Master of Science, The Ohio State University, 2007, Graduate School

Committee: Not Provided (Other) Subjects:

Bachelor of Arts (BA), Ohio University, 2024, Environmental Studies

Grassland birds have narrow habitat requirements that are influenced by food availability, habitat composition, and habitat structure. Because survival is influenced by habitat quality and availability, understanding habitat requirements is critical for conservation. I determined how Henslow's Sparrows (Centronyx henslowii) use grassland habitat in the breeding season. In the past 10 years, technology advancements have allowed researchers to study the habitat use and movement ecology of understudied birds, such as grassland birds. I deployed nanotags on 47 adult Henslow's Sparrows at two sites in southern Ohio to determine home range size and habitat use in relation to distance to edge and shrub, as well as the post-breeding dispersal and migratory timing. I predicted that Henslow's Sparrows would use core grassland habitat and avoid edge and shrubs. I found no difference in 95 % home range size between female (0.10 ± 0.03 ha) and male (0.32 ± 0.18 ha) Henslow's Sparrows. Henslow's Sparrows used shrubs when available and edge habitat as refugia after disturbance. I also found that Henslow's Sparrows use fields into August, past dates typically recommended for disturbance (e.g., mid to late July), which suggests the need to leave corridors and patches for refugia after management such as mowing or burning. I determined the fall migratory departure timing of 13 Henslow's Sparrows. I found that Henslow's Sparrows are at risk for entanglement which resulted in mortality of two birds. A third bird found entangled was found alive, entangled in vegetation, and was released after I removed the nanotag. I also found that 24 Henslow's Sparrows were able to remove nanotags and several damaged their nanotags. While I do not recommend the use of nanotags on this species in future studies, my study did result in determining fall migratory departure timing of Henslow's Sparrows in Ohio which was previously unknown.

Committee: Kelly Williams (Advisor) Subjects: Animals; Biology; Ecology; Environmental Studies; Organismal Biology; Wildlife Conservation; Wildlife Management; Zoology

Doctor of Philosophy, The Ohio State University, 2022, Environmental Science

Tropical savannas support globally important biological diversity and provide a variety of cultural and economic ecosystem-services to humans. As mosaic landscapes, they are characterized by the coexistence of woody and grassy habitats which are strongly regulated by abiotic gradients (e.g., soils, climate) and local disturbance regimes (e.g., fire, flooding and grazing). Consequentially, savannas are inherently dynamic over a variety of scales and provide an array of temporal and spatial ecological niches for wildlife. However, tropical savannas and their ecological functions have been widely degraded by intensifying human land-use and are threatened by impending climate change. Unfortunately, our scientific understanding of savanna ecology is currently limited, impeding development of appropriate conservation approaches. This is especially true of Neotropical systems. This dissertation provides new research, carried out within the Beni, a seasonally flooded Neotropical savanna in Bolivia, that aims to address critical knowledge gaps in savanna ecology. This research will contribute to developing sustainable land management and restoration initiatives to secure and protect savanna ecosystems for people and wildlife. The overarching aim was to understand how ecological (flooding) and agricultural (managed fire and cattle grazing) disturbance influences habitats and wildlife in Beni. To achieve this, three specific objectives were identified: 1) understand how restoration, through cessation of long-term cattle grazing impacts (i) regeneration, (ii) understory structure and composition, and (iii) abundance and diversity of large mammals and nocturnal birds, within the regions' naturally patchy gallery forests; 2) examine how compounded disturbance from flooding and fire shapes the distribution of woody plants and habitats across a savanna-grassland mosaic; and 3) determine functional responses of avian biodiversity to livestock removal across a savanna-grassland ec (open full item for complete abstract)

Committee: G. Matt Davies (Advisor); Christopher Tonra (Advisor); Stephen Matthews (Committee Member); Kaiguang Zhao (Committee Member) Subjects: Conservation; Ecology; Environmental Science; Range Management; Wildlife Conservation

Doctor of Philosophy (Ph.D.), University of Dayton, 2021, Biology

Invasive species are a global threat that cause major ecological and economic harm, as they are a major contributor to loss of biodiversity and ecosystem function. Introduced ants becoming increasingly ubiquitous in terrestrial ecosystems and some of the most destructive invaders can extreme numerical densities, displace native ants and non-ant arthropods, and as a result, can alter the structure and function of natural ecosystems. A recent invader of emerging importance, the tawny crazy ant, Nylanderia fulva (Hymenoptera: Formicidae), is highly successful in coastal ecosystems in the Southeastern United States. We investigated the causes and consequences of invasion by N. fulva on coastal tallgrass prairies by determining: 1) diet, trophic position, and their potential to affect large, aboveground insects; 2) the effect of invasion on native above- and belowground insect communities; 3) the factors that limit N. fulva abundance; and 4) the mechanisms of N. fulva nutrient limitation and stress. In summary, N. fulva is an omnivorous ant that obtains most of its nitrogen from plants but has the capabilities to attack and kill large aboveground arthropods, like grasshoppers. In recently invaded habitats, N. fulva invaded areas were associated with lower native ant and grasshopper abundance, but these areas also contained greater abundances of hemipteran mutualists, which likely contribute to their extreme densities and success. Additionally, in litter communities, N. fulva numerically dominated the composition of litter-dwelling arthropods, and their abundance was limited by the availability of calcium but tended to be stressed by increased concentrations of potassium and sodium in the soil. Colonies of N. fulva that were fed diets with increased levels of calcium showed the ability to increase colony biomass. Based on these findings we show the great potential of this invasive ant to rapidly decrease the abundance and richness of native arthropods, which could have lo (open full item for complete abstract)

Committee: Chelse Prather Ph.D. (Committee Chair); Albert Burky Ph.D. (Committee Member); Karolyn Hansen Ph.D. (Committee Member); Ryan McEwan Ph.D. (Committee Member); Kirsten Prior Ph.D. (Committee Member) Subjects: Biology; Ecology; Entomology

Master of Science, The Ohio State University, 2020, Environment and Natural Resources

Confronted with threats of habitat loss and climate change, birds that inhabit open-lands such as grasslands and shrublands are among the most rapidly declining groups of birds across North America. One such bird is the Northern bobwhite (Colinus virginianus; hereafter bobwhite) which inhabits heterogeneous landscapes that typically consist of shrubland, grassland, and early-successional forests. Bobwhites are declining at an alarming rate across most of their range, largely due to habitat loss from intense production agriculture. Populations along the northern periphery of bobwhite range are secondarily imperiled by high mortality from severe winter weather. Because bobwhites are a socially and economically important gamebird, there has been great interest from a variety of stakeholders to maintain suitable habitat and promote sustainable populations. As a result of the conservation attention they receive, bobwhite conservation has the potential to benefit non-target songbirds with similar land cover requirements. The umbrella species concept suggests that benefits will accrue to non-target species if viable bobwhite populations are maintained through habitat conservation. The future viability of bobwhite populations is in question in Ohio, so a comprehensive demographic study is needed to estimate probability of population persistence under a variety of future weather and population viability analysis (PVA) scenarios. The first part of my thesis focuses on landscape-scale characteristics that influence bobwhite occupancy in Ohio, and whether occupancy by other open-land species is positively predicted by bobwhite occupancy. The second part of my thesis focuses on projecting population dynamics of bobwhite in Ohio in response to future winter weather and PVA scenarios. I obtained bird survey data from the Ohio Breeding Bird Atlas (2006–2011). I used land cover data (NLCD 2011) to calculate compositional and configurational landscape metrics within a 630 m radiu (open full item for complete abstract)

Committee: Robert Gates (Advisor); Stephen Matthews (Advisor); Peterman William (Committee Member) Subjects: Ecology; Wildlife Conservation

Master of Science, The Ohio State University, 2020, Evolution, Ecology and Organismal Biology

Loss of habitat is one of the drivers of bee declines worldwide. However, conservation and habitat recreation often solely focus on the establishment of forbs as a pollen and nectar source while disregarding other resources that bees need to gather from their landscapes. The family Megachilidae is a large and diverse assemblage of bee species, the majority of which require non-floral resources for nest building. Leaf-cutter bees (genus Megachile) are perhaps the most well-known bees within the family, using cut pieces of leaves to build their nests. Like all bees, Megachile are central place foragers, requiring all of their food plants, as well as suitable leaves for nest construction, within a limited foraging range of their nest. Each female builds her nest within a tunnel in wood or a hollow stem where she constructs a linear series of brood cells lined with cut discs of leaves that protect her offspring and pollen provisions from parasites and desiccation. Poor quality leaves incur fitness costs for the female bee, including longer processing time and excessive mandibular wear. These costs drive strong preferences for specific species of leaves. I investigated the leaf traits that influence preference in Megachile to better understand how variation in vegetation surrounding the nest might limit bee success through the availability of high-quality leaves. This study focuses on reclaimed coal surface mines in Eastern Ohio because they exhibit variation in vegetation at a landscape scale relevant to bee foraging. Reclaimed mines also present novel ecological conditions that can be used to establish habitat for bee conservation. First, I described the physical characteristics of leaves found on a reclaimed mine in order to determine traits associated with leaf choice. This study focused on a representative species of leaf-cutter bee, Megachile rotundata, because of its abundance at the study site and the availability of published data on the species of leaves it (open full item for complete abstract)

Committee: Karen Goodell PhD (Advisor); Rachelle Adams PhD (Committee Member); Frances Sivakoff PhD (Committee Member); Rebecca Swab PhD (Committee Member) Subjects: Biology; Conservation; Ecology; Entomology; Environmental Management

Doctor of Philosophy, Miami University, 2015, Ecology, Evolution and Environmental Biology

The goals of this dissertation were to examine how patch and landscape level processes structure ant communities in agricultural landscapes and determine the relative roles of patch and host-level factors in determining ant-associated mite diversity and community composition. In Chapter 1, I examined ant richness, species frequencies, and community composition in 23 warm season constructed grasslands that varied in both patch and landscape level characteristics. Ant species richness was greater in older sites with sandier soils, while community composition was structured by soil texture, management, and urban land use. Frequency analyses for 14 ant species showed a wide range of responses to both patch and landscape components of the environment including age, management, soil texture, and surrounding land use. My findings support the use of ants as environmental indicators of disturbance in agricultural landscapes and show that diversity in constructed grasslands is structured by both patch and landscape level processes. In Chapter 2, I determined the relative importance of host and habitat for an ant-dependent commensalism (phoretic mites). I found that large, cosmopolitan, and abundant ant species support a greater proportion of the mite diversity. Additionally, I found that patch level characteristics, or environmental context (area, age, soil texture, and litter depth), of the host can alter the associated mite diversity. In Chapter 3, predictions of theory, herbivore resource hypotheses, and spatial parasitology were used to identify the extent of the ecological neighborhood for mites associated with ants. My results indicate that commensal mite communities are consistent with the Resource Size Hypothesis and are sensitive to ecological neighborhoods at multiple hierarchical levels including individual host ants, the host ant colony, surrounding nest community, and habitat type, but do not vary significantly among sites. In the final chapter, I examined the im (open full item for complete abstract)

Committee: Thomas Crist (Advisor); Hans Klompen (Committee Member); Melany Fisk (Committee Member); Ann Rypstra (Committee Member); John Maingi (Committee Member) Subjects: Biology; Ecology; Entomology

Master of Science, The Ohio State University, 2011, Environment and Natural Resources

Grassland birds are declining at greater rates than any other habitat guild in North America, yet conservation remains difficult due to extensive habitat loss and fragmentation throughout the urbanizing Midwest. Human presence is often associated with non-native predators (e.g., cats) and anthropogenic food sources, which collectively can promote high densities of nest predators in urban landscapes. High densities of nest predators are a concern because predation is the leading source of nest failure. Behavioral responses to predators may further diminish the value of urban habitats if birds avoid areas with high levels of predator activity, which could result in lower occupancy rates or densities of birds in urban habitat patches. In my research, I examined how habitat heterogeneity and variation in the predator community influenced the breeding ecology of grassland and early successional birds in urban parks. I asked two broad questions: (1) how do birds respond behaviorally to abundance and activity of predators in urban natural areas? (2) to what extent is avian reproductive success linked to predator communities and/or activity at plot and site scales? I collected data on avian density, nest placement, and reproductive success of eight focal species of grassland birds within 46 2-ha plots at seven urban parks near Chicago, Illinois, during 2009 and 2010. Relative abundance and activity levels of potential nest predator species, including mesopredators, small mammals, snakes, and avian predators, were estimated for each plot during surveys and as part of a collaborative study. As capture rates of small mammals increased, territory densities of Field Sparrow (Spizella pusilla), Common Yellowthroat (Geothlypis trichas), and Savannah Sparrow (Passerculus sandwichensis) declined, but density of Song Sparrow (Melospiza melodia) rose. Mesopredator capture rates were negatively associated with Common Yellowthroat and Savannah Sparrow densities within 2-ha plots, as we (open full item for complete abstract)

Committee: Amanda Rodewald (Advisor); Stanley Gehrt (Other); Jacqueline Augustine (Other) Subjects: Ecology