Redhead duck (Aythya americana) nesting and habitat change was studied in Knudson Marsh, Utah, in 1974 and 1975, and compared with earlier studies from 1950 and 1955 on the same marsh. Water condibons in 1975 were found to be similar to those in 1950, both years of favorable habitat, yet there was a decline in numbers of redheads from 500 pair s in 1950 to 50 pairs in 1975. The number of nests found also declined from 151 in 1950 to 49 in 1975. Water conditions were poor in 1955 and slightly more favorable in 1974, but there was a decline from 95 pairs and 49 nests in 1955 to 50 pairs and 23 nests in 1974. Success of active nests was greater in the present study than in 1950, but hatching success in successful nests was greater in 1950. No appreciable change in the vegetational composition of the marsh was detected between 1950 and the present study.

Coloniality and nest defence were examined in black brant <i>Branta bernicla nigricans</i> and lesser snow geese Chen caerulescens caerulescens. Increased nest density had no effect on nest survival, egg survival, or likelihood of partial clutch predation in snow geese. In brant, nest survival declined as nest density increased in 1992 and with increased distance from shore in 1993. Brant with conspecific nearest neighbours were less likely to suffer partial clutch predation in 1993, but not in 1992. Egg survival in brant increased with nest density in 1993, but decreased as density increased in 1992, however, the decrease occurred only in nests with three or four eggs. Nesting at high densities, in central positions, or far from shorelines commonly travelled by glaucous gulls <i>Larurs hyperboreus</i> and parasitic jaegers <i>Stercorarius parasiticus</i>, the primary egg predators in this study, did not provide geese with a nest or egg survival advantage because effects were lacking in snow geese and were inconsistent and contradictory in brant. Female snow geese had very high nest attendance and both sexes had high territory attendance so snow goose nests were rarely unattended during incubation. Brant had lower nest attendance than snow geese, and due to a lack food near their nests, brant left their territories to feed resulting in lower territory attendance as well. Although male brant were capable of defending the nest from avian predators and usually remained on their territories when females were absent, males were less effective defenders than incubating females. Increased vigilance and decreased resting by female brant as incubation progressed provided support for the prediction, from parental investment theory, that nest guarding effort would increase with offspring age, but there were no changes in male brant or in snow geese. However, declining nest and territory attendance by female brant and males of both species contradicted predictions from parental investment theory but were consistent with an increased need to forage as nutrient reserves declined through incubation as expected due to energetic constraints.

Northern bobwhite (Colinus virginianus) populations are irruptive along their western periphery. Previous research has failed to identify the factors associated with these irruptions, but precipitation is often assumed to be a primary causal factor. I hypothesize that the mechanism may involve demographic variables, specifically that birds entering their second breeding season are more successful than subadult breeders. A better understanding of age-specific survival and productivity in quail populations may be beneficial if managing for a population with an older age structure could ameliorate the irruptive cycles. Radiotagged bobwhites (n > 100 each year; approximately equal numbers (25) of each age-sex class) were followed throughout the breeding season (Mar. – Aug.) in 2003 and 2004 in Fisher County, Texas. Survival, nesting attempts, hatch rate, and clutch size were monitored. Probability of survival of radiotagged birds during the breeding season was S = 0.465 and S = 0.395 in 2003 and 2004, respectively; survival was similar among all age-sex classes. Nest success was greater in 2004 (52.4%, n = 42) than 2003 (28.6%, n = 35) and the 2004 breeding season was at least 20 days longer, likely due to more summer rainfall and cooler temperatures. Nest success was similar among adult and subadult hens in 2003 (4 of 21 adult nests, 6 of 14 subadult nests) and 2004 (16 of 28 adult nests, 7 of 14 subadult nests). Nest initiation was similar in 2003 (0.84 nests/adult hen vs. 0.61 nests/subadult hen), but adults initiated more nests than subadults in 2004 (1.04 nests/adult hen vs. 0.58 nests/subadult hen). Adult hens initiated 12 of 15 renesting attempts observed. Nest initiation dates and nest site selection were similar between adults and subadults. The adult:subadult ratios for 2003 and 2004 were 1:3.0 and 1:1.3 (n = 426 and n = 224, respectively). Extrapolating from the sample population, subadults contributed approximately 84% of the chicks fledged in 2003 but only 37% in 2004, while adults contributed 16% and 63% in 2003 and 2004, respectively. Results from this study suggest that if covey demographics are a component of bobwhite irruptions, the mechanism is most likely due to greater renesting effort by adult hens.

North American grasslands and grassland birds have declined drastically due to habitat degradation by fire suppression (i.e., woody encroachment), fragmentation, and conversion to croplands. A better understanding is needed of the relationships among disturbance regimes (e.g., fire), resultant vegetation changes, and grassland bird communities to effectively manage remaining grasslands and grassland birds. I assessed the relationship between post-fire succession, and mean relative abundance and nesting ecology of breeding grassland birds (i.e., nest-site selection and nest success) in mesquite-dominated rangeland of the Texas Rolling Plains, where prescribed fire is used as a tool to manage shrub encroachment. Brush cover, grass cover, and visual obstruction generally increased with post-fire succession, and bare ground decreased with post-fire succession. Species richness, grasshopper sparrows (Ammodramus savannarum), Cassin’s sparrows (Aimophila cassinii), and dickcissels (Spiza americana) responded positively to post-fire succession, and lark sparrows (Chondestes grammacus) responded negatively to post-fire succession.; abundance of these avian groups was low on the control sites. During 2004–2005, 90 grassland bird nests were monitored. I found conflicting results for vegetation parameters important to nest site selection and probability of nest success. For all species except lark sparrows, nest-site location was positively associated with visual obstruction and with grass or forb cover. However, the probability of nest success increased with lower visual obstruction, bare ground cover, or grass cover. Grassland bird abundance, nest-site location, and nest success had differing associations with vegetation variables. These results suggest that to effectively manage remaining grasslands for sustainable breeding grassland bird populations, managers should engage in practices that keep habitat in multiple vegetative successional stages.

Studies of nesting behaviours of free-ranging apes typically focus on ecological variables such as preferred tree species and areas within the home range, heights of nests, and nest group sizes. However, nesting in captive apes is rarely studied, despite the ubiquity of this sleep-related behaviour. The paucity of field data is often attributed to the inherent difficulty in observing what is essentially a nighttime behaviour. Captive settings can provide researchers with an ideal opportunity to record nesting and sleep-related behaviours, yet such research on captive apes is also scant. Topics addressed include current practices in zoos regarding conditions for sleep in great apes, the potential effects of social and environmental factors on sleep site selection, the motor patterns involved in nest construction, preferred nesting structures and substrates, and nocturnal behaviours. This thesis documented and empirically tested hypotheses concerning nest-related activities in captive chimpanzees, with an aim to generate practical recommendations for enclosure design, sleeping areas, sleeping structures, and nesting substrates that have implications for the welfare of captive apes. As with the few reports that already exist, most chimpanzees in this research frequently constructed night nests. When building a nest, some techniques appeared to be universal across individuals and groups, where others were group-specific or occasionally characteristic of only certain individuals. An experiment showed that specific materials are preferred over others for nest building. Many chimpanzees appeared to express persistent preferences for particular sleeping sites, and for some this was to maintain proximity to kin or other closely bonded individuals. In one group, individual sleeping site preferences changed across seasons, although again this was subject to individual differences. Video analyses of nighttime behaviours demonstrated that, although nests/sleep sites are primarily used for rest subsequent to retirement, a number of social and non-social activities were performed throughout the night. In conjunction with analysis of postural and orientation shifts, these data are unique in describing the nocturnal behaviours of chimpanzees out with a laboratory setting. Several aspects of nest-related behaviours showed a high degree of inter-and intra-group variation. Although this cautions against generalising findings across captive populations, research of this type has applied implications for the management of captive ape species, and can add to our as-yet meagre understanding of their nest and sleep-related behaviours.

This study was designed to investigate the impact of multiple-membership data structures in multilevel modeling. Multiple-membership arises when lower level units (e.g., students) are nested within more than one higher level unit (e.g., schools). In this case, more than one school will contribute to students' academic achievement and progress. In reality, it is inappropriate to assume a pure nesting of a student within a single school. While use of HLM requires either deletion of the cases involving multiple-membership or exclusion of prior schools attended, MMREM includes students who attend multiple schools and controls for the effect of all schools on student outcomes. The simulation study found level two variability underestimation and corresponding level one variability overestimation when multiple membership data structures were ignored. The study also revealed that when HLM failed to include multiple membership data structures, it underestimated school level predictor. With an increased numbers of mobile students under the No Child Left Behind (NCLB) Act, researchers need to understand MMREM and correctly apply it to multiple membership data structures. This MMREM approach will help improve the generalizability of findings and will improve the validity of the statistical results. / text

A drive into the country will soon confirm the effects of agriculture on the environment. Different agricultural practices such as vast fields of monocultures, forests of exotic timber, and large intensive feed lots of livestock, will be evident. The need to provide food for an increasing population particularly in Africa is the driving force behind the intensification of agriculture. The production of increased food supply is often considered without knowledge of the impacts on the environment. The North East District of Botswana is a small district compared to other districts of Botswana but unlike these large districts the population density is comparably high with a demand for agricultural space. Botswana is a desert margins area under threat of desertification with many signs of desertification being evident throughout the country. The main agricultural activity in the North East District is livestock farming with horticulture being practiced on the banks of sandy river beds. The district provided an ideal area to compare the impacts of different livestock farming techniques. Four different approaches of livestock farming were examined with the number of livestock cattle in particular, being a noticeable difference and the grazing intensity of these cattle being another important difference. This study examined the impacts of these different grazing techniques on the environment with a particular reference to birds. Data was collected using a point count system with 28 points evenly spaced in a grid across the different land uses. Each point was subject to a total of six surveys with summer and winter having three surveys each. It was expected that bird numbers and species would be impacted by the grazing intensity while the different feeding and nesting guilds may also respond to grazing intensity. Statistical analysis included geostatistical analysis, uni-variant, mult-variant and non-metric multi-dimensional scaling. The results show that birds were impacted by grazing intensity with species richness and bird numbers being negatively affected. However, feeding and nesting guilds were impacted differently. Climate change and land degradation are a reality and will impact on avian diversity and sound management practices need to be implemented to protect biodiversity in marginal areas. / Thesis (Master of Environmental Sciences)--North-West University, Potchefstroom Campus, 2013

A drive into the country will soon confirm the effects of agriculture on the environment. Different agricultural practices such as vast fields of monocultures, forests of exotic timber, and large intensive feed lots of livestock, will be evident. The need to provide food for an increasing population particularly in Africa is the driving force behind the intensification of agriculture. The production of increased food supply is often considered without knowledge of the impacts on the environment. The North East District of Botswana is a small district compared to other districts of Botswana but unlike these large districts the population density is comparably high with a demand for agricultural space. Botswana is a desert margins area under threat of desertification with many signs of desertification being evident throughout the country. The main agricultural activity in the North East District is livestock farming with horticulture being practiced on the banks of sandy river beds. The district provided an ideal area to compare the impacts of different livestock farming techniques. Four different approaches of livestock farming were examined with the number of livestock cattle in particular, being a noticeable difference and the grazing intensity of these cattle being another important difference. This study examined the impacts of these different grazing techniques on the environment with a particular reference to birds. Data was collected using a point count system with 28 points evenly spaced in a grid across the different land uses. Each point was subject to a total of six surveys with summer and winter having three surveys each. It was expected that bird numbers and species would be impacted by the grazing intensity while the different feeding and nesting guilds may also respond to grazing intensity. Statistical analysis included geostatistical analysis, uni-variant, mult-variant and non-metric multi-dimensional scaling. The results show that birds were impacted by grazing intensity with species richness and bird numbers being negatively affected. However, feeding and nesting guilds were impacted differently. Climate change and land degradation are a reality and will impact on avian diversity and sound management practices need to be implemented to protect biodiversity in marginal areas. / Thesis (Master of Environmental Sciences)--North-West University, Potchefstroom Campus, 2013

Redhead duck (Aythya americana) nesting and habitat change was studied in Knudson Marsh, Utah, in 1974 and 1975, and compared with earlier studies from 1950 and 1955 on the same marsh. Water conditions in 1975 were found to be similar to those in 1950, both years of favorable habitat, yet there was a decline in numbers of redheads from 500 pairs in 1950 to 50 pairs in 1975. The number of nests found also declined from 151 in 1950 to 49 in 1975. Water conditions were poor in 1955 and slightly more favorable in 1974, but there was a decline from 95 pairs and 49 nests in 1955 to 50 pairs and 23 nests in 1974. Success of active nests was greater in the present study than in 1950, but hatching success in successful nests was greater in 1950. No appreciable change in the vegetational composition of the marsh was detected between 1950 and the present study.

Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains vii, 59 p. : ill. (some col.), maps. Vita. Includes abstract. Includes bibliographical references (p. 23-28).