Bank Swallow (Riparia Riparia) Breeding in Aggregate Pits And

BANK SWALLOW (RIPARIA RIPARIA) BREEDING IN AGGREGATE PITS AND

NATURAL HABITATS

A Thesis Submitted to the Committee on Graduate Studies in Partial Fulfillment of the Requirements for the Degree of Master of Science in the Faculty of Arts and Science

TRENT UNIVERSITY

Peterborough, Ontario, Canada

Environmental and Life Sciences M.Sc. Graduate Program

September 2017

ABSTRACT

Bank Swallow (Riparia riparia) Breeding in Aggregate and Natural Habitats

I examined Bank Swallow (Riparia riparia) colony persistence and occupancy, in lakeshore, river and man-made aggregate pit habitat. Habitat persistence was highest on the lakeshore and lowest in aggregate pits, likely due to annual removal and relocation of aggregate resources. Bank Swallow colonies in aggregate pit sites were more likely to persist if a colony was larger or if burrows were located higher on the nesting face. I also compared nest productivity and health factors of Bank Swallows in lakeshore and aggregate pit habitats. While clutch size was the same in both habitat types, the number of fledglings from successfully hatched nests was significantly higher in aggregate pit sites than from lakeshore sites. Mass of fledgling Bank Swallows did not differ significantly between habitat types, however mass of adults from aggregate pits decreased significantly over the nesting season. Parasite loads on fledgling Bank

Swallows were significantly lower in aggregate pits than in lakeshore sites. According to these indicators, aggregate pits appear to provide equivalent or higher quality habitat for

Bank Swallows than the natural lakeshore sites, making them adequate and potentially key for this species’ recovery. Aggregate pit operators can manage for swallows by (1) creating longer, taller faces to attract birds and decrease predation, and (2) supplementing their habitat with water sources to encourage food availability.

Keywords: Bank Swallow, Riparia riparia, aerial insectivore, aggregate pits, substitute habitats, productivity rates, occupancy, colony persistence, ectoparasites

ACKNOWLEDGEMENTS

I would first and foremost like to thank my supervisor, Dr. Erica Nol. Thank you for always being there to answer my numerous questions, provide advice and support throughout this entire process. While you provided support academically, your encouragement and support for my mental health throughout this process was equally as valued. I would also like to thank my committee members, Joe Nocera and Gary Burness, for their input throughout this process. All your suggestions were insightful and helpful for making this document what it is. Thank you also to Dr. Wesley Burr for taking the time to meet during my final stages of analysis to help with R coding and analysis.

Finally, thank you to Dr. Ken Abraham for his careful edit of my final version.

I’d also like to thank my field assistants throughout the two years of field work.

Thank you to Robyn Lloyd, Madison Wikston, Gillian Leava, Andrew Beauchamp, and

Mirabai Alexander for all your work during the summers. All of you were willing to work long hours and kept a smile on your faces, despite the hot summer sun and lack of shade in pits! Thank you to everyone who came out for a day or two of volunteering throughout this project. It was so great to share my experiences with you!

My research would not have been possible without the financial support from a variety of funding agencies. Thank you to Ontario Power Generation (OPG),

Environment Canada (EC), and the Ontario Ministry of Natural Resources and Forestry

(OMNRF) for providing some financial support for this project. Thank you especially to

Marianne Leung and Bill Macdonald from OPG, Mike Cadman from EC, Mark

Browning from OMNRF, and Myles Falconer from Bird Studies Canada for assisting with some of the methods and logistics of the project. Thank you to each landowner and

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operator who allowed me on-site to conduct my research. Your interest in partnering with species at risk research and making your aggregate operations safer for wildlife is admirable.

Thank you to all my friends, lab mates, and twitter scicomm friends who have been on this journey with me and helped along the way. Whether you helped me with stats, calmed down my nerves and bouts of imposter syndrome, or helped keep me motivated and excited about science, I am appreciative of your friendship and support.

Allie Anderson, Allison Kwok, and Ariel Lenske, you three are seriously the “A” team!

Thank you for endless hours of friendship, stats help, brainstorming, and a bed to sleep on. Emma Bocking, I owe you for reading and editing my entire thesis.

Thank you to my partner in crime, Michael Colley for sticking through this whole process with me. Thank you for trying your best every day to motivate me, feed me, and believing in me, especially when I didn’t. I can’t wait for whatever is next!

Finally, thank you to my parents. I would not be where I am today without your continual love, support, and guidance. While sometimes, I may make you feel like I must have been switched at birth, you have always cheered me on no matter the direction that I go in life. Dad, thank you so much for your endless enthusiasm and interest in my work and hobbies, and especially for the hilarious cartoons about my work. Mom, thank you for all of our long talks and words of wisdom and encouragement. You have a way of always calming me down and reminding myself that I am capable of what I set my mind to. I love you both!

TABLE OF CONTENTS

ABSTRACT ...... ii ACKNOWLEDGEMENTS ...... iii TABLE OF CONTENTS ...... v LIST OF FIGURES ...... vii LIST OF TABLES ...... viii

CHAPTER 1 - GENERAL INTRODUCTION ...... 1 The Issue ...... 4 Study Objectives ...... 7 Literature Cited ...... 10

CHAPTER 2: FACTORS PREDICTING THE PERSISTENCE AND OCCUPANCY OF BANK SWALLOWS (RIPARIA RIPARIA) BREEDING IN AGGREGATE PITS AND NATURAL HABITATS ...... 14 ABSTRACT ...... 14 INTRODUCTION ...... 15 METHODS ...... 18 Study area ...... 18 Bank Characteristics ...... 20 Occupancy Surveys ...... 22 Persistence ...... 23 Statistical Analysis ...... 24 RESULTS ...... 26 Burrow Occupancy ...... 27 Persistence ...... 28 Face Reuse ...... 29 DISCUSSION ...... 29 Occupancy ...... 30 Persistence and Reuse ...... 32 CONCLUSION ...... 37 LITERATURE CITED ...... 45

CHAPTER 3: PRODUCTIVITY AND INDICATORS OF HEALTH OF BANK SWALLOWS BREEDING IN AGGREGATE AND NATURAL HABITATS ...... 50 ABSTRACT ...... 50 INTRODUCTION ...... 51 METHODS ...... 55 Study area ...... 55 Nest Survival and Reproductive Success ...... 56 Mass and Ectoparasites ...... 57 Statistical Analysis ...... 58 RESULTS ...... 61 Daily Nest Survival and Reproductive Success ...... 62 Mass and Ectoparasites ...... 63 DISCUSSION ...... 65 Reproductive Success ...... 65 Mass and Ectoparasites ...... 71 CONCLUSION ...... 76 LITERATURE CITED ...... 85

CHAPTER 4: GENERAL CONCLUSION ...... 94 LITERATURE CITED ...... 99

APPENDIX 1: BANK MEASUREMENTS OF OCCUPIED BANK SWALLOW COLONY LOCATIONS...... 100

APPENDIX 2: BANK CHARACTERISTICS, EQUATIONS USED TO CALCULATE FACE SIZE, HEIGHT, AND AREA (CALCULATED USING EXCEL)...... 103

APPENDIX 3: BANK SWALLOW COLONY COUNTS IN 2014 AND 2015 LAKESHORE AND AGGREGATE PIT HABITATS...... 106

APPENDIX 4: SOIL COMPOSITION OF OCCUPIED BANK SWALLOW BANKS DURING THE 2014 AND 2015 FIELD SEASON...... 108

LIST OF FIGURES

Figure 2. 1: Aggregate pit study sites situated within the City of Kawartha Lakes, Northumberland County and Peterborough County in Ontario, Canada, indicated by triangles. The circles indicate lakeshore sites, located within the Region of Durham on Lake Ontario ...... 39

Figure 2. 2: Plot illustrating the relationship between colony size and occupancy of burrows in natural sites to help assess bionomial model fit. The grey trend line represents a smoothed (span = 0.75) loess fit to predicted values from the lakeshore occupancy logistic regression model. Grey area surrounding this line represents the 95% confidence interval for the fitted line. Solid black circles represent burrow occupancy where occupied (value = 1) and not occupied (value=0). Sold black circles with error bars represent the proportion of occupied burrows and associated standard errors calculated and binned with relation to colony sizes...... 40

Figure 2. 3: Plot illustrating the relationship between colony size and occupancy of burrows in aggregate pit sites to help assess bionomial model fit. The grey trend line represents a smoothed (span = 0.75) loess fit to predicted values from the aggregate pit occupancy logistic regression model. Grey area surrounding this line represents the 95% confidence interval for the fitted line. Solid black circles represent burrow occupancy where occupied (value = 1) and not occupied (value=0). Black circles with error bars represent the proportion of occupied burrows and associated standard errors calculated and binned with relation to colony sizes...... 41

Figure 2. 4: The interaction of burrow height on the lakeshore (Low = 1, Not Low =0) and lakeshore colony sizes in the logit model fit. The y-axis is labeled on the probability scale, and a 95-percent confidence interval is in shading around the estimated effect. .... 42

Figure 2.5: Effects graph for the interaction of burrow height in aggregate pits (Low = 1, Not Low =0) and aggregate pit colony sizes in the logit model fit. The y-axis is labeled on the probability scale, and a 95-percent confidence interval is in shading around the estimated effect...... 43

Figure 3. 1: Interaction between adult Bank Swallow mass and the date of capture (beginning on June 1) between lakeshore and aggregate pit sites ...... 78

Figure 3. 2: Predicted means and standard errors from number of external ectoparasite models. Adult external ectoparasite load was not significantly different between aggregate pits and the lakeshore (p=0.482). Fledgling external ectoparasite load was significantly lower in aggregate pits than at the lakeshore colonies (p=0.014)...... 79

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LIST OF TABLES

Table 2. 1: Final statistical models for occupancy and persistence analysis ...... 44

Table 3. 1: Final statistical models for productivity and health objectives ...... 80

Table 3. 2: Average mass (and standard error, g) of Bank Swallows on Lake Ontario and aggregate pits in 2014 and 2015. n = number of birds banded ...... 81

Table 3. 3: Estimated nest survival rates with 95% confidence intervals from the logistic- exposure model for daily and period nest survival...... 82

Table 3. 4: Modeled mean and standard error for clutch size and number of successful fledglings per nest of Bank Swallows in lakeshore and aggregate pit habitats. n = number of nests ...... 83

Table 3. 5: Raw mean parasite load per individual Bank Swallow on the lakeshore and in aggregate pits from the 2015 field season...... 84

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CHAPTER 1 - GENERAL INTRODUCTION

For many bird species, habitat loss is considered a dominant driver of population decline (Robinson et al. 1995, MacHunter et al. 2006). Many bird groups, such as shorebirds, grassland birds, and aerial insectivores, are facing major population declines

(NABCIC 2012) that are, in part, attributed to habitat loss. Habitat loss and destruction negatively affects all phases of a bird’s life cycle. More than 75% of Canadian bird species are considered migratory (OTAGC 2013), spending only a portion of the year in

Canada, where they breed, before moving to their wintering grounds (Robbins et al.

1989, Moore et al. 1995, OTAGC 2013). While migratory birds depend on habitats that will provide an adequate food supply and protection throughout their annual cycle

(Moore et al. 1995, NABCIC 2012, OTAGC 2013), breeding habitat is particularly important in that it is where bird populations reproduce, providing potential recruits into the population as replacements for adults lost to mortality (Kurki et al. 2000, Pulliam

2000, Johnson 2007). For example, declines in Barn Swallow (Hirundo rustica) populations have been linked to changes in land use from livestock farming, meadows and hayfields, to row crops, resulting in a loss of foraging habitat and insect availability

(Evans and Robinson 2004, Kang and Kaller 2013).

Aerial insectivores (e.g., swallows, swifts, whip-poor-wills, nighthawks, martins, and flycatchers) are a guild of bird species that specialize in feeding on flying insects

(Garrison 1999, NABCIC 2012). This guild of mostly unrelated taxonomic groups is experiencing one of the greatest rates of decline amongst birds (Nebel et al. 2010,

Paquette et al. 2014). While habitat loss is considered an important driver of population

2 decline for many of these species, declines and potential changes in phenology of insect populations may also contribute to aerial insectivore population declines (Benton et al.

2002, Evans et al. 2007, Nebel et al. 2010). Changes in phenology of insect populations may account for reductions in overall insect abundance, in addition to the potential loss of synchronization of insect abundance and timing of different life stages such as nestling hatch or fledging (Nebel et al. 2010). Among this guild is the Bank Swallow (Riparia riparia), whose population has declined in Canada at a rate of 6.9 % per year, or 98% overall since 1970 (to 2012), according to survey-wide North American Breeding Bird

Survey data (BBS) (Falconer et al. 2016). While Bank Swallows were ranked by the

Committee on the Status of Endangered Wildlife in Canada (COSEWIC) as threatened in

2014 due to this decline, Ontario has been the only province or territory to list them provincially as a species at risk, where they are experiencing a rate of decline of 6.2% annually, or 93% from 1970 to 2012 (Falconer et al. 2016). Having the third largest proportion of Bank Swallows, Ontario is also home to some of the largest concentrations of Bank Swallows, primarily along the shores of Lake Erie, Lake Ontario, and the

Saugeen River (Falconer et al. 2016).

The Bank Swallow, a neotropical migrant, is the smallest swallow in the

Americas (Family: Hirundinidae), measuring 12 cm in length and weighing 10-18g. In flight, Bank Swallows are best distinguished from other swallow species by their small size, characteristic dark breast-band, and a flight pattern of quick wing-beats (Garrison

1999). Sexes can be identified, in the hand, during the breeding season by the presence of a brood patch (female) or a cloacal protuberance (male). Juvenile Bank Swallows can be

3 identified by a buff-pink wash to their throat, buff-edged upper parts, and a yellow gape

(Pyle 1997).

Primarily, Bank Swallow breeding habitat consists of vertical cliffs and banks located along ocean coasts, rivers, streams, lakes, and wetlands (Peck and James 1987,

Garrison 1998, 1999). These cliffs and banks are comprised of two sections: the talus

(sloped accumulation of rock and soil debris at the base of cliff or bank) and the face

(vertical portion of bank situated above talus). In these natural breeding habitats, colonies exist where vertical faces are created and maintained by erosion due to high wave action or wind (Garrison 1999). Banks with colonies along these natural sites are primarily composed of unconsolidated alluvial soils such as sand, clay, silts, and loams (Garrison

1998, 1999; Silver and Griffin 2009). It is on these faces that Bank Swallows will excavate the nest burrow and nest chamber, ranging in depth from 40 to 110cm (Garrison

1999, this study).

Within the last 100 years, the excavation of aggregates, such as gravel and sand, has increased primarily to meet the needs of construction and maintenance of a variety of infrastructure types, including buildings and highways (Binstock and Carter-Whitney

2011). Excavation of aggregate resources has led to an increased availability of vertical faces away from natural water bodies, and many nesting colonies are found at these aggregate pit sites (Erskine 1979, Garrison 1999, COSEWIC 2013). Arguments have been made that these anthropogenic sites can be referred to as a substitute habitat, in which these areas can provide partial substitute for natural Bank Swallow habitat. These

‘substitute habitats’ may be actively selected by the species, despite the potential availability of natural habitats (Martínez-abraín and Jimenez 2016). However, if these

4 man-made banks are not maintained, slumping and stabilization will occur, causing the colony to abandon the habitat.

The Issue

Extensive erosion control measures along lakeshores, oceans, and rivers have increased over the years, especially in areas adjacent to human settlements, to harden shoreline and prevent erosion and property loss (Garrison 1998, Graf 2006, Monk et al.

2010, TRCA 2010). The California State Government, for example, has attributed the loss of Bank Swallow populations directly to erosion control projects along the

Sacramento River (Schlorff 1992, Garrison 1998). Restoration of Bank Swallow habitat occurred through the removal of these erosion control projects to increase or halt the decline of this population (Girvetz 2010). Erosion control in Canada has been widespread, especially in areas of densely populated human settlements where shorelines are often hardened to protect against property loss (COSEWIC 2013). Erosion control measures are especially common along the Great Lakes shorelines, stabilizing for both residential and industrial use of the area (Herdendorf 1984, TRCA 2010). Continual low water levels within the Great Lakes, especially since the 1990s (Gronewold et al. 2013), have also contributed to the stabilization of lakeshore banks. While lake levels on Lake

Erie and Lake Ontario have remained relatively stable, decreases in average annual water levels, at least through 2013, have coincided with increases in the surface water temperatures and evaporation rates in all the Great Lakes (Gronewold et al. 2013).

Stabilized banks do not support Bank Swallow colonies due to their decreased slope and hardened surface making them impenetrable to the birds (Garcia 2009). Mature vegetation above and on the talus slope can also indicate a stabilized bank, which can

5 lead to abandonment of the area by Bank Swallows due to obstructions from tree roots and increasing burrow access to predators (Freer 1977, Hjertaas 1984, Garcia 2009). This form of stabilization occurs primarily in less-populated areas that lack erosion control measures, leading to further declines in breeding habitat for Bank Swallows (COSEWIC

2013). The availability of natural suitable nesting sites is perhaps the most limiting habitat requirement for breeding Bank Swallows (COSEWIC 2013, Falconer et al. 2016).

While substantial attention has been given to the destruction and degradation of natural breeding habitat of Bank Swallows, there are also many concerns that surround substitute habitats. The decline of Bank Swallow populations in Sweden (where they are referred to as “Sand Martins”) has been associated with changes in the aggregate industry, including a shift in the demand from sand to gravel and an increased directive to restore non-active pits, a practice that results in the stabilization of slumping banks (Lind et al. 2002). Similar changes in market demand from sand to gravel are occurring within the Canadian aggregate industry because of shifting demands and increased regulations

(Altus Group 2009), potentially limiting the amount of habitat available in these substitute habitats.

Research on North America’s Bank Swallow population is limited, and that which exists, is primarily directed towards the ecology of this species in natural habitats such as on rivers (Garrison et al. 1987, Schlorff 1992, Garrison 1998, Girvetz 2010, Moffatt

2005) and lakeshores (Cadman et al. 2007, Beacon Environmental 2011, Tozer and

Richmond 2013, Hatch - Sargent and Lundy 2015, Falconer et al. 2016). Bank Swallow population data in Canada are mainly limited to the North American Breeding Bird

Survey and Breeding Bird Atlases (Cadman et al. 2007, Falconer et al. 2016). Long-term

6 projects have been initiated to assess and analyze Bank Swallow occupancy trends in areas of high abundance such as along a portion of Lake Erie (Tozer and Richmond 2013,

Falconer et al. 2016) and Lake Ontario (Beacon Environmental 2011, Hatch - Sargent and Lundy 2015), and for population estimates along the Saugeen River (COSEWIC

2013). Limited unpublished reports have been produced from research in aggregate pit sites; preliminary data from these locations suggest that aggregate pit habitats can be of importance in supplementing breeding populations, though the degree of importance is unknown (Schutten 2013, Tozer and Richmond 2013, M. Browning and M. Cadman, pers. comm.). From preliminary surveys in Ontario aggregate pits, an estimate of about

68% of Ontario’s breeding Bank Swallows, in 2013, were assumed to breed in aggregate pit sites (M. Browning and M. Cadman, pers. comm.), suggesting that aggregate pits are important Bank Swallow breeding habitat.

There is limited understanding of how Bank Swallows use aggregate pit sites. For example, few data are available from Europe where Bank Swallows use aggregate pits and quarries for nesting sites (Asbirk 1976, Jones 1986). Further, the only previous studies from aggregate pit sites in Canada examined how talus height influenced Bank

Swallow site selection (Ghent 2001) and what habitat features Bank Swallows select for nesting, in a study that included aggregate pit sites as a feature (Hjertaas 1984).

Recognition of this knowledge gap has led to new research projects within aggregate pit habitats (Tozer and Richmond 2013, Falconer et al. 2016, M. Browning and M. Cadman, pers. comm., this study), focusing on trends in occupancy levels (ratio of used burrows versus total number of burrows), population estimates, habitat selection, roosting habitat, nest success, bird health, and migration monitoring.

While current surveys fill knowledge gaps about species abundance on the landscape, much is left to be discovered about nestling survival at aggregate pit sites (Schutten

2013). Whether Bank Swallows successfully breed and replace themselves in aggregate pits is unknown, as is an understanding of the stability and reuse of their colony locations from year to year. Research comparing the breeding success, individual health, and occupancy of birds in natural habitats to that of substitute habitats is also lacking (Tozer and Richmond 2013, Falconer et al. 2016). A comparison of reproductive success in aggregate pits and natural habitats is necessary to recommend whether aggregate pits could be adequate substitute habitats for this declining species. Similarly, understanding more about the bird’s reproductive success and use of these sites will allow us to determine whether these aggregate pit sites may be ecological traps for the species. As

Bank Swallows continue to lose natural nesting habitat, aggregate landscapes may become successful source habitats for the population. Exploring the role that these substitute habitats can play in the breeding success for Bank Swallows can also further develop best management practices to be used in operational aggregate pit sites.

Study Objectives

The goal of this thesis was to explore the role that aggregate pits play in Bank

Swallow productivity and habitat use. As Bank Swallow populations continue to decline, it is imperative that we increase our understanding of their different life stages to understand and mitigate threats to their survival in both natural and substitute habitats.

My thesis has two primary objectives; one presented in each of the two data chapters.

In Chapter 2, my objective is to compare Bank Swallow occupancy and persistence in natural sites and aggregate pits. I hypothesize that colony occupancy levels

(the proportion of nesting burrows containing a nesting attempt) would vary between aggregate pit and natural sites as well as be a function of burrow height, colony size, soil composition of the face, or some combination of these factors. I predict that occupancy would be lower in natural sites potentially due to lower bank refreshment. Second, I hypothesize that the annual persistence of these colonies would depend on the broader habitat (e.g., natural or aggregate pit site) in which the occupied bank was situated. I predict that lakeshore and river sites would have higher persistence than colonies in aggregate pit sites, under the assumption that aggregate pits are active and will thus likely be more ephemeral. Additionally, I hypothesize that the reuse of faces in aggregate pits would also depend on colony and landscape features such as colony sizes, size of available face, and amount of available water within 1km of the colony. I predict that all these factors would positively influence the reuse of faces in aggregate pit sites.

Establishing the degree of persistence of colonies constructed in various landscape features, in conjunction with the information from reproductive success, is important for understanding and identifying critical habitats of Bank Swallow.

In Chapter 3, my primary objective is to determine if there were differences in

Bank Swallow productivity and their general health between aggregate pits and natural lakeshore sites. First, I investigate Bank Swallow productivity between sites, examining both clutch size and number of fledglings produced per nest. Second, I examine health factors, such as mass and parasite load, to understand Bank Swallow condition between sites. I hypothesize that Bank Swallow productivity and health (mass and parasite load) will be dependent on habitat type. I predicted that Bank Swallows would have higher productivity rates and mass in the natural lakeshore sites than in the aggregate pits. This

9 assumes that natural lakeshore sites would provide better protection from predators, as well as greater food resources than aggregate pit sites would provide. I also predicted that ectoparasite load on both adult and fledgling Bank Swallows would be lower in aggregate pit sites because there are lower colony sizes, lowering the rates of parasite transmission.

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Schlorff, R.A. 1992. Recovery plan: Bank Swallow (Riparia riparia). Nongame bird and mammal section wildlife management division, report 9302. California Department of Fish and Game: Sacramento, CA., 16 pp.

Schutten, K. 2013. BANS 2013 Pit survey project – methods and preliminary data collection results. Prepared for Environment Canada – Canadian Wildlife Service Branch, Burlington, ON.

Silver, M., and C.R. Griffin. 2009. Nesting habitat characteristics of Bank Swallows and Belted Kingfishers on the Connecticut River. Northeastern Naturalist, 16: 519-534.

Toronto Region Conservation Authority (TRCA). 2010. Meadowcliffe drive erosion control project: environmental study report. Retrieved from http://www.trca.on.ca/dotAsset/83297.pdf on November 30, 2014.

Tozer, D.C., and S. Richmond. 2013. Bank Swallow research and monitoring: 2013 final report. Unpublished report to Ontario Power Generation. 27 pp.

CHAPTER 2: FACTORS PREDICTING THE PERSISTENCE AND OCCUPANCY OF BANK SWALLOWS (RIPARIA RIPARIA) BREEDING IN AGGREGATE PITS AND NATURAL HABITATS

ABSTRACT

The availability of natural and eroded banks for nesting of Bank Swallows is becoming scarcer across its range, reflecting a population decline in the species. While the species continues to nest in natural habitats, their use of aggregate pits as inland nesting sites has increased. Preliminary data suggest that aggregate pits can be important nesting habitat; however much about this habitat type is unknown. I sought to compare patterns of Bank Swallow occupancy in lakeshore and aggregate breeding sites and investigate other factors that contribute to occupancy levels, using data collected during two years of study. The second objective was to use a broader sample of data collected from other studies over a longer time period, to compare the persistence and extinction of colonies in lakeshore, river, and aggregate habitats. I collected data from three natural sites along bluffs of the north shore of Lake Ontario and eleven aggregate pits from southern Ontario during summer of 2014 and 2015. Burrow height and colony size were significant predictors of burrow occupancy on natural sites, whereas this was not the case in aggregate pits. Aggregate pit sites were more ephemeral, likely due to annual removal and relocation of aggregate resources. Bank Swallow colonies in aggregate pit sites were more likely to persist if the nesting face was larger or if burrows were located higher on the face. River colonies were less ephemeral than those in aggregate pit sites and lakeshores were the most stable habitat for Bank Swallow breeding habitat. Aggregate pit sites have the potential to attract birds and increase colony persistence by operators ensuring the designated banks have a large surface area, are tall, and refreshed frequently.

INTRODUCTION

For many colonial species of birds, knowledge about colony occupancy and persistence is important to gain insight into population dynamics, guide habitat management, and, if needed, guide recovery efforts (Barbraud et al. 2003, Robertson et al. 2007). The dynamics of how and why avian colonies form (Wittenberger and Hunt

1985, Rolland et al. 1998) and how they persist over periods of time (Barbraud et al.

2003, Robertson et al. 2007) have been frequently studied.

Colony size (the number of birds within a designated area) and persistence (the number of years a colony has been occupied over a set amount of time) have been studied for colonial herons (Barbraud et al. 2003), gulls (Robertson et al. 2007), seabirds (Chaulk et al. 2006, Zador et al. 2009), and passerines (Moffatt et al. 2005, Garcia 2009). Many of these studies have shown that the probability of persistence increases with colony size

(Brown and Rannala 1995, Chaulk et al. 2006, Robertson et al. 2007), likely as larger colonies provide social signals of habitat quality and predator protection. Previous reproductive success has also been studied with relation to colony persistence, with many species showing attraction to colonies that had been more productive in the previous year

(Cuthbert 1988, Danchin et al. 1998, Brown et al. 2000, Vergara et al. 2006). However, poor reproductive success may not always lead to colony extinction; while original breeders at a site may leave, new birds may be attracted to breed there using habitat cues

(Southern and Southern 1982, Wyman 2012). Habitat stability is a third factor relating to the probability of colony persistence, as reliable and stable sites of high quality will generally have higher site fidelity than those that are unstable (McNicholl 1975).

The Bank Swallow (Riparia riparia) is a colonial bird species that has

16 experienced a significant population decline since 1970 (COSEWIC 2013, Falconer et al.

2016). Natural Bank Swallow breeding habitat consists of vertical cliffs and banks located along ocean coasts, rivers, streams, lakes, and wetlands (Peck and James 1987,

Garrison 1998, 1999). Banks in these areas are often subjected to high levels of wind and wave erosion that maintain the vertical face (Garrison 1999). It is this erosion that not only creates these vertical faces for nesting, but also maintains them over time keeping them soft enough for Bank Swallows to excavate their relatively deep (59-90 cm,

Garrison 1999) nesting burrows. Extensive erosion control measures along lakeshores, oceans, and rivers have increased over the years, especially in areas adjacent to human settlements, to harden shoreline and prevent erosion and property loss (Garrison 1998,

Graf 2006, Monk et al. 2010, TRCA 2010). This increase in erosion control measures comes at the loss of natural nesting sites, making the availability of these natural sites one of the most limiting habitat requirement for breeding Bank Swallows (COSEWIC 2013).

While the availability of natural nesting habitat is on the decline on both lakeshores and rivers, substitute habitats (i.e. “artificial”) in the form of operational aggregate pit sites have been increasing away from lakeshores and rivers at inland sites

(Erskine 1979, Garrison 1999, COSEWIC 2013, Falconer et al. 2016). Within these aggregate pit sites, vertical faces are formed through the excavation of sand and gravel resources. However, if the vertical banks at these sites are not maintained through human intervention, slumping and stabilization will occur, causing the colony to abandon the habitat (Ghent 2001, Lind et al. 2002).

Suitable conditions in these natural and substitute habitats are highly ephemeral, suggesting that breeding locations may change frequently (Garrison 1999). In natural

17 habitats, this ephemeral nature is due to the existence of high erosion rates; in substitute habitats this is due to aggregate resource extraction and site rehabilitation. As Bank

Swallows can exhibit site fidelity to their general breeding area (Mead 1979, Garrison

1999) any loss of breeding sites may be detrimental to their productivity and population stability.

As best management practices are developed and revised for the aggregate industry, understanding of how Bank Swallows use the landscape and what landscape features they prefer is needed. Analysis of persistence rates and occupancy levels of colonial birds has been used in a variety of studies to better understand why and how birds use a landscape (Barbraud et al. 2003, Robertson et al. 2007, Garcia 2009). Thus, for this chapter, I sought to understand what factors drive Bank Swallow burrow occupancy and colony persistence between aggregate pits and natural sites.

The first objective was to investigate any differences in burrow occupancy levels

(the proportion of nesting burrows containing a nesting attempt) between aggregate pits and natural lakeshore sites, and to determine whether factors such as colony size, burrow height, and soil structure of the occupied bank, contribute to occupancy levels. I hypothesized that the occupancy levels of a colony (the proportion of nesting burrows containing a nesting attempt) would vary between natural and aggregate pit sites.

Similarly, function of burrow height, colony size, soil composition of the face, or some combination of these factors, would also predict burrow occupancy. I predict that occupancy would be lower in natural sites potentially due to lower bank refreshment.

The second objective was to explore factors that influence the persistence of colonies in lakeshore, river, and aggregate habitats. I hypothesized that Bank Swallow

18 colony persistence would vary across habitat types. I predicted that natural sites

(lakeshore and rivers) would have higher rates of persistence than aggregate pit sites, under the assumption that aggregate pits are active with will thus likely be more ephemeral. I also predicted that the reuse of bank faces in aggregate pit sites would be most influenced by colony sizes, size of available face, and amount of available water within 1km.

METHODS

Study area

This study was conducted in aggregate pits and lakeshores bluffs that supported breeding Bank Swallow populations at the beginning of the study. Aggregate pit sites were situated within the City of Kawartha Lakes, Northumberland County, and

Peterborough County of Ontario, Canada, and lakeshore sites were located on Lake

Ontario within the Durham Region (Figure 2.1).

Aggregate pit sites supporting Bank Swallows were surveyed during 2014 -2015; they were chosen based on their proximity to other study sites to minimize travel times, and permission to access properties. All aggregate pit sites were on private property owned by aggregate companies or were on land owned by the local township but designated for aggregate removal. I surveyed eleven active aggregate pits in 2014 and eight in 2015. These active colonies were visited until Bank Swallows had completed nesting and departed from the sites by early August. All colony visits were conducted on aggregate pit sites during operational hours (0700-1700) twice per week. Colonies were defined as an aggregation of three or more Bank Swallow burrows, no further than 20m

19 apart. Over the two-year study period a total of 41 discrete colonies in aggregate pits were monitored, 22 colonies in 2014 and 18 colonies in 2015; some colonies occurred on the same faces in both study years.

Aggregate pit sites ranged in their operational level with some sites active daily, while others were either occasionally active or not active during the breeding season. The primary products at these aggregate pits were sand, gravel, and rocks used for a variety of purposes such as brick mortar, pool liners, patios, and road construction. Sites ranged in size from approximately 1.2 ha to approximately 81 ha. Most Bank Swallow colonies were situated in stable bank faces along the perimeter of the excavation site, although three colonies were situated in large stockpiles. Banks containing Bank Swallow colonies varied greatly in height (including bank talus and face, range 5-14 m; Appendix 1). Eight aggregate pits had a pond located either within the site, or within 300 m of the site.

Lakeshore study sites were chosen based on previously surveyed areas along Lake

Ontario (Beacon Environmental 2011). 21 discrete colonies were monitored, 11 in 2014 and 10 in 2015. All of these colonies remained on the same portion of face between years. Lakeshore sites had no anthropogenic erosion control measures in place, so were considered examples of natural Bank Swallow habitat. Lakeshore sites consisted of sandy vertical banks of a variety of heights (Appendix 1). On the western end of the study area, bank faces tended to be smaller in size (5-9 m in height) and were comprised of a higher proportion of clay than other sites. The eastern end of the study area had taller faces (9 –

14 m), which consisted of very fine sandy soil. Surveys of Bank Swallow colonies on the lakeshore were conducted twice weekly between the hours 0700-1900.

Bank Characteristics

At all banks where birds were nesting, and as close to the colony burrows as possible, I measured talus height, face height, colony length (distance in meters from first to last burrow), and percent sand in soil. Measurements of colony length, talus height, and face height were made using a range finder, these measurements were in degrees, based on the location and elevation of the user. Degree measurements were then entered into equations that were used to calculate length (meters) and height (meters) (M.

Browning and M. Cadman pers. comm. Appendix 2).

Two soil samples were collected from the left and right side of each bank at either the lowest or highest burrow, dependent on accessibility, using a soil core (19.63 cm2 x

10.2 cm, 200cm3). If burrows were inaccessible because the banks were too high, soil samples were collected from the closest area on the face that could be reached by foot.

Soil samples were brought back to the laboratory where analyses of bulk density and soil particle composition were conducted (Kalra and Maynard 1991). I was not able to collect soil samples from the faces of three aggregate colonies. For these, I used a site mean taken from other colonies within the same site. Soil was not collected at the Darlington

Nuclear Generating Station site, due to inaccessible banks.

Soils were dried in a forced-air oven at 105o C for 24 h. Once soils were dried, they were sifted to remove larger soil compounds such as gravel and rocks. These larger items were weighed separately and removed. To obtain the soil particle composition, fifty grams of fine-textured soil (and 100g of course-textured) was transferred into a dispersion cup. Water was added to each soil sample to equal 400mL. Fifty mL of a

Calgon® solution was added to the dispersion cup and stirred in a milkshake machine, on

21 low setting for 15 minutes. After 15 minutes, the soil mixture was immediately transferred into a sedimentation cylinder and distilled water was added up to the 1-L mark, and left overnight to equilibrate to room temperature (Kalra and Maynard 1991).

The next day, a plunger was inserted into the bottom of the cylinder and stirred for 2 minutes, moving the plunger up and down the whole length of the sedimentation column.

Once the plunger was removed, a hydrometer was immediately placed into the soil mixture. A hydrometer reading was made (top of the meniscus) after exactly 40 seconds at the completion of stirring. A temperature reading was also made after the hydrometer reading to determine if the solution was room temperature (20 degrees). Hydrometer and temperature readings were then repeated after two hours.

Calculations were then performed to determine the percentages of sand, clay, and silt in the soil sample (Kalra and Maynard 1991). Hydrometer readings were temperature corrected to 20°C. To determine the amount of (a) silt and clay (%) we used:

(a) Silt + clay (%) = corrected hydrometer reading at 40 seconds x 100 Sample weight (g)

Once the content of silt-clay was found, I was able to break this further down into total percent of clay (b), sand (c), and silt (d) using the following three equations:

(b) Clay (%) = corrected hydrometer reading at 2 hours x 100 Sample weight (g)

(d) Sand (%) = 100 – (a)

Burrow Counts

Burrow counts were made from photographs of the colony. Photo edges were overlapped with photos from adjacent portions of the colony, to ensure that no burrows were missing. Photographs were then uploaded to a computer and individually counted on the computer screen. All burrows, regardless of being actively used or not, were included in this count. I completed the first burrow counts of the season shortly after colony establishment around the first week of June. A second burrow count was completed in the last week of July when most birds in the colonies had completed breeding. This second count was done to potentially account for any changes in burrow count throughout the course of a season, whether this is through new burrows being dug or burrows being lost to clumping or depredation. Only the first count was used in my statistical models, as they were the most reflective of the colony size at the peak of breeding.

Occupancy Surveys

Video recordings of a sub-sample of lakeshore and aggregate pit colonies were made to gauge the occupancy Bank Swallow burrows. The number of cameras facing each colony depended on colony size. Each camera frame for larger colonies captured at minimum, 50 burrows (Beacon Environmental 2011). Cameras recorded Bank Swallows entering and leaving the burrows for 30-minute periods. These filming events were repeated weekly to increase the accuracy in determining whether burrows were occupied or not. By repeating these visits we could see if a burrow was being used over time; if a burrow was used at minimum three times during the breeding period, it was considered

23 occupied. To ensure that the same area of bank was recorded each week, still photographs of the burrow configurations were taken and printed.

Still photographs were also used during the analysis of videos, where a numbering system was used to assign a unique identifier to each burrow. The video was fast- forwarded to 5 min and the middle 20 min was played back at a normal speed. An observer recorded the entrances and exits of birds. Removing the first and last five minutes of the video removes any disturbance that we may have caused to the colony while walking to and from the video setup. Birds were recorded as entering a burrow if they could be seen fully entering the burrow cavity or if there was evidence that hatchlings were being fed (Beacon Environmental 2011, Falconer pers. comm., 2014).

The average height of burrows for each colony was arbitrarily assigned a rank based on the potential ability of predators to reach the burrows from the bottom of the bank face, because identifying the heights of each individual burrow was not feasible. I considered burrows to be low if they were under approximately 1.5 meters in height and thus likely reachable by a mammalian predator, such as foxes and raccoons. All other burrows were assigned a height category of medium-high if they were not easily reachable by a mammal. Some colonies may have all burrows within one of these categories depending on their layout. In cases where an individual burrow straddled the two height categories I assigned the category that hosted the majority of the individual burrow.

Persistence

I collected reuse data, of an independent bank, through a variety of means.

Aggregate pit study sites were selected based on previous surveys conducted in 2013 by the Canadian Wildlife Service and the Ontario Ministry of Natural Resources and

Forestry (CWS, OMNRF, unpub data), and so I had use data from 2013-2015. Aggregate pit sites that were added in 2014 have only two years of colony use data. Lakeshore sites that were previously surveyed along Lake Ontario included use data from 2011 to 2015

(Beacon Environmental 2011, Hatch-Sargent and Lundy 2015). Reuse data from the

Saugeen River was also available from 2009 to 2015 (Canadian Wildlife Service and the

Ontario Ministry of Natural Resources and Forestry, unpub data), however only data from 2011-2015 was used to coincide with the time period that data were collected from the lakeshore.

Statistical Analysis

All statistical analyses were conducted in the program R Studio (RStudio 2015).

Occupancy Analyses

I conducted analyses of occupancy at the scale of individual burrows. I used generalized linear mixed models (GLMM) (family=binomial; lme4 package; Bates et al.

2014) to determine what factors affected individual burrow occupancy. Data on each burrow (used, not used) was paired with bank level covariates that included percent sand on nesting face, colony size (total number of burrows), and burrow height. I set my correlation threshold to be r=0.5. Due to correlations found between the predictor variables site type (e.g., lakeshore or aggregate pit) and both percent sand and colony size, two separate occupancy models were run; one for lake burrows (n=1184) and a

25 second for burrows from aggregate pit sites (n=2021). These site characteristics were also found to be different and, in general, the range of covariates did not overlap between aggregate pit and lakeshore sites, furthering the need to analyze them separately. Both models included a random effect of “colony” to account for having many burrows within a single colony.

Occupancy models were created using a stepwise approach. A full model was created with all covariates and possible interactions. Model selection was carried out by removing the effect furthest from statistical significance (α = 0.05) and re-running the model until a final model was achieved (Table 2.1). The final model was selected when a) the model fit and b) when non-significant effects were removed. While there is no standard way to test for model fit in binomial models (Flockhart et al. 2016), I attempted to do this graphically (Figures 2.2 and 2.3). Visually, my final model fit better than the previous one that included the non-significant effect, so I continued with my analysis.

Persistence and Face Reuse Analyses

Persistence was defined as at least part of the colony overlapping the area of bank occupied in the previous year. The predictor variables that I hypothesized as being important in predicting persistence were unavailable from enough lakeshore or river colonies, therefore I describe the patterns of colony persistence of these habitats. By contrast, I collected data on colony characteristics in all aggregate pits over the two years and used a logistic regression analysis to examine factors that might affect yearly occupancy levels and face reuse over 2013-2015.

Factors assumed to influence face reuse included colony size in the previous year, distance to the nearest aggregate pit, and amount of water within 1km. Distance to

26 nearest aggregate pit was used to gauge whether isolation from other potential inland habitats would increase the probability of face reuse. Similarly, total surface area of water within 1 km of colonies was included to determine if the presence and size of nearby water were important predicting face reuse. This distance was chosen as foraging of

Bank Swallows is usually concentrated within 200-500m of the breeding colony, with very few foraging flights extending further than 1000 m from the colony (Garrison 1999,

Falconer et al. 2016). Lastly, the size of the bank face was also included to see whether the amount of usable face available in the current year would influence the probability of

Bank Swallows reusing a face.

Reuse models were created in a stepwise approach. A full model was created with all covariates and possible interactions. Interactions were then removed in a stepwise approach, removing the effect furthest from statistical significance (α = 0.05) and re- running until the final model was established (Table 2.1). All models were tested for goodness of fit by using the Hosmer and Lemeshow goodness-of-fit test (Hosmer and

Lemeshow 1980).

All occupancy and reuse models were performed using the lme4 package (Bates et al. 2015). Statistical significance for all models and tests had α set at 0.05.

RESULTS

Lakeshore sites (63.0 ± 0.03%) and aggregate pit sites (60.0 ± 0.04%) had similar percentages of occupied burrows (z = -0.613, p = 0.54, n = 3205). Average colony size within the aggregate pit sites was smaller than the lakeshore sites, with maximum colony size 1/5th the size of the largest lake colony (mean colony size lakeshore: 560 ± 138 burrows, aggregate pits: 112 ± 17 burrows, Appendix 3). Faces located in aggregate pits

27 had an average percent sand composition of 78.0 ± 1.2%; lakeshore faces had a lower sand composition averaging 50.0 ± 6.0% sand (Appendix 4). The average size of available nesting face for Bank Swallows on the lakeshore was 218 ± 45m2, while available nesting face in aggregate pits averaged 92 ± 16m2 (Appendix 1).

Burrow Occupancy

The proportion of sand was not a significant predictor of burrow occupancy at either the lakeshore (z = 0.17, p = 0.87, n = 730) or in aggregate pit sites (z = 0.43, p =

0.67, n = 2021). As percent sand did not predict occupancy at either site type, it was removed from further consideration within models.

Lakeshore sites

The height of the burrow was a significant predictor of occupancy at lakeshore

Bank Swallow colonies. Low burrows had significantly lower probability of occupancy than those found higher on the bank, with low burrows 94.5% less likely to be occupied than burrows higher on the bank (Odds Ratio: 0.055, CI: 0.0177 – 0.145, z = -5.45, p <

0.01). However, this main effect was dependent on colony size, as there was a significant interaction effect (z = -3.6, p < 0.01). This interaction shows that as colony size increases, the odds of a low burrow being occupied decreases by 15% (Odds Ratio: 0.1456, CI:

0.05-0.395, Figure 2.4). Colony size alone was not a significant main effect (z = 0.81, p =

0.42).

Aggregate pit sites

Neither the height of the burrow, nor colony size had significant effects on individual burrow occupancy in aggregate pits (height: z = 0.80, p = 0.4; colony size: z =

1.82, p = 0.07). Similar to at lakeshore sites, there were interactions between main effects. At aggregate pit sites, the number of occupied burrows that were higher on the bank increased slightly as colony size increased, however in contrast to the lakeshore sites, the odds of a low burrow being occupied increased significantly as colony size increased (Odds Ratio: 1.73, CI: 1.13-2.72, z = 2.47, p = 0.01, Figure 2.5).

Persistence

Bank Swallow colonies (n = 11) surveyed at the lakeshore from 2011 to 2015 were present in all five years. Thus, they had a 100% persistence rate. River colonies fluctuated much more in their year-to-year persistence 43% present every year from

2011-2015. Colonies that did not persist every year tended to be intermittent, being absent for an average of 1 year. Only one colony site went unused for more than a single year before Bank Swallows returned to the site; it was unused for four years. Aggregate pits were the most variable in terms of colony persistence. Of the 29 bank faces with successive colonies over 2014-2015 field seasons, 19 of these were also surveyed by others in 2013. Of these 19 colonies, only 32% of them were occupied during all three survey years. While colonies in aggregate pits were quite ephemeral, when colonies did not persist on a face, new colonies were often established in new locations within the same aggregate pits. Between the 2014 and 2015 field seasons, there were three cases

(27%) in which aggregate pits were completely abandoned by Bank Swallows.

Face Reuse

For aggregate pit sites, colony size and size of available face were correlated (r =

0.51). Due to this correlation colony size was dropped as a variable from my reuse model.

Size of available face for burrowing was a significant predictor of face reuse (z = 2.03, p

= 0.04), where the probability of a colony returning to the same face significantly increased as the size of available face increased. Neither the distance to the nearest aggregate pit nor the amount of water within 1 km of the colony were significant predictors of aggregate pit face reuse (z = -0.63, p = 0.53; z = -0.79, p = 0.43 respectively).

DISCUSSION

I found that there was no significant difference in occupancy levels between lakeshore and aggregate habitats, failing to support my first hypothesis. Natural lakeshore

Bank Swallow colonies had the highest persistence rate, supporting my second hypothesis. Supporting my third hypothesis, the size of face in aggregate pit sites influenced the probability that a colony would reuse a face from one year to the next.

Contrary to size of face, the amount of available water within 1km and distance to nearest alternate pit did not influence face reuse, not supporting those predictions.

Further exploratory models found that individual burrow occupancy by Bank

Swallows at lakeshore colonies is best explained by burrow height and colony size.

Aggregate pits contrasted to the lakeshore in that neither colony size nor burrow height explained individual burrow occupancy. At both lakeshore and aggregate pit colonies, the

30 variable colony size interacted with burrow height, where the probability of burrow occupancy increased in large colonies with increasing burrow height. The opposite relationship held at aggregate pit sites.

Occupancy

There was no significant difference in occupancy levels between the lakeshore and aggregate pit sites where in both sites slightly less than two-thirds of burrows were occupied. A 50% burrow occupancy estimate has been suggested for Bank Swallow colonies, especially when attempting to estimate nesting pairs (Wright et al. 2011). This estimate is recommended despite habitat type, as it reflects the range of previously suggested occupancy values (Wright et al. 2011). Occupancy may vary based on season and due to a surplus of excavated burrows (Garrison 1999, Cadman and Lebrun-

Southcott 2013). Surplus burrows exist because a) burrows from a previous season may not be reoccupied, b) a partially dug burrow may be abandoned due to obstacles within the bank such as large stones, c) burrow instability, or d) the bird that built the burrow was unable to attract a mate (Kuhnen 1985, Garrison 1999). Occupancy levels from Bank

Swallow surveys conducted along the north shore of Lake Erie and aggregate pits in

Wellington County (Falconer et al. 2016, M. Cadman pers. comm) have been comparable to the levels of occupancy I have found in this study. Falconer et al. (2016) found an estimated occupancy level of 47-61% in 2010 and 2011 among colonies on the north shore of Lake Erie. Thus, the levels of occupancy at my study sites, within approximately

300 km of those reported in this study, are similar, although slightly above the 50% assumption.

At the lakeshore sites, burrow height was a strong predictor of burrow use with higher burrows more likely to be occupied. This was not the case in aggregate pits.

Burrow height has been identified as a contributing factor to burrow use along Lake

Ontario (Beacon Environmental 2011) and the Qu’Appelle Valley, Saskatchewan

(Hjertaas 1984). Height of the nest cavity has been an important influence on the reproductive success of other cavity nesting passerine species such as Tree Swallow

(Tachycineta bicolor; Rendell and Robertson 1989, Robertson and Rendell 1990),

European Starling (Sturnus vulgaris), Blue Tits (Parus caeruleus), and Marsh Tits (P. palustris; Nilsson 1984). Similarly, waterfowl species, such as Common Goldeneye

(Bucephala clangula) and Wood Ducks (Aix sponsa), also prefer nesting cavities situated higher in the tree (Evans et al. 2002). Many of these studies associate the preference for an increased height to a decrease in predation rates (Nilsson 1984, Evans et al. 2002,

Smalley et al. 2013, Falconer et al. 2016). While nesting relatively higher on a bank is preferable, nesting too high and hence close to the top of the bank can also increase the predation of Bank Swallow nests by skunks (Mephitis mephitis) (Stoner 1936, Ghent

2001) or snakes (Hjertaas 1984). An examination of reproductive success as a function of height may help to clarify whether there is an optimum location for creating nesting burrows.

Colony size alone did not have a strong influence on whether a burrow was occupied. However, colony size did interact with the variable of burrow height. At large colonies on the lakeshore, the probability of occupancy increased with increasing height.

The opposite relationship held at aggregate pit sites. Most Bank Swallow colonies in aggregate pit sites were small, similar to findings from other studies (Peck and James

1987, Falconer et al. 2016). The shorter faces likely limited the number of high burrows available, and it is these higher nesting faces are known to attract Bank Swallows and have greater burrow occupancy (Ghent 2001). Larger colonies, with a few hundred to over a thousand burrows, were located on the Lake Ontario lakeshore where there were larger vertical faces available to the birds.

While Bank Swallows strongly select soils with a high percentage of fine gravel and sand (Hjertaas 1984), soils must have a balance between sand, silt, and clay to be penetrable for excavation, but not be too soft so as to impede stability and increase the risk of burrow collapse (Smalley et al. 2013). In this study, the proportion of sand in a nesting face was not a significant predictor of whether a burrow was occupied. Instead, between and within the lakeshore and aggregate pits (Appendix 4) there was a wide range of soil types in which Bank Swallows nested. The portion of Lake Ontario where survey sites were situated is primarily luvisolic soils, which contain a large portion of clay-silt and sandy-silt soils (SCWG 1998). The majority of the aggregate pit sites, however, were located in an area of Ontario with predominately brunisolic soils, comprised from sandy parent material (Gillespie and Acton 1981, SCWG 1998). Bank Swallows have been reported to occupy banks with a wide range of soil composition, a result born out by my study. Composition of soil near colonies near Ottawa, Ontario was 7-10% silt and 87-

90% sand (John 1991), while soil near colonies in California ranged from 3-61% silt, 2-

30% clay, and 22-93% sand (Garrison 1999).

Persistence and Reuse

Use at lakeshore sites did not fluctuate over the 5-year study period (100% of the colonies studied persisted). While number of burrows fluctuated slightly year-to-year, the individual faces containing the colony remained the same. This study is unique in that it examines colony persistence on the same faces from year to year. Other Bank Swallow studies used a transect technique that examined the total number of burrows along designated transects over successive years (Garcia 2007, Tozer and Richmond 2013,

Hatch-Sargent and Lundy 2015). Burrow counts using this latter technique also appeared to remain relatively stable throughout the years of study, and similarly, locations where swallow colonies have been densely populated in the past seem to continue to be so. This is likely due to favourable conditions at these sites such as higher face refreshment. Bank

Swallows are also more likely to return to their breeding colony in subsequent years if they successfully fledged young at that site in the previous year and if the site has high bank stability (Freer 1979, Garrison 1999). Bank Swallow individuals exhibit moderate to high site fidelity. In other studies, experienced breeders have exhibited high site fidelity (55 - 92%; Petersen and Mueller 1979, Freer 1979, Szép 1990), likely as they are returning to places where they had been previously successful. First-time breeders have shown moderate site fidelity (46-59%; MacBriar and Stevenson 1976, Freer 1979, Szép

1990) likely returning to where they had been reared. Return rates for adults were approximately 2.5 times greater than those for first-time breeders (Freer 1979). First-time breeders of a population that did not return to their natal area have been found at colonies ranging from 15km to 200+km (MacBriar and Stevenson 1976, Mead 1979, Petersen and

Mueller 1979). While return rates could theoretically have been determine using my banding data (see Chapter 3), I banded such a small proportion of the total number of

34 birds in the colonies, that I did not encounter any individuals that I had banded in 2014 during my 2015 field work.

Use of river sites was relatively stable with most colonies disappearing for only a year at a time over the 5-year period. The Saugeen River holds the largest density of

Bank Swallows on a river body in Ontario (Sandilands 2007, Cadman and Lebrun-

Southcott 2013, Falconer et al. 2016). While the faces along the Saugeen River have remained relatively stable, burrow counts conducted during the same 5-year period have fluctuated considerably and without an apparent trend (Cadman and Southcott-Lebrun

2013). In Ontario, very few rivers support colonies of Bank Swallows, potentially due to flood control programs reducing erosion rates of river banks (Falconer et al. 2016). In

California, colony persistence along the Sacramento River has ranged from 1 to 10 years, although the majority of colonies were active for only 1-2 years (Garcia 2009).

A longer-term study is needed to understand factors affecting colony persistence at aggregate pit sites. This short-term study indicated that there was a high degree of location turnover. With a longer study period I could better compare persistence with natural sites. Given this limitation, Bank Swallow colonies in aggregate pit sites are more ephemeral due to the yearly removal and relocation of aggregate resources. With the addition of the Pits and Quarry Control Act, 1971, and the Ontario Aggregate Resources

Act, 1990, rehabilitation measures have been put in place that require slope grading and erosion control practices to faces that are not in operation (Falconer et al. 2016). Through observations in my study, many colonies that remained between 2014-2015 in aggregate pit sites were those located in relatively tall, stable faces that were not subjected to aggregate operations other than face refreshment (personal obs.). Most aggregate

35 operations seemed to be occurring in areas of the pit away from the Bank Swallow colonies during the summer months. Some operators removed aggregates from these banks during the post-breeding season (fall-spring), leaving the banks vertical for the following breeding season. A number of operators did this to both extract the resources needed for their operations and attract swallows back to these faces the following year, away from where their operations would be taking place that year. Height has previously been documented as a contributing factor to site occupancy in European populations of

Bank Swallows in natural habitats (Hjertaas 1984). Other studies have shown that higher, steeper banks are generally the first to be occupied (Jones 1987). While lakeshores are an important habitat to conserve, Bank Swallows in Saskatchewan selectively chose aggregate pit habitats over lakeshore sites (Hjertaas 1984); with estimates of 68% of

Ontario’s breeding Bank Swallows nesting in aggregate pit sites, it could be possible that

Bank Swallows are preferentially choosing these aggregate pit sites in Ontario (M.

Browning and M. Cadman, pers. comm.).

The reuse of a nesting face in aggregates pit sites was strongly influenced by the size of the available nesting face. Previous studies have also confirmed the importance of face size on colony persistence and face reuse (Garrison 1999, Moffatt et al. 2005, Garcia

2009). In these studies, larger face size, whether through an increase in height (Hjertaas

1984, Ghent 2001), length (Hjertaas 1984, Tozer and Richmond 2013), or both height and length (Hjertaas 1984, Garcia 2009), had greater probability of face reuse into the next year.

Colony size as an individual factor is linked to colony persistence, with larger colonies persisting longer than smaller ones (Garrison 1999, Moffatt et al. 2005). Studies

36 have shown that increases in face size have also lead to significant increases in colony size (Hjertaas 1984, Ghent 2001, Tozer and Richmond 2013), which mirrors my observation that these two factors are correlated. The relationship between larger colony sizes, face size, and colony persistence has been previously documented by Garcia (2009) along the Sacramento River, in California. Garcia (2009) found that short-lived colonies were smaller and in areas where small, eroded banks were formed along the river.

Similarly, many short-lived colonies within my aggregate pit sites were in newly slumped areas that had created a pocket of suitable face, such as those colonies found in large screening piles. In contrast, other short-lived colonies found in aggregate pit sites were in banks that were destroyed over the winter for resource use or had slumped over winter resulting in a non-vertical face (personal obs). The relationship between colony size and persistence is not isolated to Bank Swallows and has been reported in other species such as Ivory Gull (Pagophila eburnean; Robertson et al. 2007), Common Eider (Somateria mollssima; Chaulk et al. 2006), and Cliff Swallows (Petrochelidon pyrrhonta; Brown and Rannala 1995).

Although I was unable to measure it, bank penetrability is potentially one of the most important factors for aggregate pit site Bank Swallow management as these habitats do not receive the same amount of wind and water erosion as natural habitats. Colony persistence varies based on available habitat for Bank Swallows, however 2-3 years is a typical persistence time (Garrison 1999). If banks are not refreshed during this time, they are prone to losing their nesting quality through an increase in ectoparasite load (Freer

1977, Garrison 1989, 1991, Schlorff 1997) and hardening of the face, creating a crust.

This crust will create resistance to penetration causing the birds to possibly move to a different nesting site (Smalley et al. 2013).

CONCLUSION

Natural habitats appear to be the most reliably occupied sites and contain larger colonies of breeding Bank Swallows making them particularly valuable for conservation.

Understanding what drives a species to not only occupy habitat, but also to persist and be successful there, is essential to understanding its environment and how it is used (Blend et al. 2011). This can help managers understand variations affecting the use of this environment and aid in species management to maintain a stable population within these sites. Studies on Sand Martins in Europe have reported population declines that were associated with decreases in aggregate resource demand, stabilization of eroding slopes, and moving the extraction of these resources to fewer and larger pits as opposed to more, smaller pits (e.g., Lind et al. 2002, Heneberg 2013), suggesting that population trends may be dependent on this newer habitat type. While breeding habitat is not as consistently available in aggregate pit sites, this suggests it is important to promote opportunities for habitat maintenance in aggregate pit sites. Aggregate pits were surveyed for three years compared to the five years of data from lakeshore and river sites, these surveys should be repeated with a larger and longer data set from aggregate pit sites.

However despite a longer study period, I doubt that my conclusion, that aggregate pits are inherently less persistent, due to operator decisions, than natural sites will change.

Finally, as occupancy does not necessarily predict successful breeding, further exploration of breeding success of Bank Swallows in lakeshore and aggregate pit sites

38 will help to understand the conservation value of aggregate pit sites (Chapter 3).

Knowledge from studies such as this allows managers to understand what drives Bank

Swallows to create colonies in particular banks over others. From my study, I suggest that the creation of larger vertical faces (both taller and longer) will have a higher probability of attracting Bank Swallows. This will be useful when aggregate operators want to manage an area of their site for Bank Swallows. As larger faces with a higher number of burrows, are more persistent, aggregate pit sites looking to extract once the breeding season is over should focus on areas with smaller or no colonies if Bank Swallow conservation is an objective of their site management. While the conservation of Bank

Swallow breeding sites should be directed to stable banks that have had larger colony sizes, similarly, the refreshment of these larger colonized faces should increase the probability that Bank Swallows will recolonize this face in subsequent years. This information allows the industry to not only play an active role in conserving this threatened species, but also helps operators to manage aggregate production during the

Bank Swallow breeding season. As species at risk legislation often requires mitigation of threats to a species’ nesting habitat, gathering information on occupancy levels will give landowners a baseline against which they can compare their mitigation efforts and restoration success.

Table 2. 1: Final statistical models for occupancy and persistence analysis

Type Model Response and Covariates Family

GLMER Lake Occupancy~ Colony Size * Burrow Binomial Height + (1 | Location) Occupancy Models GLMER Pit Occupancy~ Colony Size * Burrow Binomial Height + (1 | Location) GLM Extinct ~ Colony Size + Size of Face + Binomial Aggregate Nearest Pit + Water 1km Persistence Models GLM Persist ~ Colony Size + Size of Face + Binomial Nearest Pit + Water 1km

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CHAPTER 3: PRODUCTIVITY AND INDICATORS OF HEALTH OF BANK SWALLOWS BREEDING IN AGGREGATE AND NATURAL HABITATS

ABSTRACT

Bank Swallows (Riparia riparia) are designated as Threatened in Canada, in part due to loss of natural breeding habitat along lakeshores and rivers. Excavation of gravel and sand from aggregate pits has increased availability of potential nesting habitats away from lakes and rivers, and these substitute habitats may be important to stabilize the decline in the Ontario Bank Swallow population. The objective of this study was to determine whether Bank Swallows successfully breed and maintain a productivity level similar to those that breed in natural habitats. I collected data on Bank Swallow reproductive success from 3 natural lakeshore sites along bluffs of the north shore of

Lake Ontario and 11 aggregate pits in southern Ontario, within 100 km of the lakeshore sites. While clutch size was the same in both habitats, the number of fledglings from successful nests was significantly higher in aggregate pit sites than in lakeshore sites.

Hatching success was not different between the two habitat types. Differences in numbers of fledglings can likely be attributed to lower predation pressure on nestlings in aggregate pit sites and/or higher parasite loads in natural lakeshore sites habitats. Breeding adults from aggregate pits were heavier than those from lakeshore banks, while fledgling masses were not significantly different between habitats. The mass of adults from aggregate pits decreased significantly over the nesting season. Parasite loads on fledgling

Bank Swallows were significantly lower in aggregate pits than in lakeshore sites. These indicators suggest that aggregate pits can provide at least equivalent habitat for Bank

Swallows than the natural lakeshore sites, making them potentially key for the recovery of this species in Ontario.

INTRODUCTION

Aerial insectivores, birds that feed on flying insects (Garrison 1999), are one guild of bird that is experiencing particularly steep population declines (Nebel et al. 2010,

NABCIC 2012, Falconer et al. 2016). A combination of factors is thought to contribute to this decline including loss of foraging and breeding habitat, negative effects of contaminants and pesticides, and influences of climate change (Andren 1994, Garrison

1999, Garcia 2009, Keller et al. 2014, Hallmann et al. 2014). Many species of aerial insectivore use man-made structures and human-modified landscapes as nesting areas so the loss of these habitats has emerged as an hypothesis for understanding aerial insectivore population declines. While some man-made structures are created to promote aerial insectivore population growth, such as tree swallow (Tachycineta bicolor) nesting boxes (Robertson and Rendell 1990), other nesting areas, termed as ‘substitute habitats’, were created without this intent including chimneys, barns, and bridges used by Chimney

Swifts (Chaetura pelagica), Barn Swallows (Hirundo rustica), and Cliff Swallows

(Petrochelidon pyrrhonota) respectively.

The Canadian population of the Bank Swallow (Riparia riparia) has declined by approximately 98% since 1970 (Falconer et al. 2016). Bank Swallows breed in deep burrows (mean 59-90 cm) excavated by the birds within vertical cliffs and banks located along ocean coasts, rivers, streams, lakes, and wetlands (Peck and James 1987, Garrison

1998, Garrison 1999). Breeding habitat on these cliff and bank faces is created and maintained by erosion from wave action or wind (Garrison 1999). Without this natural erosion, banks will stabilize, harden, and will no longer support Bank Swallow colonies

(Garcia 2009). Large colonies of Bank Swallows can be found along the Great Lakes in

Ontario (Falconer et al. 2016), which happens to coincide with areas of high human density (Statistics Canada 2017). This high human density has led to extensive erosion control measures along many of these cliff faces (Herdendorf 1984, TRCA 2010), drastically decreasing the availability of suitable natural nesting sites, which is suggested to be the most limiting factor for breeding Bank Swallows in Ontario (COSEWIC 2013,

Falconer et al. 2016). Extended periods of low water levels in the Great Lakes in recent decades, has also contributed to the decrease of erosion occurring in areas with lower human density (Garrison 1998, Graf 2006, Monk et al. 2010, TRCA 2010, COSEWIC

2013). These threats to the Bank Swallow’s natural breeding habitat can reduce suitable habitat causing once high-quality habitat to either become suboptimal or not suitable.

Aggregate pit sites, defined as land where the extraction of aggregate resources such as gravel, sand, clay, and rock, occurs for commercial purposes, cause changes in natural landscapes (Binstock and Carter-Whitney 2011). Within the past century, the aggregate extraction industry has developed in response to the demands of building human infrastructure. Within the last three decades, Ontario’s annual aggregate extraction has fluctuated between 100 million and 200 million tonnes (Altus Group 2009, Binstock-

Carter-Whitney 2011). The excavation of aggregate resources, specifically sand and gravel, has led to an increased availability of vertical faces, where, as a consequence,

Bank Swallow nesting colonies have established (Erskine 1979, Garrison 1999,

COSEWIC 2013). These anthropogenic habitats could be considered ‘substitute habitats’ which can provide partial replacement for the loss of original habitat. Substitute habitats

53 are sometimes actively selected by the species despite the availability of optimal or even sub-optimal natural habitat (Martínez-abraín and Jimenez 2016).

While much research on Bank Swallows in North America has been directed at their use of natural habitats, some preliminary research has begun that reports the numbers of Bank Swallows using aggregate pit habitats. Preliminary data from these surveys suggest that aggregate pits can be important to breeding populations with an estimate of 138,400 breeding pairs (or 67.7 % of Ontario’s breeding population estimated at 204,500 individuals) in aggregate pit sites (Schutten 2013, M. Browning and M.

Cadman, pers. comm.).

Although Bank Swallows use aggregate pit sites, it is not known if aggregate pits provide nesting environments where adults can reproduce successfully and hence, supply new recruits to the population. Substitute habitats in urban areas or areas of human disturbance, can become ecological traps (Martínez-abraín and Jimenez 2016).

Ecological traps exist when individuals of a species choose to settle in a habitat in which they do poorly relative to other available habitat that may be of higher quality (Robertson

1996). Individuals may continue to select this poor-quality habitat as the cues they use to select breeding habitat is found, however there is now a negative outcome instead of the positive outcome normally associated with these cues (Robertson and Hutto 2006). For example, a study on Cooper’s Hawks (Accipiter cooperii), found that urban nests produced larger clutch sizes, but nestling mortality was significantly higher (Boal 1997,

Boal and Mannan 1999) than occurred in nests situated in rural environments. Other studies, such as on Northern Mockingbirds (Mimus polygluttos; Stracey and Robinson

2012) suggest that disturbed areas, such as urban areas, have the potential for higher

54 reproductive success than those in more rural habitats (Robertson and Hutto 2006). As settling in these “poorer” habitats could result in lower health of breeders, or low reproductive output, the individual health and reproductive success of populations breeding in substitute habitats should be investigated.

Reproductive success and individual bird health are important indicators of sustainable bird populations. Many studies have used clutch size (Nilsson 1975,

Korpimaki 1984, Nilsson 1984) hatching success (Lanctot and Laredo 1994) and fledgling success (Nilsson 1975, Korpimaki 1984, Nilsson 1984, Brown and Brown

1996) as indicators of reproductive success when comparing habitat types. Similarly, a variety of health factors can be chosen as indicators of a bird’s condition. Body mass is one of the most commonly measured traits that is associated with fitness (Spengler et al.

1995, Seewagen 2008, Labocha and Hayes 2012). Many studies have acknowledged the negative impact of ectoparasite load on host fitness (Møller et al. 1990, Lehmann 1993,

Møller 1990), making this an additional trait of interest for quantifying bird health.

The primary objective of this study was to compare Bank Swallow productivity and the general health of both breeding and fledgling Bank Swallows in aggregate pits and natural lakeshore sites. I used clutch size and number of fledglings produced per nest as indicators of reproductive productivity, and body mass and ectoparasite load as indicators of Bank Swallow health. I hypothesized that Bank Swallow productivity and health would vary across the two habitat types. I predicted that Bank Swallows would have higher productivity and mass in natural lakeshore sites than in aggregate pit sites, assuming that natural lakeshore sites would provide greater food resources and better protection from predators than aggregate pit sites. I also predicted that Bank Swallow

55 ectoparasite load would be lower in aggregate pit sites due to lower colony sizes which would result in lower rates of parasite transmission across individuals (Heneberg 2009,

Smalley et al. 2013, Chapter 2).

METHODS

Study area

I conducted this study in aggregate pits within the City of Kawartha Lakes,

Northumberland County, and Peterborough County of Ontario, Canada, and lakeshore sites in Durham Region on the north shore of Lake Ontario (Ch.2 Figure 2.1). Of the three lakeshore sites, only one was used to monitor nests due to limited accessibility to high cliff nests at the other two sites. This same site was used for banding in the 2014 and

2015 field season, with a second site added for banding in the 2015 field season.

Accessing nests in aggregate pit sites was sometimes limited due to safety concerns in climbing high banks and sometimes due to site safety requirements not allowing me near bank edges. Of the 11 aggregate pit sites used in 2014 for occupancy surveys (Chapter 2), two were used to conduct nest checks and four were used for banding. Of the 8 aggregate pit sites used for occupancy surveys in 2015, three were used for nest checks and four for banding. All surveys, nest checks, and banding at aggregate pit sites were conducted during normal operational hours (07:00-17:00) and on the lakeshore between 07:00-

20:00, twice per week between May and mid-August. In each colony, nests under 1.5 m from the top of the talus slope, located at the base of the colony face, were reachable by field techs and thus accessible for monitoring. In the case of aggregate pit sites specifically, nest monitoring only occurred if permission was granted to be near the face.

Nest Survival and Reproductive Success

Nest burrows were surveyed using a probe constructed of 1 m of thin steel wire with a small (2.5 cm diameter) mirror attached with contact cement at 45o angle

(Garrison et al. 1987, Wright et al. 2011, Falconer 2013). I inserted the probe into the burrows and with the use of a small, 100 + lumen flashlight, determined the number of eggs or young in the nest. The depths of nest burrows were determined using 10 cm interval marks indicated on the probe.

I began monitoring nests on 31 May and ended 6 August in 2014, and 13 May to

30 July in 2015. Banks with active nests were photographed and each burrow was given a number written on a printed photograph that was used to identify nests at subsequent visits. Photographed burrows were checked every three days for a nesting attempt. I defined a nesting attempt as an occupied burrow having visible eggs or hatchlings. Active nests continued to be checked every 3 days to determine the outcome, while accessible non-active burrows also continued to be checked for late-nesting individuals or re-nesting birds.

Clutch size was determined by counting the maximum number of eggs recorded per nest. Hatchlings continued to be monitored until the day they fledged. A nest was considered successful if at least one young successfully fledged, which was defined as at least one nestling remaining in the nest until at least 18 days of age (Garrison 1999).

Nests were classified as failed if the eggs did not hatch after 16 days, the maximum incubation time reported in Ontario (Peck and James 1987, Garrison 1999), or if nest contents were missing before the expected fledgling date. To determine clutch initiation

57 date and age of chicks, a mean of 14-day incubation and 18-day nestling period, was assumed (Garrison 1999). The date the first egg was laid was then determined by back counting one egg per day from when eggs were first seen. If at our first visit, we saw hatchlings, an approximate age was estimated by using an illustrated ageing guide for

Barn Swallows (Hirundo rustica; Jongsomjit et al. 2007, Fernaz et al. 2012), a species that has a similar incubation and nestling period as the Bank Swallow (Garrison 1999,

Brown and Brown 1999). Clutch initiation was then determined by counting back to hatching date, applying the mean 14-day incubation period, and then finally, counting back more days based on the number of eggs.

Mass and Ectoparasites

Bank Swallows were captured and banded at seven aggregate pit and two lakeshore sites over the course of 2014-2015, using two methods. Birds were captured in order to gather measurements on mass and external ectoparasite load and then banded to ensure that the individual was recorded only once. Banding also provided the opportunity to recapture individuals either later in the season or in later years to understand more about individual health and site fidelity.

To capture adult and fledgling Bank Swallows opportunistically, a mist net was placed within 1 meter of the bank. For the targeted capture of individual birds at particular burrows where birds were known to be breeding, I used a butterfly net placed over the opening of an individual burrow entrance after observing a bird enter (Freer

1979). Birds flew into the nest and were captured as they exited their burrows. Targeted capture was used to capture fledglings on their first flight, and only once young in the

58 individual burrows reached approximately 18 days of age to lower the possibility of forcing young to fledge early.

Each captured bird was banded with a Canadian Wildlife Service aluminum band

(under CWS sub-permit #10515-C to T. Burke). Natural wing chord, from bird wrist to end of primary feathers, fat score (scale of 1-6; Dunn 2003), and mass (nearest 0.1 grams) were recorded for each captured individual. Sex was determined for adult birds using the size of brood patch, with females having a larger brood patch than males (Cowley 1999), or the presence of a cloacal protuberance (Pyle 1997). Fledglings could not be sexed. In

2015, visible ectoparasites were counted on the individual’s right wing and opportunistically as we assessed fat. Feather mites were individually counted on the right wing’s third primary feather.

Statistical Analysis

All statistical analyses were conducted in the program R Studio (RStudio 2015).

Daily Nest Survival

A logistic-exposure method (Schaffer 2004) was used to assess factors influencing daily survival of nests. This method accounts for the number of exposure days to which the nest was subjected, and creates a resulting function that can be used to estimate the daily average survival probability for each of the lakeshore and aggregate pit sites (Shaffer 2004). This model consists of the binary response variable, nest survive or fail, and the fixed variable of site type. As each nest had multiple visits, individual nests/burrows within each site were included as a random effect.

Reproductive Success

A set of general linear models was created to test hypotheses for reproductive success (Table 3.1). The model for clutch size, used a Poisson distribution in the lme4 R package (Bates et al. 2015), and included covariates of site type and date of clutch initiation. A chi-squared test was used to test model fit for these count data (p < 0.05).

The models for total number of hatchlings and model for fledglings both were analyzed using a zero-inflated model to account for the many nests for which there were no hatchlings or fledglings recorded (Table 3.1). These models were tested in a step-wise manner, testing the fit of a Poisson distribution, negative binomial, and then zero-inflated model until the best fit was found using AIC. I then checked to see how many zeros were observed versus how many were predicted by the zero-inflated model to ensure that the two values were similar.

These zero-inflated models include the covariates of site type, date of clutch initiation, and burrow depth. Both models included an interaction term between site type and date of clutch initiation, however this interaction term was subsequently dropped for hatchlings as there was no significant interaction term. The zero-inflated model is a two- part model using the pscl package in R (Zeileis et al. 2008). The first part, a count portion that uses a Poisson distribution, analyzes the variation in the number of young per nest between the two types of habitat. The second part is binary, analyzing the probability of a failure (0), or the probability of success (1). Fledgling model covariates changed between which variables applied to the zero-inflation portion specifically, helping to control for non-significant variables (Jung et al. 2005). Standard errors from both the fledgling and hatchling model were obtained from a bootstrapping procedure based on 2000 repetitions.

I also included the effects of date and burrow depth to determine if there were potential interactions between these variables and the two site types (e.g., if nests at either habitat type happened to be deeper or if nests were initiated later which then resulted in differential reproductive success). Date of clutch initiation can have an influence on clutch size (Murphy 1986, Rowe et al. 1994) and survival of later hatched nestlings

(Rowe et al. 1994). Similarly, burrow depth might also influence survival of young as deeper burrows could provide better protection from predators.

Mass and Ectoparasites

Bank Swallow masses for adults and fledglings were analyzed separately. As body mass is typically correlated with structural size (Labocha and Hayes 2012), the covariate of wing length was included to account for potential differences in the structural sizes of individuals. For fledglings wing length was a surrogate for the age of the young as they continue to grow once they leave the nest. Generalized linear models were used to examine whether differences in mass could be attributed to site type, date of capture, size of bird (as determined by wing chord measurements), or sex (adults only)

(Table 3.1). Interactions were also assessed within the model to determine whether mass differed between site types throughout the season, between different sized birds within each sex, and if mass changed throughout the season based on sex. General linear models

(for each age class) for the response variable body mass were fitted with a Gaussian distribution (R Core Team 2016). Model fit was tested using a chi-squared test (p<0.05).

General linear models, using a negative binomial distribution (Jackman 2015), were also conducted on the response variable, total number of external ectoparasites on banded Bank Swallows, to determine whether variation in parasite load could be

61 explained by site type, time of capture throughout the season, size of bird (as determined by wing chord), or sex. Similar to the analyses of body mass, interactions were also assessed within the model to see whether total ectoparasite load differed between site types throughout the season, between different sized birds within each sex, or changed throughout the season based on each sex. Interactions for these models ended up being removed due to no significant interactions. These analyses were also conducted on adult and fledgling Bank Swallows separately and model fit was tested using a chi-squared test

(p < 0.05). The analysis of parasite loads from adults was restricted to birds captured from 1 June to 15 July 2015 because this was the range of dates for which I had data from both lakeshore and aggregate pit sites.

My models were not able to include year as a fixed effect or site as a random effect because the same sites were not necessarily occupied during both years of our study. Similarly, capture sites changed between years because the location of colonies on the bank sometimes changed between years and we were no longer able to access the nests within the colony for capture of birds.

RESULTS

During the 2014 and 2015 breeding season, average clutch initiation date was significantly earlier at lakeshore sites (16 May ± 0.94 SE) than at aggregate pit sites (30

May ± 0.85 SE). The earliest clutch to be initiated on lakeshore sites was on 8 May,

2015, while the earliest clutch to be initiated at aggregate pit sites was on 17 May, 2015.

The latest nest to be initiated on the lakeshore was on 25 June, 2014, while the latest nest to be initiated in aggregate pit sites was on 19 June, 2015.

Daily Nest Survival and Reproductive Success

Of the burrows examined, 194 had visible eggs or hatchlings recorded and were included in the model (2014: lakeshore n = 39, aggregate pit n = 30; 2015: lakeshore n =

62, aggregate pit n = 63) used for daily nest survival analyses. Of these 194 nests, I assigned dates of clutch initiation and determined clutch size and number of fledged young from 163 burrows (2014: lakeshore n = 10, aggregate pit n = 29; 2015: lakeshore n

= 62, aggregate pit n = 62). Daily nest survival (DNS) and period nest survival (PNS) did not differ significantly (z = -1.345, p = 0.179) between the lakeshore and aggregate pit sites (Table 3.3).

There was no significant difference in clutch size between nests at lakeshore sites

(5.4 ±1.1 eggs per nest, n = 72) and aggregate pit sites (5.52 ± 1.2 eggs per nest; n = 91, z

= 0.2, p = 0.84). There was a non-significant decline in clutch size of nests initiated later in the season in both site types (z = -1.73, p = 0.08). Similarly, the number of hatchlings per Bank Swallow nest did not differ significantly between habitat types (z = -0.01, p =

0.99, Table 3.4). Of the nests that had eggs hatch, the number of hatchlings per nest did not differ significantly between the lakeshore (odds ratio: 1.08, CI: 0.92-1.32, z = 522, p

= 0.60, n = 58) or aggregate pit sites (n = 74).

Of the nests that had at least one young successfully fledge, the zero-inflated model indicated that breeding adults in aggregate pit sites raised significantly more young per successful nest (2.41 ± 0.05, odds ratio: 1.72, CI: 1.28-2.44, z = 3.23, p < 0.01, n =

63) than those nesting on the lakeshore (2.12 ± 0.05, n = 58, Table 3.4). However, aggregate pit sites had significantly more nests that raised no young in comparison to

63 lakeshore sites, even though eggs in those nests hatched (z = 2.44, p = 0.01).

Additionally, the odds of producing more successful fledglings within a single nest, at either site type, declined by 3% for each day that clutch initiation began later in the breeding season (odds ratio: 0.97, CI: 0.95-0.99; z = -3.87, p < 0.01). However, date of clutch initiation was also significantly negatively correlated with zero-counts, meaning that nests initiated later in the season were more likely to produce at least one young (z =

-2.13, p = 0.03). Burrow depth had no significant effect within the count portion of the model and was dropped. However within the zero-inflated portion of the model, I found that burrow depth significantly helped protect against nestling mortality (z = -2.42, p =

0.02), where deeper burrows would have a higher chance of at least one fledging young.

Mass and Ectoparasites

I captured and banded a total of 185 Bank Swallows (lakeshore n = 69, aggregate pit n = 116) in 2014, and 202 Bank Swallows (lakeshore n = 86, aggregate pit n = 116) in

2015. The average mass of adult Bank Swallows on the lakeshore was 13.0g ± 0.12 SE, while the average mass of adults in aggregate pits was 12.9 ± 0.10 grams.

The effect of site type on adult body mass depended on the date at which the birds were captured. Although the masses of Bank Swallows captured at aggregate pits were initially higher than those captured at the lakeshore, mass of Bank Swallows banded in aggregate pits significantly declined by 0.04 grams each day the field season progressed

(t = -3.4, p < 0.01, Figure 3.2). No such decline was seen at the lakeshore sites. Wing chord did not predict adult mass in either site type (t = 1.0, p = 0.31). Similarly, at either

64 site type there was no difference in mass between the sexes (t = -0.17 p = 0.86, Table

3.2).

The average mass of fledgling Bank Swallows on Lake Ontario was 13.2 ±0.12 grams. The average mass of fledglings from aggregate pits was 13.0 ± 0.12 grams (Table

3.2). Wing chord did not predict fledgling mass (t = -0.82, p = 0.41). There was no difference in fledgling mass based on the habitat type (t = -1.34, p = 0.18), or the date of capture (t = -1.12, p = 0.19). The mass of fledgling Bank Swallows, caught at the nests as they fledged from burrows, did not differ throughout the season between the lakeshore and aggregate pits (t = 1.12, p = 0.26).

A total of 202 Bank Swallows (lakeshore n = 86, aggregate pit n = 116) were assessed for external ectoparasites in the 2015 field season, including 35 adults and 51 fledglings on the lakeshore and 36 adults and 80 fledglings in aggregate pit sites (Table

3.5). External ectoparasite loads of adults did not differ significantly between aggregate pit (model mean = 23.94 ± 3.94, z = -0.70, p = 0.48) and lakeshore sites (predicted mean

= 25.70 ± 5.71, Figure 3.2). All other covariates, capture date, sex and wing chord, were not significant.

The trend for ectoparasite load in fledgling Bank Swallows was different than those seen in adults. The ectoparasite load was significantly lower on fledglings from aggregate pits (mean parasite load per bird = 10.75 ± 0.87, z = -2.56, p = 0.014) than from lakeshores (mean parasite load = 14.46 ± 1.43, Figure 3.2, Table 3.5). There was a significant increase in ectoparasite load found on fledgling Bank Swallows later in the season at both site types (z = 3.48, p < 0.001). At both site types, fledgling Bank

Swallows that were larger in size experienced significantly higher ectoparasite load (z =

4.52, p < 0.01).

DISCUSSION

This is the first study to examine and compare the health and reproductive success of Bank Swallows in aggregate pits with those from natural lakeshore sites. I found that, contrary to my hypothesis, the measures of productivity (clutch size, number of hatchlings, and number of fledglings) did not vary significantly between lakeshore and aggregate pit sites. Bank Swallow pairs in aggregate pits, however, raised a higher number of fledglings per successful nest than swallows nesting at the lakeshore. While successful nests in aggregate pit habitats raised more fledglings per nest, aggregate pits also had a higher proportion of unsuccessful nests, those that produced no fledglings.

Adults in aggregate pits had an initially higher adult mass than those captured on the lakeshore, however this mass declined significantly as the season progressed, supporting my hypothesis of mass depending on habitat type. Finally, ectoparasite load on fledgling

Bank Swallows was significantly lower in aggregate pit sites, consistent with my prediction. However, there was no significant difference in the ectoparasite load of adults between the site types, not supporting this prediction.

Reproductive Success

Period nest survival (PNS) for Bank Swallows in my study was high for both lakeshore sites (PNS = 0.87) and aggregate pit sites (PNS = 0.80). A previous study on

Bank Swallows in Saskatchewan found PNS ranged from 43.5-63.4% in 1980 and 1981, respectively (Hjertaas 1984). Other species, especially ground and tree nesters who are more susceptible to predation than burrow nesters, generally have much lower rates of period nest survival such as Eastern Wood-Pewees (Contopus virens; Falconer 2010,

23%, Knutson et al. 2004, 43%) and Dickcissels (Spiza americana; 14.3-15.2%;

Zimmerman 1981). The high nest success of Bank Swallows that we observed reaffirms the value of inhabiting inaccessible nest sites such as those in high banks and deep cavities.

While aggregate pit sites had a higher proportion of nests that fledged no young, nests with at least one successful young produced more young, on average. The larger number of unsuccessful nests at aggregate pit sites is probably attributable to the greater slumping and burrow collapse experienced by nests in aggregate pits, often engulfing the entire burrow with sand and killing all young (personal obs). A previous study detected a similar lower overall nest success in aggregate pit sites in southwestern Ontario, however, the difference in that study between lakeshore and aggregate pit sites was relatively small

(Tozer and Richmond 2013).

While the total number of fledglings was the only productivity response variable that differed significantly between site types, this difference was not related to nest variables including clutch size and hatching success. Thus, the reason for this difference in fledgling productivity could be attributed to a difference in predators acting directly on older nestlings between site types. While both site types experienced predation on nests or fledglings, I observed different causes of predation. At aggregate pit sites, predation occurred primarily on lower burrows, by ground predators such as raccoons (Procyon

67 lotor) and red fox (Vulpes vulpes). These burrows would be dug out by the mammals and all nest contents consumed, likely contributing to higher number of unsuccessful nests.

American Kestrels (Falco sparverius) have been observed targeting flying adults and fledglings in aggregate pit sites in other jurisdictions (Freer 1973, Windsor and Emlen

1975), and catching Bank Swallows at their burrow entrance (Freer 1973, Windsor and

Emlen 1975). While I observed aerial predators targeting flying Bank Swallows at my aggregate pit sites, I did not observe any direct predation at the burrows at the aggregate pit sites. Burrows at lakeshore sites appeared to experience predation by a wider variety of species. While lower burrows were susceptible to predation by ground predators at lakeshore sites (Sieber 1980), there were visibly more avian predators. Previously documented avian predators at Bank Swallow colonies such as Common Raven (Corvus corax) and American Crows (C. brachyrhynchos) (COSEWIC 2013, Falconer et al.

2016) were also observed on our lakeshore sites. I also observed frequent predation of single fledglings at the burrow entrances by Common Grackles (Quiscalus quiscula) and

Ring-billed Gulls (Larus delawarensis). These predators were observed depredating burrows specifically, instead of individuals in flight. In addition, predation events were also captured on footage from video occupancy surveys (Chapter 2). Fledgling Bank

Swallows move towards the burrow entrance by 15 days old to be fed by adults (Garrison

1999), increasing their exposure to these avian predators. This observed qualitative difference in the number of predator species and possible depredation rates could have led to the increased productivity rates witnessed in aggregate pit sites. Conducting further studies to gather quantitative data on predation rates would increase the understanding of

68 how predators may influence productivity between natural lakeshore and substitute habitats.

Another possible explanation for increased productivity rates in aggregate pit sites could be the significantly lower number of external ectoparasites found on fledglings at these sites. A number of studies have indicated a negative relationship between external ectoparasites and nestling survival and growth in colonial-nesting birds (Brown and

Brown 1986, Brown and Brown 1996, Brown and Brown 2004), cavity or burrow nesters

(Fitze et al. 2004), or both colonial and burrow nesters, such as Bank Swallows (Szep and

Møller 1999). Larger colony sizes, such as found at our lakeshore sites, is just one factor linking to the abundance and transmission of ectoparasites on Bank Swallows (Hoogland and Sherman 1976). As lakeshore sites had larger colonies, nests at these sites could be exposed to higher levels of ectoparasites, especially in nests where burrows were reused, thus potentially explaining a lower rate of reproductive success.

Average clutch initiation date was significantly earlier at lakeshore sites than at aggregate pit sites, however there was no significant difference in clutch size overall. The later initiation of nests at aggregate sites could indicate that these sites are less preferable to BANS than the lakeshore or that young or inexperienced birds tend to choose these sites. Nests could also be initiated later due to physiological limitations in the date at which reproduction can start, particularly faced by birds of poorer condition, alternatively, it could be an adaptive strategy to maximize adult condition before their first breeding attempt of the season (Row et al. 1994, Low et al. 2015), or perhaps food availability. While delayed breeding may improve parental condition to prepare for egg laying, this comes with a disadvantage of poorer offspring condition (Low et al. 2015). I

69 was not able to age the adult BANS so did not evaluate further reasons for the differences in initiation dates, however this could be a future area of study.

At both natural lakeshore and aggregate pit sites, I documented a small decline in clutch size and a statistically significant decline in the number of successfully fledged young for birds that initiated clutches later in the season. Thus, date has a strong influence on Bank Swallow reproductive success, supporting observations by Hjertaas

(1984) and Garrison (1999) in Bank Swallows and other species (Peak 2007, Bonnot et al. 2008). Many other studies on birds have also detected a negative relationship between date and clutch size (Peterson 1955, Rowe et al. 1994, Murphy 1986, Öberg et al. 2013,

Low et al. 2015). This relationship could exist because of a reduction in food supply later in the season (Murphy 1986, Rowe et al. 1994) or if the cost of reproduction is much higher later in the season (Murphy 1986, Hochachka 1990), reducing the number of young for which adults could care. Similar to my findings, a seasonal decline in the value and survival of offspring has also been documented in a variety of species such as sparrowhawks (Accipiter nisus (L.)), Song Sparrows (Melospiza melodia), Northern

Wheatear (Oenanthe oenanthe), respectively (Newton and Marquiss 1984, Hochachka

1990, Low et al. 2015).

The conditions responsible for driving some Bank Swallow individuals to breed later in the season are unknown. Some studies have found there can be carry-over effects to individuals who breed later; a late breeding individual may not have enough time to fully restore its body condition prior to the next breeding season (Shaw and Levin 2013;

Low et al. 2015). This is likely true of migratory species that face high energetic costs outside of reproduction such as migration and molt (Low et al. 2015). Thus, a Bank

Swallow expending energy later in the season for reproduction may not be able to compensate for this expense before molt or migration takes place. While some studies have attributed late breeding attempts to second clutches (Hjertaas 1984, Bull 1985), second broods in Bank Swallows have not been confirmed in North America (Peck and

James 1987, COSEWIC 2013) and I found no evidence of this occurring at any site. Peck and James (1987) have suggested that incidents with a potential second clutch may only represent late nesting attempts by different adults in previously successful burrows.

The loss and degradation of foraging habitat and consequent negative effects on food supply has been regarded as one of the greatest threats to recovery for the Bank

Swallows (COSEWIC 2013, Falconer et al. 2016). While there is much uncertainty concerning insect population trends (Cardoso et al. 2011), studies have noted declines in benthic chironomids along the Great lakes between 1982 and 2003 (Soster et al. 2011,

Cooper et al. 2014). Lower numbers of chironomids could cause returning individuals to breed later as it will take longer to fully restore their conditions after their long migrations, once they reach breeding grounds, and thus potentially reducing the number of offspring and new recruits into the population.

In addition to Bank Swallow, Belted Kingfisher (Megaceryle alcyon) and most woodpeckers construct their own burrows and/or cavities for the rearing of young

(Garrison 1999, Kelly et al. 2009). Other species such as the Northern Rough-winged

Swallow (Stelgidopteryx serripennis) is more of a nest opportunist, nesting in already excavated burrows (Hill 1988). Burrow nests are especially effective at protecting eggs and young from predators and additional length in the burrow gives added security

(Hansell and Overhill 2000). I observed that the odds of Bank Swallows having a

71 successful nest increased as burrow depth increased. With similar nesting habitats to

Bank Swallows, Northern Rough-winged Swallows have been hypothesized to have a nest-depth preference based on their predators (Hill 1988). Deeper burrows could be a means to offset the reach of mammalian predators, including the distance they are typically able to dig when attempting to depredate nests burrowed within a bank (Hill

1988). Not only does added burrow depth improve security from predators, but in aggregate pit sites, burrows built deeper in the bank could protect these nests from bank surface collapse (Hjertaas 1984). The collapse of burrows with successful nesting was observed during the field season at aggregate pit sites where in the event of bank slumping, shallow nests were often destroyed by either being swept away or buried from above with the slumping bank, destroying their nest contents. After bank collapse, adults with deeper burrows were observed digging out new entrances to their occupied burrows and having their nests still intact. Alternatively, having burrows that are too deep can cause adults to expend more energy while feeding young and tunnel entry and exit times are extended. This means that young in deeper nests could be fed at slower rates or less frequently than those in more shallow burrows (Hill 1988). Thus, selection should favour intermediate burrow depths.

Mass and Ectoparasites

Fledgling Bank Swallow mass did not differ significantly between sites. This suggests that Bank Swallow adults at both site types were equally able to feed their young throughout the breeding season. A different trend, however, was seen in Bank

Swallow adults. Lakeshore adults had a consistent weight throughout the season,

72 implying that they were not losing mass during incubation or provisioning of young.

Adults within aggregate pit sites lost mass as the breeding season progressed, perhaps suggesting that while they could adequately supply food to their young, they were not able to fully recover their own body condition.

Another explanation for this seasonal decrease in mass for Bank Swallows breeding in aggregate pits could be that they are adaptively reducing their wing loading.

By reducing their mass adaptively, Bank Swallows could be increasing their flight efficiency for foraging at further distances at aggregate pit sites, thus reducing the energy that they would expend while in flight (Norberg 1981, Rayner 1988, Croll et al. 1991,

Rogers 2015). This energy saved from reducing their wing load could lead to the increase of the parents’ reproductive success (Croll et al. 1991), which was occurring in aggregate pits. Birds may also reduce their wing loading to increase their flight abilities when exposed to predation (Carrascal and Polo 1999, Gentle and Gosler 2001). While I observed lakeshore sites to have a greater number of avian predators of fledgling Bank

Swallows, aggregate pits anecdotally had higher numbers of American Kestrel targeting adults or fledged young in flight (personal obs.).

In temperate environments such as in Southern Ontario, food availability fluctuates substantially throughout the summer breeding season (Thomas et al. 2001).

Many birds are known to adapt their breeding to peaks in food abundance, likely as an evolutionary strategy to help maximize fitness of both the parents and offspring (Thomas et al. 2001). The relationship between seasonality and insect abundance is complex and often very difficult to predict without years of study (Paquette et al. 2013). In the two years of this study, levels of insect biomass differed between lakeshore and aggregate pit

73 sites (Beauchamp 2016). The biomass of lakeshore insects, as measured by sticky traps placed in my sites, fluctuated significantly throughout the season, while the aggregate pit biomass remained relatively stable but was much lower than that of the lakeshore

(Beauchamp 2016). This lower insect abundance likely meant that Bank Swallows not only had a lower food supply, but they may have needed to fly further to forage effectively.

Of the 15 aggregate pit sites in my study, 7 had direct access to water where aquatic insects could reproduce. These aquatic habitats within the foraging areas are especially important as a source of local emergent aerial insect supply (Falconer et al.

2016). In south-western Ontario, foraging habitat of Bank Swallows is usually concentrated within 200-500m of the breeding colony, with very few flights extending further than 1000 m from the colony (Garrison 1999, Falconer et al. 2016). Falconer et al. (in press), found that on the north shore of Lake Erie, Ontario, Bank Swallows were four times more likely to be found foraging near the colony than at 500 meters away.

Aggregate pits in the United Kingdom had birds foraging within 260 m (mean = 200 m) of the colony when adults were provisioning nestlings and within 690 m (mean = 600 m) during nest building (Turner 1980). However, greater foraging distances could occur, especially during periods of low insect abundance (Turner 1980, Ghilain and Bélisle

2008), or potentially at sites where there is limited access to water. Additional studies should look at the influence of a water source, within 1km of the aggregate pit site, to determine any relationship this factor may have with adult and juvenile mass.

Reproduction is a costly process, especially for individuals who breed later in the season (Murphy 1986, Hochachka 1992), as there is generally a reduction in food supply

(Murphy 1986, Rowe et al. 1993). The quality of breeding habitat can determine resource availability, in turn affecting individual survival and reproductive success (Johnson

2007). If food supply at my aggregate pit sites is lower, it could make the cost of reproducing at these sites much higher for Bank Swallow adults, despite higher productivity at the aggregate pit sites. This is especially true since Bank Swallows initiated nesting attempts later in aggregate pit sites than on lakeshore study sites and insect biomass at these sites has declined towards the end of their breeding season.

If Bank Swallows are expending more energy later in the season, especially to forage, then fall migration may take a larger toll on them than those who breed earlier.

Older Bank Swallows have higher fidelity rates (55-92%) than first-time breeders (Freer

1979, Szép 1990, Szép 1999), especially at sites where breeding was successful (Freer

1979). Thus, adults who were late nesters and were reproductively successful in previous years may return to these sites in a lower condition (Low et al. 2015). Thus, while these substitute habitats can provide new recruits to the population, it is important that before we begin promoting these areas as suitable habitat, we ensure that these habitats are not ecological traps for the adult population. Conducting further studies on survival rates of adults that breed in aggregate pit sites, furthering our knowledge on diet requirements and habitat requirements surrounding the colony, can broaden our understanding as to whether adults are being negatively affected at aggregate pit sites. Similarly, additional studies should also focus on reduced wing loading in Bank Swallows at aggregate pits to determine whether this is a) a plausible reason for mass reduction aggregate pit sites and b) whether this could be occurring due to avian predation on site or increased foraging distances.

While bird species have evolved defenses against parasites (Clayton and Moore

1997), parasites can cause mortality and have a negative impact on the host’s reproductive ability and survival (Møller et al. 1990, Hudson and Dobson 1997, Danchin et al. 1998, Lindström 2000, Proctor 2003). Colonial and cavity nesting birds, like Bank

Swallows, are suspected to be the most susceptible to parasites due to both their reuse of nests and their social habits (Alexander 1974, Møller 1990, Brown and Brown 1996,

Tomás et al. 2007). Bank Swallows have been known to host bird lice, fleas, mites and ticks (Rothschild and Clay 1957, Hoogland and Sherman 1976). While other studies have shown that ectoparasites can reduce Bank Swallows reproductive success (Szep and

Møller 1999), this is the first study to document ectoparasite load on Bank Swallows between habitat types. My study revealed that fledgling Bank Swallows at aggregates pit sites had fewer ectoparasites than fledgling Bank Swallows at lakeshore sites. Previous studies have noted that nest burrows with frequent reuse can form a base population of ectoparasites (Møller 1990). Bank Swallows tend to recolonize sites that had successful breeding (Freer 1979). Reuse of successful nests (both within the same year and between years) has also been recorded in populations of both Barn Swallows (Hirundo rustica) and Cliff Swallows (Møller 1990, Brown et al. 1995). If erosion of Bank Swallow nesting habitats between years is low, some or all burrows from the previous year may still remain intact and possibly be reused; Bank Swallows will often remove the nest material from previously used burrows and construct a new nest to possibly decrease ectoparasite load (Haas et al. 1980, Garrison 1999). Faces containing Bank Swallow colonies in aggregate pit sites were more ephemeral due to the yearly removal and relocation of aggregate resources (Chapter 2) whereas my lakeshore study sites had been

76 used for at least 5 consecutive years. On the lakeshore, bank refreshment will occur only if erosion levels are high causing the bank to collapse between years. Due to the combination of erosion control projects and low lake levels along the Great Lakes

(Herdendorf 1984, TRCA 2010, COSEWIC 2013), it is likely that erosion along this area has lessened, at least through my study period. During my two field seasons, I observed that many burrows from the previous nesting year were still visible in early spring at lakeshore sites. Bank Swallow surveys conducted along Lake Ontario in previous years also detected burrows from previous years amongst reused colonies (Hatch - Sargent and

Lundy 2015). This lack of face refreshment could be contributing to the higher ectoparasite load found within the lakeshore study areas.

Colony size is another factor aiding in the abundance and transmission of ectoparasites on Bank Swallows (Hoogland and Sherman 1976). Larger colonies will typically have a greater number of ectoparasites present. This was evident in my study where lakeshore sites, generally reused from year to year, not only had significantly higher ectoparasite loads among fledglings but were also larger in size while aggregate pit sites had lower ectoparasite loads and smaller colony sizes (Chapter 2).

CONCLUSION

While this study shows promising results for aggregate pit sites to be productive and important breeding grounds, this study was restricted to a relatively small geographic area, and, especially for the nest success data, I was only able to follow a small proportion of total nests in a relatively small proportion of sites. Further studies should be completed to determine whether aggregate pit sites are providing suitable habitat for this threatened species. However, aggregate pit operators and managers can play a key role in

77 developing their sites to suit the needs of this species to ensure their protection and health. While we have determined that longer, and taller faces should be created and refreshed to attract Bank Swallow to a particular face (Chapter 2), aggregate pit managers and operators should also ensure that the bird’s health is not put at risk by being in these habitat types. With regards to banks, aggregate pit managers could reduce the probability of predation by mammals through removal of excess talus at the bottom of the vertical face. While there was no effect of water on Bank Swallow occupancy (Chapter 2), water could play a role in fledgling success, individual health through providing a more stable food source, and date of colony establishment. Providing a water source, large enough to produce insects throughout the Bank Swallow breeding season, could benefit Bank

Swallows in aggregate pits and this relationship should be further researched.

Figure 3. 1: Interaction between adult Bank Swallow mass and the date of capture (beginning on June 1) between lakeshore and aggregate pit sites

Table 3. 1: Final statistical models for productivity and health objectives

Response Type Model Response and Covariates Family Variable Binomial Daily/Period Survival GLMER Survival ~ Site Type + with link = Nest (1|SiteBurrow) logistic Survival exposure model

Poisson Reproductive Clutch GLM Clutch Size ~ Site Type + Day of Success Size Clutch Initiation

Number of Zero- # of Hatchlings ~ Site Type + Poisson Hatchlings inflated Day of Clutch Initiation + Burrow Depth

Number of Zero- # Successful Fledglings ~ Site Poisson Fledglings inflated Type + Day of Clutch Initiation | Site Type + Day of Clutch Initiation + Burrow Depth – 1

Adult GLM Adult Mass ~ Site Type * Season Gaussian Bird Mass Mass Day + Sex + Wing Chord

Fledgling GLM Fledgling Mass ~ Site Type * Gaussian Mass Season Day + Wing Chord

Adult GLM Adult Total Parasite Load ~ Site Negative Ecto- Parasite Type + Date Banded + Sex binomial parasites Load + Wing Chord

Fledgling GLM Fledgling Total Parasite Load ~ Negative Parasite Site Type + Date Banded binomial Load + Wing Chord

Table 3. 2: Average mass (and standard error, g) of Bank Swallows on Lake Ontario and aggregate pits in 2014 and 2015. n = number of birds banded

Year Lakeshore n Aggregate Pit n

Adults 2014 12.88 (± 0.23) 20 12.60 (± 0.08) 36

2015 13.13 (± 0.14) 35 13.1 (± 0.18) 35

Fledgling 2014 13.21 (± 0.17) 49 12.79 (± 0.14) 56

2015 13.09 (± 0.17) 51 13.06 (± 0.17) 80

Table 3. 3: Estimated nest survival rates with 95% confidence intervals from the logistic- exposure model for daily and period nest survival.

Site Type Estimate 95% lower limit 95% upper limit a) Daily Nest Survival

Lakeshore 0.996 0.9910 0.9978

Aggregate 0.993 0.9913 0.9978

b) Period Nest Survival

Lakeshore 0.870 0.749 0.932

Aggregate 0.799 0.756 0.932

Table 3. 4: Modeled mean and standard error for clutch size and number of successful fledglings per nest of Bank Swallows in lakeshore and aggregate pit habitats. n = number of nests * Standard error from fledgling and hatchling model was obtained from a bootstrapping procedure based on 2000 repetitions.

n Lakeshore n Aggregate Pits Clutch Size 72 5.4 (± 1.1) 91 5.5 (± 1.2)

Hatchlings per 62 3.95 (± 0.04) 74 3.6 (± 0.03) nest Fledglings per 58 2.12 (±0.05) 62 2.41 (± 0.05) successful nest

Note: Clutch size estimates were derived from a glm model with a Poisson distribution containing site type and date of egg lay. Hatchling estimates were derived from a negative binomial model containing covariates of site type, date of egg lay and burrow depth. Fledgling estimates were derived from negative binomial model with the count portion containing covariates of site type and date of egg lay, and the zero-inflated portion containing covariates of site type, date of egg lay and burrow depth.

Table 3. 5: Raw mean parasite load per individual Bank Swallow on the lakeshore and in aggregate pits from the 2015 field season.

Site Age n Total

Lake HY 51 14.6 (±1.5)

AHY 35 23.5 (±3.0)

Pit HY 80 11.6 (±1.1)

AHY 36 24.6 (±2.8)

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CHAPTER 4: GENERAL CONCLUSION

This project has identified that aggregate pit sites have the potential to become successful breeding habitat to provide recruits and potentially stabilize the Ontario population. This makes aggregate pit sites adequate and potentially important for conservation planning. While this study has increased the understanding that the role aggregate pits have the potential to play regarding Bank Swallow nesting habitat, much is still unanswered.

Despite having a higher proportion of unsuccessful nests and lower persistence levels, productivity as measured by the number of successful fledgling birds in nests that hatched young, in aggregate pits was higher than successful nests in lakeshore sites and the health factors measured at aggregate pit sites were similar to those on the lake. Prior to this study, there had been little research on Bank Swallow health and reproductive success in aggregate pit habitats. My research has explored the role that aggregate pit sites play in Bank Swallow breeding and provided new information to help fill in critical knowledge gaps listed in the Bank Swallow Recovery Strategy about the species’ vital rates and sink/source dynamics (Falconer et al., 2016). This research will also provide new information on how these artificial habitats may be important for species recovery and stresses the need for best management practices to be developed and implemented in operational aggregate pit sites. Effectiveness of these habitats depends on the commitment of all stakeholders, from government bodies to aggregate pit operators.

The results from this work suggest that aggregate pits can be productive Bank

Swallow breeding habitat. However, I recommend that the following areas of research receive further attention. First, while successful burrows in aggregate pit sites produced a

95 significantly greater number of fledglings than those monitored at the lakeshore, more burrows in aggregate pits failed completely, producing no young. Despite this, measures that included all nests, including daily and period nest survival did not differ significantly between lakeshore and aggregate pit sites. My study, however, further investigated Bank

Swallow productivity by observing clutch size, hatching success and number of fledged young. This study was confined to a relatively small proportion of sites. Therefore, further studies adding to this dataset spanning a larger geographic area would offer more insight into productivity levels across Ontario.

Further research could also be conducted questioning why a higher number of nests completely failed in aggregate pit sites, as reported by my zero-inflated model. This could be done by operators mechanically manipulating banks within aggregate pits to create a lower talus, taller bank face, and stabilizing the face. This could further explore the prediction that nest predation and bank collapse were the origin of these failed nests and seek to find ways to lower the chance of these events happening.

Another area for further research stems from the result that adult mass is decreasing at aggregate pit sites over time. This result could be due a number of factors including: birds breeding later in the season at aggregate pit sites (Murphy 1986,

Hochachka 1992, Shaw and Levin 2013), a lower food supply later in the season

(Murphy 1986, Rowe et al. 1993) or at aggregate pit sites in general (Beauchamp 2016), or lowering their mass adaptively to have a reduced wing load. While aggregate pits were able to produce a higher number of fledglings than the lakeshore habitat, choosing this substitute habitat might come at some cost to adult survival, warranting further research.

This can be done by examining potential carry over effects of low mass on migration

96 potential and speed. The first phase of such a study could be accomplished through the use of nanotag technology (Falconer et al. in prep) to track Bank Swallows at least on their southern migrations away from the breeding grounds. Once nanotags can sustain longer battery lives for small birds, tracking Bank Swallows back to breeding grounds the following year would be beneficial to help understand carry over effects of low mass on migration and speed. Similarly, nanotags could be used to study bird foraging rates and distance in aggregate habitats and compare this to mass throughout the season in a recapture study. Additionally, gathering mass data from aggregate pit sites in other locations across Ontario will allow us to determine whether this may be a localized issue, or occurring across the greater landscape.

Finally, aggregate pit sites are less stable from year to year, especially in operational sites, as banks are destroyed for resource extraction and only sometimes replaced. If Bank Swallows in Ontario are actively seeking and selecting aggregate habitats over lakeshore habitats, such as what was modeled in Saskatchewan (Hjertaas

1984), it is important that there is adequate and continuing nesting habitat available to them. The use of banding and nanotag technology can also be applied to accomplishing further studies into both these questions. Banding a high number of individual Bank

Swallows could assist in answering questions regarding site fidelity and use of aggregate pit sites. While banding is fairly cost effective, intensive sampling will need to be done in successive years to increase chances of a recapture in original and nearby habitats. Once technology is available for smaller bird species, tracking Bank Swallow migration to breeding grounds will help to gain further insight into their site fidelity rates and the process whereby they select colonies for breeding.

Longer-term data are needed on colony persistence in aggregate pits; gathering persistence data from aggregate pit sites that both do and do not intentionally maintain banks for swallows could also be of importance to managers. Additionally, it would be interesting to look further into the data to see if colonies located low on banks are the latest to be occupied. Further study on soil penetrability within aggregate pit sites will be beneficial as the persistence of colonies within these aggregate pit sites could depend on the need for face refreshment.

An estimated 68% of Ontario’s breeding Bank Swallows nested in aggregate pit sites in 2013 (M. Browning and M. Cadman, pers. comm.), could suggest that perhaps

Bank Swallows in Ontario are also seeking out and selecting these habitat types (Hjertaas

1984). Studies focused on substitute habitats, such as aggregate pit sites, have noted their potential to become ecological traps (Martínez-abraín and Jimenez, 2016, Robertson and

Hutto, 2006). It is imperative that we gain further understanding into the benefits these sites have as a potential source of recruits for Bank Swallow populations and examine any potential negative carry over effects that may increase adult mortality. By understanding what these negative effects are, further studies will be able to highlight ways in which they could be mitigated.

In conclusion, more research and site management needs to be completed to gain a comprehensive understanding of the value and contribution aggregate habitat have to

Bank Swallow sustainability. My recommendation for aggregate operators and site managers hoping to assist with the management and protection of this species would be to ensure long, tall, vertical faces are available away from operational areas. Similarly, these faces should be refreshed every few years to continue attracting Bank Swallows to

98 the face and to maintain appropriate soil penetrability. Providing a water source on site will potentially help with providing a local food source for these birds.

LITERATURE CITED

Beauchamp, A. 2016. Is the timing of Bank Swallow, Riparia riparia, reproduction associated with flying insect abundance? Undergraduate Thesis. Trent University, Peterborough, Ontario, 49 pp.

Hjertaas, D.G. 1984. Colony site selection in Bank Swallows. Master's Thesis. Univ. of Saskatchewan, Saskatoon, 129 pp.

Hochachka, W.M. 1990. Seasonal decline in reproductive performance of song sparrows. Ecology, 71: 1279-1288.

Martínez-abraín, A., and J. Jimenez. 2016. Anthropogenic areas as incidental substitutes for original habitat. Conservation Biology, 30(3): 593-598.

Murphy, M.T. 1986. Temporal components of reproductive variability in eastern kingbirds (Tyrannus tyrranus). Ecology, 67: 1483-1492.

Robertson, B. A., and Hutto, R. L. (2006). A framework for understanding ecological traps and an evaluation of existing evidence. Ecology, 87(5): 1075-1085.

Rowe, L., D. Ludwig, and D. Schluter.1994. Time, condition, and the seasonal decline of avian clutch. American Natualist, 143(4): 698–722.

Shaw, A.K. and S.A. Levin. 2013. The evolution of intermittent breeding. Journal of Mathematical Biology, 66: 685-703.

Tozer, D.C., and S. Richmond. 2013. Bank Swallow research and monitoring: 2013 final report. Unpublished report to Ontario Power Generation. 27 pp.

100

APPENDIX 1: BANK MEASUREMENTS OF OCCUPIED BANK SWALLOW COLONY LOCATIONS.

Total face Total face Colony Colony size size Habitat Face Face Site Name Colony Year *without *with Type Length Height estimate estimate (m) (m) 2 (m ) (m2) 1 2014 40.90 1.34 54.74 5.47 2 2014 27.17 1.63 44.20 30.94 3 2014 24.90 1.76 43.90 26.34 4 2014 37.57 2.18 81.82 49.09 Lakefield 5 (Face 1) 2014 44.01 4.16 182.89 128.02

5 (Face 2) 2 2014 23.69 0.71 16.83 8.42

13 2015 28.97 4.20 121.73 85.21

322 2015 44.45 2.30 102.42 102.42 3 2015 20.75 2.93 60.88 48.71 1 2014 21.58 5.18 111.70 33.51 Westone 1 2 2015 36.77 5.20 191.11 28.67 1 (Face 1) 2014 21.50 6.33 136.09 88.46 1 (Face 2) 2014 21.70 1.77 38.50 25.02 Pit Westone 2 1 (Face 1) 2015 21.56 4.23 91.19 72.95 1 (Face 2) 2015 39.19 2.13 83.57 50.14 1 2014 33.42 10.50 351.04 140.42 2 2014 74.76 7.16 535.24 481.71 3 2014 29.31 5.65 165.70 107.71 Vivian 1 2015 25.44 10.24 260.63 156.38 2 2015 75.81 5.61 425.65 383.09 3 2015 26.89 4.90 131.67 92.17 1 (Face 1) 2014 15.64 3.50 54.69 41.01 1 (Face 2) 2014 20.20 1.89 38.13 5.72 Westwood 2 (Face 1) 2014 33.31 3.10 103.13 61.88 2 (Face 2) 2014 18.66 4.28 79.91 23.97 1 2015 15.52 2.93 45.43 13.63

101

2 2015 54.88 2.30 126.46 101.17 3 2015 10.98 3.09 33.86 23.70 1 (Face 1) 2014 60.25 4.05 244.08 109.84 1 (Face 2) 2014 10.53 1.43 15.01 3.00

Drain 2 2014 19.88 4.21 83.71 33.48 Brothers 1 2015 49.12 2.99 146.92 44.08 2 2015 14.91 7.14 106.41 74.49 3 2015 9.58 3.73 35.70 14.28 1 (Face 1) 2014 5.50 2.79 15.35 9.21 1 (Face 2) 2014 13.83 2.13 29.43 7.36 2 2014 16.25 2.96 48.02 14.40 Finlay 1 3 2014 16.30 8.23 134.24 46.98 1 2015 25.62 1.73 44.31 26.59 2 2015 37.48 4.76 178.47 71.39 1 2014 37.99 7.18 272.64 190.85 McGee 2 2014 18.11 5.19 93.94 37.58 1 2015 46.29 9.76 451.82 225.91 2 2015 39.32 8.88 349.04 209.42 Baltimore 1 2014 18.30 2.50 45.00 9.00 Finlay 2 1 2014 5.33 1.94 10.31 8.25 Kawartha 1 2014 16.03 1.77 28.37 19.86 Lake 1 2014 158.91 1.47 233.41 163.39 Courtice 2 2014 96.30 2.88 277.13 138.56 Treatment Plant 1 2015 87.79 1.69 147.97 88.78 2 2015 244.00 1.19 291.49 116.60 1 2014 49.38 5.60 276.49 165.89 Lake 2 (Face 1) 2014 30.17 4.60 138.90 69.45 2 (Face 2) 2014 31.27 8.35 261.16 104.47 Wilmot Creek 2 (Face 3) 2014 9.91 5.75 56.92 34.15 3 2014 61.78 5.66 349.94 139.97 1 2015 52.40 5.43 284.33 255.90 2 2015 75.80 3.26 247.39 123.69

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3 2015 64.66 6.24 403.69 282.59

1 (Face 1) 2014 197.29 6.04 1191.95 357.58 Darlington 1 (Face 2) 2014 110.35 8.33 919.57 551.74 Nuclear 2 2014 32.14 8.52 273.73 123.18 3 2014 63.54 10.83 687.95 275.18 4 2014 102.68 5.69 583.72 116.74 5 2014 23.12 6.81 157.51 31.50 6 2014 59.09 10.61 626.89 94.03 1 (Face 1) 2015 219.36 5.36 1175.60 470.24

1 (Face 2) 2015 169.49 2.27 384.92 153.97 2 2015 99.93 8.05 804.28 241.28 3 2015 145.33 6.25 908.31 363.32 4 2015 9.92 3.15 31.27 9.38 5 2015 58.19 6.06 352.88 105.86

* Due to the fact that not all banks are a perfect rectangle, an estimate was taken in field to determine not only the amount of “rectangle” that comprised the face, but also how much of the face was comprised of suitable habitat (ie. what percentage of the bank could Bank Swallows actually burrow into). This was recorded as a percent estimate. By applying this estimate to the total face size, a more accurate measurement of total suitable face could be determined.

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APPENDIX 2: BANK CHARACTERISTICS, EQUATIONS USED TO CALCULATE FACE SIZE, HEIGHT, AND AREA (CALCULATED USING EXCEL).

Definitions:

Bank Face – Area of bank that is vertical, located above the talus (when present).

Bank Talus – Lower portion of bank that is sloped away from bank face to ground.

Distance to left/right edge of face – The horizontal distance in meters from edge of bank face to researcher.

Top Face Angle – Reading in radians at the top of the bank face, not including any crown (taken with a range finder in inclination mode).

Top Talus Angle – Reading in radians at the top of the talus (taken with a range finder in inclination mode).

Base Talus Angle – Reading in radians at the base of the talus (taken with a range finder in inclination mode).

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Usable Estimate – Estimate the amount of face that would take up a perfect rectangle and the amount within that on the face that is usable. For example not including areas of high gravel, high vegetation or vegetation overhang, etc.

Equations:

1. Angle between Left and Right side of bank (Final Angle)

= �� > ��ℎ� �� , 360 − �� + ��ℎ� ��, ��ℎ� �� − �� )

2. Total Face Length

= √( �� ! + �� ℎ� �� ! − 2 ∗ �� ∗ �� ℎ� �� ∗ cos �� )

3. Bank Talus Angle = �� − ��

4. Face Angle = �� − ��

5. Talus Radians = ��(�� )

6. Face Radians = ��(�� )

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7. Step 1

�� ! + �� ! − = 2 ∗ �� ∗ �� ∗ cos ��

8. Step 2 sin �� ∗ �� = 180 − (�� asin ) ��1

9. Step 3

�� ! + �� ! = − 2 ∗ �� ∗ �� ∗ cos ��

10. Step 4 sin Talus Radians ∗ Distance to Talus Base = �� asin Step 3

11. Step 5 = 180 − �� 4 − �� 2

12. Talus Height (Step 6) = ( cos �� 5 ∗ ��3)

13. Total Face Area without usable estimate

= �� ℎ ∗ �� ℎ�

14. Total Face Area with usable estimate

= �� ℎ ∗ �� ℎ� ∗ �� %

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APPENDIX 3: BANK SWALLOW COLONY COUNTS IN 2014 AND 2015 LAKESHORE AND AGGREGATE PIT HABITATS.

# of Burrows 1st # of Burrows last Habitat Type Site Name Year Colony week June week July Lakefield 2014 1 72 56 2014 2 67 54 2014 3 26 25 2014 4 57 41 2014 5 80 40 2015 1 152 101 2015 2 87 21 2015 3 46 46 Westone 1 2014 1 50 49 2015 1 53 51 Weststone 2 2014 1 346 283 2015 1 264 232 Vivian 2014 1 170 130 2014 2 408 392 2014 3 47 46 Pit 2015 1 144 267 2015 2 272 64 2015 3 79 45 Westwood 2014 1 271 223 2014 2 51 38 2014 3 28 28 2015 1 94 45 2015 2 103 206 2015 4 28 8 Drain Brothers 2014 1 350 313 2014 2 34 20 2015 1 160 145 2015 2 54 36 2015 3 44 43 Finlay 1 2014 1 59 56 2014 2 16 11

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2014 3 25 28 2015 1 31 50 2015 2 47 53 Baltimore 2014 1 15 15 Finlay 2 2014 1 79 63 McGee 2014 1 283 254 2014 2 33 33 2015 1 308 347 2015 2 74 60 Kawartha Lakes 2014 1 8 8

Courtice Water 2014 1 NA 50 Treatment Plant 2014 2 NA 133 2015 1 100 71 2015 2 147 177 Wilmot 2014 1 NA 1044 Lakeshore Creek 2014 2 NA 1089 2014 3 NA 702 2015 1 953 1003 2015 2 726 734 2015 3 760 623 Darlington 2014 1 NA 1932 2014 2 NA 402 2014 3 NA 511 2014 4 NA 156 2014 5 NA 22 2014 6 NA 33 2015 1 2301 2085 2015 2 407 308 2015 3 230 198 2015 4 21 13 2015 5 49 28

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APPENDIX 4: SOIL COMPOSITION OF OCCUPIED BANK SWALLOW BANKS DURING THE 2014 AND 2015 FIELD SEASON.

*Two soil samples were taken within each colony and average percentage of sand, silt and clay (± standard error) composition are presented.

Habitat Site Name Colony Year % Sand % Silt %Clay Type 1 2014 80±8.0 8±2.5 12±5.5 2 2014 80±8.0 8±2.5 12±5.5 3 2014 75±4.0 14±8.5 11±4.5 4 2014 70±1.5 10±0.5 20±1 Lakefield 5 2014 83±1.0 2±0.5 15±0.5 1 2015 58±11.0 15±3.0 27±8.0 2 2015 73±3.1 10±1.8 17±2.2 3 2015 72±3.0 13±1.0 15±4.0 1 2014 64±8.1 19±4.5 17±3.6 Westone 1 1 2015 81±5.0 11±4.5 8±0.5 1 2014 59±25.0 9±5.0 32±20.0 Westone 2 1 2015 80±2.0 5±1.5 15±0.5 1 2014 87±0.5 0 13±0.5 Pit 2 2014 83±1.0 1±1 16±0 3 2014 83±2.0 1.5±1.5 15±0.5 Vivian 1 2015 87±0.5 0 13±0.5 2 2015 85±0 1±0 14±0 3 2015 89±3.0 0.5±0.50 10±3.5 1 2014 78±0 5±0 17±0 2 2014 79±3.0 6±3.5 15±.0.5 3 2014 78±5.5 10±3.0 12±2.5 Westwood 1 2015 87±2.0 1±0 12±2.0 2 2015 77±1.5 11±2.0 12±0.5 3 2015 79±2.5 7±1.5 14±1.0 1 2014 78.3±1 6±1 15.7±0 Drain Brothers 2 2014 78.3±0 6±0 15.7±0

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1 2015 80±0.5 4±0.5 16±0 2 2015 82±0.5 3±0 15±0.5 3 2015 83±1.0 3±0.5 14±0.5 1 2014 73.5±5.4 9.5±2.9 17±2.5 2 2014 70±3.5 15±4.0 15±0.5 Finlay 1 3 2014 73.5±5.4 9.5±2.9 17±2.5 1 2015 68±1.4 10±6.5 22±7.9 2 2015 83±1.5 3±1.0 14±0.5 1 2014 83±1 6±5 11±4.0 McGee 2 2014 85±4.5 4±0.5 11±4.0 1 2015 84±1.0 3±1.0 13±2.0 2 2015 84±3.5 4±2.5 12±1.0

Baltimore 1 2014 83±0 2±1.0 15±1.0

Finlay 2 1 2014 83±0 5±4.0 12±4.0 Kawartha Lake 1 2014 67±8.0 18±4.0 15±4.0 2014 37±2.5 27±0 36±2.5

Courtice 2014 34±5.0 21±1.5 45±3.5 Treatment Plant 2015 37±4.4 30±4.0 33±0.4 2015 37±7.6 21±1.0 42±8.6

2014 29±10 57±9.0 14±1.0 Lakeshore 2014 74±3.0 11±3.0 15±0 2014 39±2.2 45±2.9 15±1.2 Wilmot Creek 2015 54±3.9 35±1.5 11±2.3 2015 81±0 6±0 13±0 2015 71±1.6 17.5±5.5 11.5±3.9 Darlington Nuclear 2014 NA NA NA

2015 NA NA NA