Assessment of aquatic plant selection by waterfowl has been conducted during the winters of 1997-2000 on 49 0.2-0.79 ha research ponds in north central Texas. Ponds were categorized by dominant plant species into eight habitat types. Census with waterfowl species identification were performed to investigate impacts of aquatic vegetation and water depth on waterfowl. Eighteen waterfowl species were observed. Peak migration occurred in late December/early January. Mixed native ponds and mixed native/hydrilla ponds were the most frequently selected habitat types. The study included correlation analysis between pond water levels and waterfowl use. Full ponds received greatest use followed by half full ponds, while almost empty ponds received minimal use. Time activity budgets were conducted on waterfowl utilizing mixed native and hydrilla ponds to compare waterfowl time partitioning on native aquatic vegetation versus hydrilla. Although only minor differences were found in time budgets, social status appears to be strongly related to habitat selection. Ducks on native ponds were paired (86%), conversely no ducks on hydrilla ponds were paired. Hydrilla pond although frequently utilized, were populated by lower status birds mostly single hens.

In the summer of 1932, an investigation of some biological, physical, and chemical conditions at the Bear River Migratory Waterfowl Refuge, Utah, was begun at the Utah State Agricultural College to determine some of the factors governing the biological productivity of brackish-water marshes. Unfortunately, lack of funds made it impossible to continue work beyond the first season.

Emerging influenza viruses continue to challenge public health. The problem is public health science professionals have been battling emerging human influenza diseases with tactile and reactionary methods because there is a lack of knowledge and data at the human-animal interface. This research was a baseline study of the proportion of influenza A virus (IAV) in urban and rural communities in California. The population was artificial recirculating water ponds in the geographic locations of rural and urban Californian communities. Surface water samples [N = 182] were collected from artificial recirculating ponds in California. Positivity for IAV was verified by real time RT-PCR, MDCK cells for virus infectivity, nucleotide sequencing of the RNA genome, and phylogenic analysis of IAV H5N1 strains. The proportion of IAV in rural and urban ponds favored the greater burden of IAV in urban ponds over rural ponds. The presence of waterfowl and IAV M gene sequence positivity were found not to be significantly related. The geochemical properties--pH, salinity, and water temperature at time of collection--were not predictors of IAV infectivity. This baseline research study validated these water ponds as resource sites for IAV surveillance and monitoring. The social change implications of this study can be recognized at the national and international levels, to the population level, and to the individual level by providing geospatial analysis and spatial-temporal data for IAV surveillance, initiating biosecurity measures to protect poultry industries in the United States and Brazil, and contributing to the current IAV strain library. Contributions to the IAV strain library may be used to develop vaccines against human pandemics.

The aim of this study is to improve our understanding of the ecology, spatiotemporal patterns, and risk of infectious pathogens of migratory waterfowl, using the blue-winged teal (Anas discors, BWTE), as a model. From 2007-2010, 1,869 BWTE were sampled in the prairie provinces (Alberta, Saskatchewan and Manitoba, Canada) to examine infection status and/or evidence of previous exposure to avian influenza virus (AIV), West Nile virus (WNV), and avian paramyxovirus-1 (APMV-1), in relation to host demographic variables (age, sex, body condition, exposure to other pathogens), other ecological variables such as local waterfowl breeding population density and local pond density, and year. The probability of AIV infection depended on an interaction between age and AIV antibody status. Hatch year birds with antibodies to AIV were more likely to be infected, suggesting an antibody response to an active infection. After hatch year birds with antibodies to AIV were less likely to be infected, suggesting immunity resulting from previous exposure. AIV infection was positively associated with local BWTE density, supporting the hypothesis of density dependent transmission. Exposure to WNV and APMV-1 were also associated with age and year. Furthermore, the probability of WNV exposure was positively associated with local pond density rather than host population density, likely because ponds provide suitable breeding habitat for mosquitoes, the primary vectors for transmission. We also investigated large-scale spatiotemporal trends in apparent prevalence of AIV across Canada and the United States throughout the year, using data from national avian influenza surveillance programs in Canada and the US in 2007-2010. Our analyses revealed that age, sex, year of sampling, flyway, latitude, and season (categorized by stages of the BWTE annual life cycle) were all important variables in predicting probability of AIV infection. There was an interaction between age and season. During late summer staging (August) and fall migration (September-October), hatch year birds were more likely to be infected than after hatch year birds, however there was no difference between age categories for the remainder of the year (winter, spring migration, and breeding season). Probability of infection increased non-linearly with latitude, and was highest in summer, corresponding to the beginning of fall migration when densities of birds and the proportion of susceptible hatch year birds in the population are highest. Birds in the Pacific, Central and Mississippi flyways were significantly more likely to be infected compared to those in the Atlantic flyway. Observed trends in seasonal, annual, and geographic patterns of AIV infection in BWTE across Canada and the US were primarily driven by the dynamics of AIV infection in hatch year birds. Our results demonstrate demographic as well as seasonal, latitudinal and flyway trends across Canada and the US. This research provided further evidence for the role of wild dabbling ducks, particularly BWTE, in the maintenance and ecology of AIV. This improved understanding of the role of BWTE as natural hosts, and the geographic, demographic and temporal variables that affect infection and transmission parameters, moves us closer to deciphering the overall ecology of the virus and its transmission and transportation pathways at the individual, population and continental levels. This knowledge, in turn, will permit development of better tools to predict and perhaps to prevent possible outbreaks in domestic animals as well as in humans.

Several factors have contributed to impeding the progress of migratory waterfowl spatial modeling, such as (1) waterfowl’s reliance on wetlands, (2) lack of understanding about shifts in distributions through time, and (3) large-scale seasonal migration. This doctoral dissertation provides an array of tools to address each of these concerns in order to better understand and conserve this group of species. The second chapter of this dissertation addresses issues of modeling species dependent on wetlands, a dynamic and often ephemeral habitat type. Correlation models of the relationships between climatic variables and species occurrence will not capture the full habitat constraints of waterfowl. This study introduces a novel data source that explicitly models the depth to water table, which is a simulated long-term measure of the point where climate and geological/topographic water fluxes balance. The inclusion of the depth to water table data contributes significantly to the ability to predict species probability of occurrence. Furthermore, this data source provides advantages over traditional proxies for wetland habitat, because it is not a static measure of wetland location, and is not biased by sampling method. Utilizing the long-term banding bird data again, the third chapter examines the behavior of waterfowl niche selection through time. By using the methods developed in chapter two, probability of occurrence models for the 1950s and the 1990s were developed. It was then possible to detect movements in geographic and environmental space, and how movements in these two spaces are related. This type of analysis provides insight into how different bird species might respond to environment changes and potentially improve climate change forecasts. The final chapter presents a new method for predicting the migratory movement of waterfowl. The method incorporates not only the environmental constraints of stopover habitat, but also includes likely distance and bearing traveled from a source point. This approach uses the USGS’ banding bird database; more specifically, it relies on banding locations, which have multiple recoveries within short time periods. Models made from these banding locations create a framework of migration movement, and allow for predictions to be made from locations where no banding/recovery data are available. / text