The Australian Zebra Finch (Taeniopygia guttata) is an important animal model for vertebrate development and behavior. New research initiatives in the fields of epigenetics rely heavily on injecting hormones and environmental toxins directly into the eggs of different bird species such as zebra finches and other passerine songbirds to replicate the effects maternal condition on offspring. However, the widely used method of egg-injections does not accurately replicate physiological conditions, as the injected substances remain concentrated at the injection site for extended periods and do not diffuse into the developing tissues. Therefore, we propose an alternative method to injection protocols that takes advantage of the porous nature of eggs. Corticosterone (CORT), a major vertebrate stress hormone, dissolved in ethyl alcohol was applied to the surface of zebra finch eggs daily. The effect of this treatment on decreasing hatching success shows that topical hormonal treatments are a viable alternative to egg injection.

Nesting and early life is a period of high mortality for many turtle species, so understanding how turtles select nest sites, and how those nest sites impact hatching success, may be important for successful species conservation. In this research, my objective was to 1) understand how the environment around potential nest sites (canopy, understory, and soil) influences gopher tortoise nest-site selection at burrows and 2) how that nest environment both directly (nest microclimate: temperature and moisture) and indirectly (nest characteristics: nest depth, distance from burrow, canopy and understory cover, percent clay in soil, and lay date) affects hatching success in naturally incubated tortoise nests. In the summers of 2022 and 2023, I conducted repeated searches at burrows to locate nests at the Jones Center at Ichauway and the Greenwood Ecological Reserve in southwestern Georgia. I collected soil samples, measured canopy and ground cover at gopher tortoise nest locations (n=132) and an equal number of comparison non-nest burrows. At nest sites, I also monitored temperature and moisture throughout incubation. To evaluate nest-site selection, I compared burrows with and without nests using multiple logistic regression to create a suite of five biologically relevant candidate models and compared models with Akaike's Information Criterion adjusted for small sample sizes. The top three models identified canopy cover and understory vegetation cover as the only significant predictors of nest presence at burrows, with tortoises in the sites nesting at burrows with lower understory and canopy cover. Furthermore, there was an interaction between the understory vegetation and canopy cover effects, where the effect of understory cover decreased as canopy cover increased. This suggests that the vegetation effect may be primarily driven by an avoidance of shade, whereby nests laid in burrows with high canopy cover were so shaded that understory vegetation had a weaker influence on nest-site selection. When tortoises nested in burrows with lower canopy cover, which was far more common than high canopy cover at our sites, they also avoided understory vegetation so that nest sites were least shaded. These results suggest that maintaining habitats with very open overstories may be most important for allowing gopher tortoises access to preferred nest sites. To quantify the direct and indirect effects of nest environment on hatching success, I built a structural equation model (SEM) in a Bayesian framework in which hatching success was affected by nest temperature and moisture, which were themselves affected by nest site characteristics. I found that nest microclimate could be predicted moderately well from characteristics of the nest environment (R2=0.25-0.49), with lay date influencing both temperature and moisture, vegetation affecting temperature, nest position influencing moisture and temperature variability, and percent clay in soil influencing moisture. Hatching success was highest at lower mean temperatures and moistures and at intermediate levels of temperature and moisture variability, but the ability of this model to predict hatching success was low (R2=0.10). I observed very high hatching success (87.5%) and, thus, eggs were generally receiving the conditions they needed to successfully develop and there was not much variation in hatching success to explain. This framework may be useful for investigating environmental causes of lower hatching success at less robust tortoise populations that may be experiencing low rates of natural hatching success. / Master of Science / Many turtle species experience high rates of mortality in early life, so understanding how turtles select areas to nest, and how those places impact hatching success, may be important for successful species conservation. In this research, my objective was to 1) understand how the environment around potential nest locations (vegetation and soil) influences where gopher tortoise place nests at burrows and 2) how the conditions of that nest location both directly and indirectly affect hatching success in natural gopher tortoise (Gopherus polyphemus) nests. In the summers of 2022 and 2023, I conducted repeated searches at burrows to locate nests at the Jones Center at Ichauway and the Greenwood Ecological Reserve in southwestern Georgia. I collected soil samples, measured canopy and vegetative ground cover at gopher tortoise nest locations and an equal number of burrows without nests. At nest sites, I also monitored temperature and moisture throughout incubation. To evaluate how tortoises chose nest locations, I created models to compare tortoise burrows with nests to burrows that were available for nesting, but where no nest was placed. The top three models identified canopy cover and understory vegetation cover as the only significant predictors of nest presence at burrows, with tortoises in my sites nesting at burrows with lower understory and canopy cover. Furthermore, there was an interaction between the understory vegetation and canopy cover effects, where the effect of understory cover decreased as canopy cover increased. This suggests that the vegetation effect may be primarily driven by an avoidance of shade, whereby nests laid in burrows with high canopy cover were so shaded that understory vegetation had a weaker influence on nest-site selection. When tortoises nested in burrows with lower canopy cover, which was far more common than high canopy cover at my sites, they also avoided understory vegetation so that nest sites were least shaded. These results suggest that maintaining habitats with open overstories may be most important for allowing gopher tortoises access to preferred nest sites. To quantify the direct and indirect effects of nest environment on hatching success, I built a structural equation model (SEM) in which hatching success was predicted by nest temperature and moisture, which were themselves predicted by nest-site characteristics. This allowed me to evaluate both the direct effects of nest temperature and soil and the indirect pathways by which nest environment may be influencing hatching success. I found that nest temperature and moisture could be predicted moderately well from characteristics of the nest environment (R2=0.25-0.49), with the date the nest was laid influencing both temperature and moisture, vegetation around the nest affecting temperature, nest position influencing moisture and temperature variability, and percent clay in soil influencing moisture. Hatching success was highest at lower mean temperatures and moistures and at intermediate levels of temperature and moisture variability, but the ability of this model to predict hatching success was low (R2=0.10). I observed very high hatching success (87.5%) and, thus, eggs were generally receiving the conditions they needed to successfully develop and there was not much variation in hatching success to explain. This framework may be useful for investigating environmental causes of lower hatching success at less robust tortoise populations that may be experiencing low rates of natural hatching success.

<p>Tree sparrows (Passer montanus) have been studied in two areas in Sweden since 1997. At both sites, tree sparrow eggs had remarkably low hatching success. On average only 60% of the eggs hatched. Analyses have shown that this was caused by embryonic mortality, which was highly sex biased. About 70 % of the dead embryos were males, while about 65 % of all fledged nestlings were females. Impaired hatching success here related to two factors. Hatching success was lower for pairs with a male in poor body condition, and it was lower in areas with a high local population density. </p><p>A sex bias in the mortality early in life has been demonstrated in several species. Since the competitive ability of males is determined by conditions early in life, parents with poor provisioning capacity should prefer to produce female offspring in broods reared under poor conditions. The body condition of a tree sparrow during the nestling stage was well correlated to the condition as an adult, and pairs in which the male parent was in poor condition produced chicks in poor condition. Since the breeding success of a pair depended more on the condition of the male, females appear less affected by conditions early in life. Parents with poor provisioning capacity appear to bias offspring survival towards females, and a difference in the early susceptibility may be adaptive. </p><p>Changes in birth sex ratios have in some cases been suspected to result from exposure to estrogenic environmental pollutants. This was examined by exposing great- and blue tit embryos to a synthetic estrogen. Although there was a difference in the mortality rate, the difference was present also in the control groups, why this could not be attributed to estrogen exposure.</p>

Tree sparrows (Passer montanus) have been studied in two areas in Sweden since 1997. At both sites, tree sparrow eggs had remarkably low hatching success. On average only 60% of the eggs hatched. Analyses have shown that this was caused by embryonic mortality, which was highly sex biased. About 70 % of the dead embryos were males, while about 65 % of all fledged nestlings were females. Impaired hatching success here related to two factors. Hatching success was lower for pairs with a male in poor body condition, and it was lower in areas with a high local population density. A sex bias in the mortality early in life has been demonstrated in several species. Since the competitive ability of males is determined by conditions early in life, parents with poor provisioning capacity should prefer to produce female offspring in broods reared under poor conditions. The body condition of a tree sparrow during the nestling stage was well correlated to the condition as an adult, and pairs in which the male parent was in poor condition produced chicks in poor condition. Since the breeding success of a pair depended more on the condition of the male, females appear less affected by conditions early in life. Parents with poor provisioning capacity appear to bias offspring survival towards females, and a difference in the early susceptibility may be adaptive. Changes in birth sex ratios have in some cases been suspected to result from exposure to estrogenic environmental pollutants. This was examined by exposing great- and blue tit embryos to a synthetic estrogen. Although there was a difference in the mortality rate, the difference was present also in the control groups, why this could not be attributed to estrogen exposure.

Three tern species, Roseate Tern (Sterna dougalli), Bridled Tern (Sterna anaethetus) and Crested Tern (Sterna bergii) co-bred at Baisha islet, east-north of Penghu, in the summer of 2006. Each species favored different kind of environment for nesting. All Crested Terns nested in the flat plane with vegetation; Roseate Terns in the cliff near the vegetation, and Bridled Tern primarily nested near the vertical rock or under a rocky roof. The Crested Tern had the highest nesting density, and Bridled Tern nested loosely. The hatching success of Roseate (75%) and Crested Tern (73%) were significantly higher than that of Bridled Tern (30%). Roseate and Crested Tern laid eggs synchronously and had apparently two wave of egg laying and the breeding performances between early- and late-laying period were quite different. The relationship between hatching success and nest-site characteristics of the three species was investigated. The results revealed that hatching success of Roseate Tern increased with the number of walls and neighbors. Early-laying nests (79%) and central nests (72%) were more successful than late (11%) and edge nests (45%) of Roseate Terns. The laying-period was also important factors affecting hatching success of Crested Tern. Overall, the low hatching success of the late-laying nests may be due to the change of environmental conditions and the losing advantage of group breeding in the late season. The low hatching success of Bridled Tern was considered owing to the asynchronous laying pattern, loosely built nesting and weak parental behaviors.

At present, the Florida Burrowing Owl is being threatened by extensive habitat development throughout their small range in the state. Unfortunately, developers are able to collapse burrowing owl burrows during the non-breeding season and flush the owls from an area. In other areas such as Arizona and British Columbia translocation is being utilized to mitigate the effects of development on burrowing owls. In March 2006, the only translocation of burrowing owls in Florida was conducted by Mosaic Phosphate Company. The purpose of this thesis was to elucidate the effects of translocation on Florida burrowing owls. Topics of research include activity budgets, insect trapping, burrowing owl diet, prey availability, and hatching success for two populations of Florida burrowing owls in Hillsborough and Polk Counties, Florida. Results of this study indicate that translocation has little effect on Florida Burrowing Owl activity budgets. There were significant differences in scanning, time spent in the burrow, and resting between the control and treatment groups (p < 0.05). Though differences in behavior were present between translocated and non-translocated study groups, there was no statistically significant difference (p < 0.025) between the pre-and post translocation study group. Results of the prey availability study indicate that while there are significantly different amounts of arthropods between study areas (p < 0.025), a threshold or satiation point may have been reached at these areas, as trapping results do not match diet results. This satiation point may have been due to cattle dung present at the burrowing owl's breeding areas, which provides a micro-habitat for many prey items. While hatching success was lower for the post translocation group compared to the pre-translocation group, hatching success also was decreased for the control group.This overall decrease indicates that translocation was not the main factor affecting the hatching success of our study groups.

Hurricanes can cause considerable damage along the coastlines of the United States. There are very little data relating hurricanes and sea turtle nesting. Hurricane season (June- November) and sea turtle nesting season, for the study period, (March- September) overlap in Broward County, Florida. This paper examines the relationship between the Hurricane Impact Index (HII) and hatching success of loggerhead sea turtles (Caretta caretta) and HII and washout rate. For ten of the eleven storms studied, there was no significant relationship between HII and hatching success (percent). Tropical Storm Ophelia (2005) showed a significantly higher (p=0.0206) hatching success after the storm’s passing than before the storm’s passing. There was a significant relationship between washout rate and HII (p=0.026).

Habitat loss is among the biggest threats to conservation worldwide, so habitat restoration plays an increasing role in endangered species management. This is especially true for species with high site fidelity, such as nesting marine turtles. Sand replenishment is commonly used to restore coastal beaches after severe erosion events, and may affect marine turtles and other species that live or reproduce in that habitat. I investigated how abiotic characteristics of sand used in a dune restoration project at Archie Carr National Wildlife Refuge, Florida, affected reproduction of the federally-endangered green turtle (Chelonia mydas). Sand structure and composition can affect egg development and hatching success by altering nest conditions, with nests in fine-grain or very coarse sand suffering decreased hatching success. I determined that calcium carbonate content (27.0% ± 1.4 SE vs. 15.1% ± 3.8 SE), moisture content (3.29% ± 0.26 SE vs. 4.59% ± 0.25 SE), and grain size (427.53 µm ± 14.1 SE vs. 274.66 µm ± 29.1 SE) differed significantly between natural and restored dunes. Hatching success of green turtles (44.7% ± 6.2 SE vs. 65.8% ± 5.3 SE) was significantly lower on restored dunes compared to natural dunes with an estimated loss of 22,646 hatched eggs. Hatching success also decreased as the nesting season progressed. These results demonstrate the importance of regulating fill material used in beach restoration projects; substrate characteristics are easily evaluated and can significantly influence marine turtle hatching success.

Captive husbandry programs in zoos have documented nesting behavior and have successfully hatched Manouria emys emys, but data on sex determining mechanisms and sex ratios are absent. A total of 30 M. e. emys eggs were artificially incubated at five different temperatures in constant humidity. Mean incubator temperatures were 24.99°C, 25.06°C, 27.18°C, 28.00°C, and 30.79°C. Incubation duration ranged from 60 days to 92 days, and hatching success was 50%. Sex determined by histology and laparoscopy resulted in male differentiation at low temperatures (24.99°C, 27.18°C) and female differentiation at high temperatures (30.79°C). Pivotal temperature was estimated to be 29.29°C. The following investigation into temperature-dependent sex determination (TSD), including its presence or absence, pattern, and pivotal temperature, has implications for studies of adaptive significance of reproductive behaviors and of chelonian phylogenetic history. Additionally, the proposed study can provide foundations for conservation management decisions, and for captive breeding programs.

The survival rates of pre-emergent sea turtle hatchlings are critically dependent upon temperature. This study aimed to determine if changes in air temperature can explain some of the variability in hatching success observed over a 12 year period for loggerhead sea turtle (Caretta caretta) nests in Broward County. Air temperature data for the hatching seasons of 1999 to 2010 were obtained from the NOAA National Climatic Data Center’s Fort Lauderdale beach station. The loggerhead sea turtle hatching data collected by the Broward County Sea Turtle Conservation Program from the same time period was examined to assess the potential effects of air temperature on the hatching success and the incubation duration. Mean yearly incubation times were analyzed for trends and compared to mean nesting season temperatures. The relationships between the incubation durations and mean seasonal and intra-seasonal air temperature fluctuations as well as the relationship between hatching success and air temperature was tested for significance. The hatching success was also compared to the incubation times in order to establish if shorter incubation durations, were related to lower hatching success rates. There have been large fluctuations in the average daily hatching success rates ranging from 10 to 100% over the twelve years examined in this study in Broward County. Significant decreases in incubation durations were apparent during times of increasing average air temperatures. In five of the twelve seasons there was also a significant relationship between the hatching success rates and the average air temperature, in which lower hatching success rates were evident during times of higher average air temperatures. There was a significant correlation between the incubation durations and the hatching success rates in six of the seasons as well, suggesting that lower hatching success rates are related to shorter incubation times. The pattern in average yearly hatching success rates were significantly related to the average monthly air temperatures in July suggesting that lower hatching success rates during the month of July were a result of higher temperatures during this time of the hatching season. A better understanding of the effects that air temperature has on loggerhead sea turtle clutches in Broward County can provide future insights for the fluctuating survival rates of sea turtle clutches and if the changes are natural or the result of conservation efforts.