Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental toxicants found in anthropogenic mixtures such as crude oil, air pollution, vehicle exhaust, and in some natural combustion reactions. Single PAHs such as benzo[a]pyrene (BaP) also impact fish behavior when animals are exposed in early life stages and for short periods of time. Aquatic animals such as fish may encounter BaP through road runoff and oil spills, but few studies have examined the impact of aqueous exposure on adult fish, and fewer have examined the resulting fitness-relevant behavioral consequences of BaP and PAH mixtures and their long-term persistence. This dissertation targets this gap in the literature by examining how aqueous exposure to BaP influences anxiety-like behavior, learning, and memory in adult zebrafish, and how parental exposure to the PAH mixture, crude oil, combined with hypoxia affects social and exploratory behavior in unexposed larval zebrafish. We found that learning and memory were not affected by 24 hour exposure to BaP, that anxiety-like behavior was minimally affected, and that locomotor parameters such as distance moved and times spent in darting and immobile states were significantly altered by exposure to BaP. Additionally, we found that parental exposure to crude oil and hypoxia decreased larval velocity. Additionally, …

The bristlenose pleco (Ancistrus cirrhosus) is a species of armored catfish in the Loricariidae family that breathes air facultatively when the aquatic environment becomes hypoxic. The bristlenose pleco uses its highly vascularized stomach as an air breathing organ. The two main goals of this developmental study were to determine the size of onset of air breathing and to determine the frequency of air breathing behavior in bristlenose plecos from juveniles to adults. Developing juveniles reach functional maturity within four to six months of hatching and grow to an adult size of eight to ten cm in length. To examine the developmental timing for the onset of air breathing, we tested different sized juveniles beginning at one cm up until 8 cm in length. The developmental timing for the onset of air breathing was measured by exposing each fish to a slowly decreasing aquatic oxygen content from 100% air saturation down to 8% air saturation. Fish were first able to breathe air at just over 2 cm and 1 gram in mass. There was a weak negative correlation between fish length and % air saturation at which air breathing began. When exposed to 15% air saturation, frequency of air breathing was …

Invasions from coho salmon were first reported in the Cape Horn Biosphere Reserve (CHBR) in 2019 which is the most southern distribution registered to date. The CHBR is known for its high number of endemic species and unique biodiversity, such as the native fishes Galaxias maculatus and Aplochiton taeniatus. There are now three invasive salmonid species in the rivers of CHBR and are a potential threat to the native fish taxa. Stable isotope and gut content analysis were used to understand resource utilization by both native galaxiid and invasive salmonid taxa, as well as aquatic macroinvertebrates and riparian spiders. The natural laboratory study approach applied to this research, allowed for comparisons of differences within streams that contain conditions in which fish do not occur naturally, to sites in which high densities of invasive salmonid exist. Analysis of the trophic niche and diet in this study showed the importance of marine resource use by the native galaxiid and coho salmon juveniles supported with elevated δ15N and δ34S ratios. Diet analysis also confirmed there was the highest similarity between the coho salmon juveniles and the native fish. Altered behavior and habitat use was shown through the isotope and diet analysis for the …

Hypoxia as a stressor has physiological implications that have been a focal point for many physiological studies in recent years. In some studies, hypoxia had large effects on the organ tissue degeneration, which ultimately effects multiple ecological processes. These organ tissue studies played a part in the development of new fields like neurocardiology, a specialty that studied the relationship between the brain and the heart. This thesis focuses on how hypoxia-induced cardiac arrest alters the amounts of GLYT2, a glycine reuptake transporter, in the central nervous system of zebrafish, Danio rerio. At 7 days post-fertilization (dpf), zebrafish were exposed to acute, severe hypoxia until they lost equilibrium, and minutes later, subsequent cardiac arrest occurred. Zebrafish were then placed into recovery groups to measure the GLYT2 levels at multiple points in zebrafish recovery. Fish were then sacrificed, and their brains dissected. Using immunofluorescence, the outer left optic tectum of the zebrafish was imaged, and mean image pixel fluorescent intensity was taken. There were significant changes (one-way ANOVA) in the levels of GLYT2 compared to that of the control groups during the course of recovery. GLYT2 levels continued to rise through the 24-hour recovery mark but did not show significant difference after …

Conservation corridors, areas of land connecting patches of natural land cover, are frequently cited and implemented as a restorative strategy to counteract fragmentation. Current corridor ecology focuses on experimental corridor systems or designed and built conservation corridors to assess functionality. Such systems and designs are typically short, straight swaths of homogenous land cover with unambiguous transitions between patches. Quantifying the degree to which amorphous landscape configurations, tortuosity, and heterogeneity of land cover and land uses within the corridor has on functional connectedness is a crucial yet overlooked component of corridor efficacy studies. Corridor literature lacks a robust and repeatable methodology for delineating existing landscape elements, recognizing arbitrary edges, and identifying the start and end of ambiguous transitions between the patches and corridor. Using a set of landscapes being studied as part of a global assessment of corridor efficacy, I designed a workflow that standardizes the boundary of corridor-patch interfaces. The proposed method is a quantitative and repeatable approach that minimizes the subjectivity in corridor delineations. This research investigates the degree to which the existence of a corridor modifies the structural and functional connectivity between patches connected by a corridor compared to an intact reference area.

My thesis focuses on the conservation consequences of the hybridization of Lesser Prairie-Chickens in Kansas. Specifically, examining how past land management practices altering the species ranges impact the distinctiveness of Lesser Prairie-Chickens. Each chapter is an individual publication that addresses if the Greater and Lesser Prairie-Chicken are distinct when applying the morphological and biological species concepts. Chapter 2 compares the evolutionary history and morphological construct of Lesser Prairie-Chickens and other Galliformes using morphometric analysis. Chapter 3 uses low-resolution microsatellite data to reflect recent changes at the population level. This study aims to observe the Greater and Lesser Prairie-Chicken using the morphological and biological species concepts, two of the many species concepts, to determine the distinctiveness and rate of hybridization for these closely related species.

Crude oil commonly enters freshwater aquatic ecosystems as thin sheens forming on the water surface. Oil contains mixtures of toxic compounds called polycyclic aromatic hydrocarbons (PAHs), some of which are known to be photodynamic, increasing toxicity when combined with ultraviolet radiation. Benthic macroinvertebrate communities are commonly utilized as bioindicators, and as such rely on abundant data in literature concerning benthic macroinvertebrates' relative tolerances to a wide range of pollutants. A series of 10 plastic traps, half of which were filtered from UV radiation, were deployed in an urban pond for 27 days to determine colonization preferences of benthic macroinvertebrates to UV exposure. Results of this in situ experiment indicated that the majority of aquatic insects collected from traps inhabited the UV exposed treatment group, particularly the nonbiting midge, Chironomidae. A series of bioassays were then completed to investigate the sensitivities of a Chironomidae species to thin sheens of crude oil in the presence and absence of UV radiation. All bioassays were conducted using 10 day old Chironomus dilutus larvae cultured in the lab. The series of C. dilutus bioassays were all conducted under the same water quality parameters, temperatures, and oil sheen dosing methods, under a 16:8 photoperiod and exposed …

Here, we show that training with multiple noncommunicable diseases (NCDs) is both feasible and beneficial to modeling this class of diseases. We first use data from the Cancer Genome Atlas (TCGA) to train a pan cancer model, and then characterize the information the model has learned about the cancers. In doing this we show that the model has learned concepts that are relevant to the task of cancer classification. We also test the model on datasets derived independently of the TCGA cohort and show that the model is robust to data outside of its training distribution such as precancerous legions and metastatic samples. We then utilize the cancer model as the basis of a transfer learning study where we retrain it on other, non-cancer NCDs. In doing so we show that NCDs with very differing underlying biology contain extractible information relevant to each other allowing for a broader model of NCDs to be developed with existing datasets. We then test the importance of the samples source tissue in the model and find that the NCD class and tissue source may not be independent in our model. To address this, we use the tissue encodings to create augmented samples. We test …

Current evidence suggests that thyroid hormones (THs) may impact development of the immune system. However, studies that explore the role of THs in immune development are limited, and the mechanisms leading to alterations in immune function are poorly understood. It is important to elucidate the role of THs in immune development given that many environmental contaminants have been shown to disrupt TH homeostasis and may also have negative impacts on the immune system. As such, the main goal of this study was to determine the long-term consequences of early life stage (ELS) hypothyroidism on immune function. To achieve this goal, it was first necessary to further characterize basic immune function in the selected model species, the fathead minnow (FHM, Pimephales promelas). Preliminary studies were conducted to describe the transcriptomic response to Yersinia ruckeri and adapt assays for the assessment of respiratory burst and phagocytic cell activity. To determine the long-term effects of ELS hypothyroidism, FHMs were exposed to the model thyroid suppressant propylthiouracil (PTU) from <1 to 30 days post hatch and reared under normal conditions. Upon reaching adulthood, ex vivo immune cell function and the in vivo immune response to Y. ruckeri were assessed. Fish exposed to PTU experienced …

Improving growth, lowering mortality rates, and having a faster turnaround to harvest is essential for the future of commercial aquaculture. The primary goal of this study was to determine if introducing a single strain probiotic Lactobacillus rhamnosus IMC 501 into the feed regimen of a commercially important aquaculture freshwater fish, Mozambique tilapia (Oreochromis mossambicus), would decrease mortality; change metabolic rates; and increase tissue wet mass (MW), standard length, growth rate and feed conversion rate (FCRs). IMC501 was added to the fishmeal in four increasing concentrations and compared to a control without probiotics. Results from two-way ANOVAs showed that both treatment levels and elapsed time had a significant effect on both mean standard length and wet mass; in the latter case, time points and treatments interacted with one another, showing that tilapia grew best with a moderate level of probiotics present. The growth benefits of probiotics continued for months after the initial treatments. Oxygen consumption (metabolic rate) was measured using closed respirometry and resulted in recording the first values for juvenile tilapia treated with probiotics. For oxygen consumption, there were significant treatment and time effects with significant interactions, indicating that metabolism increased with probiotics once the dosage exceeded three times the …

This study investigated whether oxLDL and/or angiotensin (Ang) II signaling pathways mediate traffic-generated air pollution- exposure induced alterations in blood-brain barrier (BBB) integrity and permeability in a healthy wild type (C57Bl/6) mouse model; additionally, whether these outcomes are exacerbated by a high fat-diet investigated. An environmentally relevant concentration of a mixture of vehicle engine exhaust (MVE) was used. To investigate the hypotheses, 12 wk old male C57Bl/6 mice on either a high fat (HF) or low fat (LF) diet were randomly assigned to inhalational exposure of either filtered-air (FA) or 30 µg PM/m3 diesel exhaust + 70 µg PM/m3 gasoline exhaust (MVE) for 6 hr/day for 30 days. Additionally, we examined mechanisms involved in MVE-mediated alterations BBB integrity using a novel BBB co-culture in vitro model, consisting of mouse primary cerebral vascular endothelial cells on an apical transwell and astrocytes in the basal compartment, which was treated with plasma from the mice on our exposure study. Our in vivo exposure study results showed that MVE inhalation resulted in increased circulating plasma oxLDL and Ang II, compared to FA controls. Additionally, we observed increased cerebral microvascular expression of oxLDL receptors, LOX-1 and CD-36, and Ang II receptor subtype 1 (AT1) in …

Reptiles can often experience perturbations that greatly influence their metabolic status (e.g., temperature, exercise, digestion, and ontogeny). The most common cause of fluctuations in metabolic status in post-embryonic reptiles is arguably digestion and physical activity (which will be further referred to as exercise). The objective of this thesis is to determine the mechanisms involved in CO2 transport during digestion, determine the mechanisms that allow for the maintenance of acid-base homeostasis during digestion, and observing the effect of an understudied form of exercise in semi-aquatic reptiles on the regulation of metabolic acidosis and base deficit. This dissertation provided evidence for potentially novel and under investigated mechanisms for acid-base homeostasis (e.g., small intestine and tissue buffering capacity; Chapters 3 & 4), while also debunking a proposed hypothesis for the function of an anatomical feature that still remains a mystery to comparative physiologist (Chapter 2). This thesis is far from systematic and exhaustive in its approach, however, the work accomplished in this dissertation has become the foundation for multiple distinct paths for ecologically relevant investigations of the regulation of metabolic acidosis/alkalosis in reptiles.

Peregrine falcon subspecies taxonomy is widely debated due to uncertainty in their evolutionary history and unresolved phylogenetic reconstruction using both morphological and molecular data. Previous genetic work has shown limited support for subspecies taxonomy largely as a result of molecular markers used, potential contemporary gene flow, incomplete lineage sorting, and ancestral polymorphisms. With the advent of next-generation sequencing, the cost of generating large amounts of sequence data has dropped significantly, making whole genome re-sequencing (WGR) studies of non-model organisms more tangible. In this study, WGR methods have been utilized to investigate the phylogenetic relationships among all 20 currently recognized peregrine falcon subspecies. By generating whole-genome data for all 20 subspecies, subspecies specific diagnostic SNPs have been identified to aid in subspecies delimitation. Results of this study broadly support current subspecies, however, reveal that further study is needed to investigate regional relationships among subspecies in Asia, Australia, and western North America. With these results, conservation efforts can be further supported by allowing for accurate delimitation of local subspecies and subspecies boundaries.

There is increasing evidence indicating that exposure to air pollutants may be associated with the onset of several respiratory diseases such as allergic airway disease and chronic obstructive pulmonary disorder (COPD). Many lung diseases demonstrate an outgrowth of pathogenic bacteria belonging to the Proteobacteria phylum, and the incidence of occurrence of these diseases is higher in heavily polluted regions. Within the human body, the lungs are among the first to be exposed to the harmful effects of inhaled pollutants and microbes. Research in the past few decades have expounded on the air-pollution-induced local and systemic inflammatory responses, but the involvement of the lung microbial communities has not yet been well-characterized. Lungs were historically considered to be sterile, but recent advances have demonstrated that the lower respiratory tract is replete with a wide variety of microorganisms - both in health and disease. Recent studies show that these lung microbes may play a significant role in modulating the immune environment by inducing IgA and mucus production. Air pollutants have previously been shown to alter intestinal bacterial populations that increase susceptibility to inflammatory diseases; however, to date, the effects of traffic-generated air pollutants on the resident microbial communities on the lungs have not …

Recent epidemiological studies have demonstrated a correlation between the manifestation of non-alcoholic fatty liver disease (NAFLD) and ambient air pollution levels, which is exacerbated by the presence of other risk factors, such as diabetes, dyslipidemia, obesity, and hypertension. We investigated the hypothesis that exposure to a mixture of gasoline and diesel engine emissions (MVE) coupled with the concurrent consumption of a high-fat (HF) diet promotes the development of a NAFLD phenotype within the liver. Three-month-old male C57Bl/6 mice were placed on either a low fat or HF diet and exposed via whole-body inhalation to either filtered (FA) air or MVE (30 µg PM/m3 gasoline engine emissions + 70 µg PM/m3 diesel engine emissions) 6 hr/day for 30 days. Histology revealed mild microvesicular steatosis and hepatocyte hypertrophy in response to MVE exposure alone, compared to FA controls, yielding a classification of "borderline NASH" under the criteria of the modified NAFLD active score (NAS) system. As anticipated, animals on a HF diet exhibited moderate steatosis; however, we also observed inflammatory infiltrates, hepatocyte hypertrophy, and increased lipid accumulation, with the combined effect of HF diet and MVE exposure. Immunofluorescence staining and RT-qPCR of the liver revealed the presence of lipid peroxidation, altered expression …

This project focused on the relationship between instream flows and smallmouth buffalo (Ictiobus bubalus) recruitment in the Gulf Coastal Plain of Texas. The flow regime is the dominant factor in lotic systems and, consequently, the relationship between instream flows, including impacts to natural flow regimes, and life-history is a subject of growing interest. Smallmouth buffalo is a good model to investigate the relationship between river flows and variable interannual recruitment success of periodic life-history strategist fish species. Smallmouth buffalo were collected from the Brazos, Colorado, and Guadalupe Rivers of Texas, U.S.A., and otoliths were extracted from individuals in the field and sectioned and photographed in the lab. Photographs of sectioned otoliths were used to estimate age and thus the year in which the individual was spawned by counting back from the time of capture. Population age structure (i.e. a ‘state' or condition at a point in time) was used to infer effects of flow variation on a rates-based process (i.e. recruitment). After controlling for mortality using recruitment index values, interannual variation in recruitment was modeled using multiple components of the flow regime quantified as indicators of hydrologic alteration (IHA) variables based on daily discharge data from USGS gaging stations in …

The present study sought to determine some morphological and physiological critical windows during very early development in zebrafish exposed to crude oil. I hypothesized that exposed zebrafish would present a decrease in survival rate and body mass, and an increase in routine oxygen consumption (ṀO2), and critical oxygen tension (PCrit). To test these hypotheses, zebrafish were acutely exposed (24 h) during different days of development (1 to 6 days post-fertilization, dpf) to different concentrations of high-energy water-accommodated fractions (HEWAFs). The endpoints of survival, body mass, routine oxygen consumption, and critical oxygen partial pressure were measured at 7 dpf. Survival rate decreased based on the exposure concentration but not as a function of the day of crude oil exposure. No significant effects were found in PCrit. Body mass was reduced by the different concentrations of HEWAF, with the size of the effect varying with exposure day, with the effect strongest on when exposure occurred at 2 and 3 dpf. Oxygen consumption (ṀO2) differed significantly depending upon the day of exposure in fish exposed to crude oil. Specifically, HEWAF exposure significantly increased ṀO2 in larvae exposed at 3 dpf (9.081 µmol O2/g/h, ±0.559) versus 2 dpf (6.068 µmol O2/g/h, ±0.652) and 6 …

This dissertation examined the phenotypic plasticity of endothermic, flight and respiratory physiology in response to developmental oxygen exposure in the moth Manduca sexta. Development in both 10% O2 hypoxia and 30% O2 hyperoxia treatments were used to look at the physiological consequence on both ends of the oxygen spectrum. Hypoxic insects reached smaller sizes as adults and had longer pupation lengths than controls. Hyperoxic insects were larger at the end of the larval stage, had increased larval growth rates, but also had longer developmental larval developmental times and pupation lengths than controls. There was a decrease in both metabolic rate and thorax temperatures of hypoxic reared insects at normoxic levels. In flight trials hypoxic insects had the lowest critical flight PO2, and the hyperoxic insects had the highest PO2. There was an increase in hypoxic insect flight muscle mitochondria oxygen consumption in permeabilized fibers, but this did not translate to the isolated flight muscle mitochondria metabolic rates. Rearing oxygen level did not significantly affect mitochondrial density and size; myofibril density and size, or tracheal density and size in flight muscle. Overall, I found that higher levels of organization were more susceptible to the effects of chronic oxygen exposure and found …

The present studies determine the accumulation of persistent organic pollutants (POPs) in three pinniped species, evaluate the relationship with relevant biomarkers of exposure, and calculate toxic effect thresholds. Stranded harp and hooded seals were found to be accumulating PBDEs at levels which could pose a based on threshold levels determined in this study. Northern fur seals are accumulating all three classes of POPs (PCBs, PBDEs, and OCPs) with significant relationships being seen with blubber percent lipid. Correlations between contaminant concentrations and expression levels of relevant biomarkers were seen potentially indicating an effect on multiple pathways. Overall risk can be hard to determine due to factors such as sex and age. Broad threshold response values and hazard quotients were calculated for toxic effect endpoints in pinnipeds. Overall these results suggest that certain populations of pinnipeds are at high risk of experiencing toxic effects due to POP exposure, but it is important to understand effects even at lower concentrations. The relationship between exposure, toxic effects, and other stressors, both environmental and physiological, can impact the overall fitness and survival of pinnipeds.

Microalgae being photosynthetic and having quick growth cycles can prove to be excellent candidates as biofactories for the production of aromatic compounds like para-hydroxybenzoic acid (pHBA) that act as a monomer in liquid crystal polymers. We developed transgenic lines of the model alga Chlamydomonas reinhardtii by performing nuclear transformation using electroporation. The transgenic cell lines expressed the ubiC gene that utilized chorismate from the shikimate pathway as a substrate to produce pHBA. The maximum yield of pHBA measured in these lines was 80 mg/L. Accruing pHBA can be toxic to the cells and the mechanism by which C. reinhardtii could detoxify pHBA is not known. C. reinhardtii genome was thus scanned for sequences similar to UDP-glucosyltransferase (UGT) that can transfer the glucose moiety to pHBA, rendering it non-toxic to the cell lines. Our analysis suggested the absence of any potential UGTs that could glycosylate pHBA and detoxify it. We further performed feeding experiments to test the ability of wt-type C. reinhardtii cells to detoxify pHBA and understand its fate. C. reinhardtii cells were fed with varying concentrations of pHBA and harvested at different time intervals. The HPLC chromatograms indicated a majority of the pHBA was catabolized. Based on these results, …

Considering the high reproductive investment of the social male and the cost to the female of losing this benefit by soliciting copulations outside the social pair bond, it is expected that most raptor populations would exhibit low to no occurrence of extra-pair paternity (EPP). This holds true for the majority of raptor species studied to date with only one exception of an urban Cooper's hawk (Accipiter cooperii) study which reported an unexpectedly high extra-pair young frequency of 19.29%. In our study we examined the frequency of EPP within a red-shouldered hawk (Buteo lineatus) population residing in the suburban/urban matrix of southwest Ohio. During the breeding seasons of 2018 and 2019, 181 breeding age and nestling individuals were color-banded and sampled for genetic analysis using nine microsatellite loci. After genotyping a total of 40 broods (with at least two nestlings per brood) and both presumptive parents of each brood, no clear evidence of EPP was detected. However, at one nest site, the entire brood of four chicks was not sired by the adult male observed during the courtship period, nor another adult male observed tending the chicks later in the season. We suspect that this particular nest represented two instances of …

In the lower Rio Grande Valley of south Texas, more than half the nesting groups of Harris's hawks (Parabuteo unicinctus) include at least one auxiliary group member in addition to a breeding pair. To provide further insight into cooperatively breeding raptors, I evaluated sociality in Harris's hawks through the dual benefits framework. I explored the formation, structure, and stability of cooperative group formation across a spatially variable study area, which includes high levels of urbanization and development as well as remote, undisturbed native habitats with low anthropogenic impact. I used color banding, regular censuses of active territories, and a microsatellite relatedness analysis to examine patterns of sociality, including delayed dispersal, the effect of auxiliary group members on reproductive output, parentage of broods, and the relatedness of auxiliaries compared to the nestlings in their territories. I confirmed cooperative polygamy with genetic techniques for the first time in Harris's hawks and found 58% of juvenile hawks delayed dispersal for at least 6 mo. Using the dual benefits framework, I found social associations that formed through delayed dispersal followed predictions for resource-defense benefits, but sociality among mature non-related hawks more closely followed predictions associated with collective action benefits, specifically reproductive output was significantly …

While female mimicry and lower status signaling hypotheses of delayed plumage maturation have received much discussion in the literature, the experimental tests of these hypotheses have been infrequent. Those experimental tests often use a simulated intruder method with artificial model intruders rather than using live conspecific birds as intruders. Subadult male painted buntings (Passerina ciris) possess delayed plumage maturation where they appear visually identical to adult females during their first potential breeding season, while adult males are strikingly different in plumage coloration. Here I test the behavioral responses in a territorial population of painted buntings that exhibits extreme delayed plumage maturation using a simulated territorial intrusion experiment to measure territorial male behavioral response when presented with live caged intruders of both subadult and adult males. Territorial adult males were significantly more likely to initiate an attack and continue to attack caged adult male intruders than compared to caged subadult male intruders. This result supports both the female mimicry and status signaling hypotheses, and does not support the cryptic hypothesis. Additionally, in anecdotal observations, territorial males occasionally performed mating display behaviors to caged subadult male intruders. These results further suggest that territorial male painted buntings may identify subadult males as potential …

The American Kestrel (Falco sparverius) is the smallest and most abundant falcon in North America with a wide geographic range. Unfortunately, surveys have suggested that some kestrel populations have been in decline since the 1950s, though the nominal causes of this decline are unknown. Migratory movement patterns and connectivity have yet to be established for any population of migratory kestrels. In Chapter 2, I investigated methods for attaching migration trackers to kestrels. Specifically, I showed that leg-loop style harnesses may have negatively affected return rates whereas backpack harnesses did not. Based on these results, I recommend that backpack-style Teflon harnesses is the safest and most effective method for attaching tracking devices to small raptors. In Chapter 3, I quantified survivorship for kestrels wintering in north Texas to identify the timing of kestrel mortality. Notably, I found that juvenile kestrels had similar annual survival rates as adults (81.6% versus 79.5%). High overwintering survival in north Texas indicated that once kestrels arrived on their wintering grounds, they were highly likely to survive to spring migration. In Chapter 4, I investigated pairing behaviors previously undocumented in wintering kestrels. I found that winter pairing was relatively common, but more prevalent in urban environments than …