#56-16 Effects on fences of wildlife connectivity, habitat selection, and community interactions
Justin Brashares, ESPM, UC Berkeley
Connectivity, the degree to which a landscape facilitates or impedes animal movement, is
essential to wildlife population viability and the health of the whole ecological communities. Anthropogenic barriers such as roads and fences are widely believed to reduce landscape connectivity. While the impact of roads on wildlife movement has grown into a field unto itself, the effects of fences on wildlife are not well studied, even though fences are ubiquitous across the western United States and much of the world. The dearth of research may seem surprising considering the frequent anecdotal observations of fences a) causing separation of female ungulates from their young, b) impeding or disrupting wildlife migration routes and c) being used by large carnivores to corner or trap prey. However, understanding the impact of fences requires insight into the fine-scale movement of animals that, until recently, was nearly impossible outside of direct observation. Today's new high-resolution GPS positioning and accelerometer technologies can deliver precise information on animal location and movement speed at intervals as small as 5 seconds. This technological innovation provides a novel and critically important opportunity to study the effects of fencing on wildlife habitat connectivity. We propose to conduct just such a study over several years at HREC. The insights from this study will greatly advance broad areas of wildlife ecology and management and also aid land managers in planning for wildlife connectivity and in working with land-owners to minimize their impacts on wildlife populations and communities.
#55-16 Ecological impacts of invasive wild pigs
John Harper, UCCE Mendocino, Roger Baldwin, Wildlife, Fish and Conservation Biology, Elizabeth Hiroyasu
The wild pig (Sus scrofa) is a pervasive invasive species that is present throughout
California. Pigs cause damage to both natural and managed systems through their foraging, predation on wildlife and livestock, and transfer of disease. Consumption of plants and animals, as well s trampling of sensitive areas, may impact species richness, diversity, and ecosystem function as a whole. While wild pigs have been shown to have high reproductive rates elsewhere in the United States, few studies have addressed the population processes and dynamics in California's environments. Using a multi-part, interdisciplinary approach, this project will assess wild pig populations and examine habitat selection, population growth, and ecological impacts. Three separate experiments will be conducted over a three-year period to provide critical information about habitat selection and population growth in North Coast wild pig populations. This work will expand our understanding of the extent and nature of wild pig impacts in sensitive riparian and vernal pool systems, and will provide insights to the recovery of these systems. The research will provide important information of the impacts and risks of wild pig invasion to policy makers, land managers, and other key stakeholders. Outputs from this research will inform policy and management by: identifying areas at high risk of pig invasion, assessing their impacts on riparian and vernal pool habitats, assessing the type, nature, and extent of damage occurring on both wild and managed areas, and assessing the population dynamics of wild pigs.
#54-12 Effects of non-native mosquitofish on a California pond ecosystem
Cheryl Briggs, Dept. of Ecology, Evolution, and Marine Biology, UC Santa Barbara
Dan Preston, Dept. of Ecology & Evolutionary Biology, University of Colorado
This study examines the impacts of a widespread aquatic invasive species, the western mosquitofish (Gambusia affinis) on a native California pond community using a Before-After-Control-Impact (BACI) design that employs quantitative survey approaches to document mosquitofish effects on native zooplankton, invertebrates, and amphibians. By quantifying the biomass of emergent insects and amphibians from both sides of the pond, we can also address how mosquitofish alter the energetic linkages between aquatic and terrestrial habitats. Use of an outdoor mesocosm experiment, in addition to HREC’s Hog Lake, aided our investigation of mosquitofish impacts over a gradient of nutrient concentrations. Our results have implications for understanding how mosquitofish restructure food webs, while also having direct relevance to managing pond ecosystems in California, which support a diversity of threatened species.
#50-09 Turkey Vulture Nest Selection Criteria
Greg Giusti, UCCE, Mendocino & Lake Counties
Long-term quantitative life history studies in different parts of the breeding range are needed to evaluate the factors affecting the status and health of turkey vulture (Cathartes aura) populations. Limited information exists for western populations except in generalized format such as “typically roosts in large trees—e.g., cottonwood, and on rock outcrops and on saguaro cactus in southern Arizona”. This project investigates decadent, hollow oak (Quercus spp) trees at Hopland that are being used as nesting sites by vultures. We are measuring the availability of nest trees in a diverse oak woodland habitat, as well as observing nesting behavior and use of nest trees by other wildlife via use of remote camera installations over multiple seasons.
#53-96 Genetic and Morphological Stability of Isolated Populations of Small Mammals
Douglas Kelt, Dept. of Wildlife Fish & Conservation Biology, UC Davis
This research continues work initiated in 1959 at Hopland by Dr. Walter E. Howard on voles (Microtus californicus) at HREC. This work is based on the premise that extreme isolation of a species known to exhibit substantial multi-year cycles in population numbers may have led to demographic bottlenecks in these vole populations. We are investigating loss of genetic variation in isolated vole populations, as well as a specific morphological response to reduced genetic variation. This response - fluctuating asymmetry - may occur when animals are unable to compensate for "environmental abuse" during development. HREC’s rodent enclosures are highly suitable to this project because of the duration of isolation (46 years, or somewhat more than 60 Microtus generations), and the presence of pitfall traps that allow simulated emigration (this prevents populations from expanding exponentially, a dynamic known as the “fence effect”).