Nesting success is an important vital rate affecting the reproductive fitness of birds, and predation typically is the single most important factor affecting nesting success. Presumably, birds should nest in locations that maximize nest survival. If specific nest characteristics increase the probability that a nest will hatch, natural (phenotypic) selection could favour use of sites with these features, producing nonrandom patterns of nest site use. Alternatively, birds that are highly selective in nest site choices might be at a disadvantage if predators learn to forage preferentially in these locations and improve their efficiency in depredating nests; in this case, random nesting patterns could be favoured. Finally, it has been hypothesized that predation pressure can influence nest site selection patterns of entire bird communities. If predators develop a search image to hunt for bird nests, then nests that are most similar to each other, irrespective of species, should sustain higher mortality. To evaluate these hypotheses, I quantified nest site selection patterns of multiple species of ground-nesting dabbling ducks in areas where predation pressure was normally high, and compared these patterns to those on areas where predation was relaxed. Predation pressure was experimentally reduced by removing common predators of duck nests and females (mainly red foxes, coyotes, skunks and raccoons) on some study areas and not on others (controls). Predator removal and natural causes produced a 10-fold difference in duck nesting across study sites, allowing for investigation of effects of predation pressure on nest site selection of ducks. Coarse scale habitat selection patterns were similar to results reported in previous studies; blue-winged teal and northern shoveler were found more often in native grassland than in other habitat types, while gadwall and mallard nests occurred more frequently in shrub patches when compared with other habitat patches. A difference in nest site characteristics was observed between hatched and depredated nests for gadwall and northern shoveler but not for blue-winged teal and mallard. However, in all species, the nest site selection patterns were non-random. Thus, the process of nest predation did not shape patterns of nest site choice. Contrary to predictions, inter-specific overlap in nest site features was not related to predation pressure: nests that overlapped most with features of other species did not suffer higher predation, nor did inter-specific overlap in nest characteristics decrease during the nesting season. These findings were inconsistent with the hypothesis that community-level patterns of nest site use are differentiated as a result of predation pressure. Long-term work on nest site use by individually marked females of numerous ground-nesting bird species would be informative, as would experimental studies of other hypotheses about factors affecting nest site choices in birds.

Nesting success is an important vital rate affecting the reproductive fitness of birds, and predation typically is the single most important factor affecting nesting success. Presumably, birds should nest in locations that maximize nest survival. If specific nest characteristics increase the probability that a nest will hatch, natural (phenotypic) selection could favour use of sites with these features, producing nonrandom patterns of nest site use. Alternatively, birds that are highly selective in nest site choices might be at a disadvantage if predators learn to forage preferentially in these locations and improve their efficiency in depredating nests; in this case, random nesting patterns could be favoured. Finally, it has been hypothesized that predation pressure can influence nest site selection patterns of entire bird communities. If predators develop a search image to hunt for bird nests, then nests that are most similar to each other, irrespective of species, should sustain higher mortality. To evaluate these hypotheses, I quantified nest site selection patterns of multiple species of ground-nesting dabbling ducks in areas where predation pressure was normally high, and compared these patterns to those on areas where predation was relaxed. Predation pressure was experimentally reduced by removing common predators of duck nests and females (mainly red foxes, coyotes, skunks and raccoons) on some study areas and not on others (controls). Predator removal and natural causes produced a 10-fold difference in duck nesting across study sites, allowing for investigation of effects of predation pressure on nest site selection of ducks. Coarse scale habitat selection patterns were similar to results reported in previous studies; blue-winged teal and northern shoveler were found more often in native grassland than in other habitat types, while gadwall and mallard nests occurred more frequently in shrub patches when compared with other habitat patches. A difference in nest site characteristics was observed between hatched and depredated nests for gadwall and northern shoveler but not for blue-winged teal and mallard. However, in all species, the nest site selection patterns were non-random. Thus, the process of nest predation did not shape patterns of nest site choice. Contrary to predictions, inter-specific overlap in nest site features was not related to predation pressure: nests that overlapped most with features of other species did not suffer higher predation, nor did inter-specific overlap in nest characteristics decrease during the nesting season. These findings were inconsistent with the hypothesis that community-level patterns of nest site use are differentiated as a result of predation pressure. Long-term work on nest site use by individually marked females of numerous ground-nesting bird species would be informative, as would experimental studies of other hypotheses about factors affecting nest site choices in birds.

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.

Texas A&M University (TAMU) supports a substantial breeding population of mourning doves (Zenaida macroura) with one of the highest nest densities in Texas. There has been a long history of mourning dove research on the TAMU Campus, with initial population studies conducted in the 1950’s, and the most recent studies occurring in the 1980’s. The TAMU Campus and surrounding areas have experienced substantial changes associated with urbanization and expansion over the last 50 years, altering mourning dove habitat on and around campus. The objective of this study was to examine mourning dove nesting and production in an urban setting and determine how microhabitat and landscape features affect nest-site selection and nest success. Specifically, I (1) examined trends in mourning dove nesting density and nest success on the TAMU Campus, and (2) identified important microhabitat and landscape features associated with nest-site selection and nesting success. Mourning dove nests were located by systematically searching potential nest sites on a weekly basis from the late-March through mid-September. Nests were monitored until they either failed or successfully fledged at least 1 young. A total of 778 nests was located and monitored on campus. All nest locations were entered into ArcView GIS. An equal number of nests were randomly generated in ArcView and assigned to non-nest trees to evaluate habitat variables associated with nest-site selection for mourning doves. Binary logistic regression was used to evaluate the significance of microhabitat and landscape variables to nest-site selection and nest success. Comparisons with data collected in 1950, 1978, and 1979 showed relatively similar nesting densities, but a significant decrease in nest success over time. A comparison of microhabitat features between actual nest trees and random locations (non-nest trees) indicated increasing values of tree diameter at breast height and tree species were important predictors of mourning dove nest-site selection. Landscape features found important in dove nest-site selection were proximity to open fields, roads, and buildings. Proximity to roads and buildings also were significant predictors of nest success. Combining significant microhabitat and landscape variables for nest-site selection increased the predictability of the model indicating a possible hierarchical nest-site selection strategy.

Mottled ducks (Anas fulvigula) are a non-migratory waterfowl species endemic to the western Gulf Coast, with a separate, genetically distinct subspecies (A. fulvigula fulvigula) occurring in peninsular Florida. Birds from Texas, Louisiana, and Florida were released in coastal South Carolina from 1975-1983, and banding data suggest an expanding population. I monitored 72 mottled duck nests and captured and radio-marked 196 pre-breeding and nesting females between 2010 and 2014 to study breeding ecology of these birds in the Ashepoo, Combahee, Edisto Rivers Basin. Nest success averaged 12% and varied with vegetation height and year. Indicated breeding pair surveys revealed breeding mottled ducks select managed wetland impoundments, predominately influenced by water depth. Future research should investigate ecology of nest predators of mottled ducks to devise successful habitat management strategies for breeding birds. Preliminary evidence suggests that managed wetland impoundments are important to breeding and brood rearing mottled ducks in coastal South Carolina.

The Northern Goshawk has been a species of concern since its decline in the early 1990s, which has been attributed in part to loss of critical breeding and wintering habitat. Nest site selection of goshawks has been correlated with certain specific site characteristics including, but not limited to, forest species composition, forest stand size, diameter of nest tree, percent cover, tree height, site slope, and aspect. The goshawk holds the status of a Management Indicator Species (MIS) on all of the six national forests in Utah. This status requires annual monitoring to track goshawk numbers and to address any activities on the forests that may affect nest site activity. Findings from the annual nesting data showed that some territories have been more active than others. We summarized the data from the three national forests in southern Utah in order to understand differences in nesting habitat among the forests. We also analyzed the nesting habitat variables slope, elevation, and nest tree species statistically to determine if they could be used as predictors of nest activity. We found that slope and elevation were not good predictors while nest tree species was significant in its ability to predict nest activity. We concluded the nesting habitat variables we selected were insufficient in their ability to predict nest activity and other variables such as prey species availability, weather conditions in the spring, and forest cover type might be needed to create a model that more accurately predicts nest activity.

Wild Turkey (Meleagris gallopavo) survival, habitat use, and nest-site characteristics were studied on Malmaison Wildlife Management Area, Mississippi, 2003-2004. Survival rates were 0.55, 0.0004, 0.26, and 0.30 for jakes, adult gobblers, juvenile hens, and adult hens, respectively for the entire study. Spring survival for all groups was 0.51 (95% CI 0.36, 0.65) and was least among seasons. Predation (65%) and harvest (21%) were major causes of mortality. Brood hens used bottomland hardwood stands, pine plantations, and old fields more than expected during the post-nesting period. Non-brood hens used bottomland hardwood stands more than expected during the pre- and post-nesting periods. Forbs were the predominant vegetation type at nests. Vegetation height was 0.3-0.6 m for all nest sites. Vertical screening cover for all nests was in the 21-40% obscurity category at 1 m and 41-60% category at 3 and 5 meters. Vine composition differed between successful (2%) and unsuccessful (20%) nests (P = 0.03).

No description available.

Master of Science / Division of Biology / David A. Haukos / The ring-necked pheasant (Phasianus colchicus) is a popular and economically important upland gamebird in Kansas. Population declines have stakeholders seeking methods to manage populations on agricultural lands. Cover crops planted during the breeding period may provide important resources pheasants require for survival and successful reproduction. I evaluated three cover crop mixes; a custom mix, commercial mix, a wildlife mix, and a chemical fallow control in three counties in western Kansas, during 2017 and 2018 to determine their potential as a management practice for increasing pheasant habitat. I tested the relative effects of spring cover crops on female pheasant survival, nest survival, nest-site selection, and mesocarnivore occupancy. Females pheasants (73) were captured via nightlighting during February – April and fitted with 15-g very-high-frequency radio collars and monitored by telemetry. I placed 58 camera traps on field edges and within cover crop treatments from April to September. Vegetation data were collected at nests and random points to assess nest-site selection and weekly random vegetation points were sampled within treatments. I used known fate and nest survival models in the package RMark interface in R to investigate adult and nest survival (R Core Team 2018). Adult breeding season survival was 0.57 (SE < 0.0001, CI = 0.5739 – 0.5740). Percent spring cover crop positively influenced adult survival (AICc wi = 0.450). Nest survival was 0.36 (SE < 0.001, CI = 0.3614 - 0.3614). Daily nest survival followed a pattern of high survival that gradually declined over the breeding season. Resource selection functions suggest female ring-necked pheasants selected vegetation between 5-7 dm at 50% VOR for nest sites (AICc wi = 0.97). Chi-square analyses suggest females selected Conservation Reserve Program (CRP) patches for nest sites more than expected during both years (2017 χ²₄ = 26.49, P < 0.001; 2018 χ²₄ = 9.80, P = 0.04). CRP supported 57% of nests and 56% of successful nests relative to other cover types. All three of the monitored nests in cover crops were depredated. Ring-necked pheasant occupancy was greatest on edges of treatments (ψ = 0.97, SE = 0.081) and influenced by proportion of the Chick Magnet seed mix (AICc wi = 0.68). Mesocarnivore occupancy was greatest on treatment edges with a constant occupancy of 0.99 (SE = 0.47, AICc wi = 0.66). Spring cover crops provide cover and foraging resources when the majority of agricultural practices are fallow. Spring cover crops do not provide sufficient vertical cover for nesting until after peak nesting occurs, especially during cooler than average winter and spring conditions such as 2018. However, there are tangible benefits of spring cover crops to other biological periods, such as adult female survival, and brood resources if placement of cover crops is targeted near quality nest habitat. My results indicates wheat is an ecological trap for nesting due to increased predation and destruction during harvest. Providing quality nest structure will reduce females nesting in wheat. Incorporation of spring cover crops is a beneficial wildlife management tool that can increase ring-necked pheasant habitat on the landscape.

Climate change is threatening biodiversity, causing populations and species to adapt, or otherwise, become extinct. Sea turtles have survived dramatic climate changes in the past, however, due to a history of intense human exploitation, and the current anthropogenic threats, their current resilience may be jeopardized. The main pursuits of this thesis were to i) evaluate the resistance of green turtles to predicted climate change impacts, using a globally significant rookery, in Poilão, Guinea-Bissau, as a case study; and ii) assess key population parameters to inform the conservation management of this resource. As the work developed I additionally had the opportunity to study the dynamics of an emerging disease in a juvenile foraging aggregation from Puerto Rico, which contributed to a broader understanding of resilience in this species. Specifically, I investigate the nest site selection behaviour of green turtles, their nesting environment, and the outcomes for their offspring, at Poilão, and apply this information to infer on the resilience of this population under future scenarios of climate change. I explore the connectivity established by the dispersal of post-hatchlings from Poilão, followed by their recruitment to foraging grounds, to set the geographical context of this major population. Lastly, I model the dynamics of Fibropapillomatosis, which affects juvenile green turtles globally, and examine the potential for disease recovery. The green turtle rookery in Poilão shows some resilience to expected climate change impacts. This significant population likely contributes to all juvenile foraging aggregations along the west coast of Africa, and to some extent to those in South America. Currently, green turtles are capable of recovery from Fibropapillomatosis, however, the incidence of disease may be enhanced by climate change.