Behavioral state resource selection in invasive wild pigs in the Southeastern United States

Elucidating correlations between wild pig (Sus scrofa) behavior and landscape attributes can aid in the advancement of management strategies for controlling populations. Using GPS data from 49 wild pigs in the southeastern U.S., we used hidden Markov models to define movement path characteristics and assign behaviors (e.g., resting, foraging, travelling). We then explored the connection between these behaviors and resource selection for both sexes between two distinct seasons based on forage availability (i.e., low forage, high forage). Females demonstrated a crepuscular activity pattern in the high-forage season and a variable pattern in the low-forage season, while males exhibited nocturnal activity patterns across both seasons. Wild pigs selected for bottomland hardwoods and dense canopy cover in all behavioral states in both seasons. Males selected for diversity in vegetation types while foraging in the low-forage season compared to the high-forage season and demonstrated an increased use of linear anthropogenic features across seasons while traveling. Wild pigs can establish populations and home ranges in an array of landscapes, but our results demonstrate male and female pigs exhibit clear differences in movement behavior and there are key resources associated with common behaviors that can be targeted to improve the efficiency of management programs.

Connecting the Dots: Behavioral State Resource Selection in Wild Pigs in the Southeast United States

Background Invasive wild pigs (Sus scrofa) are behavioral generalists that have the potential to alter ecosystems across broad spatial scales. Elucidating the correlation between wild pig behavior and landscape attributes can aid in the advancement of management strategies for controlling populations. Methods Using GPS data from 49 wild pigs in the southeastern U.S., we used movement characteristics to distinguish and define behaviors and explore the connection between these behaviors and resource selection for both females and males between two distinct seasons based on forage availability. We extracted three biologically relevant behaviors of wild pigs from our movement data using hidden Markov models, which we inferred to represent resting, foraging, and traveling behavioral states. We then used multi-scale resource selection functions to quantify resource selection at the population and home-range scales for each behavioral state. Results Females demonstrated a crepuscular movement pattern in the high-forage season and a variable pattern in the low-forage season, with increased traveling and foraging activity during the daytime and evening hours, while males consistently demonstrated a nocturnal pattern across both seasons. At the population scale, wild pigs selected for forest vegetation types (i.e., upland pines, upland hardwoods, bottomland hardwoods) in both the low- and high-forage seasons, likely reflecting their ubiquitous establishment throughout the landscape. At the home-range scale, wild pigs selected for bottomland hardwoods and dense canopy cover in all behavioral states. In addition, males demonstrated selection for a variety of vegetation types while foraging in the low-forage season compared to the high-forage season and demonstrated an increased use of linear anthropogenic features (e.g., roads) across seasons while traveling. Conclusions Our results demonstrate male and female pigs exhibit clear differences in movement behavior. Further, although wild pigs can establish populations and home ranges in an array of landscapes and habitat types, there are key resources associated with common behaviors they select consistently at a fine scale that can be targeted in conservation and management programs across their invasive range.

Feasibility of Igniting Prescribed Fires in Bottomland Hardwood Forests

There is emerging interest in using prescribed fire to manage bottomlands for wildlife habitat, invasive species control, and overall forest function. We evaluated the feasibility of conducting prescribed fires in bottomland hardwood forests in west-central Alabama as part of a broader strategy to control the invasive shrub Chinese privet (Ligustrum sinense). We used 22 small-scale plots (0.04 hectares) in areas with residual slash from privet cutting operations and initiated prescribed fires on each to assess the overall feasibility and the relation of in-stand weather (i.e., microclimate), stand composition, and litter measurements to fire behavior. Overall, prescribed fire ignition was difficult, and only half the trials successfully burned >10 percent of the plot. We found that stand composition was most correlated with percent plot burned, and plots with higher proportions of tree species with flammable leaf traits (e.g., Quercus spp.) tended to burn best. Although further investigation is warranted, managers interested in using prescribed fire for bottomland hardwoods likely face short time windows and limited forest conditions in which fires can be reliably set. Study Implications There is increasing interest in using prescribed fires in bottomland hardwood forests. This exploratory study evaluated whether prescribed fires could be reliably set in bottomlands. Prescribed fires were difficult to establish and tended to be very patchy with fire spread related to tree canopy composition (because of differences in leaf litter flammability) and litter loads. Results suggest that it would be difficult to apply fire on a large scale in bottomland hardwood forests and that small-scale fires could only be set under certain conditions.

Towards a Characterization of Working Forest Conservation Easements in Georgia, USA

We examine the attributes of working forest conservation easements in Georgia. Easement contracts and baseline reports are inspected to investigate easement themes, land use types, recreation opportunities, hydrological features, and forest management activity. Easement themes are heavily weighted towards themes of protecting natural habitat and preserving the conservation values of properties. Predominant land use types include wildlife food plots, bottomland hardwoods, and planted pine stands. Common hydrological features found were small creeks/streams and ponds. Lastly, forest management was characterized as having small amounts of restrictions present, with forest management being largely similar to other unencumbered property in the southeastern USA. This information can be used as a reference for landowners interested in establishing a working forest conservation easement (WFCE) on their property as well as a tool for comparison for researchers investigating easement characteristics in other regions.

Hydrologic Modifications Challenge Bottomland Hardwood Forest Management

Bottomland hardwoods are floodplain forests along rivers and streams throughout the southeastern United States. The interrelations among hydrology, soils, geomorphic landforms, and tree species composition are the foundation of forest management in bottomland hardwoods, and historically their correspondence has allowed for somewhat predictable forest responses based upon the hydrogeomorphic setting. However, extensive hydrologic and geomorphic modifications in floodplains have disrupted these interrelations and, on many sites, have created novel disturbance regimes resulting in unpredictable forest responses. Reduced or altered timing of surface flooding and groundwater declines are common in the region and have favored increases in stem densities, particularly of species less tolerant of flooding and more tolerant of shade. In these highly modified systems, more process-level understanding of floodplain hydrology, soil moisture dynamics, interspecific tree competition, and regeneration is needed to develop more effective management prescriptions and for forestry to be represented in integrated water-resource management decisions.

Genetic Control of Growth Traits and Inheritance of Resistance to Bacterial Leaf Scorch in American Sycamore

Open-pollinated progeny tests of American sycamore (Platanus occidentalis L.), which included 55 open-pollinated families selected from several prior Westva - co progeny tests and seed orchards and six control-pollinated families were established in 2002 and 2003. The half-sibling families were planted at two sites in western Kentucky and southeastern Missouri. The six full-sibling families, generated from selections based on exhibition of parental disease resistance and susceptibility to a variety of diseases, were also planted near Stoneville, MS at the US Forest Service Center for Bottomland Hardwoods Research. All full-sibling families planted at the Stoneville site were inoculated in the fall 2002 with the leaf-scorch-causing bacterium, Xylella fastidiosa. Diameter and height data for trees of both half- and full-sibling families were recorded at ages three, five, seven, and nine at the various sites. Bacterial leaf scorch disease presence was also recorded as symptomatic or asymptomatic/ mildly symptomatic. Average family heritability across ages was 0.58, 0.50, and 0.55 for height, diameter, and volume, respectively, indicating that increased growth traits can be gained from family selection. In conjunction with derived age-age correlations, selection based on age-five data results in the greatest gain per unit time for age nine gains for half-sibling families. Breeding for bacterial leaf scorch resistance can also be successfully undertaken if proper selection and breeding of two resistant parents are undertaken which can result in a 4.5 fold decrease in the probability in symptoms of offspring by age nine. Results indicate a large potential for increased growth and disease resistance in American sycamore through traditional breeding.