Browsing by Author "Richard Lancia, Committee Member"

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The Effects of Food Abundance, Foraging Rules and Cognitive Abilities on Local Animal Movements
(2006-11-22) Favreau, Jorie Marie; Richard Lancia, Committee Member; Nick Haddad, Committee Member; Roger A. Powell, Committee Chair; Michael Mitchell, Committee Member; Roland Kays, Committee Member; George R. Hess, Committee Member
Movement is nearly universal in the animal kingdom. Movements of animals influence not only themselves but also plant communities through processes such as seed dispersal, pollination, and herbivory. Understanding movement ecology is important for conserving biodiversity and predicting the spread of diseases and invasive species. Three factors influence nearly all movement. First, most animals move to find food. Thus, foraging dictates, in part, when and where to move. Second, animals must move by some rule even if the rule is "move at random." Third, animals' cognitive capabilities affect movement; even bees incorporate past experience into foraging. Although other factors such as competition and predation may affect movement, these three factors are the most basic to all movement. I simulated animal movement on landscapes with variable amounts of food per food patch, variable number of patches, and variable spatial distributions of food patches. From the results of my simulations, I formulated a series of hypotheses about the effects of food abundance on animal movement in nature. I also resolved the apparent paradox of real animals' movements sometimes correlating positively and sometimes negatively with food abundance. I simulated variable foraging rules belonging to 3 different classes of rules (when to move, where to move, and the scale at which to assess the landscape). Simulating foraging rules demonstrated that variations in richness and density tend to have the same effects on movements, regardless of foraging rules. Still, foraging rules affect the absolute distance and frequency of movements. In my third set of simulations, I simulated a range of spatial and temporal cognitive constraints and demonstrated that omniscience is not necessarily the optimal cognitive state from an energetic standpoint. I tested my hypotheses on the effects of food abundance with data from free ranging female black bears (Ursus americanus) in Pisgah Bear Sanctuary (North Carolina, USA) and female kinkajous (Potos flavus) in Parque National Soberanía (Panama), two species with low predation risk. Depending on the season, black bear movements can be explained, by food patch richness, density or both richness and density. Kinkajou move length but not number of moves can be explained by patch richness and density. Instead of kinkajous adjusting their number of moves when food density changed, kinkajous increased the amount of time they foraged. Moonlight was also a good predictor of number of moves. None of kinkajous' 3 dietary preferences best explained moves.
Inventory and Assessment of the Reptile and Amphibian Community of Bull Neck Swamp, Washington County, North Carolina.
(2008-02-13) Hutchens, Stan Jonathan; Chris DePerno, Committee Chair; Richard Lancia, Committee Member; Ken Pollock, Committee Member
Recent declines in reptile and amphibian populations across the globe have encouraged an increased desire to discover, document, and monitor these taxa. Arguably, the greatest cause is land-use change. Management interests for Bull Neck Swamp (BNS) encouraged research to inventory the reptile and amphibian community and to document possible impacts of land-use practices, such as silviculture and site preparation. Four habitat preserves were delineated based on plant community, leaving 1, 554ha (3, 841ac) available for management. Comparisons between habitat assemblages were used to determine if preserves were occupied by more vulnerable species and land-use effects on these species. However, variations in behavioral or environmental variables, and detection probabilities between capture techniques could provide misleading data for assemblage comparisons of community parameters. Therefore, 11 different capture techniques were employed to obtain better samples of habitat assemblages. To determine the accuracy of sampling techniques at inventorying species, techniques were categorized into primary (i.e., drift fence arrays with pitfall and funnel traps, visual encounter surveys, and coverboard arrays), secondary (i.e., road searches, polyvinyl chloride (PVC) piping grids, auditory surveys, and line transects), and tertiary (opportunistic encounters, aquatic funnel traps, crayfish traps, and basking traps) methodologies. All techniques had variable distributions and were evenly represented in all five areas when possible. All captured individuals were marked; snakes were double-marked with visible implant fluorescent elastomer to augment a concomitant laboratory experiment. Initial capture data were used to derive estimates of species richness (S) and modified Chao — Jaccard similarity indices (JSI). During May to August, 2005 and 2006, 1, 581 total captures represented 33 species, giving an estimated species richness of 34. Primary techniques sampled an estimated species richness of 14 and two unique species, species detected by only one sampling technique. Estimated species richness for secondary and tertiary techniques was 29 and 25, with three and seven unique species, respectively. If primary techniques alone were used, 59% of the reptile and amphibian community, including 10 unique species, would have been missed. Observed and estimated species richness for habitats ranged from 7 to 32 and 13 to 44, respectively. Chao — Jaccard similarity indices ranged from 0.59 to 1.0, with nine comparisons over 0.75, which indicated high similarity between habitat assemblages. These results suggested that land-use practices should be carefully planned and implemented to reduce effects to the reptile and amphibian community of BNS. Empirical results supported the use of elastomers for snakes. It is recommended that future inventory studies for all taxa employ as many capture techniques as logistically and spatially possible to derive accurate species richness. Also, assemblage comparisons should rely on species composition when determining conservation plans.
Seasonal Relationships Between Birds and Arthropods in Bottomland Forest Canopy Gaps
(2005-02-02) Bowen, Liessa Thomas; Theodore Simons, Committee Member; Richard Lancia, Committee Member; John Kilgo, Committee Member; Daniel J. Robison, Committee Co-Chair; Christopher E. Moorman, Committee Co-Chair
I investigated the influence of arthropod availability and vegetation structure on avian habitat use at the center, edge, and adjacent to forest canopy gaps in 2001 and 2002. I used mist-netting and plot counts to estimate abundance of birds using three sizes (0.13, 0.26, and 0.5 ha) of 7-8 year old group-selection timber harvest openings during four seasons (spring migration, breeding, post-breeding, and fall migration) in a bottomland hardwood forest in the Upper Coastal Plain of South Carolina. I used foliage clipping, Malaise trapping, and pitfall trapping to determine arthropod abundance within each habitat, and I used a warm water crop-flush on captured birds to gather information about arthropods eaten. I observed more birds, including forest interior species, forest-edge species, field-edge species, and several individual species, in early-successional canopy gap and gap-edge habitats than in surrounding mature forest during all seasons. I found a significant interaction between season and habitat type for several groups and individual species, suggesting a seasonal shift in habitat use. Captures of all birds, insectivorous birds, foliage-gleaners, ground-gleaners, aerial salliers, Hooded Warbler (Wilsonia citrina), Northern Cardinal (Cardinalis cardinalis), White-eyed Vireo (Vireo griseus), and Black-throated Blue Warbler (Dendroica caerulescens) were positively correlated with understory vegetation density during two or more seasons. I found relationships between insectivorous birds and leaf-dwelling Lepidoptera, insectivorous birds and ground-dwelling arthropods, foliage-gleaning birds and foliage-dwelling arthropods, and aerial salliers and flying arthropods, as well as between individual bird species and arthropods. Relationships were inconsistent, however, with many species being negatively correlated with arthropod abundance. Coleopteran, Lepidopteran, and Aranid prey items represented the greatest proportions of crop-flush samples during all seasons. Proportional consumption of Coleopteran and Hemipteran prey items was higher than their proportional availability, and consumption of Aranid and Hymenopteran prey items was lower than their proportional availability during all seasons. Individual bird species and guilds consistently consumed similar proportions of certain groups of arthropods from spring through fall migration, with no apparent seasonal shift in diet composition. My research suggests that many species of birds selectively choose mid-successional gap and gap-edge habitat over surrounding mature forest during the non-breeding season, and the creation of small canopy gaps within a mature forest may increase local bird species richness. It is less obvious how arthropod availability affects bird habitat use across seasons. A structurally diverse mosaic of habitat types, including regenerating canopy gaps within a mature forest, may provide valuable habitat for birds and a variety of arthropod prey items across multiple seasons.
A Serosurvey of Feral Pigs (Sus scrofa) in Eastern North Carolina.
(2010-10-12) Sandfoss, Mark; Christopher DePerno, Committee Chair; Kevin Gross, Committee Member; Richard Lancia, Committee Member; Suzanne Kennedy-Stoskopf, Committee Member