Rio Grande wild turkey (Meleagris gallopavo intermedia) numbers in the southeastern region of the Edwards Plateau (EP) have shown a significant decline since the 1970s; however, the remainder of the EP had stable populations during this period. Since 2001, research has been conducted in the southeastern EP evaluating factors which could be responsible for the decline of Rio Grande turkeys in this region of Texas. I used digital cameras to evaluate the effect of nest predation on the reproductive success of Rio Grande wild turkeys in the region. Nest predation was the leading cause of nest loss in my study and I documented frequent predation events involving ≥1 predator species. While studying nest predation, I examined the effects of my methods, and those commonly used by others, on nest success. Nests with cameras failed at the same frequency as those without cameras but at a faster rate. Predation rates observed for artificial nests underestimated predation rates of real nests. Additionally, I photographed known turkey nest predators at 27% of random points with no eggs, suggesting that nest predation could be a random process depending on the nest predator’s unique search image. I also examined the spatial structure of the habitat surrounding nest locations of turkeys on my study sites to evaluate the effect of disturbance on nest-site selection. Out of 59 nests located on the Kerr Wildlife Management Area from 2005 through 2007, only 5 were in areas that had not been burned in the 9 years prior. Turkeys in my study consistently chose areas characteristic of the fire maintained, oak–juniper savanna historically found in the region.

Abstract Globally, populations of several wader species are in decline. However, for most populations, information on abundance, its changes and the causes of declines is insufficient for designing successful management strategies to recover threatened populations. In this thesis I studied the status and population trends, nesting success, genetic structure and viability of a small, declining and threatened Temminck's stint population in the Bothnian Bay in the northern Baltic Sea. Historical population data, recent population counts in the early 1990s and in 1999–2002 and the demographic data showed that the decline is continuing, paralleled by declines in nesting success, recruitment and adult survival. Decline in nesting success was caused by a coincident increase in nest predation. Depredation was the main cause of nest losses. The common gull (Larus canus) and the ruddy turnstone (Arenaria interpres) were found to be the most important nest predators. I tested if an increase in nest concealment and consequent decrease in visibility lowers the efficiency of the early-departure antipredator behaviour of the species. An expected positive correlation emerged between visibility and flushing distance in the presence of alarm-giving birds, but not without them. This indicates that Temminck's stint exploits signals from other birds as early warning of an approaching predator. More nests were lost to predation on narrow than on wide shores. The nest predation rate was not related to habitat (natural vs. man-made) nor to differences in microhabitat characteristics associated with concealment. Overall variability of the mitochondrial control region was low in the one northeast Siberian and the three Fennoscandian populations studied. The occurrence of two maternal lineages in all Fennoscandian populations points to mixing of two previously isolated populations. The overall microsatellite genetic structuring (6 loci) in Fennoscandia was low. The pairwise comparison revealed a low but significant degree of differentiation between the Bothnian Bay and the two other Fennoscandian populations. However, no clear indication of genetic effects of small population size in the Bothnian Bay was detected. Matrix and Pradel-λ projection models, based on a ten year (1994–2003) capture-recapture data set, predicted a steep future decrease and a high risk of extinction within 50 years. Without immigration the decline would lead to extinction within 20 years. Population growth was the most sensitive to changes in adult survival, the rate of which declined during the study. Factors affecting adult survival most likely operate primarily during the non-breeding season in locations specific to the study population that are virtually unknown. Management efforts in the Bothnian Bay should, in addition to improving hatching success, first of all guarantee availability of wide, low-sward coastal breeding habitats for potential immigrants and recruits.

Predation is an important ecological process that shapes life-history traits, community dynamics, and species coexistence and therefore has been suggested to explain many patterns in avian ecology. Although many studies have reported spatial, temporal, or interspecific patterns in nest predation, relatively few studies have been designed to identify the specific mechanism(s) that underlie these patterns. I examined mechanisms underlying the risk of nest predation in birds by (1) reviewing nine of the most commonly cited hypotheses to explain spatial, temporal, and interspecific variation in the risk of nest predation, (2) conducting a comparative analysis of the nest-concealment hypothesis to examine which methodological issues, extrinsic factors, and species traits influence whether or not foliage density affects the risk of nest predation, and (3) testing six mechanistic hypotheses to determine the underlying cause(s) of intra-seasonal decreases in the risk of nest predation.Many of the hypotheses invoked to explain spatial, temporal, and interspecific variation in the risk of nest predation lack clearly defined mechanisms. I suggest that future studies explicitly define the mechanism and assumption(s) of each hypothesis prior to implementing empirical tests.I found that the discrepancy in results among past studies that have examined the nest-concealment hypothesis was due to interspecific differences in a variety of intrinsic and extrinsic factors that affect nest predation but have previously been ignored. The effects of nest concealment on nest placement and probability of nest predation vary among species and this variation is predictable based on the bird's morphological traits and characteristics of the ecosystem.Increased risk of nest predation early in the breeding season appears to be due, in part, to foliage phenology and spatial and temporal changes in predator behavior. The risk of nest predation was negatively associated with foliage density early, but not late, in the breeding season. Supplemental food provided to nest predators resulted in a numerical response by nest predators, increasing the risk of nest predation at nests located near feeders. I show that intra-seasonal changes in environmental features and predator behavior affect patterns of nest predation, which can influence timing of breeding.

Magister Scientiae (Biodiversity and Conservation Biology) - MSc (Biodiv and Cons Biol) / It is widely reported that snakes can be major predators of avian nests, but the use of a single avian prey type by competing species has rarely been examined. This study aimed to investigate predation of a single food resource by the sympatric snakes Naja nivea and Dispholidus typus. Specifically, I aimed to 1) identify factors influencing snake presence in sociable weaver colonies and 2) quantify snake predation and potential differences in the consumption of prey by the two competing snakes. I used repeated visual surveys of sociable weavers to obtain presence-absence data of cape cobra and boomslang in sociable weaver colonies over an entire breeding season. I related the presence-absence data of the two snake species to spatially- and temporally-variable factors using principal component analyses (PCA) and multiple logistic regression analyses. The presence of snakes in sociable weaver colonies is primarily influenced by temporal factors, but spatial factors also play a role.

No description available.

Across the globe, wildlife populations are facing increasing challenges, with many taxonomic groups significantly declining. Among endangered vertebrates (including birds, non-avian reptiles, fishes, mammals, and amphibians), turtles are one of the most threatened groups with over 60% of the 356 recognized species classified as threatened or worse. Bog turtles (Glyptemys muhlenbergii), are among the most imperiled of North American freshwater turtles. These small, secretive turtles have declined by up to 90% in parts of their range, which consists of the Northern Population and the Southern Population, and spans the eastern U.S. from New York to Georgia. These declines are mainly documented in the northern part of their range, but recent work in North Carolina suggests that turtles in the southern part of their range are similarly declining. Prior to this research, surveys aimed at estimating abundance had not been conducted in Virginia since the late 1990's. The research described here was conducted as part of a state-wide population assessment of bog turtles in Virginia. For my first chapter, I conducted capture-mark-recapture surveys in six wetlands in Floyd County, Virginia during 2019 and 2020, and generated abundance estimates. These wetlands had been surveyed in the same manner in 1997, which provided me the opportunity to compare recent abundance estimates with those generated from the 1997 data. My analyses suggest that turtle abundance across these six sites has declined by approximately 50% since 1997. This decline appears to be driven by, but not wholly attributable to, the alteration and loss of habitat at 2-3 of the 6 sites. Habitat loss is acknowledged as one of the major drivers of population declines throughout the range of the bog turtle, in addition to illegal collection for the international pet trade. Due to the life history traits of this species (long life span and low fecundity), the loss of an individual from any life stage from the population can have detrimental effects. While many turtle populations are not heavily impacted from periods of low reproductive success, numerous subsequent years of complete nesting failure can negatively impact population-level survival. Recent studies have suggested that anthropogenically subsidized nest predators may be playing a role in continued nest failure at certain wetlands. My second chapter investigated the factors associated with anthropogenic footprint (i.e., buildings) and infrastructure that may be driving nest predation by these subsidized predators. In 2019 and 2020, I conducted a field experiment in 35 wetlands which utilized artificial turtle nests to investigate variation in nest predation across Montgomery and Floyd Counties, Virginia. I found that increases in the percent of developed land-use and other metrics of anthropogenic disturbance significantly increased nest predation, while increases in the percent of land-use without roads or buildings significantly decreased nest predation. The findings from these two chapters are consistent with population trends documented in other parts of the bog turtle range, and build upon prior studies to investigate drivers of nest predation. These results provide information that can be used by managers to aid in the conservation of this state endangered species, and suggest further courses of research for future projects. / Master of Science / Across the globe, wildlife populations are facing increasing challenges, with many taxonomic groups significantly declining. Turtles are one of the most threatened groups of vertebrates with over 60% of the 356 species of turtle classified as threatened or endangered. Bog turtles (Glyptemys muhlenbergii), are among the most imperiled of North American freshwater turtles. These small, secretive turtles have declined by up to 90% in parts of their range, which consists of the Northern Population and the Southern Population, and spans the eastern U.S. from New York to Georgia. Prior to this research, no information on population trends was available for Virginia. To address this knowledge gap, I conducted surveys for bog turtles in six wetlands in Floyd County, Virginia during 2019 and 2020, and used the data from those surveys to estimate how many turtles were present in the wetlands. These wetlands had been surveyed in the same manner in 1997, which provided me the opportunity to compare recent estimates with those generated from the 1997 data. My analyses suggest that the total number of bog turtles present across these six sites has declined by approximately 50% since 1997. This decline appears to be caused at least in part by the alteration and loss of habitat at 2 of the 6 sites. Habitat loss is thought to be one of the major drivers of population declines throughout the range of the bog turtle, in addition to illegal collection for the international pet trade. Recent studies have suggested an additional problem, that anthropogenically subsidized nest predators may be playing a role in continued nest failure at certain wetlands. Animals such as raccoons, skunks, and bears can persist in greater numbers around human habitation, as we provide extra food sources such as garbage, bird feeders, deer feeders, etc. I investigated the factors associated with human infrastructure that may be driving nest predation by these subsidized predators. In 2019 and 2020, I conducted a field experiment in 35 wetlands using artificial turtle nests to investigate variation in nest predation across Montgomery and Floyd Counties, Virginia. I found that nest predation was significantly higher in areas with a higher percent of developed land-use. The findings from these two studies are consistent with population trends documented in other parts of the bog turtle range, and build upon prior studies to investigate drivers of nest predation. These results provide information that can be used by managers to aid in the conservation of this endangered species, and suggest further courses of research for future projects.

This study is dealing with questions of environmental influences on predation risk in Northern Lapwings nests. I for example measured and evaluated nest krypsis and counting nest densities. I as well did marking of nests and dealed with question whether it has influence on nest predation. Another part of this resech was identifying of Lapwings nests predator.

Imported fire ants are invasive and cause injury to people, crops, livestock and wildlife. Disturbance may increase abundance and activity of fire ants. However, native grass field buffers established for grassland birds require periodic disturbance. I experimentally tested if fire ant mound density and foraging activity changed after burning and disking in native grass buffers and examined relationships among fire ants, vegetation, and grassland bird and butterfly metrics in undisturbed buffers. In 2008, disking increased mound density and foraging activity, but burning did not. In 2009, disking had no effect, but effects of disking the previous season persisted. Fire ant metrics were not related generally to bird or butterfly metrics. Mound density and foraging activity were related negatively to grass cover and related positively to forbs. Burning had less influence on abundance and activity of fire ants, and may better conserve grassland habitats in areas with fire ants.

Changes in abundance of interactive species can have cascading, community-wide effects (Soule et al. 2003). Raccoons (Procyon lotor) prey on a competitor for marine turtle eggs, the Atlantic ghost crab (Ocypode quadrata). Conservation of marine turtles often includes managing raccoons-the most obvious egg predator-which may have broader ecological effects, and unknown effects on egg predation. Neither the relationship between raccoons and ghost crab density nor the effects of ghost crab density on egg predation are well understood. I studied raccoon-ghost crab interactions and the effects of environmental variation on their activity during the 2007 marine turtle nesting season on Canaveral National Seashore, FL. My goal was to model predator activity and identify efficient management strategies to reduce egg predation. Raccoon activity increased with increasing habitat diversity and edge of the dominant cover type, coastal strand. Raccoon activity increased locally and became less variable near segments of beach accessed for human recreation, but activity was greater on undeveloped beach, where habitat diversity and edge were greater. Ghost crab density and size were primarily affected by sand characteristics and recreation but decreased with increasing raccoon activity in June, which may have contributed to sustained declines in ghost crab density. Hatching success of marine turtles decreased with increasing ghost crab egg predation, suggesting ghost crabs are an important cause of egg mortality and not merely scavengers on unhatched eggs. Egg predation by ghost crabs was unrelated to ghost crab density or size, likely a result of monitoring limitations, but raccoon activity increased with increasing egg predation by ghost crabs, supporting previous research and experimental evidence suggesting ghost crabs can facilitate secondary nest predation by raccoons. This indirect interaction has strong implications for marine turtle conservation, because its strength may increase with increasing ghost crab density, potentially negating the effects of raccoon removal.

No description available.