Phenological Relationships of Nesting Barn Swallows

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5-2014 PHENOLOGICAL RELATIONSHIPS OF NESTING BARN SWALLOWS IN A SWALLOW-FLY-CATTLE SYSTEM AND THEIR POTENTIAL ROLE IN SUPPRESSION OF PEST FLIES IN A WARMING CLIMATE Claire Stuyck Clemson University, [email protected]

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PHENOLOGICAL RELATIONSHIPS OF NESTING BARN SWALLOWS IN A SWALLOW-FLY-CATTLE SYSTEM AND THEIR POTENTIAL ROLE IN SUPPRESSION OF PEST FLIES IN A WARMING CLIMATE

A Thesis Presented to the Graduate School of Clemson University

In Partial Fulfillment of the Requirements for the Degree Master of Science Wildlife and Fisheries Biology

by Claire Michelle Stuyck May 2014

Accepted by: Dr. Ron J. Johnson, Committee Chair Dr. William C. Bridges Dr. Jeffrey C. Hallo

i ABSTRACT

Conservation efforts for birds that provide ecosystem services in agricultural systems require management approaches that cross disciplines. This information is communicated through a variety of outlets but rarely in ways that interface effectively with normal management approaches. The disconnect between agriculture and wildlife conservation reduces the likelihood that ecosystem service benefits will be realized. One understudied ecosystem service provided by birds such as barn swallows (Hirundo rustica) is their role in suppression of flies that are pests to livestock. Climate change, however, may differentially affect flies that respond largely to temperature, and swallows that migrate and respond to photoperiod and other local variables. Chapter two uses barn swallow nesting records from citizen science databases, and growing degree-days (GDD) to assess swallow nest initiation in relation to published GDD for fly emergence. Survival analysis indicates that GDD are a stronger indicator of when barn swallows nest than is day-of-year. Our day-of-year and GDD data provide no evidence to indicate that timing of barn swallow nest initiation has changed over time and nest initiation appears to be still in synchrony with fly resources. The use of GDD allows more precise tracking of swallow nesting and, as a common measurement tool, facilitates comparisons with fly emergence that can be used to elucidate interactions and management options across the swallow-fly-cattle system. To better understand the feasibility of incorporating barn swallows into an integrated pest management approach, it is important to consider the audience that will be implementing the technique. Chapter three documents perspectives of cattle organization leaders across the United States using an online questionnaire.

ii Overall response rate from the 320 leaders contacted was 48.8%. Follow-up phone interviews with a subsample of 25 leaders provided additional clarity and understanding.

Our results suggest that cattle organization leaders favorably view barn swallows and the potential benefits that barn swallow management might contribute to help reduce pest fly populations. Continued communication is needed as research is conducted toward development of sound management strategies that benefit swallow conservation and livestock producers.

iii DEDICATION

I dedicate this thesis to my parents, Christopher and Pamela Stuyck, who have never faltered in their encouragement and support in all endeavors I pursue.

iv ACKNOWLEDGMENTS

I am appreciative for the teamwork, efficiency, and expertise of my committee. I am especially thankful to my advisor, Dr. R.J. Johnson, who has not only guided and supported me in all facets of this project, he has taught and shared valuable experiences that continually strengthen and shape me as a student, teacher, researcher and, more importantly, as a person. I am thankful for Dr. W.C. Bridges’ expert knowledge, assistance, and instruction in statistical analysis. I am thankful for Dr. J.C. Hallo’s encouragement and guidance in all aspects of instrument design, protocol, and analysis. I am particularly thankful to J. Courter who nurtured and guided me in various stages of my project; our early brainstorming and his interest helped bring concept to reality. I am appreciative of the faculty and staff of both the SAFES and AVS departments who have continually provided a supportive and engaging work environment.

I thank my family and friends for their tireless encouragement and willingness to accept the engrossment of my fragmented mind. I am truly fortunate to have an enduring network that aided me even when I didn’t know I needed it. All the refreshing outdoor excursions, warm coffee, a steady supply of pickles, and subtle joys of the day-to-day will not be forgotten.

v TABLE OF CONTENTS

Page

TITLE PAGE ...... i

ABSTRACT ...... ii

DEDICATION ...... iv

ACKNOWLEDGMENTS ...... v

LIST OF TABLES ...... viii

LIST OF FIGURES ...... ix

CHAPTER

I. INTRODUCTION AND LITERATURE REVIEW ...... 1

References ...... 10

II. GROWING DEGREE-DAYS AS A TOOL TO TRACK PHENOLOGICAL RELATIONSHIPS OF THE BARN SWALLOW-FLY-CATTLE SYSTEM: IMPLICATIONS FOR SYNCHRONY IN RELATION TO A WARMING CLIMATE ...... 17

Abstract ...... 17 Introduction ...... 17 Methods ...... 22 Results ...... 24 Discussion ...... 25 Tables ...... 33 Figures ...... 37 Acknowledgements ...... 40 References ...... 40

III. PERCEPTIONS OF UNITED STATES CATTLE ASSOCIATION PRESIDENTS ABOUT BARN SWALLOWS AND THEIR POTENTIAL ROLE IN SUPPRESSION OF PEST FLIES ...... 47

vi Table of Contents (Continued)

Page

Abstract ...... 47 Introduction ...... 47 Questionnaire Methods ...... 52 Interview Methods ...... 55 Questionnaire Results ...... 56 Interview Results ...... 61 Discussion ...... 62 Tables ...... 70 Figures ...... 75 Acknowledgements ...... 80 References ...... 80

IV. CLOSING THOUGHTS AND REFLECTIONS ...... 85

References ...... 87

Page

APPENDICES ...... 89

A: Questionnaire Instrument ...... 90

vii LIST OF TABLES

Table Page

2.1 The measured ‘time to event’ methods and their corresponding strength of fit in the ‘nest initiation probability’ model including climate division as covariate ...... 33

2.2 Factors in growing degree-days models that affect the time-to-event ‘nest initiation probability’ for the first brood of barn swallow nesting, using January 1, Base 50°F ...... 34

2.3 Mean (with standard error) growing degree-days (GDD) and associated day-of-year (DOY) for first-egg dates of nesting barn swallows for 0.50 probability of nest initiation ...... 35

2.4 Growing degree-days (January 1, base 50°F, except as indicated for face fly) at first adult emergence of pest flies of cattle ...... 36

3.1 Percentages of reported membership demographics among beef, dairy, and OS groups ...... 69

3.2 Percentages of reported leader demographics among beef, dairy, and OS groups ...... 70

3.3 Correlations between leader and membership demographics ...... 71

3.4 Percentages of leaders in beef, dairy, and OS groups that answered agree or strongly agree to statements reflecting opinions of producers in their organization ...... 72

3.5 Percentages of leaders in beef, dairy, and OS group’s that answered agree or strongly agree to statements reflecting willingness to manage for barn swallows ...... 73

viii LIST OF FIGURES

Figure Page

2.1 Locations within the study region that reported nesting (n= 680) from the Puget Sound Bird Observatory (n=138; 2005-2012) and Cornell Lab of Ornithology Nest Record Program (n=542; 1965-1992) ...... 37

2.2 Nest initiation probabilities using the six growing degree-day calculation methods ...... 38

2.3 Barn swallow nest initiation probability in relation to growing degree-days (January 1st, base 50°F accumulation) ...... 39

3.1 Percent (%) of leaders indicating the extent to which barn swallows nesting on buildings is a problem ...... 74

3.2 Models of respondent willingness to consider managing barn swallows to protect them or reduce pest flies as part of an IPM scheme based on the extent to which nesting on buildings is a problem and group classification ...... 75

3.3 Codes and frequencies assigned for interview responses to the question “What are the most important issues with pest fly management?” ...... 76

3.4 Codes and frequencies assigned for interview responses to the question “What do you think about barn swallows?” ...... 77

3.5 Codes and frequencies assigned for interview responses to the question “Where do your views of barn swallows come from?” ...... 78

ix CHAPTER ONE

INTRODUCTION AND LITERATURE REVIEW

There is an increasing global awareness of the relationships between agriculture and wildlife conservation (Johnson et al. 2011) but few studies link these two fields

(Perrings et al. 2006). The intensity of agricultural practices harms birds, especially during important nesting periods (Møller 2001; Ambrosini et al. 2002; Baeta et al. 2012;

Robillard et al. 2013). The ecosystem services birds provide (e.g., pollination, nutrient cycling, seed dispersal, pest suppression; Sekercioglu 2012, Johnson et al. 2011) are increasingly being acknowledged in agriculture because of the potential value to both agriculture and wildlife (Whelan et al. 2008). Perhaps the greatest way birds support agriculture is by providing biological pest suppression in crop or livestock systems. For example, western bluebirds (Sialia mexicana) nesting in Californian vineyards result in lower larval beet armyworm populations (Jedlicka at al. 2011), nesting falcons reduce grape damage in New Zealand (Kross et al. 2011), and insectivorous birds on Central

American coffee farms experienced significantly lower damage from the coffee berry borer (Hypothenemus hampei; Johnson et al. 2010, Karp et al. 2013). This information is communicated through a variety of outlets but rarely in ways that interface effectively with normal management approaches. The disconnect between agriculture and wildlife conservation reduces the likelihood of realized benefits of ecosystem services. One understudied ecosystem service provided by birds such as barn swallows (Hirundo rustica) is their role in suppression of flies that are pests to livestock.

Pest flies and Cattle

1 Four fly species of special interest are horn flies (Haematobia irritans), face flies

(Musca autumnalis), house flies (Musca domestica) and stable flies (Stomoxys calcitrans). These flies spend the majority of their life cycles in conjunction with cattle and all rely on the manure and soiled hay of cattle to reproduce (Hall et al. 1982; Meyer and Petersen 1983; Mullens and Meyer 1987; Schmidtmann 1988; Krasfur and Moon

1997; Krafsur et al. 1999; Castro et al. 2008). Both horn and stable flies are biting flies associated with decreases in livestock weight gains and milk production. For example, the horn fly is estimated to cost the cattle industry US$730 million in lost production of milk and daily gains of meat cattle annually (Drummond et al. 1981; Schmidtmann

1985). Stable flies are considered to be the second most important pest overall to cattle and they cost the beef cattle industry about $2.2 billion a year (Taylor et al. 2012). House and face flies, in contrast, are non-biting flies that cause irritation and increased tearing around the eyes of cattle. These flies are associated with disease transmission

(particularly pink eye and Thelazia eyeworms; Rutz et al. 2010). Other negative effects include reduced feed conversion efficiency, increased stress on young animals, blood loss, hide damage, public health, and public nuisance concerns (Campbell et al. 1981;

Kinzer et al. 1984; Byford et al. 1992; Wieman et al. 1992; Campbell et al. 2006; Rutz et al. 2010).

Historically, conventional methods of controlling these pests involved insecticide applications to the animal or animal areas around the farm or as feed additives (Benson and Wingo 1963; Mian and Mulla1982; Rutz et al. 2010). These methods are not totally effective. Currently, there are no known effective measures to control stable flies

2 (Ferguson 2011). Additionally, there are mounting concerns regarding insecticide resistance. For example, high levels of pyrethroid (a synthetic chemical insecticide) resistance are observed in areas across the United States (Rutz et al. 2010). Face, house, and horn flies are documented to develop resistance to pesticides over time (Scott et al.

2000; Marçon et al. 2003; Oyarzún et al. 2008; Kaufman et al. 2009; Rutz et al. 2010).

Rutz et al. (2010) suggest that repetitive treatments of insecticides kill a larger proportion of natural enemies of pest species and create conditions that require subsequent treatments to maintain reduced fly populations. Not only is it difficult to determine the detrimental costs of fly pests, it is difficult to quantify the effects of pest suppression methods. With the creation of Integrated Pest Management (IPM) programs, alternative methods to control harmful pests, including pest flies, have become more readily adopted.

Barn Swallows and Cattle

A preference for nesting around human-made dwellings near cattle dates back over 2,000 years (Møller 1994) and additional evidence of the barn swallows’ close relationship with cattle and people can be found in literary works such as the Bible

(Psalms 84:3, Isaiah 38:14, Jeremiah 8:7), Shakespeare (Richard III Act 5, The Winter’s

Tale Act 4), and Aristotle (Nicomachean Ethics) as well as cultural superstition. It was once believed that if a barn swallow’s nest was destroyed that a farmer’s cows would no longer produce milk or that their milk would turn bloody (Cocker and Mabey 2005).

With the onset of industrial agricultural methods, barn swallow and other bird populations have declined in agricultural areas (Brown and Brown 1999, Marzluff et al.

3 2001, Møller et al. 2008). Møller et al. (2008) identifies bird species, such as the barn swallow, that are long distant migrants, aerial insectivores, and farmland habitat specialists to be at risk of altered migration and nesting phenology, in addition to declines, because they are susceptible to the effects of agricultural intensification, urbanization, and increased insecticide usage. Possible explanations for barn swallow declines are thought to involve loss of habitat in rural areas as rural areas are converted to urban and suburban development (Brown and Brown 1999). Evidence of barn swallow declines resulting from urbanization is particularly strong near cattle operations where barn swallows have maintained populations historically (Møller 2001).

Grüebler et al. (2010) hypothesized that foraging conditions are more favorable around cattle because of the prevalence of dung that many insects, including flies, use for breeding and consumption. Despite the flies and other insects that cattle attract, the pesticides used to combat insect pests have been implicated in previous barn swallow population declines in Israel (Turner 1991). Boutin et al. (1999) lists the barn swallow as a species at risk from pesticide use because they exhibit high feeding site fidelity and are thus more likely to be exposed to pesticides. Also contributing to their preference for farms, barn swallows gain an advantage from nesting in higher and more constant temperatures provided by buildings housing livestock (Gruebler et al. 2010). Changes in the design and construction of these buildings through the use of materials such as vinyl and metal siding have resulted in unsuitable nesting sites (Erskine 1992). Gruebler et al.

(2010) argued that keys to increasing barn swallow populations were to improve foraging conditions with increased airborne insects (including flies) and to ensure quality

4 microclimate around the nest. Both the negative and positive effects of farm activities on barn swallows populating livestock farms have been investigated. However, the benefits that barn swallows contribute to livestock production have not been well studied.

Studies comparing the success of barn swallows on conventional and organic farms have found varied results, in part because organic farms vary in degree of being wildlife-friendly (Quinn et al. 2012). Studies conducted in the Great Plains of the United

States found higher barn swallow numbers on organic farms than nonorganic (Beecher et al. 2002); overall differences were attributed to vegetation and associated food resources on organic farms. In contrast, Kragten et al. (2009) found that organic farms in the

Netherlands did not attract more barn swallows than conventional farms and they did not attribute the differences between organic and conventional farms as a factor in barn swallow declines.

Barn Swallows and Flies

Barn swallows are solely insectivorous and previous studies suggest that their nesting cycles coincide with abundance of insects needed to support themselves and raise viable young (Robins 1970) but a direct relationship between nesting date and insect phenology has not been investigated in the United States. As noted above, barn swallows, flies, and cattle have been affiliated for over 2,000 years (Møller 1994). Two millennia is probably enough time to allow for natural selection to favor barn swallows that coincide nesting dates with peaks in fly populations. Lack (1950) states that natural selection has promoted concurrence of breeding seasons and optimal food availabilities, better ensuring the greatest success in raising offspring. Flies are the most common insect in the

5 barn swallow diet (39.5% overall and up to 82% in spring) in North America (Beal 1918;

Brown and Brown 1999). Because barn swallows also forage near the ground (usually between 1-10m up) they consume flies in the same space where cattle experience pest fly populations. Moreover, barn swallow foraging may provide further benefit by disturbing fly activity, resulting in less feeding time for flies and increasing the likelihood that they might be captured by other fly management tools (e.g., fly tape).

Barn swallows do not directly harm agricultural production, although there are concerns about the concentration of droppings under nests around buildings that shelter livestock or people (Fossler et al. 2005; Pangloli et al. 2008). Thus, although generally seen as beneficial birds, barn swallow nests are often removed from around buildings. A consequence of nest removal is fewer breeding swallows returning in subsequent years

(Safran 2004). Recent studies have cast considerable doubt on barn swallows acting as vectors for disease such as Salmonella (Haemig 2008). Barn swallow use of nest structures near people makes them easier to manage and attract compared with other aerial insectivores. Nesting conflicts could potentially be reduced and foraging benefits enhanced with proper management of droppings and nest placement away from problem areas (Link 2005).

Although the majority of farmers studied in Florida (Jacobson et al. 2003) and in

Cuetzalan, Mexico (Lopes-del-Toro et al. 2009) reported that they enjoy birds and recognize several species of birds on their farms, many producers are unaware of the important pest suppression services birds provide and they lack the resources needed to manage for sustainable bird populations on their farms. If farmers recognized direct

6 benefits of barn swallows associated with pest fly suppression, they might encourage barn swallows (e.g., by providing or maintaining nesting structures) in sites that did not conflict with human health or activities.

Producer Perspectives

A key question about barn swallows around livestock is how producers perceive the presence of these birds on their farms or near their buildings. Perspectives of nature and the environment are typically thought to be more positive with organic or sustainable producers than with conventional (Kragten et al. 2009). Studies conducted in the

Netherlands, however, suggest that both conventional and organic farmers have similar positive feelings towards barn swallows (Lubbe and De Snoo 2007; Kragten et al. 2009).

Perspectives in the United States may differ from those in Europe. Factors such as leadership within the cattle industry and pest management techniques have not been investigated in relationship to attitudes towards ecosystem services provided by barn swallows. Furthermore, it appears there are no studies assessing the perceived role of barn swallows on cattle farms or the willingness of producers to manage for barn swallows. Documenting the perspectives of cattle producers will help to determine where education and management suggestions can be created or emphasized to 1) meet the needs and interests of producers, and 2) understand barriers and incentives for the incorporation of barn swallows in Integrated Pest Management schemes.

Growing Degree Days

Growing degree days (or accumulated heat units) are familiar to most producers and used regularly in agriculture to schedule the most efficacious times for planting and

7 pesticide applications (Adams undated; Miller et al. 2001; Murray 2008). Because the phenology of plants and invertebrates highly depends on growing degree-days (UC IPM

2003), heat units could also affect species at higher trophic levels (such as barn swallows) that feed on insects. Preliminary assessments suggest that barn swallow clutch initiation date is influenced by spring temperatures (Dolenec et al. 2009) and a recent study conducted in Denmark found that higher degree days at the time of breeding were associated with smaller second clutches (Ambrosini et al. 2011). The smaller second clutches occurred apparently because of nesting asynchrony with maximum quantities of food resources (Ambrosini et al. 2011). The importance of synchrony with food resources has been shown in other studies; for example, by shifting egg laying in warmer years, female great tits (Parus major) are more synchronized with local food resources and maintained high reproductive fitness (Schaper et al. 2012). It has not been investigated whether a correlation between growing degree-days and clutch initiation in barn swallows exists in the United States. An ability to predict specific lifecycle stages such as nest initiation could allow refinement of management practices (such as adjusting insecticide application schedules that effect fly species) to benefit the health of bird populations that provide important farm services. Moreover, a correlation between nest initiation in barn swallows and growing degree-days would allow comparisons to pest fly emergence, predicted using growing degree-days.

Project Goals

The goal of this project is to elucidate the ecological relationships and associated mechanisms between barn swallow (Hirundo rustica) nesting ecology and the emergence

8 of several costly and harmful livestock pests, particularly horn flies (Haematobia irritans), face flies (Musca autumnalis), house flies (Musca domestica) and stable flies

(Stomoxys calcitrans). Because of their previously noted negative effects on cattle and production, these four species of flies are the primary livestock pests included in this project.

My research goal was to develop a simple method to predict barn swallow nesting dates using growing degree-days and to examine patterns between barn swallow nesting phenology and fly abundance. I used historical and recent barn swallow data from citizen science resources to examine whether growing degree-days (a standard method for predicting insect and plant life cycles) are a viable means of predicting barn swallow nest initiation. Chapter one provides an overall introduction and literature review. Chapter two investigates the hypothesis that there is a predictable relationship between barn swallow nesting and cumulative temperature, measured through growing degree-days. I further investigate whether this relationship can be used to provide specific management recommendations to livestock producers. If nesting date and growing degree-days or other measurable weather variables are interlinked, comparisons can be made between the life cycles of barn swallows and fly pests to determine whether synchronous or asynchronous trophic linkages between them exist. Understanding how these linkages interface helps broaden understanding about how climate change affects species that respond to different phenological cues. Because barn swallows respond to photoperiod and experience a variety of weather conditions across broad migratory routes (Balbontin et al. 2009), they could be responding to climate change differently from flies that

9 respond largely to local temperature (Berry and Campbell 1985; Lactin et al 1995).

Furthermore, chapter three addresses cattle organization leaders’ perspectives, and future research questions geared towards their interests. Overall conclusions from my research and lessons learned along the way are contained in chapter four. Chapters two and three are written in publication formats.

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16 CHAPTER TWO

GROWING DEGREE-DAYS AS A TOOL TO TRACK PHENOLOLGICAL RELATIONSHIPS OF THE BARN SWALLOW-FLY-CATTLE SYSTEM: IMPLICATIONS FOR SYNCHRONY IN RELATION TO A WARMING CLIMATE

Abstract Barn swallows, cattle, and various fly species have lived in close association for

>2,000 years. Flies breed in manure and are harmful pests of cattle. Barn swallows consume flies (~82% of nesting diet) and likely disturb fly activity, potentially an additional tool to reduce fly impacts. Climate change, however, may differentially affect flies that respond largely to temperature, and swallows that migrate and respond to photoperiod and other local variables. We used Barn Swallow nesting records, from citizen science databases, and growing degree-days (GDD) to assess swallow nest initiation in relation to published GDD for fly emergence. Survival analysis indicates that

GDD are a stronger indicator of when barn swallows nest than is day-of-year. Our day- of-year and GDD data provide no evidence to indicate that timing of barn swallow nest initiation has changed over time and nest initiation appears to be still in synchrony with fly resources. Spatial variation in response to GDD, however, for both flies and swallows, indicates a need to assess interactions on a site-by-site basis. The use of GDD allows more precise tracking of swallow nesting and, as a common measurement tool, facilitates comparisons with fly emergence that can be used to elucidate interactions and management options across the swallow-fly-cattle system.

Introduction

17 The timing and driving mechanisms behind important life-cycle events, particularly reproduction, have been widely studied for decades. Photoperiod is traditionally accepted as a key factor in the endogenous rhythms that govern reproductive cycles in birds (Farner 1964; Sharp 1996; Sharp 2005). Recently, temperature and precipitation have received increasing attention for their role in reproductive events such as clutch size (Lloyd 1999; Winkler et al. 2002), clutch initiation (Visser et al. 2009), reproductive success (Stevenson and Bryant 2000) and behavior (Conway and Martin

1999).

Breeding and migration are the most energetically costly life-cycle events birds experience (Visser and Both 2005). Food resources must provide sufficient energy and nutrients to produce eggs, raise offspring, and better ensure the survival of fledglings

(Perrins 1965; Charmantier et al. 2008) and parents (Thomas et al. 2001). Arguably, long-distance migrants that breed in the temperate zone must rely on short fluctuating seasons of food availability to provide adequate food resources to achieve reproductive success and maintain suitable condition to migrate at the end of the season (Klaassen

1996).

The timing of peak food resources varies spatially and temporally. Endogenous mechanisms and responses of birds to local factors tend to synchronize the timing of nesting with availability of food resources (Carey 2009). Many species such as great tits

(Parus Major), zebra finches (Taeniopygia castanotis), and budgerigars (Melopsittacus undulates) show annual variation of clutch initiation in association with weather conditions (Schaper et al. 2011; Davies 1977; Wyndam 1980).

18 Responses to climatic trends have become increasingly relevant in recent years as concerns about the impacts of global climate change on trophic linkages between birds and their food resources have been investigated. Of particular concern are the trophic linkages between birds that perform ecosystem services (e.g., pollination, pest suppression) and their food resources. The potential reduction or loss of bird-derived ecosystem services because of global climate change-induced asynchrony could result in realized losses of economic, social, cultural, and ecological value (Şekercioğlu et al.

2004; Schröter et al. 2005; Montoya and Raffaelli 2010). It is therefore imperative to assess important phenological events and to understand the associated mechanisms that affect life-cycle events such as breeding. A challenge in evaluating trophic linkages between birds and their food resources is the lack of a “universal yardstick” to track phenological relationships (Visser and Both 2005). Birds, which are endothermic and highly mobile, differ from their food resources such as invertebrates and associated vegetation, which experience a spatially narrow range of climatic conditions. Local invertebrates and invertebrate-associated vegetative growth may be responding to seasonal cues that migratory birds do not experience from wintering grounds.

An evolutionary relationship that may be experiencing asynchrony associated with climate change is that of the barn swallow (Hirundo rustica) and its main invertebrate food resource, flies (Diptera). The barn swallow is a globally occurring long- distance migrant in decline (Møller et al. 2008; Nebel et al. 2010) and is an obligate aerial insectivore that has preferentially lived around cattle for over 2,000 years (Møller 1994a).

Dipteran flies make upwards of 82% of the breeding barn swallow’s diet (Brown and

19 Brown 1999). The historic relationship between domestic cattle and barn swallows may have developed from the increased biomass and quantity of flies (Diptera) associated with cattle operations. It has been well documented that reproductive success, number of breeding pairs, and offspring survival of barn swallows increases around cattle farming

(Møller 1984, 2001; Ambrosini et al. 2002; Grüebler et al. 2010). Grüebler et al. (2010) found that proximity of livestock and manure around nest sites increased the annual output of barn swallows by 1.6 chicks. Barn swallows probably nest when fly populations around cattle are sufficient to meet high energetic demands of breeding. Robins (1970) suggested this relationship between timing of nest initiation and fly abundance is critical for healthy adults and successful rearing of viable young. Flies are attracted to cattle as a food resource and for the fecal substrate used for reproduction (Coffey 1966).

Consequently, the cattle industry suffers substantial direct and indirect economic losses associated with flies (Rutz et al. 2010). For example, stable flies cost the beef cattle industry about $2.2 billion a year (Taylor et al. 2012). Barn swallows may reduce the harmful effects of fly pests on cattle by consuming flies and by disturbing fly activity.

Because barn swallows respond to photoperiod and experience a variety of weather conditions across broad migratory routes (Balbontin et al. 2009), they could be responding to climate change differently from flies that respond largely to local temperature (Berry and Campbell 1985; Lactin et al 1995). Thus, a question in the swallow-fly-cattle system is how barn swallows compared to flies are responding to climate change and whether asynchrony in bird-fly trophic relationships could be developing.

20 Courter (2012) proposed the concept of growing degree-days (GDD) as a potential tool to predict nesting dates of birds and to assess associated effects of temperature on their food resources. Many organisms (e.g., invertebrates and plants) require a certain amount of heat to complete development, which is often referred to as physiological time (UC IPM 2003). GDDs or accumulated heat units is a calculated measure of physiological time, using upper and lower temperature development thresholds; the accumulated temperature between thresholds required to complete development remains fairly constant for a specific plant or invertebrate organism

(McMaster and Wilhelm 1997; UC IPM 2003). Bridging the gap across trophic levels would provide a useful assessment and management tool for evolutionary-ecological linkages, and would be a valuable asset to phenological studies of species that may be affected by global climate change.

GDDs is a concept familiar to most agricultural producers and is used regularly to schedule planting times and pesticide applications to optimize product growth (Adams undated; Miller et al. 2001; Murray 2008). The phenology of plants and invertebrates depends largely on temperature and GDDs (UC IPM 2003), and could also affect species at higher trophic levels. Preliminary results suggest that barn swallow clutch initiation date is influenced by spring temperatures (Dolenec et al. 2009) and a recent study conducted in Denmark found that higher GDD at the time of breeding were associated with smaller second clutches (Ambrosini et al. 2011). This reduction in clutch size could be linked with an asynchrony associated with peak food resources.

21 The Denmark study found a relationship between GDD and clutch initiation

(Ambrosini et al. 2011) but no such correlation has been described in North America.

Such a relationship could be used to assess the timing of barn swallow nesting in relation to food resources, represented by the emergence of flies in the swallow-fly-cattle system.

This study investigates the hypothesis that there is a predictable relationship between cumulative temperature, measured through GDD, and nest initiation. If nesting date and measurable weather variables are interlinked, comparisons can be made to determine whether the timing of barn swallow nesting has changed in relation to the timing of fly emergence. If historical relationships have remained constant, the GDD of barn swallows and that of flies would have the same pattern now as in the past. If flies still emerge at similar GDD as in the past, as expected (Higley et al. 1986; Iler et al. 2013), but barn swallows have changed, then the potential for developing asynchrony between swallow nesting and fly emergence would be expected. Furthermore, we suggest this relationship could be used to develop specific management recommendations to livestock producers.

Methods Data Collection We transcribed historical nesting data (1965-1992) from nesting cards provided by Cornell Lab of Ornithology Nest Record Program. Recent data (2005-2012) were provided by the Puget Sound Bird Observatory (PSBO) that conducts an ongoing study of barn swallow nesting at the Woodland Park Zoo in Seattle, Washington. We used only nest records that included multiple observations and a clearly identifiable first egg date.

Nest initiation was defined as the first egg date, the date the first egg of the clutch was

22 laid. Each entry was verified for transcription accuracy by a second person prior to analysis. We analyzed 680 nesting records total across five states; Nebraska, New York,

Ohio, and Wisconsin nests were historical (1965-1992, n=542) and Washington nests were recent (2005-2012, n=138) (Figure 2.1). Weather data were accessed through the

National Climate Data Center (http://www.ncdc.noaa.gov) and High Plains Regional

Climate Center (http://www.hprcc.unl.edu/). First-egg dates were then matched with the weather data, which included climate division and accumulated GDD based on specific start dates and base temperatures. Climate divisions were originally established by the

USDA’s Weather Bureau and are defined within a state by county lines, drainage basins, or major crops (Guttman and Quayle 1995). They track general climatic conditions and act as a good metric for local climate (Courter et al. 2013).

Data analysis Nesting dates were converted into day-of-year using a Microsoft Excel 2010 ‘day of year’ function. The barn swallow is a double-brooded species and nesting data exhibited a bimodal distribution. To differentiate between first and second broods, multivariate cluster analysis was used to divide nesting dates into two groups.

Observations that were more than three standard deviations from the overall mean of the first brood were considered to be recording errors (outliers) and were removed from the data set (Courter et al. 2013). One standard deviation represented 10.63 days (mean day- of-year = 148.82; standard error of mean = 0.51) for the first brood. No observations in our data fell outside three standard deviations. The second brood was excluded and the first brood was used for analysis.

23 A “survival analysis” approach was used to model the relationship of nest initiation probability and time-of-year. Survival analysis is a collection of statistical methods that have been used in a variety of disciplines to answer questions related to timing and duration until the occurrence of an event (Mills 2011). Previous nesting studies have applied survival analysis techniques to answer questions related to nesting success (Nur et al. 2004), longevity, and lifetime reproductive success (Saino et al. 2012).

In our study, we evaluated the fit of day-of-year and of GDD variables to the occurrence of nest initiation. For GDD assessments, we used two base temperatures (Base 50°F or

41°F) and three accumulation start dates (January 1st, March 1st, or May 1st). The decision concerning which measure of time-of-year provided the best fit to use in subsequent analyses was based on whole model chi-square tests. ‘January 1, base 50°F’ provided the strongest fit and was used in subsequent models to develop the best predictive model of clutch initiation. We included latitude, longitude, year, and climate division as covariates.

To meet convergence assumptions, climate division designation for an individual nest was adjusted to the nearest climate division when no other nest was contained in its initial designation. The time-of-year associated with 0.25, 0.50, and 0.75 probability of nest initiation were estimated for specific locations, latitudes, longitudes, years, and climate divisions of interest. All calculations were performed using JMP (JMP 10.0, SAS

Institute).

Results All of the six GDD methods assessed in this study were more strongly related to nest initiation than was traditional day-of-year (Table 2.1, Figure 2.2). Among the

24 different GDD methods, base 50°F with accumulation from January 1st provided the best measure of time-of-year in the survival analysis model. Improved models included latitude and longitude as highly significant effects, but when climate division was included, both latitude and longitude became nonsignificant (Table 2.2). The term ‘year’ was not significant in any model, indicating that the probability of nest initiation was independent of year. Climate division was the only significant covariate in the best fitting survival analysis model (x2 = 266.69, p<0.0001; Table 2.1). Although GDD provides better model fit, there is wider spatial variation in accumulated GDD than in DOY across specific nest initiation locations (Table 2.3).

Discussion One ecological question that is becoming increasingly relevant is how birds and their food resources are responding to warming temperatures, and whether the timing of key events is remaining in synchrony. Our data show that temperature accumulation measured as GDD is a strong predictor of nest initiation probability for barn swallows.

DOY was also found to be a good predictor of nest initiation, but was not as effective as

GDD at predicting response, even though day-of-year seems relatively consistent. The large spatial differences in mean GDD may be explained by regional weather effects that climate division encompasses in our models. The nest initiations used in our study occurred between a fairly narrow range of latitudinal bands (i.e., 41 to 47 degrees N) but across considerable longitudinal variation (i.e., -122 to 72 degrees W). This variation in latitude and longitude, which was used in early models and encompassed in later models by the ‘Climate Division’ term, suggested that more northern nesting barn swallows

25 might respond differently to GDD than more southern. Latitudinal variation between northern and southern bands has been reported in other studies (Balbontin et al. 2009), and was evident in our results. Moreover, land features such as large bodies of water may affect response of birds to GDD. For example, in Nebraska, half of nesting barn swallows had laid their first-egg by 827 GDD, a considerably larger threshold than in any other state (Table 2.3). Nebraska is the only state in our study without a large body of water and subject to wide daily temperature variation. This may be further supported by our data in that both Wisconsin and Nebraska shared the same mean day-of-year to nest initiation (152 DOY) but Wisconsin barn swallows were found to have laid their first egg by 553 GDD. Because of spring weather variability in Nebraska, barn swallow populations may require more GDD (i.e., delay nesting) until sufficient GDD have accumulated to ensure that vital food resources are reliable and abundant enough to produce and raise young. All other states in our study are bordered by large bodies of water, which influence weather and may be responsible for other region-specific cues.

Our results provide no evidence that recent nest initiation dates differ from historical although the variability of local weather across sites makes comparison difficult with the available data. Mean DOY dates for nest initiation show a fairly narrow range and no pattern (χ2 = 0.322; p = 0.570) to indicate a difference between recent (2005-2012,

Washington) and historical (1965-1992, other sites) periods (Table 2.3). Although growing degree-days provide a closer model fit to nest initiation, the wide variation in

GDD across sites does not allow across-site comparison to fly emergence data. GDD for recent data from Washington, however, was 170, which was the lowest of all sites and

26 opposite of what would be expected if the swallows were responding to climate change.

For example, Ambrosini et al. (2011) found barn swallows in Denmark initiating nests at higher GDD over time, as expected if they were responding to a warming climate. In our case, the low GDD in Washington was likely related to the cool local and relatively stable climate. This site is also on the western side of the state and close to Puget Sound. Both the sound and the Pacific Ocean could help stabilize the weather in western Washington, resulting in less GDD accumulation while at DOY similar to that of other sites.

These findings show that use of GDD will require assessment within areas of similar climate unless a more universal GDD method is found. One potential new approach to reduce site-to-site variability in GDD calculations is the use of remote sensing technologies (e.g., Moderate Resolution Imaging Spectroradiometer; MODIS) and its derived products (e.g., Normalized Difference Vegetation Index; NDVI) to indicate the starting time of green-up (Zhang et al. 2007). The tight linkages between these high resolution satellite images and green-up closely relates to site-specific temperature (Pettorelli et al. 2005) and, thus, insects, and appears to improve GDD calculations (Courter 2012). These technologies were not available for the historical nest initiation years included in this study but may eventually refine and provide a more accurate link between GDD calculations and organisms over wide spatial scales.

Regardless of the site variability, our findings show that within site, GDD provides a better fit for nest initiation than does DOY, a relationship that may become increasingly relevant as climate warms because, unlike DOY, GDD dates are based on biological relationships between accumulated heat units and associated food resources for swallows.

27 Moreover, the establishment of a tool that spans trophic levels provides a basis for further study, as we better understand the linkages within the system.

An important factor in nest initiation timing for long-distance migrants is the timing of arrival from wintering grounds. Barn swallows in North America have been reported to arrive earlier; for example, Butler (2003) reports that barn swallows arrive back to Cayuga Lake Basin, NY six days earlier on average than in historical periods.

Earlier arrival may allow barn swallows to arrive with enough time to adjust and respond to temperature cues in breeding grounds to maintain consistent nest initiation from year- to-year. Our data suggest a lack of year-to-year variation in nest initiation and that barn swallows are continuing to follow historical nesting patterns, especially in relation to

GDD, despite climate change. Our findings differ from a European study where barn swallows were found to be initiating clutches at increasingly higher GDD, suggesting a mismatch with local spring phenology in Denmark (Ambrosini et al. 2011). Earlier migratory returns may allow time to catch important nesting phenology cues that facilitate local assessment of food potential, important for an aerial insectivore where temperature variability affects immediate food availability (Jones 1987). While records indicate that barn swallows are arriving earlier in both North America and Europe

(Tryjanowski et al. 2002; Mills 2005), the Denmark clutch-initiation study (Ambrosini et al. 2011) occurred at a high latitude (57°N) where the effects of climate change on phenology are expected to be much more pronounced (Stenseth and Mysterud 2002).

This difference in latitude may explain the differences in synchrony between Ambrosini et al. (2011) and our findings. Our findings provide evidence that GDD for barn swallow

28 nest initiation in our study have not changed over time and that barn swallows are still in synchrony with needed food resources to reproduce successfully.

Published GDD for fly emergence allow comparisons with GDD for our barn swallow nest initiation, resulting in a common tool to evaluate interactions across trophic levels. The relationship with GDD for both, however, is variable across space and identifies a need to assess synchrony on a site-by-site basis to accurately understand interactions. Castro et al. (2008) notes in his study of the horn fly that predicted development times for populations outside their study area may be different if those flies evolved different thermal requirements. Based on literature searches, it appears that first emergence data for flies and for barn swallow nesting are currently limited. Our data in conjunction with what is known of fly emergence phenology provides an initial assessment of the swallow-fly-cattle system as a guide until additional site-specific data are available. Fly first-emergence data found in literature, at latitudes similar to our barn swallow data, report emergence to occur around 100 GDD (January 1st, base 50°F accumulation) with ranges from 40 to 296 GDD (Table 2.4). Fly response to GDD is expected to remain constant in relation to local temperatures but there are other factors that may influence fly emergence that have not yet been well studied (Ellwood et al.

2012). We assume that fly populations after first emergence, while cyclic and subject to variable weather conditions, likely remain at sufficient levels to support breeding barn swallows. Prior to first emergence, levels of flies are expected to be insufficient to support nesting. Based on timing of fly emergence reported in literature in comparison to

GDD for barn swallow nest initiation from our study, most barn swallows initiate nesting

29 at about the time of fly emergence (Figure 2.3). These findings indicate that barn swallows are nesting during periods expected to have sufficient levels of flies to support breeding needs and, thus, are in synchrony with their flies. Although nesting barn swallows in our study appear to be in synchrony overall, individual populations may be experiencing asynchrony with fly resources. For example, in a Washington climate division where we lack fly emergence data, 50% of barn swallows have nested by 170

GDD, compared to the overall mean of 366 GDD across all sites (Table2.3).

Even though this study indicates that barn swallow nest initiation relates to temperature, swallows are endothermic and may respond to other cues such as nest site fidelity, sexual selection (Møller 1994b) and additional weather variables (e.g., precipitation) when making nesting decisions. In addition, barn swallows are migratory and may be responding to other cues in other locations along their migratory route rather than solely in their nesting grounds. For example Sayago and MacGregor-Fors (2010) found that precipitation in Mexican wintering grounds affected arrival to breeding grounds, which in turn may have an effect on nesting timing and reproductive success

(Møller 1994b).

The observed relationship with GDD may be explained physiologically through the endogenous mechanisms that govern avian reproduction. Barn swallows are income breeders (i.e., form eggs from current food intake; Ward and Bryant 2006) and rely on weather-dependent food resources. While opportunistic, the inability to use alternative food resources necessitates strategies to optimize parental survival, sometimes at the cost of seasonal reproductive success. Glucocorticoid corticosterones, the main energy-

30 regulating hormones in birds that are released in response to stressful events (Wingfield and Kitaysky 2002), are responsible for behavioral and physiological changes during nesting. Barn swallows in a Switzerland study experienced significant increases in plasma corticosterone when mean daytime temperature declined, and thus insect availability and parental body mass decreased (Jenni-Eiermann et al. 2007). Elevated glucocorticoids have been correlated with reduced nestling feeding rates and increased likelihood of nest abandonment (Jenni-Eiermann et al. 2007). Further, barn swallows experiencing lower temperatures in the days preceding clutch initiation and, thus, in poor physical condition due to less insect availability, produce eggs smaller in mass and with less antioxidants and immune factors, which may also reduce hatchability (Saino et al.

2004). The physiological relationship between elevated glucocorticoids brought about by poor weather conditions and, thus, reduced insect quantity and quality, may be especially strong in barn swallows. It is possible that these physiological responses through natural selection have resulted in barn swallows that have higher lifetime reproductive success and parental survivability when responding to temperature when making nest timing decisions.

Understanding the mechanisms behind reproductive timing in relation to food resources, and the availability of an applicable measurement tool, allows integrated approaches to be created that benefit both barn swallows and cattle producers seeking to reduce pest fly populations. Enacting management decisions that aid barn swallows during important nesting events may aid populations in decline. Although our data suggest that barn swallows in northern latitudes of the United States in North America are

31 still in synchrony with fly food resources overall, individual populations may differ. We demonstrate that GDD are a viable measurement tool that spans trophic levels, allowing assessment of barn swallow nest initiation trends in relation to an insect food resource, and a basis for the phenological evaluation of how climate change affects the swallow- fly-cattle system. Moreover, the use of GDD provides a familiar communication tool for phenological information that stakeholders can apply in management of the swallow-fly- cattle system.

32 Tables

Table 2.1: The measured ‘time to event’ methods and their corresponding strength of fit in the ‘nest initiation probability’ model including climate division as covariate.

TIME TO EVENT METHOD* χ2 P-VALUE Day-of-year 48.0089 0.0003 GDD base 50°F, January 1st accumulation 266.6883 <0.0001 GDD base 50°F, March 1st accumulation 188.8248 <0.0001 GDD base 50°F, May 1st accumulation 67.5835 <0.0001 GDD base 41°F, January 1st accumulation 264.8939 <0.0001 GDD base 41°F, March 1st accumulation 203.2807 <0.0001 GDD base 41°F, May 1st accumulation 52.6883 <0.0001

• GDD (Growing degree-days) or accumulated heat units are a calculated measure of

physiological time based on the accumulated temperature between an upper and lower

threshold from a set starting date (UC IPM 2003).

33 Table 2.2: Factors in GDD models that affect the time-to-event ‘nest initiation probability’ for the first brood of barn swallow nesting, using January 1, Base 50°F.

NEST INITIATION PROBABILITY χ2 P-VALUE FACTOR Latitude 0.4677 0.4940 Longitude 0.8496 0.3567 Year 0.2097 0.6470 Climate Division 86.6946 <0.0001

Table 2.3: Mean (with standard error) GDD and associated day-of-year (DOY) for first- egg dates of nesting barn swallows for 0.50 probability of nest initiation at one specific site in each state represented in this study.

STATE (COUNTIES) CLIMATE MEAN GDD MEAN DOY* DIVISION (SE) (SE) Nebraska (Johnson, Adams) 2508 827 (75.6) 152 (2.1) New York (Seneca, Thompson) 3010 326 (11.5) 147 (0.8) Ohio (Lake) 3303 379 (20.2) 146 (1.2) Wisconsin (Lacrosse) 4704 553 (56.9) 152 (2.4) Washington (King) 4503 170 (7.7) 151 (1.1) Overall ---- 366 (9.2) 149 (0.5) *DOY (day-of-year); for example, 149 is equivalent to May 29.

35 Table 2.4: GDD (January 1, base 50°F, except as indicated for face fly) at first adult emergence of pest flies of cattle, based on literature shown.

FLY SPECIES EMERGENCE LOCATION SOURCE house fly (Musca domestica) 99.8 ± 28.4 Alberta, Canada Lysyk 1993 stable fly (Stomoxys 114.4 ± 15.2 Alberta, Canada Lysyk 1993 calcitrans) 40-296 Ontario, Beresford and Sutcliffe 2009 Canada 235 Nebraska Taylor and Berkebile 2011 face fly (Musca autumnalis) 70* California, Krasfur and Moon 1997 Iowa, Minnesota horn fly (Haematobia No data found irritans)

* 70 GDD base 12°C

36 Figures

Figure 2.1: Locations within the study region that reported nesting (n= 680) from the

Puget Sound Bird Observatory (n=138; 2005-2012) and Cornell Lab of Ornithology Nest

Record Program (n=542; 1965-1992).

January 1, Base 50 January 1, Base 41 1.00.0 1.00.0

0.80.2 0.80.2

0.60.4 0.60.4

0.40.6 0.40.6

0.2 0.2 0.8 0.8

0.0 0.0 1.0 1.0 0 200 400 600 800 1000 0 500 1000 1500 2000

March 1, Base 50 March 1, Base 41 1.00.0 1.00.0

0.80.2 0.80.2

0.60.4 0.60.4

0.40.6 0.40.6

0.2 0.2 0.8 0.8

0.0 0.0 1.0 1.0 0 200 400 600 800 1000 0 500 1000 1500 2000

Probability of Nest Initiation May 1, Base 50 May 1, Base 41 1.00.0 1.00.0

0.80.2 0.80.2

0.6 0.4 0.60.4

0.4 0.40.6 0.6

0.2 0.2 0.8 0.8

0.0 0.0 1.0 1.0 0 200 400 600 800 1000 0 500 1000 1500 2000 Growing Degree-days

Figure 2.2: Nest initiation probabilities using the six GDD calculation methods.

0.0 1.0

0.2 0.8

0.4 0.6

Fly emergence

0.6 0.4

Barn Swallow

0.8 0.2 Probability Intiation Nest

1.0 0.0 0 100 200 300 400 500 600 700 800 900 Growing Degree-Day Accumulation

Figure 2.3: Barn swallow nest initiation probability in relation to GDD (January 1st, base

50°F accumulation) with the horizontal line representing the approximate growing degree-day emergence range for pest flies based on reports for house flies (Lysyk 1993), stable flies (Lysyk 1993; Beresford and Sutcliffe 2009), and face flies (Krasfur and Moon

1997). Jan 1 Base 50 Accumulation

39 Acknowledgements We thank Cornell University and the Puget Sound Bird Observatory for providing barn swallow nesting data; we are grateful for the countless contributors to these resources whose meticulous and perceptive observations made this study possible. We thank J. Courter for his expertise and insightful advice. We thank the Clemson University

Creative Inquiry students for tirelessly transcribing nesting observations.

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46 CHAPTER THREE

PERCEPTIONS OF UNITED STATES CATTLE ASSOCIATION PRESIDENTS ABOUT BARN SWALLOWS AND THEIR POTENTIAL ROLE IN SUPPRESSION OF PEST FLIES

Abstract Conservation efforts for birds that provide ecosystem services in agricultural systems require management approaches that cross disciplines. Barn swallows, an aerial insectivore, provide a service to cattle producers by suppressing pest flies that are a substantial problem to the livestock industry. To better understand the feasibility of incorporating barn swallows into an Integrated Pest Management approach, it is important to consider the audience that will be implementing the technique. We documented perspectives of cattle organization leaders across the United States using an online questionnaire. Overall response rate from the 320 leaders contacted was 48.8%.

Follow-up phone interviews with a subsample of 25 leaders provided additional clarity and understanding. Our results suggest that cattle organization leaders favorably view barn swallows and the potential benefits that barn swallow management might contribute to help reduce pest fly populations. Sustaining collaborative interests and effective implementation options requires continued communication as research is conducted toward development of sound management strategies.

Introduction Today, the earth houses and feeds over seven billion people and 38% of the surface area is used for agriculture (Foley et al. 2011). With thirty million km2 used for animal agriculture alone and population increases of 75 million people per year, the demands on agriculture are growing (Foley et al. 2011). The United States beef and dairy

47 industries are the most productive (per unit product) in the world, and together are responsible for 30.3% ($72.5 billion) of the total $239.3 billion cash receipts received by all United States farmers (Ayee et al. 2009).

One of the largest concerns for the cattle industry and most difficult to manage is dealing with pest flies, including house, stable, face, and horn flies. Both horn and stable flies are biting flies associated with decreases in livestock weight gains and milk production. It is estimated that the horn fly has cost the cattle industry US$730 million in lost production of milk and daily gains of meat cattle annually (Drummond et al. 1981;

Schmidtmann 1985). Stable flies are considered to be the second most important pest overall to cattle and they cost the beef cattle industry about $2.2 billion a year (Taylor et al. 2012). House and face flies, in contrast, are non-biting flies that cause irritation and increased tearing around the eyes and are associated with disease transmission, particularly Pink Eye and Thelazia Eyeworms (Rutz et al. 2010). Other negative effects include reduced feed conversion efficiency, increased stress on young animals, blood loss, hide damage, public health, and public nuisance concerns (Campbell et al. 1981;

Kinzer et al. 1984; Byford et al. 1992; Wieman et al. 1992; Campbell et al. 2006; Rutz et al. 2010).

Historically, conventional methods of controlling these pests involved insecticide applications to the animal or animal areas around the farm or as feed additives (Benson and Wingo 1963; Mian and Mulla 1982; Rutz et al. 2010). These methods are not totally effective and there are increasing concerns about pesticide resistance; for example, high levels of resistance in horn flies to pyrethroids have developed in areas across the United

48 States (Rutz et al. 2010). Face flies and house flies have also been known to develop resistance to pesticides over time (Scott et al. 2000; Campbell 2006; Kaufman et al. 2009;

Rutz et al. 2010). In addition, there are no known effective measures to control stable flies (Ferguson 2011). Repetitive treatments of insecticides kill a large proportion of natural enemies of pest species and create conditions that require additional treatments to maintain reduced pest fly populations (Rutz et al. 2010). Not only is it difficult to determine the detrimental costs of fly pests, it is difficult to measure and determine the effects of pest suppressors. With the creation of the Integrated Pest Management (IPM) programs, alternative methods of controlling harmful pests, including pest flies, have become more readily adopted.

Despite pressures for greater food volume (Kendall and Pimentel 1994; Lotze-

Campen et al. 2008), there is increasing global interest in sustainable practices to help conserve the natural environment and associated ecosystem services important to both people and agriculture. Agriculture is a key driver in global biodiversity loss (Tilman

1999; Gaston et al. 2003), which is being exacerbated by climate change (Chapin III et al.

2000; Jetz et al. 2007). One aim of sustainable animal agriculture is to use fewer pesticides while avoiding pesticide resistance or other unintended impacts. This poses a problem in the increasing demand for animal products where quality, production, and profit are reliant in part on pest suppression.

The need for sustainable solutions provides an opportunity to examine relationships between livestock, pest flies, and fly predators. The globally distributed barn swallow (Hirundo rustica) has lived in close association with livestock for over

49 2000 years (Møller 1994) and 82% of their diet in spring is flies, including pest flies of livestock (Brown and Brown 1999). Although fly-consuming birds offer potential pest- suppression benefits for livestock, they are harmed by the intensification of agricultural practices, especially during important nesting periods (Gruebler et al. 2010). Aerial insectivores have been experiencing declines throughout North America since the 1960s, which in part is attributed to a decrease in food base related to high pesticide use and also indirectly affecting reproduction (Nebel et al. 2010). Yet barn swallows provide a potential benefit to animal agriculture via pest suppression.

For the development of barn swallow conservation management as part of an

Integrated Pest Management program, it is important to understand both economic and social perspectives of private landowners (Laubhan and Gammonley 2001) and to include as many stakeholders as possible from various levels and backgrounds to clarify overall perceptions of environmental issues (Woodhead et al. 2000). There have been numerous studies about farmer socio-economic predictors and barriers to the adoption of sustainable and environmentally friendly practices. However, these studies often cover a relatively small geographic area and some have contradictory findings (Cardoso and

James 2012). Additionally, few such studies are species specific. For example, Jacobson et al. (2003) found that overall farmer willingness to adopt practices that attract birds was not correlated with economic or noneconomic incentives, whereas Meadows (2012) reported that willingness was correlated to financial constraints.

It can be difficult to get representative opinions of farmers across large spatial scales, perhaps in part because farmers are often spread out geographically, where contact

50 information is not readily available or up to date. In addition, large percentages of farmers do not respond to surveys and several factors such as the time of year when the survey is sent, amount of compensation, the sender of the survey, and the perceived length of the survey affect survey participation (Pennings et al. 2002). We propose an alternative method to predicting farmer perspectives on a broad spatial scale by assessing producers in industry-specific organization leadership positions. Farmers in cattle organization leadership positions may be able to accurately report perceptions of their members about environmental issues and the feasiblity of innovative fly management practices. The majority of cattle farmers belong to breed or industry specific organizations (Jacobson et al. 2003; Corner et al. 2008), and Jacobson et al. (2003) concluded that innovations to current farming practices that could boost bird populations should be shared through social networks and media channels. The role of these organizations and ultimately the leaders that run them provide many potential benefits to their members such as playing the role of a government-industry liaison and having a hand in policy decisions (Campbell 1966; Jordon et al. 1994). Leaders of these organizations are often experienced producers themselves, and generally are easily contacted. Further, they are more likely to use modes of contact such as email and are more likely to respond to feedback requests.

The purpose of this study was to gain specific insights into perceptions about 1) flies as pests of cattle, 2) barn swallows in general, and 3) feasibility of incorporating barn swallows into Integrated Pest Management systems. We used a linear mixed- methods approach to investigate cattle industry organization leaders’ perspectives across

51 the United States (excluding Hawaii and Alaska). Because leader perceptions may differ from those of members, we included a question to assess how well leaders thought they knew the views of their members.

Questionnaire Methods We used cattle organization websites and direct contact with organization personnel to compile an initial contact list of 379 cattle organization leaders across the

United States. Hawaii and Alaska were excluded because breeding populations of barn swallows are non-existent or insufficient. For our purposes, a leader was identified as being president of the organization, or when no presidential seat was held, the person holding the highest seat on the board of directors. The initial sample population was stratified into three groups: beef cattle organizations (n=239), dairy cattle organizations

(n=74), and organic and/or sustainable (OS) cattle organizations (n=66). OS cattle organizations included those with organic or sustainable within the name and/or direct mission of the organization. Heritage breed organizations were also included in the OS group, because these breeds are often targeted in sustainable and organic operations.

Heritage breeds were identified through the American Livestock Breeds Conservancy and are defined as true genetic breeds or endangered breeds that have purebred status and are managed following sustainable practices (ALBC 2009). Because of the limited number of organizations in the dairy and OS groups, all leaders were included in the sample; however, for the beef cattle organizations we selected a random sample of 200 leaders, leaving a total of 340 potential leader contacts. The questionnaire was initiated in

December 2012 and was completed in February 2013. This study period was chosen

52 because United States farmers have been most receptive to surveys during the months of

November through February (Pennings et al. 2002).

The questionnaire contained 21 questions (Appendix A). We asked several questions that assessed background organization demographics including whether beef or dairy, confinement or pasture based, certified organic, and size of operation. In addition, we asked leaders to report their experience with each of these areas. Leaders were asked to report the level of office they held (national, regional, or state) and how well they knew the views of their members (not well, fairly well, moderately well, or very well).

Respondents were asked to report their organization’s goals of encouraging Integrated

Pest Management, as well as conservation and environmental efforts (specific written goals, general written goals, no written goals but generally encourage, or none). Leaders were asked to rate the degree to which fly pests were a problem for their members and how satisfied they were with the cost, effectiveness, effort needed, risk of unintended consequences, and availability of new techniques in current fly management methods.

Further, leaders were asked to report the degree to which barn swallow nesting on buildings is a problem. Several statements about barn swallows were provided for leaders to rate using a five point Likert scale (e.g., strongly disagree, disagree, neither agree or disagree, agree, strongly agree). Following a brief paragraph proposing barn swallows as part of an Integrated Pest Management practice to suppress flies, direct questions about incorporating barn swallows into fly management practices were presented. Leaders were then asked to rate how likely would producers in their organization would be to consider several management practices to help barn swallows and what factors might inhibit

53 adoption of such practices. We also asked how likely respondents would be to share the information from our study with members. A final question was included, inviting participants to participate in a follow-up phone interview.

Questionnaire design and administration, following a modified Dillman

Technique (Dillman 2009), was deployed through an online survey program (i.e.,

SurveyMonkey). One week following an initial survey invitation, the survey was sent to respondents for the first time. At four weeks and seven weeks following the initial invitation, reminders were send to nonrespondents. Nonrespondents at eight weeks were called by phone a maximum of three attempts to encourage participation. The final survey reminder was sent on the ninth week and the survey was closed the tenth week. To increase response rate, all contacts were addressed individually and provided with a personalized access code for the survey. This further ensured that people outside the sample population could not skew the survey results.

Data analysis involved two steps. The first step was to calculate observed frequencies to question responses. The purpose of this step was to develop an overall profile of the typical participant and organization represented in the survey, and to see if certain question responses had unusually high or low frequencies. The second step was to test for differences in the question response frequencies for different groups using chi- squared analysis (for example, did the frequency of answers to the “feasibility to use

Barn Swallows as part of an IPM program” questions differ among the beef, dairy, and

OS organization respondents). For statistical comparison, we combined the categories of strongly agree and agree, and strongly disagree and disagree. Logistic regression analysis

54 was used to determine the strength of multiple associated variables (e.g., demographics and type of organization goals) to question responses. Fisher’s Least Significant

Difference was used to test for differences among multiple groups. For further statistical analysis, opinion questions were assigned a numerical code (i.e., 1= strongly disagree, 2= disagree, 3= neither agree nor disagree, 4=agree, 5=strongly agree). Multivariate regression was used to create prediction models to answer objective three regarding feasibility of incorporating barn swallows into IPM systems. All calculations were performed using JMP (JMP 10.0, SAS Institute).

Interview Methods A follow-up phone interview was conducted in February and March 2013 following completion of the online questionnaire. To ensure the proper participant was contacted, each participant who volunteered for a follow-up interview was asked to provide their name and phone number in the questionnaire. A purposive sampling approach was used to select respondents out of the 51 who volunteered. Selections were first determined by inclusion of questionnaire responses across all extremes, and then based on the group they belonged to. The appropriate number of interviews to conduct was determined using data saturation, the point at which little new information emerged

(Marshall 1996).

We used a semi-structured interview format based on Seidman’s interviewing framework (Seidman 2006). Each participant was contacted a maximum of five times and the initial contact was used to set up an interview time if they were unable to participate at the time of contact. All interviews were conducted by the same interviewer and audio

55 recorded with subject’s permission. The interviewer and undergraduate research assistants transcribed all interviews and, if requested by the interviewee, we emailed a copy of the transcript to the interviewee to verify accuracy.

Content analysis, a method that involves searching text for recurring words or themes, was performed on transcriptions from the phone-interviews (Patton 2002).

Transcripts were coded based on procedures described by Miles and Huberman (1994).

Coding is the process of segmenting data into simpler, generalized categories that may be used to expand new questions and levels of interpretation (Coffey and Atkinson 1996).

Codes were developed as they emerged from the transcripts (i.e., inductively) using the interview questions as an organizing framework. Only one code was assigned to each idea or topic expressed in response to a particular question. However, codes that represented the same or similar ideas were created and assigned when they emerged in responses to other questions. Transcribed text was coded only once, by the code pertaining to the most relevant question. However, multiple codes could be assigned to a single respondent’s response to a question. The frequencies of codes were calculated for each. Any text coded as miscellaneous was excluded for purposes of clarity.

Questionnaire Results The initial sample of 340 contacts had 20 that were invalid (e.g., incorrect email address), leaving a final sample (n=320) consisting of 194 beef, 66 dairy, and 60 OS contacts. Of the 320 questionnaires sent, 156 (51.9 % beef, 26.3% dairy, and 21.8% OS) were received and analyzed. Overall response rate was 48.8% (156/320) resulting in a margin of error of 7.85% with a 95% confidence level. The response rates for the beef,

56 dairy, and OS groups respectively were: 41.8% (81/194), 62.1% (41/66), and 56.7%

(34/60).

Organization characteristics and leader experiential profiles were compared among groups (Table 3.1 and Table 3.2 respectively). When leaders’ background experience was compared with the organization demographics of the reported operations, strong relationships were found between all corresponding variables (Table 3.3). There was no difference in response among the groups when leaders reported how well they knew their members. Most (96.7%) leaders reported knowing their members’ views and only 3.3% of leaders reported that they did not know their members’ views well. Most

(70%) leaders reported that their organizations had no goals to encourage Integrated Pest

Management, though 27% indicated that they had no written goals but generally encouraged them. Similarly, 43% of leaders reported that their organizations had no goals at the time to encourage conservation or environmental efforts, but 40% reported that they had no written goals but generally encouraged such efforts. Responses to both questions were not significantly related to demographic variables, but they were related to each other (χ2= 24.5, p=0.0036). Additionally, how well the leaders reported knowing their members was also positively related to reported goals of conservation and environmental efforts (χ2=19.9, p=0.0182).

Pest fly Perspectives

Half (50%) of the leaders indicated that flies were a moderate problem, 31% reported that flies were a slight problem, and 17% a large problem. Only 1.6% of leaders

57 reported that flies were not a problem. There were no significant relationships between the extent that flies were a problem in relation to any demographic variable.

The majority of leaders reported that members in their organization were somewhat satisfied with the ‘cost’, ‘effectiveness’, ‘effort needed’, and ‘availability or awareness of new techniques’ for pest fly management, and less than 3% were totally satisfied with these areas. In contrast 44% of leaders identified members within their organization to be mostly satisfied with ‘risk of untended consequences’ and this was the only factor not related to the group the leader belonged to or any other demographic variable. While the majority reported they were somewhat satisfied, the larger the reported problem with flies, the less satisfied the respondents were with pest fly management cost (p= 0.0011, r2=0.130) and effectiveness (p= 0.0039, r2=0.108).

Barn Swallow Perspectives

Many (45%) leaders indicated that barn swallow nesting on buildings was perceived as ‘not a problem’ for members in their organization and a ‘small problem’ for

35% (Figure 3.1). There was no significant relationship between responses and demographic variables.

Responses to three out of five opinion statements about barn swallows were related to which group the leader belonged (Table 3.4), and ‘wanting to know more about barn swallows’ was the only statement not related to the extent to which barn swallow nesting was reported as a problem. Overall, many (43%) leaders disagreed with the statement that producers in their organization actively discourage barn swallows and 47% reported that they neither agreed nor disagreed. In response to a statement about whether

58 most producers in their organization actively try to attract barn swallows, 38% disagreed.

Overall, many leaders (47%) agree that producers in their organization think barn swallows are beneficial to their farm and 43% agree that producers want barn swallows on their farm. The majority (66%) of OS leaders agreed with the statement about members wanting barn swallows on their farm, a greater percentage than indicated by dairy (40%) and beef (34%) leaders. In overall response to statements about wanting to know more about barn swallows, only 15% disagreed and many (44%) agreed or strongly agreed with the statement that most producers in their organization want to know more.

Innovative method interest

Leaders’ responses on whether most producers in their organization would be willing to consider adjusting Integrated Pest Management practices to protect barn swallows, and managing for barn swallows as a way to reduce fly pest numbers, were related to the group in which the leader belonged, the extent of environmental and conservation goals of the organization, and concerns about swallow nesting on buildings

(Figure 3.2). Responses to what extent barn swallow nesting on buildings was a problem had the strongest relationship to willingness to consider adjusting IPM practices to protect barn swallows (χ2 = 37.18, p<0.0001) and as a way to reduce fly pest numbers (χ2

= 26.84, p=0.002). Whether or not there were conservation or environmental goals was the weakest associated variable to both statements (protect: χ2 = 13.60, p=0.0344; reduce flies: χ2 = 15.53, p=0.0164). Which group the leader belonged to was related only to managing barn swallows as a way to reduce pest fly numbers (χ2=12.4 p<0.05; Table

3.5). Both models included group of the leader and the extent to which barn swallows

59 were perceived as a problem. When environmental goals were included in models, the effects were weakly significant and reduced strength of fit. Similarly, likelihood to consider management for barn swallows decreased with increased perceptions of problems with nesting. While following the same trend as beef and OS, dairy indicated an overall decreased likelihood to consider managing for barn swallows for protection or to reduce fly numbers (Figure 3.2). Overall, 54% agreed that most producers in their organization would be willing to consider adjusting IPM practices to protect barn swallows. An even larger percentage (64%) agreed that most producers would be willing to consider managing for barn swallows as a way to reduce pest fly numbers. Only 9% and 8% of all leaders disagreed to each statement, respectively. No leader in the OS strata disagreed to either statement, in addition they reported the highest percentages of agreement among the three groups on both statements (Table 3.5).

Leaders opinions about whether or not their members would be willing to adopt specific management practices for barn swallows were related to various demographic variables. Most (54%) responded ‘maybe’ to installing nest shelves in appropriate places, as well as establishing field margins (50%), altering mowing practices (43%), and altering timing of pesticide applications (59%). While many (38%) leaders reported

‘maybe’ for maintaining existing nests, 36% reported they would be ‘likely’ to adopt this practice. The only management practice that a large plurality (47%) reported they would be ‘likely’ to adopt was maintaining natural water sources on their operation. Planting hedgerows was the only management practice that the majority (51%) of leaders reported that would be ‘unlikely’ for producers in their organization to consider.

60 Regarding likelihood of barn swallow management, responses to statements about the influence of potential factors (i.e., availability of outside professional assistance, available cost share programs, effectiveness, cost, effort, time, and risk of unintended consequences) found six that were weakly related to responses about perceived fly or barn swallow nesting problems. The majority of leaders scaled six out of the seven factors as ‘very much influencing’ likelihood to manage for barn swallows except for the

‘availability of outside professional assistance,’ which most (58%) leaders scaled as

‘somewhat influencing’.

Interview Results The 25 interviews conducted lasted on average 14.5 minutes ranging in length from 5.23 to 29.35 minutes. Most (14) interviewees reported that fly management was of high importance; four reported it was of moderate importance and four reported it was of low importance. Three respondents indicated that fly management was only of high importance during certain times of the year or on certain parts of their operation. The largest concern leaders had with current fly management practices was the efficacy of methods available (Figure 3.3). Only one respondent was not familiar with barn swallows. Of the leaders interviewed, 20 reported having barn swallows on their personal operation, two were unsure, and three did not have barn swallows on their operation. The majority of leaders (13) reported that they had a positive perception of barn swallows and only one reported disliking birds in general (Figure 3.4). Perceptions of barn swallows were most commonly reported to come from personal experience with them (Figure 3.5).

Most of the interviewees (12) reported that their views of barn swallows have not

61 changed over time, and six reported that their views have become increasingly positive over time through education and experience with them. The majority of respondents (13) reported that barn swallows did not affect day-to-day management practices. However, five reported that they try not to harm barn swallows and two of those respondents expressed interest in adopting practices to attract more; three respondents reported that they remove problem nests and one respondent reported cleaning up droppings. Most

(19) leaders thought that barn swallows could be incorporated into pest fly management practices and four reported that the feasibility of including barn swallows would be situation specific. Respondents identified six key factors that operators take into account when considering barn swallows as part of fly management practices: ease of attracting barn swallows, the associated costs, how effective they are at controlling fly populations, unintended consequences (i.e., droppings and disease), the time it takes, and any conflicting laws or regulations.

Discussion In developing new management approaches that cross disciplines, it is important to communicate with the audience that will be implementing a technique. Barn swallow life history demonstrates close life cycle ties with cattle, indicating that cattle operators are key in making decisions that could affect barn swallows. Both cattle operators and barn swallows have the potential to benefit from management objectives because flies are a significant food resource for the swallow and an economically harmful pest of cattle.

Our study elucidates key questions important for establishing a sound framework for potential management decisions in the future.

62 The findings of our study are in agreement with current literature about the importance of pest fly management to cattle industries. Pest fly management presents a continued challenge to operators in our study and only a marginal number (1.6%) reported pest fly management not to be a problem. In an effort to understand specific difficulties with current management, we included an item in the questionnaire to gage satisfaction with cost, effectiveness, effort needed, risk of unintended consequences, and availability of new techniques. Respondents were more likely to report satisfaction with cost and effectiveness with decreasing perceptions of problems with fly pests. No area of satisfaction clearly differed from others, however, because low numbers of respondents were neither completely dissatisfied nor satisfied. Follow-up interviews helped to clarify perceptions of pest fly problems; interviewees reported that the efficacy of the method was the most important issue with pest fly management, followed by animal welfare, and the safety of the control method (Figure 3.3). The absence of an effective and prudent method in terms of welfare and safety presents a need for new pest management concepts.

There is potential for barn swallow management to help meet the needs of cattle operators with pest fly problems, but the realization of this interdisciplinary approach requires an understanding of current perceptions of barn swallows. Kellert (1985) identified human perceptions as a critical part of constructing a sound rationale and effective species management approach. Overall responses in both the questionnaire and interviews were predominately positive. To better understand how perceptions of barn swallows might be influenced, interviewees were asked where their views of barn

63 swallows came from (Figure 3.5). Most (10) interviewees described one or more experiences with barn swallows as the origin of their perceptions. Others (4), explained that experiences or views of people they knew affected their opinions. A more utilitarian perspective was taken by interviewees (5) that stated they formed their opinions based on what the barn swallows provide or have provided for them; all five clarified that the swallows suppressed pests such as mosquitoes, flies, or more generally noted: bugs. Two interviewees attributed their love of nature to their positive perception of barn swallows.

Only one interviewee reported that they did not like birds. In explanation, the respondent described problems with rock doves (Columba livia) and European starlings (Sturnus vulgaris), two nonnative birds recognized as problematic in agricultural systems. The respondent further expressed concern for the transmission of diseases such as salmonella, and related a personal story about a barn swallow that swooped near the face of a friend who ventured too close to its nest. In the example expressed by this participant, nuisance problems from pest birds apparently caused negative perceptions that more broadly affected perceptions of other birds (Johnson 1990, 1994). There is a need for more cross- disciplinary work for conservation of birds that need it, but also solutions for when conflicts occur (Johnson et al. 1995). There is also need for engagement of people in conservation and management issues to effectively deal with real-world challenges

(Kareiva and Marvier 2012). Meeting the needs of stakeholders whose primary interests may not be conservation, builds and strengthens relationships towards pathways that do benefit conservation.

64 One widely reported concern with barn swallows is the construction of mud nests on buildings. Even interviewees that had favorable views of barn swallows reported that nesting on buildings could be a problem, although only 3.3% of questionnaire respondents reported this to be a large problem (Figure 3.1). The extent to which a participant reported nesting on buildings as a problem was strongly related with willingness to consider management of barn swallows for both reduction of pest flies and conservation of swallows (Figure 3.2). Because the greatest frequency of origins of views come from experience, greater leverage should be granted to conflicts such as nesting location discord that may arise.

Our study illustrates that the majority of leaders perceive barn swallow management as a potential alternative method to suppress pest flies. Less clear are influences that affect decisions (e.g., cost, effort, and time) regarding practices that they would be willing to enact to attract and maintain barn swallows. All factors in the questionnaire pertaining to their influence on willingness to manage for barn swallows were reported as highly influential except for ‘availability of outside assistance,’ which was reported as ‘somewhat’ influential. In order to gain clarity, interviewees were asked to identify the most important factor when considering the use of barn swallows to suppress pest flies on their operations. Six key factors emerged from the interviews, the top three being the ease of barn swallow attraction, the cost, and effectiveness of the birds in suppressing pests. Interviewees consistently mentioned a need for more quantifiable information to make a more educated decision about willingness to manage for barn swallows as part of an Integrated Pest Management. Of particular interest were two

65 action to outcome questions: “how many flies does a barn swallow eat?” and “how do I attract the number of barn swallows I need?” These questions relate to barn swallow numbers and to whether barn swallows might effectively suppress flies and associated fly impacts on cattle. Currently, this poses a gap in scientific knowledge that has been identified by our participants as needed information if they are to conduct viable management practices for barn swallows.

There were few differences in responses for any questions in the questionnaire among beef, dairy, and OS participants. This lack of difference can be explained in both the questionnaire and interviews. Participants in interviews consistently mentioned past or current memberships in other cattle organizations that differ from their primary classification in this study and reflect a breadth of livestock experience. While they are primarily classified into one of three different groups, it is likely that many participants could fall into secondary or tertiary classifications. It may further be explained by the wide variety of experience with other types of cattle industry operations that many participants in the questionnaire had. It is important to note that several of these leaders, as discovered in the interviews, are primarily employed in professions not directly related to the cattle industry (e.g., medical doctor, certified public accountant, registered nurse, university educators) or involved with additional activities (e.g., 4-H youth mentor through Cooperative Extension, land trust board member) that lend greater perspective to contentious issues. A reality that is often overlooked, but seen in our study, is that producers are community contributors faced with issues of cattle production.

Interestingly, other studies of producers’ views of barn swallows did not differ between

66 conventional and organic producers (Kratgen et al. 2009). While these studies were conducted in locations outside the United States and made up of producers, rather than leaders of cattle organizations specifically, the lack of difference between conventional and organic producers supports our finding that barn swallows are viewed favorably across all three groups. With indication that the views of leaders and their members are similar, the use of cattle association leaders in this study has provided a successful alternative at understanding representative opinions of cattle producers through that of their association leaders.

Interview respondents belonging to the dairy group offered an explanation to the negative responses of barn swallow opinion questions as well as the overall lower willingness to consider management for barn swallows relative to beef and OS groups.

As outlined in the Grade “A” Pasteurized Milk Ordinance (2011) the FDA requires dairy operations to be inspected at least once every six months, with state regulators (e.g., the state department of agriculture or health department) upholding these standards as a baseline, which can be more or less stringent according to individual state laws. The presence of birds or evidence of bird occupation is an infraction that could result in deductions during inspection. Operators must pass inspections or their permit will be suspended, and thus render them unable to move fluid milk until violations are corrected and the permit reinstated. The feasibility of managing barn swallows in certain dairy systems (e.g., tie-stall or flat barns) might result in direct violation of the Grade “A”

Pasteurized Milk Ordinance. It is also possible that multi-generational dairy operators may have experiences or close interactions with people who have routinely deterred birds

67 from their parlors or operations. Conventional style operations (e.g., free-stall barns) that are designed to provide separate housing and milking facilities for cows were indicated by one respondent to be the best candidate for the application of barn swallow management to reduce pest flies. Other respondents expressed interest in managing for barn swallows on other areas of their operations that did not conflict with milking parlor regulations.

Providing environmental and economic reasoning to justify conservation actions is known to increase conservation behaviors (De Young et al. 1993). Communication with cattle operators needs to address the concerns and interests of the operator, and be conveyed through accepted informational resources. Jacobson et al. (2003) state that information must be readily available to both conventional and organic farmers in order to foster farming practices that enhance birds. However, a gap between the lack of available reliable information about alterative methods of farming, and the awareness of the need for sound farming methods exists (Hess 1991). A large majority of leaders in our study reported that they would be willing to share information with their organizations about barn swallow management to reduce pest flies. In follow-up interviews, respondents provided 14 different methods of communication that would be effective at sharing information to cattle operators. The majority of these respondents

(20) identified cattle or trade magazines as key methods of reaching cattle operators; the next most frequently listed methods were the Internet (5) and Cooperative Extension (5).

The consistent identification of cattle/trade magazines as a method of communication to cattle operators by all three groups in our study indicates that a viable method of

68 communicating management alternatives exists. However, there are numerous trade/cattle magazines that disseminate information to different interest groups (e.g., specific cattle breeds, cattle types, management types), which complicates efforts when trying to contact groups broadly through a single publication.

Our results reinforce the need for alternative methods of pest fly suppression and also indicate that cattle operators are willing to consider methods that support conservation objectives. The overall positive perception of barn swallows across all groups was indicated in our study to be primarily driven by experience, not only with the barn swallow but also through interactions with other birds. An understanding of the impacts of associations with other avifauna supports the need for interdisciplinary management approaches when proposing alternative management practices. While the majority of respondents indicated willingness to consider barn swallow management as a method to suppress pest flies, the need for explicit action to outcome information was identified as a determinant for further receptivity to the concept. Additionally, continued communication with cattle operators who might implement management techniques will further elucidate operation-specific barriers, and provide feasible solutions to fit the operators’ needs. Our study provides evidence that there is potential to work towards solutions of interdisciplinary issues that benefit both barn swallow conservation and livestock pest management.

69 Tables

Table 3.1: Percentages of reported membership demographics among beef, dairy, and OS groups. Significance at p < 0.05 of Fisher’s LSD test horizontally across the three groups for each demographic. Letters within rows that differ indicate significant differences between groups.

MEMBERSHIP DEMOGRAPHICS BEEF DAIRY OS Average Type % Beef 99.2a 8.8b 80.1c Dairy 0.8a 91.2b 19.9c Average Management % Pasture 87.6b 26.6a 84.2b Intensive 12.4b 73.4a 15.8b Average Size % Small 69.7b 32.6a 81.1b Moderate 23.5b 42.7a 14.7b Large 6.4b 20.7a 0.9b Very Large 0.3a 3.8a 3.2a Certified Organic % 3.1a 2.3a 5.7a

Table 3.2: Percentages of reported leader demographics (experience and perceived knowledge) among beef, dairy, and OS groups. Chi-squared tests indicate differences in demographics among leader groups.

LEADER VARIABLES BEEF DAIRY OS χ2 P Type Experience 86.79 <0.0001 Beef Only 86.8 0 62.1 Dairy Only 0 71.0 10.3 Beef and Dairy 13.2 29.0 27.6 Management Experience 20.34 0.0004 Pasture Based Only 60.7 20.8 51.7 Intensive Only 0 20.8 3.5 Both 39.3 58.3 44.8 Size Experience NS Small 32.3 19.2 44.8 Moderate 21.0 11.5 6.9 Large 4.8 0 0 Small and Moderate 24.2 19.2 27.6 Small, Moderate, and Large 9.7 23.1 13.8 Small and Very Large 0 3.9 0 Moderate and Large 0 3.9 3.5 Moderate, Large, and Very Large 1.6 7.7 0 All 6.5 11.5 3.5 Level of Office Held 24.53 <0.0001 National (%) 15.2 10.7 56.7 Regional (%) 13.6 10.7 13.3 State (%) 71.2 78.6 30.0 Knowledge of Member Views NS Not well (%) 3.1 6.9 0 Fairly Well (%) 26.6 31.0 30.0 Moderately Well (%) 45.3 31.0 43.3 Very Well (%) 25.0 31.0 26.7

71 Table 3.3: Chi-square test values showing clear correlation (all values p < 0.0001)

between leader and membership demographics.

DEMOGRAPHIC Type of cattle Type of management Size of operation Type of cattle 117.57 ------Type of management ---- 69.02 ---- Size of operation ------226.90

Table 3.4: Percentages of leaders in beef, dairy, and OS groups that answered agree or strongly agree to statements reflecting opinions of producers in their organization.

Significance of p < 0.05 is indicated by an asterisk.

Agree or Strongly Agree Responses 2 Most producers in my organization: Beef (%) Dairy (%) OS (%) χ Actively try to attract barn swallows 9.2 8.3 31.0 9.9*

Actively discourage barn swallows 21.9 20.0 3.5 5.18

Think barn swallows are beneficial to their farm 39.1 44.0 69.0 12.8*

Want barn swallows on their farm 34.4 40.0 65.5 13.8*

Want to know more about barn swallows 42.2 32.0 58.6 5.2

Table 3.5: Percentages of leaders in beef, dairy, and OS group’s that answered agree or strongly agree to statements reflecting willingness to manage for barn swallows.

Significance of p < 0.05 is indicated by an asterisk.

Most producers in my organization would be Agree or Strongly Agree Responses 2 willing to consider: Beef (%) Dairy (%) OS (%) χ Adjusting IPM practices to protect barn 50.0 46.2 69.0 6.0 swallows Managing for barn swallows as a way to reduce 64.6 53.9 72.4 12.4* pest fly numbers

74 Figures

50%

40%

30%

20% (%) Percent 10%

Not a a Not problem large A problem small A problem

moderate A problem

Figure 3.1: Percent (%) of leaders indicating the extent to which barn swallows nesting on buildings is a problem.

swallows 2 For protection For

1 Dairy 1 1.5 2 2.5 3 3.5 4 OS Beef

5 ies

Willingness to manage barn 2

1 ﬂ pest of reduction For

1 1.5 2 2.5 3 3.5 4

View nesting on buildings as a problem

Figure 3.2: Prediction models of respondent willingness to consider managing barn swallows to protect them or reduce pest flies as part of an IPM scheme (5 point scale: 1 =

Strongly Disagree and 5 = Strongly Agree) based on the extent to which nesting on buildings is a problem (4 point scale: 1 = Not a Problem and 4 = A Large Problem) and group classification (beef, dairy, or OS).

Productivity of Animals

Labor

Cost

Safety of Control Method

Animal Welfare

Method Eficacy

0 2 4 6 8 10

Figure 3.3: Codes and frequencies they were assigned to interview responses to the question “What are the most important issues with pest fly management?”

77 Provide a service Positive Charismac Neutral Do not bother me Negative Nesng occasional annoyance

0 2 4 6 8 10 12 14 Do not like birds

Figure 3.4: Codes and frequencies they were assigned to interview responses to the question “What do you think about barn swallows?”

78 Intrinsic

Outside inluence

Function

Experience

0 2 4 6 8 10

Figure 3.5: Codes and frequencies they were assigned to interview responses to the question “Where do your views of barn swallows come from?”

79 Acknowledgements We are thankful for all questionnaire and interview participants who generously gave their valuable time to share meaningful information with us. We are thankful to E.

Baldwin, T. Dobbins, and S. Rodriguez for their expert advice and consultation with instrument design and implementation methods. We are thankful for the Clemson

University Creative Inquiry program and undergraduate students E. Gettler, G.

McDonald, A. Devore, L. Love, C. Adams, and H. Pruett for their time and help.

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84 CHAPTER FOUR

CLOSING THOUGHTS AND REFLECTIONS

“My sorrow in having been for so long on two losing sides (agriculture and conservation) has been compounded by knowing that those two sides have been in conflict.” -Wendell Berry

Research is a revolving and continually dynamic story. The origins of my work are rooted in a passion for conservation and agriculture. My undergraduate background in

Animal and Veterinary Science, and Environmental and Natural Resources provided me with the opportunity to view discipline-specific issues through an interdisciplinary lens, stimulating a desire to cultivate unique approaches to contentious issues.

The increased global awareness of the relationships between agriculture and wildlife conservation (Johnson et al. 2011) outpaces the few studies that link these two fields (Perrings et al. 2006). I believe that novel interdisciplinary approaches can provide viable solutions to real world problems that benefit both agriculture and wildlife conservation. My project clarifies the apparent evolutionary associations between cattle, flies, and barn swallows, assessing the potential impact of climate warming, especially in view of local (cattle operation) to continental (long-distance migration) differences in conditions and relevant cues. These results are pertinent to global cattle-fly issues from the ecological components and from the potential to offer new approaches to assist food security and bird conservation. I further address the perspectives of cattle operators whose needs and interests are important to understand if viable management strategies are to be proposed and enacted.

85 The work I have completed sets the stage for future studies that will build a

“package” aimed at benefiting avian conservation and livestock production. The incorporation of translated barn swallow breeding phenology models into extension and integrated pest management resources for producers provides a tool (i.e., growing-degree days) beneficial for timing of relevant management practices. The use of remote sensing technologies (e.g., MODIS) and it’s derived products (e.g., NDVI), could aid in the refinement of growing-degree day models by decreasing the amount of site-by-site variability (Courter 2012). This information is important ecologically to help clarify the contradictory findings of localized studies (Both et al. 2006; Both et al. 2009). For example, Ambrosini et al. (2011) found a mismatch between barn swallow nest initiation and local spring phenology in Denmark; however, our study provides evidence that barn swallows in the United States have remained in synchrony with fly food resources. In addition to broadening the spatial scale, continued observation of barn swallow breeding phenology will be useful in light of climate change, allowing further monitoring of future synchrony within the cattle-swallow-fly system. Further, my work has articulated a need to quantify the swallow-fly predator-prey relationship. Informing stakeholders of the realized impact of barn swallow predation and disturbance on fly populations would provide incentive for nonparticipating persons to engage in management practices that benefit both swallows and producers.

Of special interest to me is inquiry into the biochemical responses behind the weather stimuli that alter barn swallow breeding phenology. A thorough understanding of reproductive physiology has yet to be reported in non-domesticated aves. Much research

86 still supports the concept that photoperiod is the primary driver of avian breeding phenology (Farner 1964; Sharp 1996; Sharp 2005). While the endocrine responses of light on reproduction are well understood in some aves (e.g., domesticated poultry), temperature is not (Visser et al. 2009). A couple studies (Ward and Bryant 2006; Jenni-

Eiermann et al. 2007) have explored the reproductive response of barn swallows to some weather variables, but have provided little understanding of the endogenous mechanisms that affect clutch-initiation.

The research I have conducted in my time at Clemson University is inherently interdisciplinary, addressing the global need for sustainable agricultural systems that maintain the quantity and quality of food production to meet ever-growing demands while incorporating avian biodiversity and conservation. While the story is still being told, it is my hope that my work contributes to an increased understanding of our world in a context that seeks mutually beneficial solutions.

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87 Farner DS. 1964. The photoperiodic control of reproductive cycles in birds. American Scientist 52: 137-156.

Sharp PJ. 1996. Strategies in avian breeding cycles. Animal Reproduction Science 42:505-513.

Sharp PJ. 2005. Photoperiodic regulation of seasonal breeding in birds. Annals of the New York Academy of Sciences 1040:189-199.

Visser ME, Holleman LJM, and Caro SP. 2009. Temperature has a causal effect on the timing of avian reproduction. Proceedings of the Royal Society B 276: 2323-2331.

Ward S and Bryant DM. 2006. Barn swallows Hirundo rustica form eggs mainly from current food intake. Journal of Avian Biology 37: 179-189.

APPENDICES

89 Appendix A

Questionnaire Instrument

Questions 1 – 7 are background to help us better understand your overall responses.

1. What types of cattle operations do your members have? (Please indicate approximate percentage in each category) ______% Beef Cattle ______% Dairy Cattle

2. What types of cattle operations make up your organization? (Please indicate approximate percentage in each category) ______% Intensive/Confinement based (ex. feed lot, free-stall, etc.) ______% Pasture based (ex. grazing, ranch, etc.)

3. Does your organization include any Certified Organic operations? (Please indicate approximate percentage) ______% Certified Organic

4. What size operations are included in your organization? (Please indicate approximate percentage in each category) ______% Small (1 – 99 head) ______% Moderate (100 – 499 head) ______% Large (500 – 1,999 head) ______% Very large (2,000+ head)

5. At what level of your organization are you involved as an office holder? (Please select one) o National o State à Which state? ______o County à In which state? ______

6. What types of cattle operations do you have the most experience with? This survey asks about several types and some may be uncommon or not included in your organization. I have a good bit of experience with… (Check all that apply)

o Beef o Dairy o Pasture o Confinement o Certified Organic o Small (1 – 99 head) o Moderate (100 – 499 head) o Large (500 – 1,999 head) o Very large (2,000+ head)

90 7. In responding for your organization, how well do you know the views of your members?

oNot well oFairly well oModerately Well oVery Well

Questions 8 – 11 are about livestock fly pests.

8. Are fly pests problematic on operations in your organization? (Please select one)

o Not a problem o Slight problem o Moderate problem o Large problem

9. How satisfied are producers in your organization with current methods of fly management? (Please select the number that corresponds to each statement.)

Satisfaction with Pest Fly Management Mostly Mostly Totally Totally Satisfied Satisfied Satisfied Somewhat Somewhat Not Satisfied Not

Costs 1 2 3 4 Effectiveness 1 2 3 4 Effort needed 1 2 3 4 Risk of unintended consequences 1 2 3 4 Availability or awareness of new techniques 1 2 3 4

10. Does your organization have goals to encourage Integrated Pest Management (IPM)? o Have specific written goals to encourage IPM o Have general written goals to encourage IPM o No written goals but generally encourage IPM o None at this time o Other:______

11. Any comments or additional details for question 10? ______

Questions 12 – 15 are about Barn Swallows.

Barn Swallows are often seen swooping low behind tractors and mowers that stir up insects, and around livestock buildings where there are flies. Barn swallows can be identified by their long forked tail, reddish-brown throat and forehead, buffy or cinnamon color below, and blue-black color above.

12. Barn Swallows often place mud nests under the eaves of buildings or other structures and sometimes on rafters inside of buildings. Based on interactions within your organization, is nesting on buildings a problem? (Please select one)

o Not a problem o A small problem o A moderate problem o A large problem

13. Any comments or additional details for question 12? ______

92 14. How do you think most producers in your organization view Barn Swallows? (Please select one number that corresponds to each statement).

Most producers in my organization… Agree Agree Neither Neither Strongly Strongly Strongly Agree o Agree Disagree Disagree Disagree

Actively try to attract Barn Swallows 1 2 3 4 5

Actively discourage Barn Swallows 1 2 3 4 5

Think Barn Swallows are beneficial to their farm 1 2 3 4 5

Want Barn Swallows on their farm 1 2 3 4 5

Want to know more about Barn Swallows 1 2 3 4 5

15. Does your organization have goals to encourage conservation or environmental efforts? o Have specific written goals to encourage these efforts o Have general written goals to encourage these efforts o No written goals but generally encourage these efforts o None at this time o Other:______

Please read this paragraph before answering the following questions.

Barn Swallows eat only insects, mostly flies. In fact, during the spring and summer, flies make up 82% of the Barn Swallow’s diet. Several kinds of flies are harmful to cattle and thus costly to cattle operations, and current control methods are not always effective. Barn swallows may offer a potential alternative or supplement to traditional fly control methods because they feed around cattle and eat high numbers of flies. As such, Barn Swallows could provide a valuable service to cattle producers. Barn Swallow populations, however, are declining worldwide. This decline has been attributed to the decline in cattle operations and more intensive farming practices on those cattle operations that remain.

93 Questions 16 - 21 are about potential interest in managing for Barn Swallows as part of an Integrated Pest Management system.

16. Do you think producers would be willing to consider including Barn Swallows as part of an Integrated Pest Management fly management program? (Please select one number that corresponds to each statement)

gree

Most producers in my organization would be Agree Agree Neither Neither Strongly Strongly Agree or or Agree Disagree Disagree

willing to consider… Strongly Disa Adjusting integrated pest management practices 1 2 3 4 5 to protect Barn Swallows Managing for Barn Swallows as a way to reduce 1 2 3 4 5 fly pest numbers

17. Which management practices do you think producers would be willing to consider to attract or help Barn Swallows? (Please select one number that corresponds to each statement)

Most producers in my organization would be kely

willing to consider… Not Applicable Never Unlikely Maybe Li Definitely Altering timing of pesticide applications NA 1 2 3 4 5

Altering mowing practices NA 1 2 3 4 5

Establishing field margins NA 1 2 3 4 5

Installing nest shelves in appropriate places NA 1 2 3 4 5

Maintaining existing nests NA 1 2 3 4 5

Maintaining natural water sources on your farm NA 1 2 3 4 5

Planting hedgerows NA 1 2 3 4 5

94 18. Which factors might influence the likelihood of producers to consider management for Barn Swallows as part of fly suppression? (Please select one number that corresponds to each statement)

Factors influencing likelihood of management for Barn Swallows for fly suppression Not at all at Not Influenced Influenced Influenced Influenced Somewhat Very Much Very Completely

Availability of outside professional assistance 1 2 3 4 Available cost share programs 1 2 3 4 Effectiveness of Barn Swallows in reducing fly 1 2 3 4 pests The cost 1 2 3 4 The effort needed 1 2 3 4 The time needed 1 2 3 4 Risk of unintended consequences 1 2 3 4 Other: ______1 2 3 4

19. What size or type of beef cattle or dairy operation(s) do you think might be most feasible for incorporating Barn Swallows as part of an Integrated Pest Management system? ______

20. If research finds that Barn Swallows could effectively contribute to fly pest management, do you think your organization would be interested in helping share the information? o Definitely o Likely o Maybe o Unlikely o Never

21. Please share any other comments, ideas, or suggestions: ______

95 Would you be willing to help by participating in a short follow-up phone interview?

o No o Yes à Your name: ______Phone number where we could contact you: ______

Thank you for your professional help in completing this survey!