Habitat Use and Abundance Patterns of Sandhill Cranes in the Central Platte River Valley, Nebraska, 2003-2010. - Todd Buckley

• Thesis Defense
• 11/2/2011

The Central Platte River Valley (CPRV) in Nebraska is an important spring stopover area for the midcontinent population of sandhill cranes (Grus canadensis). Alterations to crop rotation and loss of native habitat in the CPRV pose a risk to the future population. Personnel made observations of agricultural fields along designated routes in the CPRV from 2003-2010 to record the presence of cranes and estimate abundance. I developed and evaluated models to predict habitat use and flock sizes of cranes. My results suggest diverse crop rotations in large fields far from development but near roosting habitat are the most beneficial stopover habitat conditions for cranes in the CPRV. However, seasonal variation in the distance travelled to fields suggests roosting habitat might be limiting the distribution of cranes. Understanding the use of the Platte River by cranes is critical for future management of roosting habitat. Personnel made observations of the Platte River during aerial surveys from 2004-2010 to determine the presence of cranes and estimate roost sizes. I developed and evaluated models to predict roosting habitat use and roost sizes. Segments of the Platte River not adjacent to disturbance, wider than 150 meters, and free of tall woody vegetation received the highest use and contained the largest roosts. The results of my entire study suggest management in the CPRV for cranes should be focused west of Kearney, Nebraska, due to the potential for roosting habitat expansion and the characteristics of surrounding agricultural fields.

Breeding fidelity and landscapes effects on distribution of mallards and duck broods in the Nebraska Sandhills - Zach Cunningham

• Thesis Defense
• 7/15/2011

n/a

Avian Influenza Surveillance in Wild Migratory Birds in the United States, 2007-2009, and Effects of September Hunting Seasons on Survival, Harvest, and Recovery Rates of Canada Geese Banded in Southeast Nebraska - Scott Groepper

• Thesis Defense
• 7/12/2011

Highly-pathogenic avian influenza virus (HPAIV H5N1) poses risks to wild birds, poultry, and humans. Personnel with the United States Department of Agriculture-Animal Plant Health Inspection Service-Wildlife Services, state, and tribal wildlife agencies collected 168,940 samples from migratory birds from 2007-2009 to test for presence of HPAIV H5N1. No HPAIV was found, but other subtypes were discovered, including H5 and H7. I estimated prevalence of avian influenza virus by flyway and found prevalence was lowest each year in the Atlantic Flyway (6.7%-8.3%), highest in the Pacific Flyway in 2007 (13.3%) and 2008 (13.4%), and highest in the Mississippi Flyway in 2009 (15.9%). I plotted prevalence monthly and found July-October was optimal time for sampling due to highest prevalence in all flyways. Dabbling ducks had significantly higher prevalence of AIV ( = 14.1%, range = 9.3%-19.4%) than other functional groups across all flyways and study years. My results suggest future surveillance should focus on species from the dabbling duck functional group.

Restoration efforts in Nebraska have contributed to increased populations of resident Canada geese (Branta canadensis) that now are considered a nuisance. In 2004, an early September hunting season was initiated to reduce populations. I analyzed band returns from geese banded in Nebraska to determine if early September hunting seasons affected survival, harvest, and recovery rates. The top model in my survival analysis revealed early September hunting seasons did not reduce survival of geese (S = 0.696). In addition, models indicated survival was not different between geese inside and outside the early hunting zone (southeast vs. northeast, S = 0.711) and survival did not differ by sex (S = 0.708). Survival differed between the metropolitan areas of Omaha and Lincoln, Nebraska (S = 0.742 and 0.678, respectively). A combination of urbanization and non-migratory behavior may be leading to higher survival of geese in Nebraska.

Challenges for the Implementation of Adaptive Management and two Quantitative Applications - Jamie McFadden

• Thesis Defense
• 11/8/2010

Adaptive management is becoming an increasingly popular management-decision tool within the scientific community. The application of adaptive management is appropriate for complex natural-resources management problems high in uncertainty. Two primary schools of thought have developed that may yield varying levels of success as they primarily differ in stakeholder involvement and model complexity. We evaluated peer-reviewed literature that incorporated adaptive management to identify components of successful adaptive management plans and to make comparisons between the two schools of thought. Identifying the elements of successful adaptive management is advantageous to natural-resources managers considering adaptive management as a decision tool, such as those managing the Platte River, Nebraska. The Platte River is a complex ecosystem where resource management decisions affect endangered and threatened species such as the Interior Least Tern (Sternula antillarum athalassos) and Piping Plover (Charadius melodus). Because high uncertainty is associated with the responses of these species to habitat restoration and other resource uses and management efforts differ between the lower Platte River (LPR) and the central Platte River (CPR), we developed quantitative applications for each section. For terns and plovers on the LPR, we developed a population model that estimates population characteristics for on-channel and off-channel breeding and nesting habitat. The population model is a valuable tool in measuring and managing adaptively the annual status of the two avian species on the LPR. The ability of this quantitative model to adapt to new information makes it ideal for projecting management implications within an adaptive management context. As the CPR is further along in the adaptive management process, we developed a multi-model analysis based on simulated data to simplify hypotheses and prioritizing research and management needs. By utilizing statistical models for evaluating management consequences, iterative decision-making will for continuous updating as more monitoring data becomes available, influencing future management decisions. The process of evaluating effects of ecological features is helpful in setting and prioritizing objectives and implementing actions for adaptively managing complex ecosystems.

The Textural Discontinuity Hypothesis and its relation to nomadism, migration, decline and competition - Aaron Alai

• Thesis Defense
• 11/30/2009

The causes of nomadism, migration, and decline in vertebrates are debated issues in the ecological sciences. Literature suggests nomadism may arise in species that specialize in granivory, nectivory, or the utilization of rodent outbreaks. Literature suggests species become migratory because they exploit certain scarce or variable food types. Species decline is hypothesized to be the result of many different factors as well; large species, island species and specialists may be more prone to decline.

A fresh perspective regarding the causes for species nomadism, migration, and decline is being investigated with the Textural Discontinuity Hypothesis. The Textural Discontinuity Hypothesis stems from complex systems analysis and posits that body mass distributions form clusters within ecological systems, and that those body mass clusters reflect discontinuous distributions of resources. Additionally scientists have posited that species at the edges of body mass clusters may be exposed to highly variable resources. Nomadic and declining bird species populations occur at the edges of body mass clusters more frequently than expected. Migratory bird species also may be located at the edges of body mass clusters more frequently than expected. The morphological spacing of species within clusters may yield clues regarding species interactions. The distribution of species within a body mass cluster would have low variance if species within a cluster interact with each other strongly – morphological overdispersion has been documented in many animal communities and reflects strong competitive interactions among species.

I analyzed nomadism, migration, and decline in South African birds using an information-theoretic approach. I assembled a series of plausible models based upon suggested or theoretically predictive characteristics. Additionally, I used a series of Monte Carlo simulations to investigate the distribution of species within clusters, in terms of body mass.

Results suggest that a combination of species characteristics, including the distance to the edge of a body mass cluster, explain the complex phenomena of nomadism, migration and decline. Generally there was no single model supported, and often many models were in the confidence set, providing only weak inference. Within body mass clusters, there is more variance among species than null expectations, thus with my dataset morphological overdispersion is not present within body mass clusters. Nomadism, migration, and decline are complex phenomena which incorporate different species characteristics, perhaps explaining why such debate still exists over the causes of such phenomena