui Parrotbill use versus availability of different woody vegetation sizes classes, n = 14. * denotes siguificance at a = 0.05.

Tree Size Class Use Availability Slope SE t p-value Conclusion Medium trees 0.43403 0.42540 0.967 0.2123 4.55 *0.00 U < A '"w Small trees 0.41127 0.15684 2.65 0.6843 3.88 *0.00 U>A Shrubs 0.14342 0.01307 6.72 4.935 1.36 0.2 U=A Large Trees 0.01128 0.40469 Shrubs 0-2.9 dbh, small trees 3-15 dbh, medium tress 16-53 dbh, large trees, ~ 54 dbh. Use (U) and availability (A) are relative proportions; availability is the mean value for basal area of each tree size class, use is the mean value of foraging time. Siguificant regressions with slopes greater than one siguify nse greater than availability. Slopes less than one siguify use less than expected based on availability. Figure 3.1. Distribution of Maui Parrotbill across the study site. All I O-hectare areas surveyed for parrotbill (MAP A) and vegetation are indicated by letters. Foraging observations were conducted in shaded areas only.

64 25%

20%

15%

10%

5%

Figure 3.2. Mean percent time parrotbilI (n = 14) spent foraging on different plants, height tier and trees size class in 8 different horne ranges in Manawainui.

65 50% 45% 40% 35% 30% 25% 20% 15% 10% 5% 0% -1-- Medium trees Small trees Shrubs

5% 0%-1-- Canopy Subcanopy Understory

Figure 3.2. (Continued) Mean percent time parrotbiII (n = 14) spent foraging on different plants, height tier and trees size class.

66 • Excavate o Pluck/Glean I1llProbe Ell Pry III Twig splitting

Figure 3.3. Total foraging events observed for Maui Parrotbill in Manawainui (n = 60) broken down by plant and foraging behavior.

35 30 • Excavate 25 o Pluck/Glean 20 !!ilProbe 15 DPry 10 1m Twig splitting 5

O~~-.~~~3L,J~-.~~-L-L,J~~

Figure 3.4. Total foraging events observed for Maui Parrotbill in Manawainui broken down by substrate type and behavior, n = 60

67 140 120 • Excavatim 100 o Pluck/Glean 80 Ell Probe 60 40 20 0

Figure 3.5. Total foraging events for Maw Parrotbill in Hanawi (n = 358) broken down by plant and behavior. Maw Forest Bird Recovery Project, unpubl. data.

100 90 80 • Excavation 70 o Pluck/Glean 60 I!il Probe 50 iii! Twig splitting 40 mWrench 30 20 10 0 Bark Bud Epiphyte Flowers Green Live Ripe Wood fruit leaf fruit

Figure 3.6. Total foraging events for Maui Parrotbill in Hanawi broken down by substrate and behavior, n = 350. Maui Forest Bird Recovery Project, unpubl. data.

68 CHAPTER 4. CONCLUSION

Habitat loss and degradation affect many species world wide. In Hawai'i, the effects of habitat loss are magnified by the sensitive nature of its insular ecosystems and specialized flora and fauna. The Hawaiian honeycreeper family is frequently recognized as an evolutionary marvel. Unfortunately this amazing group of birds has been quite negatively affected by anthropogenic changes with habitat loss at the forefront.

Management for limiting factors such as habitat are current priorities of numerous conservation programs in Hawai'i. However, in many cases the most important limiting factors have not been identified, making inferences about threats to small disjunct populations difficult.

For my Master's research, I attempted to identify limiting habitat factors for the

Maui Parrotbill, one of the most endangered honeycreepers in Hawai'i that may still benefit from conservation efforts. Current research for this species focuses on breeding biology and predator control. Future recovery efforts seek to restore areas of degraded habitat, and to reintroduce captive-reared birds into new areas.

Little is actually known, however, about the habitat requirements of this species. This paucity of knowledge is surprising, given the high costs involved with ambitious reintroduction projects. Premature introduction of this species into habitat which has not yet been assessed for suitability could be costly and detrimental because habitat quality ultimately determines the reproduction and survival of an organism. The evaluation of habitat is a critical first step toward implementing a sound wildlife management or

69 monitoring program (Wiens and Rotenberry 1981a) and rigorous quantification of habitat should precede any reintroduction program (Armstrong and McLean 1995).

The reintroduction guidelines set forth by the International Union for the

Conservation ofNature and Natural Resources stress the importance of evaluating the suitability of potential habitat (IUCN 1998) for reintroductions and translocations.

Reintroduction and/or translocation projects should carefully consider habitat quality and quantity at the release site, as well as numbers of individuals released, and the relationship of the release site to the animal's historic range (Wolf et al. 1998).

Reintroductions into new areas frequently fail because of immature or inadequate habitat,

or because key factors responsible for a species' initial extirpation have not been

adequately identified and remedied (Armstrong and Ewen 2002). Incorporating a

scientific experimental approach with hypothesis testing (Armstrong and McLean 1995,

Seddon et al. 2007) can, however, greatly enhance the outcome of potential

reintroduction projects by more accurately identifYing significant habitat parameters.

The overriding goal of this research was to use an inferential approach to assess a

potential release site for parrotbill in Haleakalii National Park. Specifically, I addressed

how forest stand structure and composition affected Maui Parrotbill distribution in

Manawainui and how these factors might influence the suitability of this area as a

potential release site for captive-reared birds. My primary questions were: 1) do forest

structure and plant species composition determine Maui Parrotbill use at the macrohabitat

(home range) scale (Chapter 2), 2) do forest structure and plant species composition

determine Maui Parrotbill use at the microhabitat (foraging site) scale (Chapter 2), and 3)

70 do Maui Parrothill selectively fomge on certain plant species, vegetation stmtum, and tree size classed in proportion to their relative abundance (Chapter 3).

I expected that ifMaui Parrothill were not using all available habitat in

Manawainui at the macrohabitat (home range) scale, I would be able to identify specific habitat variables that could account for this distribution. Furthermore, if parrothill were not using all available habitat (10-hectare areas) in my study site, I expected habitat use at smaller scales, in this case fomging sites, to be non-random and selective. I found that parrotbill exhibited preferential use at multiple scales. At the macrohabitat scale, I found significant differences between used and unused areas for forest structure, plant composition, and overall plant diversity. Areas which were occupied by parrotbill were characterized by larger trees and density of understory, subcanopy and canopy layers.

Parrotbill avoided areas dense with small trees and shrubs. Important plants at the macrohabitat scale were Cheirodendron. llex, and Melicope.

At the microhabitat scale, I collected data within a nested hierarchy at three increasing scales of resolution at O-m (fomgingplant), 1-m and 2m mdii. No significant differences were apparent at the 2-m scale; however, significant differences in overall

piant composition appeared to influence use at the 1-m scale. Parrotbill avoided areas

dense with M polymorpha. At the finest or O-m scale within fomging sites, I found that

parrotbill selectively fomged on specific plant species, vertical height stmtum and tree

size class in disproportion to their availability throughout each home range. Preferred

fomging plants included Cheirodendron, Rubus, Melicope, Coprosma, and Acacia.

Parrotbill utilized the sub canopy, canopy, and smaller-sized trees more than expected

71 based on availability. At this level of my analysis I found preferential use of Acacia /wa, not detected in the macrohabitat (home-range) portion of the study. Likewise, smaller diameter trees appeared important for Maui Parrotbill foraging sites; however, areas

overly dense with small trees were avoided at the macrohabitat level. These data

highlight the relevance of certain plants and aspects of forest structure for parrothill and

also highlight the importance of including implicit spatial scales in future studies for this

species. Maui Parrotbill used home ranges and foraging sites based on the presence of

scale-specific habitat variables.

MANAGEMENT IMPLICATIONS

In Manawainui, management for feral ungulates in existing areas, as well as new

areas below 1600m elevation is highly recommended. Recovery of the Metrosideros­

Acacia forests which occur at lower elevations could provide additional habitat for Maui

Parrotbill. Fencing and feral ungulate removal in these areas however, are not the only

remedies. Restoration in newly fenced areas should include out planting a variety of

plants, such as Cheirodendron. Acacia. Rubus. Melicope, Coprosma. Vaccinium.

Myrsine, Ilex. and Broussasia and diversity of tree size classes and vegetation layers.

Parrotbill use many different types of plants for foraging which may reflect temporal

changes in invertebrates. Thus, maintaining forest diversity may be crucial to supplying

adequate invertebrate food resources throughout the year. In existing parrotbill habitat at

upper elevations, selective thinning in forest overly dense with Metrosideros might

initiate conditions for invertebrate infestations. Wood boring larvae have been known to

72 infest areas affected by perturbations such as logging or fire and selective logging may increase available foraging habitat for Maui Parrotbill. A variety of plants (as mentioned above) could also be planted in selectively cleared areas.

The suitability of alternate release areas such as Kabikinui, Polipoli and

Waikamoi Preserve should also be explored. The fires that swept through Polipoli in

2006 could provide conditions suitable for invertebrate infestation, as well as restoration of native plants. However, the subsequent reintroduction of captive-reared parrotbill into new areas should be used to enhance, not replace, the aforementioned forest restoration

efforts. Captive propagation and reintroduction efforts have become popular recovery objectives for many wildlife conservation efforts throughout the world. In Hawai'i this

approach has been especially emphasized for its avifauna. These programs, however, are

not a panacea for recovering endangered species and, given the expense, should be

implemented with caution. Reintroductions should include hypothesis testing (see research implications below) if at all possible, so that information may be gained

regarding failures as well as successes (Seddon et a1. 2007). In the case of the Maui

Parrotbill, quantitative vegetative assessments should be conducted in existing parrotbill

habitat as well as prior to, concurrent with, and after reintroduction efforts. Many studies

on the US mainland and elsewhere routinely combine assessments of vegetation with

long term demographic studies on breeding and/or foraging biology. Studying habitat

attributes in areas where Maui Parrotbill currently persist can assist biologists trying to

restore designated recovery areas. It is difficult to restore new habitat without knowledge

of the factors most critical to survival in existing habitat.

73 Fu1uRE RESEARCH

Obtaining detailed infonnation on habitat use and quality could assist managers in designating recovery areas. Vegetation surveys should be conducted in and around

current breeding sites for Maui Parrotbill as well as at foraging sites and should include

spatial and temporal components. I used a conservative estimate ofMaui Parrotbill home range size in my vegetation surveys. Future studies might included comparisons at

different home range sizes and might detail habitat use for male and female birds

separately. Do males and females respond to nesting habitat differently? Orians and

Wittenberger (1991) who studied yellow-headed blackbirds (Xanthocephalus xanthocephalus) found that vegetation requirements for nesting habitat were scale­

dependent and different for each sex. Two other important questions are: 1) Do male and

female parrotbill respond differently to foraging habitat? 2) Is foraging habitat or nesting

habitat the more critical determinant of habitat use?

Parrotbill response to changing vegetation in restored areas should be monitored

with regard to home range size, i.e. does parrot bill home range size change with regard

to abundance of a particular plant species or denseness of vegetation for foraging and

nesting? Since vegetation may be used as a metric for food availability, fluctuations in

territory size and conspecific aggression may result from fluctuations in food resources

(Maher and Lott 2000). Pejchar et al. (200S) found that 'Akiap

home ranges in A. koa plantations with little understory and limited foraging resources.

Thus in territorial species, such as Maui Parrotbill and 'AkiapOlii'au, home range size

may ultimately dictate the population size an area can sustain.

74 In conclusion, the recovery of endangered birds in Hawai'i will be accompanied by an exceedingly complex process confounded by natural, social and political challenges. Science must playa key role. Understanding habitat is an important component of that role. In this study, I found that vegetation, a frequently overlooked yet critical component, can be a useful determinant of habitat use patterns for an endangered bird, the Maui Parrotbill. I encourage the replication of this work in additional areas to corroborate these findings and urge additional research to understand the food that forms the basis for these preferences.

75 APPENDIX A. ALL AREAS SURVEYED FOR VEGETATION AND MAUl

PARROTBILL IN MANA WAINU!

Number Home MAPA of range Present MAPA Sex X Y ID N 0 798558 2291307 He N 0 798558 2291623 HD N 0 798558 2291939 HE N 0 798874 2290674 HG N 0 798874 2290991 HI N 0 798874 2291307 HI N 0 798874 2291623 HK Y I U 798874 2291939 HL N 0 799191 2290674 HM Y 2 M,F 799191 2290991 HN Y 2 M,U 799191 2291307 HO N 0 799191 2291623 HP Y 2 M,F 799191 2291939 HQ Y 2 M,F 799507 2290991 HR Y I M 799507 2291307 HS N 0 799507 2291623 HT Y 2 M,F 799507 2291939 HU Y I M 799823 2291307 HW Y I M 799823 2291623 HX Y 2 M,F 800139 2291623 HZ N 0 800455 2291307 HH The size of each survey area was set at 10 hectares. Sexes of individuals are as follows: M=male, F=female, U=unknown sex. The center of each home range is represented by X andY coordinates

76 APPENDIX B. ALL O.04-HA VEGETATION PLOTS USED IN THE HABITAT

ANALYSES AND CORRESPONDING UTM COORDINATES

Plot Home Range X Coordinate Y Coordinate HCl HC 798580.98 2291302.02 HC2 HC 798602.15 2291340.14 HC3 HC 798553.56 2291237.08 HC4 HC 798603.43 2291258.64 HC5 HC 798554.74 2291356.25 HD1 HD 798517.91 2291646.85 HD2 HD 798556.94 2291653.78 HD3 HD 798585.38 2291667.3 HD4 HD 798511.61 2291601.9 HD5 HD 798581.54 2291573.78 HE! HE 798531.44 2292009.48 HE2 HE 798525.62 2291879.61 HE3 HE 798593.59 2291926.5 HE4 HE 798550.45 2291949.67 HE5 HE 798623.91 2291996.31 HG1 HG 798913.18 2290608.94 HG2 HG 798914.37 2290745.46 HG3 HG 798823.14 2290599.62 HG4 HG 798939.43 2290642.97 HG5 HG 798865.12 2290607.18 HH1 HH 800520.46 2291326.15 HH2 HH 800406.84 2291299.03 HH3 HH 800421 2291259.22 HH4 HH 800396.6 2291339.15 HH5 HH 800500.73 2291233.6 HIl HI 798920.64 2291003.66 HI2 HI 798860.45 2290956.12 HI3 HI 798883.74 2290994.17 HI4 HI 798822.2 2290940.51 HI5 HI 798902.32 2290918.73 HJ1 HJ 798910.91 2291290.08 77 Plot Home Range X Coordinate Y Coordinate HJ2 HJ 798845.45 2291282.42 HJ3 HJ 798910.33 2291379.04 HJ4 HJ 798838.56 2291251.22 HJ5 HJ 798910.43 2291228.92 HI<1 HI< 798906.96 2291583.31 HK2 HK 798820.57 2291664.74 HK3 HK 798950.52 2291605.96 HI<4 HI< 798805.18 2291700.05 HKS HK 798864.58 2291692.15 HLl HL 798913.73 2291895.61 HL2 HL 798917.39 2292014.03 HL3 HL 798856.72 2291953.37 HL4 HL 798805.98 2291923.9 HL5 HL 798872.74 2291876.1 HMI HM 799245.29 2290722.34 HM2 HM 799258.69 2290653.59 HM3 HM 799116.54 2290726.96 HM4 HM 799243 2290627.39 HM5 HM 799199.49 2290720.16 HNI HN 799200.96 2291042.25 HN2 HN 799182.67 2290946.39 HN3 HN 799265.69 2290912.63 HN4 HN 799149.25 2291030.4 HN5 HN 799212.43 2291006.93 HOI HO 799240.38 2291235.7 H02 HO 799181.39 2291307 H03 HO 799267.5 2291333.51 H04 HO 799121.55 2291266.98 H05 HO 799239.01 2291274.72 HPI HP 799119.41 2291549.54 HP2 HP 799224.68 2291677.64 HP3 HP 799214.43 2291577.35 HP4 HP 799183.24 2291620.11 HP5 HP 799140.84 2291649.33 HQ1 HQ 799262.72 2291985.18 HQ2 HQ 799179.01 2292010.87 HQ3 HQ 799208.82 2291870.65 HQ4 HQ 799232.19 2291910.06

78 Plot Home Range X Coordinate Y Coordinate HQ5 HQ 799266.02 2291954.45 HR1 HR 799446.07 2290913.03 HR2 HR 799482.09 2290964.55 HR3 HR 799569.48 2290947.29 HR4 HR 799484.63 2290917.58 HR5 HR 799497.71 2291019.17 HS! HS 799468.18 2291253.42 HS2 HS 799470.82 2291375.23 HS3 HS 799574.5 2291344.72 HS4 HS 799558.62 2291241.82 HS5 HS 799491.15 2291296.02 HT1 HT 799506.41 2291616.13 HT2 HT 799564.22 2291553.67 HT3 HT 799491.86 2291697.89 HT4 HT 799504.93 2291579.67 HT5 HT 799446.88 2291638.08 HU1 HU 799466.95 2291866.27 HU2 HU 799432.9 2291900.5 HU3 HU 799569.44 2291968.86 HU4 HU 799585.65 2291924.71 HU5 HU 799540.92 2291884.92 HW1 HW 799802.07 2291330.37 HW2 HW 799843.21 2291305.25 HW3 HW 799891.3 2291345.25 HW4 HW 799805.37 2291360.32 HW5 HW 799821.25 2291237.54 HX1 HX 799865.13 2291634.97 HX2 HX 799765.29 2291566.1 HX3 HX 799766.87 2291680.13 HX4 HX 799808.42 2291665.44 HX5 HX 799812.96 2291632.79 HZ1 HZ 800096.28 2291656.67 HZ2 HZ 800132.16 2291661.03 HZ3 HZ 800215.7 2291615.51 HZ4 HZ 800\76.53 2291602.08 HZ5 HZ 800069.16 2291562.52

79 APPENDIX C. SPECIES LIST AND TAXA CODES FOR ALL HERBACEOUS

AND WOODY PLANT TAXA FOUND IN MANAWAINUI

Taxon Code Taxon Common Name Acakoa Acacia koa A. Gray Koa

Ageade Ageratina adenophora (Spreng.) R. Piimakani King & H. Robinson Alyoli Alyxia oliviformjs Gaud. Maile

Astspp. Astelia menziesiana Sm. Pa'iniu

Broarg Broussaisia arguta Gaud. Kanawao

Carspp. Carex species L.

Chetri Cheirodendron trigynum (Gaud.) A. 'Olapa Heller Cibspp. Cibotium species Hapu'u

Clearb Clermontia arborescence (H. Mann) Hillebr. Clegra Clermontia grandiflora Gaud. 'Ohii wai

Copern Coprosma ernodeoides A. Gray Kiikaenene

Copfol Coprosma foliasa A. Gray Pilo

Copmon Coprosma montana Hillebr. Pilo

80 Taxon Code Taxon Common Name Copoch Coprosma ochracea W. Oliver Pilo

Copspp. Coprosma species Pilo

Cyakun Cyanea kunthiana Hillebr. Hiihii

Cyaspp Cyanea aculeatijlora Rock Hiihii

Cyrspp Cyrtandra species J. R. Forster & O. Ha'iwale Forster Dead Dead anything

Desnub Deschampsia nubigena Hillebr.

Dicsp Dicranopteris linearis Underw. Uluhe

Dodvis Dodonea viscosa Jacq. 'A'ali'i

Elapho Elaphoglossum species

Pepspp Peperomia species Ruiz & Pav. ' Ala' ala wai nui

Hedter Hedyotis terminalis (Hook and Manono Amott) W.L. Wagner & Herbst Hollan Holcus lanatus L. Velvet grass

Hyprad Hypochaeris radicata L. Hairy eat's ear

I1eano flex anomala Hook & Amott Kawa'u

Korspp. Korthalsella species Tiegh Hulumoa

81 Taxon Code Taxon Common Name Labven Labordia venosa Sherif

Leptam Leptecophylla tameiameiae (Cham. & Piikiawe Schlechtend). F. v. MueI!. Lycspp. Lycopodium species

Lysrem Lysimachia remyi Hillebr. Kolokolo

Macspp. Machaerina angustustifolia (Gaud.) 'Uki T. Koyama Melclu Melicope clusiifolia A. Gray 'Alani

Melorb Melicope orbicularis Hillebr. 'Alani

Melspp. Melicope species 'Alani

Metpol Metrosideros polymorpha Gaud 'Ohi'a

Myrema Myrsine emarginata (Rock) Hosaka Kiilea

Myrles Myrsine lessertiana A. DC Kiilea

Nergra Nertera granadensis (L. Fi!.) Druce Miikole

Orefur Oreobolus furcatus H. Mann

Physpp. Phyliostegia glabra (Gaud.) Benth Ulihi

Pitcon Pittosporum confertiflorum A. Gray Hii'awa

Psymau Psychotria mauiensis Fosb. Kiipiko

82 Taxon Code Taxon Common Name Rubhaw Rubus hawaiensis A. Gray 'Akala

Scaspp Scaevola species Naupaka

Smimel Smilax melastomifolia Hoikuahiwi

Stekam Stenogyne kamehamehae Wawra

Stespp Stenogyne species

Tetoah Tetraplasandra oahuensis (A. Gray) 'Ohemauka

Uncunc Uncinia unicinata (L. fil.) Kiikenth

Vaccal Vaccinium calycinum 8m. 'Ohelo

Vacden Vaccinium dentalUm Sm. 'Ohelo

Vacret Vaccinium reticulatum Sm. 'Ohelo

Plant follows Wagner et al. 1999

83 LITERATURE CITED

Abbitt, R. J. F., and J. M. Scott. 2001. Examining differences between recovered and

declining species. Conservation Biology 15:1274-1284.

Adams, E., and M. L. Morrison. 1993. Effects of forest stand structure and composition

on Red-Breasted Nuthatches and Brown Creepers. Journal of Wildlife

Management 57:616-629.

Anderson, M. 2001. A new method for non-parametric multivariate analysis of variance.

Austral Ecology 26:32-46.

Armstrong, D. P., and J. G. Ewen. 2002. Dynamics and viability of a New Zealand robin

population reintroduced to regenerating fragmented habitat. Conservation Biology

16:1074-1085.

Armstrong, D. P., and I. G. McLean. 1995. New Zealand translocations: theory and

pmctice. Pacific Conservation Biology 2:39-54.

Atkinson, C., K. Woods, R. Dusek, L. Sileo, and W. Iko. 1995. Wildlife disease and

conservation in Hawai'i: pathogenicity of (Plasmodium relictum)

in experimentally infested liwi (Vestiaria coccinea). Parasitology I1:S59-S69.

Baker, P. E. 2001. Status and distribution of the Po'ouli in the Hanawi Natural Area

Reserve between December 1995 and June 1997. Studies in Avian Biology

22:144-150.

84 Baker, P. E., and H. Baker. 2000. Maui 'Alauahio Paroreomyza montana. in A. Poole

and F. Gill, editors. The Birds of North America, No. 504. The Academy of

Natural Sciences, Philadelphia, PA and The American Ornithologists' Union,

Washington DC.

Banko. P. C., R. David, J. Jacobi, and W. Banko. 2001. and recovery

strategies for endemic Hawaiian birds. Studies in Avian Biology 22:359-376.

Bergin, T. M. 1992. Habitat selection by the Western Kingbird in Western Nebraska: a

hierarchical analysis. Condor 93:903-911.

Berlin, K. E., T. K. Pratt, J. C. Simon, and J. R. Kowalsky. 2000. Plant phenology in a

cloud forest on the island of Maui, Hawai'i. Biotropica 32:90-99.

Berlin, K. E., J. C. Simon, T. K. Pratt, J. R. Kowalsky, and J. S. Hatfield. 2001.

'Akohekohe response to flower availability: seasonal abundance, foraging,

breeding, and molt. in J. M. Scott, C. V. Riper, and S. Conant, editors. Studies in

Avian Biology, No. 22, Lawrence, KS.

Bibby, C. J., N. D. Burgess, D. A. Hill, and S. H. Mustoe. 2000. Bird Census Techniques,

2nd edition. Academic Press, London.

Blackburn, T. M., P. Cassey, R. P. Duncan, K. L. Evans, and K. J. Gaston. 2004. Avian

extinction and mammalian introductions on oceanic islands. Science 305: 1955-

1958.

85 Block, W. M., and L. A. Brennan. 1993. The Habitat Concept In Ornithology. Theory

and Applications. Pages 35-91 in D. M. Power, editor. Current Ornithology.

Plenum Press, New York.

Bmun-Blanquet, J. 1932. Plant Sociology: The Study of Plant Communities. McGraw

Hill, New York, NY.

Butler, R. G. 1980. Population size, social behavior, and dispersal in house mice: a

quantitative investigation. Animal Behavior 28:78-85.

Cody, M. L., editor. 1985. Habitat Selection in Birds. Academic Press, Orlando.

Cuddihy, L. W., and C. P. Stone. 1990. Altemtion of Native Hawaiian Vegetation:

Effects of Humans, Their activities, and Introductions. University of Hawaii

Press, Honolulu.

Davies, K. F., C. Gascon and C.R Margules. 2001. Habitat Fragmentation:

Consequences, Management, and Future Resource Priorities. Pages 81-97 in M.E.

Soule and G. H. Orians, editors. Conservation Biology: Research Priorities for the

Next Decade. Island Press, Washington, DC.

Dodge, K. M., R. C. Whitmore, and E. J. Hamer. 1990. Analyzing foraging use versus

availability using regression techniques. Studies in Avian Biology 13:318-324.

Dufrene, M., and P. Legendre. 1997. Species assemblages and indicator species: the need

for a flexible asymmetrical approach. Ecological Monographs 67:345-366.

86 Freed, L. A. 2001. Significance of old growth forest to the Hawai'i 'Akepa. Pages 173-

184 in J. M. Scott, S. Conant, and C. van Riper 111, editors. Evolution, Ecology,

Conservation, and Management of Hawaiian Birds: A Vanishing Avifauna. Allen

Press, Lawrence, Kansas.

Fretwell, S. D. 1972. Populations in a Seasonal Environment Princeton University Press,

Princeton, New Jersey.

Fretz, J. S. 2002. Scales offood availability for an endangered insectivore, the Hawaii

Akepa. Auk 119:166-174.

Groombridge, J. J., J. G. Massey, J. C. Bruch, T. Malcolm, C. N. Brosius, M. M. Okada,

B. Sparklin, J. S. Fretz, and E. A. VanderWerf. 2003. An attempt to recover the

Po'ouli by translocation and an appraisal of recovery strategy for bird species of

extreme rarity. Biological Conservation 118:365-375.

Heglund, P. G. 2002. Foundations of species-environment relations. in J. M. Scott, P. G.

Heglund, and M. 1. e. a. Morrison, editors. Predicting Species Occurrences:

Issues of Accuracy and Scale. Island Press, Washington DC.

Henshaw, H. W. 1902. Birds of the Hawaiian Islands. T.G. Thrum, Honolulu.

Hilden, O. 1965. Habitat selection in birds: a review. Annales Zoologici Fennici 2:53-75.

Hobbs, N. T. 2003. Challenges and opportunities in integrating ecological knowledge

across scales. Forest Ecology and Management 181:223-238.

87 Hutto, R. 1985. Habitat selection by non-breeding migratory landbirds. Pages 455-476 in

M. L. Cody, editor. Habitat Selection in Birds. Academic Press, Orlando.

Hutto, R. 1990. Measuring the availability offood resources. Studies in Avian Biology

13:6-13.

IUCN. 1998. Guidelines for reintroductions. IUCN (World Conservation Union), Gland,

Switzerland and Cambridge, UK.

Jacobi, J. 1989. Vegetation maps of the upland Hawaiian plant communities on the

islands of Hawai'i, Maui, Moloka'i, and Lanai. PSCU Technical Report 68,

University of Hawaii, Manoa.

James, F. C., and H. H. Shugart. 1970. A quantitative method of habitat description.

Audubon Field Notes 24:727-736.

James, H. 2001. Systematics introduction. in J. M. Scott, S. Conant, and C. van Riper III,

editors. Evolution, Ecology, Conservation, and Management of Hawaiian Birds:

A Vanishing Avifauna. Allen Press, Lawrence, Kansas.

James, H. F., and S. L. Olson. 1991. Descriptions of thirty-two new species of birds from

the Hawaiian Islands: Part II. Passeriformes. Ornithological Monographs 46: 1-88.

Johnson, D. H. 1980. The comparison of usage and availability measurements for

evaluating resource preference. Ecology 61:65-71.

Johnson, M. D. 2007. Measuring habitat quality: a review. Condor 109:489-504.

88 Jones, J. 2001. Habitat selection studies in avian ecology: a critical review. Auk 118:557-

562.

Kotlier, N. B., and J. D. Wiens. 1990. Multiple scales of patchiness and patch structure:

A hierarchical framework for the study of heterogeneity. Oikos 59:253-260.

Kristan, W. B., and J. M. Scott. 2006. Hierarchical models for avian ecologists. Condor

108:1-4.

Kristan, W. B. I. 2006. Sources and expectations for hierarchical structure in bird-habitat

associations. The Condor:5-12.

Kruskal, J. 1964. Nonmetric multidimensional scaling: a numerical method.

Psychometrika:115-129.

Larson, D. 1., and C. E. Bock. 1986. Determining avian habitat preference by bird­

centered vegetation sampling. Pages 37-46 in J. Verner, M. 1. Morrison, and C. J.

Ralph, editors. Wildlife 2000: Modeling Habitat Relationships of Terrestrial

Vertebrates. University of Wisconsin Press, Madison, Wisconsin.

Lockwood, J. 1., J. E. Green, K. Wakelee, E. VanGelder, S. Ashe, and R. Aburomia.

1994. A description of Maui ParrotbiII (Pseudonestor xanthophrys) nests and

nesting behavior .• Elepaio 56:61-64.

Loope, 1. 1., R. J. Nagata, and A. C. Medeiros. 1992. Introduced plants in Haleakalii

National Park. Pages 551-576 in C. P. Stone, C. W. Smith, and T. J. Tunison,

89 editors. Alien Plant Invasions in Native Ecosystems ofHawai'i: Management and

Research. University of Hawai'i Press, Honolulu.

Luck, G. W. 2002. The habitat requirements of the rufous tteecreeper (Climacteris rufa).

preferential habitat use demonstrated at multiple spatial scales. Biological

Conservation 105:383-394.

MacArthur, R. H. 1958. Population ecology of some warblers of northern coniferous

forests. Ecology 39:599-619.

MacArthur, R. H., and E. R. Pianka. 1966. On the optimal use of a patchy environment.

American Naturalist 100:603-609.

Mace, G. M., J .M. Baillie, S. R. Beissinger, and K.H. Redford. 200 I. Assessment and

management of species at risk. Pages 11-30 in M. E. a. O. Soule, G.H., editor.

Conservation Biology: Research Priorities for the Next Decade. Island Press,

Washington, DC.

Maher, C. R., and D. F. Lott. 2000. A review of ecological determinants ofterritoriality

within vertebrate species. American Midland Naturalist 143: 1-29.

Martin, T. 1988. Process organizing open-nesting bird assemblages: competition or nest

predation? Evolutionary Ecology 2:37-50.

Mather, P. 1976. Computational Methods of multivariate analysis in physical geography.

J. Wiley and Sons, London.

90 McCune, B., and J. B. Grace. 2002. Analysis of Ecological Communities. MJM Software

Design, Gleneden Beach, Oregon.

McGarigal, K., S. Cushman, and S. Stafford. 2000. Multivariate Statistics for Wildlife

Ecology and Research. Springer-Verlag, New York.

Meffe, G. K., and C. R. Carroll. 1997. Principles of Conservation Biology. Sinauer

Associates, Sunderland.

Mielke, P. W. 1984. Meteorological applications ofpennutation techniques based on

distance functions. in P. R. Krishnaiah and P. K. Sen, editors. Handbook of

Statistics. Elsevier Science, New York, New York.

Mielke, P. W., and K. J. Berry. 2001. Pennutation Methods, A Distance Function

Approach. Springer-Verlag, New York.

Morris, D. W. 1987. Ecological scale and habitat use. Ecology 68:362-369.

Morrison, M. L., and L. S. Hall. 2002. Standard tenninology: toward a common language

to advance ecological understanding and application. Pages 43-52 in P. G. H. J.M.

Scott, and M.L. Morrison et aI., editor. Predicting Species Occurrences: Issues of

Accuracy and Scale. Island Press, Washington D.C.

Morrison, M. L., B. G. Marcot, and R. W. Mannan. 1992. Wildlife-Habitat Relationships.

University of Wisconsin Press, Madison, Wisconsin.

91 Moser, E. B., J. W.C. Barrow, and R. B. Hamilton. 1990. An exploratory use of

correspondence analysis to study relationships between avian foraging behavior

and habitat. Pages 309-317 in M. 1. Morrison, C. J. Ralph, J. Verner, and J. J.R.

Jehl, editors. Studies in Avian Biology.

Mountainspring, S. 1987. Ecology behavior and conservation of the Maui Parrotbill.

Condor 89:24-39.

Muller, K. L., J. A. Stamps, V. V. Krishnan, and N. H. Willits. 1997. The effects of

conspecific attraction and habitat quality on habitat selection of territorial birds

(Troglodytes aedon). American Naturalist 150:650-661.

Noon, B. R. 1981. Techniques for sampling avian habitats. General Technical Report

RM-87, USDA Forest Service, Fort Collins, Colorado.

North, M. P., J. F. Franklin, A. B. Carey, E. D. Forsman, and T. Hamer. 1999. Forest

stand structure of the northern spotted owl's foraging habitat. Forest Science

45:520-527.

Olson, S. L., and F. C. James. I 982a. Prodromus of the fossil avifauna of the Hawaiian

Islands. Smithsonian Contributions to Zoology 365: I-59.

Olson, S. L., and H. F. James. I 982b. Fossil birds from the Hawaiian Islands: evidence

for wholesale extinctions before western contact. Science 217:633-635.

92 Olsson, 0., U. Wiktander, A. Malmqvist, and S. G. Nillson. 2001. Variability of patch

type preferences in relation to resource availability and breeding success in a bird.

Oecologia 127:435-443.

Orians, G. H., and J. F. Wittenberger. 1991. Spatial and temporal scales in habitat

selection. American Naturalist 137:S29-S49.

Pejchar, L. 2004. Ecology of an endangered honeycreeper and implications for

conservation of private land. Ph.D dissertation. University of California, Santa

Cruz.

Pejchar, L., K. D. Holl, and J. L. Lockwood. 2005. Hawaiian honeycreeper home range

size varies with habitat: implications for native Acacia koa forestry. Ecological

Applications 15: 1053-1 061.

Perkins, R. C. L. 1903. Vertebrata. in D. Sharp, editor. Fauna Hawaiiensis. Vol. I, Part

IV. The University Press, Cambridge.

Peterson, D. 1976. Introduction. Pages 23-40 in D. Peterson, editor. The Scientific Report

of the Manawainui Research Project. University of Hawai'i, Honolulu.

Pratt, H. D. 1994. Avifaunal change in the Hawaiian islands, 1893-1993. Studies in

Avian Biology22:103-118.

93 Pratt, T. K., S. G. Fancy, and C. J. Ralph. 2001a. 'Aldapola'au (Hemignathus munroi)

and Nukupu'u (Hemignathus lucidus). in A. Poole and F. Gill, editors. The Birds

of North America. The Birds of North America Inc, Philadelphia.

Pratt, T. K., J. C. Simon, K. E. Berlin, and J. R. Kowalsky. 2001b. Home range and

territoriality of two Hawaiian honeycreepers, the 'Akohekohe and Maui

Parrotbill. Condor 103:746-755.

Remsen, J. V. 1985. Community organization and ecology of birds of high elevation

humid forests of the Bolivian Andes. Ornithological Monographs 36:733-756.

Remsen, J. V., and S. K. Robinson. 1990. A classification scheme for foraging behavior

of birds in terrestrial habitats. Pages 144-160 in M. L. Morrison, C. J. Ralph, J.

Verner, and J. Jehl, editors. Studies in Avian Biology, No. 13. Allen Press,

Lawrence, Kansas.

Restani, M., and J. Marzluff. 200 1. Avian conservation under the endangered species act:

expenditures versus recovery priorities. Conservation Biology 15: 1292-1299.

Reynolds, M. H., and T. J. Snetsinger. 2001. The Hawai'i rare bird search 1994-1996.

Studies in Avian Biology 22: 133-143.

Robinson, S. K., and R. Holmes. 1982. Foraging behavior offorest birds: the

relationships among search tactics, diet, and habitat structure. Ecology 63: 1918-

1931.

94 Robinson, S. K., and R. Holmes. 1984. Effects of plant species and foliage structure on

the foraging behavior offorest birds. Auk 101:672-684.

Root, T. 1988. Environmental factors associated with avian distributional boundaries.

Journal of Biogeography 15:489-505.

Rosenberg, K. V. 1990. Dead leafforaging specialization in tropical forest birds:

measuring resource availability and use. Studies in Avian Biology 13:360-368.

Rosenzweig, M. 1. 1981. A theory of habitat selection. Ecology 62:327-335.

Rotenberry, J. T. 1981. Why measure bird habitat? General Technical Report RM-87,

USDA Forest Service, Rocky Mountain Forest and Range Experiment Station,

Fort Collins, Colorado.

Rotenberry, J. T. 1985. The role of habitat in avian community composition:

physiognomy or floristics? Oecologia 67:213-217.

Scott, J. M., S. Mountainspring, F. 1. Ramsey, and C. B. Kepler. 1986. Forest Bird

Communities of the Hawaiian Islands: Their Dynamics, Ecology, and

Conservation. Studies in Avian Biology 9.

Seddon, P. J., D. P. Armstrong, and R. E. Maloney. 2007. Developing the science of

reintroduction biology. Conservation Biology 21:303-312.

Simon, J. C., P. E. Baker, and H. Baker. 1997. Maui Parrotbill (Pseudonestor

xanthophrys). in A. Poole and F. Gill, editors. The Birds of North America, No.

95 311. The Academy of Natural Sciences, Philadelphia P A and the American

Ornithologists' Union, Washington DC.

Simon, J. C., T. K. Pratt, K. E. Berlin, and J. R. Kowalsky. 2000. Reproductive ecology

of the Maui Parrotbill. Wilson Bulletin 112:482-490.

Sipura, M. 1999. Tritrophic interactions: willows, herbivorous and insectivorous

birds. Oecologia 121:537-545.

Smith, F. D. M., R. M. May, R. Pellew, T. H. Johnson, and K. R. Walter. 1993. How

much do we really know about the current extinction rate? Trends in Ecology &

Evolution 8:375-378.

Smith. T. M., and H. H. Shugart. 1987. Territory size variation in the ovenbird: the role

of habitat structure. Ecology 68:695-704.

Southwood, T. R. E. 1960. The abundance of the Hawaiian trees and the number of their

associated species. Proceedings of the Hawaiian Entomological Society 17.

Southwood, T. R. E. 1977. Habitat, the template for ecological strategies. Journal of

Animal Ecology 46:337-365.

Steele, B. B. 1993. Selection of foraging and nesting sites by black-throated blue

warblers: their relative influence on habitat choice. Condor 95:568-579.

Stemmerman, M. A. 1976. The Scientific Report of the Manawainui Research Project.

University of Hawaii, Honolulu.

96 Swezey, O. H. 1954. Forest Entomology in Hawaii. Bishop Museum Press, Honolulu,

Hawai'i.

Tabachnick, B. G., and L. S. Fidell. 1996. Using Multivariate Statistics. Harper and Row,

New York.

Tweed, E. J., J. T. Foster, B. L. Woodworth, P. Oesterle, C. Kuehler, A. Lieberman, T.

Powers, K. Whitaker, W. B. Monahan, J. Kellerman, and T. Telfer. 2003.

Survival, dispersal, and home-range establishment of reintroduced captive-bred

Puaihoi, Myadestes palmeri. Biological Conservation 111: 1-9.

USFWS. 2006. Revised Recovery Plan for Hawaiian Forest Birds. U.S. Fish & Wildlife

Service, Honolulu, Hawai'i.

Van Home, B. 1983. Density as a misleading indicator of habitat quality. Joumal of

Wildlife Management 47:893-901. van Riper, C., and J. M. Scott. 2001. Limiting factors affecting Hawaiian native birds.

Studies in Avian Biology 22:221-233.

V anderW err, E. A. 1993. Scales of habitat selection by foraging' Elepaio in undisturbed

and human-altered forests in Hawai'i. Condor 95:980-989.

Walters, J. R., S. J. Daniels, J. H. Carter, and P. D. Doerr. 2002. Defining quality of Red­

cockaded Woodpecker foraging habitat based on habitat use and fitness. Journal

of Wildlife Management 66: 1064-1 082.

97 Wiens, J. A. 1976. Population responses to patchy environments. Annual Review of

Ecology and Systematics 7:81-120.

Wiens. J. A. 1989. Spatial scaling in ecology. Functional Ecology 3:385-397.

Wiens, J. A., and J. T. Rotenberry. 1981a. Censusing and the evaluation of avian habitat.

Studies in Avian Biology 6:522-532.

Wiens. J. A., and J. T. Rotenberry. 1981b. Habitat associations and community structure

of birds in shrubsteppe environments. Ecological Monographs 51:21-41.

Wiens, J. A., J. T. Rotenberry, and B. Van Home. 1987. Habitat occupancy patterns of

North American shrubsteppe birds: the effects of spatial scale. Oikos 48:132-147.

Wilcove. D. S., D. Rothstein, and J. Dubow. 1998. Quantifying threats to imperiled

species in the United States. Bioscience 48:607-615.

Wolf, C. M .• T. Garland, and B. Griffith. 1998. Predictors of avian and mammalian

translocation success: reanalysis with phylogenetically independent contrasts.

Biological Conservation 86:243-255.

98