Wildlife Community Ecology I

Contributed Paper
ROOM: HCCC, Room 20
SESSION NUMBER: 36
 

8:10AM Not All Effects Are Created Equal: the Influence of Beavers on Multi-Taxa Biodiversity in Mixed-Use Landscapes
Glynnis A. Hood
Species having disproportionate influence on their environment are often described as keystone species, given their impacts on multiple trophic levels within ecological communities. I analyzed how beavers (Castor canadensis) influence multi-taxa biodiversity in and adjacent to 26 ponds (n = 16 protected area; n = 10 agricultural) within the southern dry mixed-wood boreal forest in east-central Alberta, Canada. Ponds were further categorized as those actively occupied by beavers (active) and those lacking beavers (inactive). Specific taxa included mammals (pellet counts per m2), aquatic invertebrates, birds (multiple guilds), amphibians, and riparian vegetation. Mammal and vegetation surveys involved 100-m long x 2-m wide belt transects, while invertebrate and bird/amphibian surveys employed D-net sampling and call and visual surveys, respectively. Mammalian species richness was not significantly different among the sites; however, relative abundance of moose (Alces alces) was higher in both active an inactive ponds in the park than those on agricultural lands. Aquatic invertebrate diversity and distributions differed relative to land type, pond occupancy, and within-pond habitats. Beaver-occupied ponds had the highest biodiversity, with specific differences in beaver channels. For bird guilds, the total number of ducks (regardless of species) was highest on active beaver ponds in the park, with the second highest abundance on inactive ponds in the park. Passerines were most abundant adjacent to active beaver ponds inside the park, while shorebirds were most abundant at active beaver ponds in the park and inactive agricultural ponds. Regardless of land type (agricultural vs. protected area), wood frogs (Lithobates sylvaticus) were most common in active beaver ponds. Finally, there were species-specific differences in vegetation diversity among the pond types. Most notably, species richness was lowest at agricultural ponds that were occupied by beavers. This research enhances our understanding of how activities by beavers influence of ecological communities in mixed-use landscapes.
8:30AM Wolf Predation on Calves and Its Impact on the Declining Moose Population in Northeastern Minnesota
William J. Severud; Tyler R. Obermoller; Glenn D. DelGiudice
Minnesota’s northeastern moose (Alces alces) population has declined 65% from 2006 to 2018. Wolf (Canis lupus) predation on adult and calf moose have been shown to limit populations. We sought to investigate the quantitative impact of wolf predation on calves on the northeastern Minnesota moose population. We deployed GPS collars on 54 neonates in 2013 and 2014 and monitored calves for survival and cause-specific mortality. We additionally monitored 105 uncollared calves of GPS-collared dams in 2015 and 2016. Wolves were confirmed or suspected to have killed 30% of adult moose in a companion study during 2013-2018. Wolf-kills were the leading cause of calf mortality during 2013-2016. Predation accounted for 84% of all natural mortalities, with wolves having the greatest impact overall (77% of predation events). Wolves also inflicted injuries that eventually killed calves due to septicemia. Wolf-kills were located relatively farther from roads compared to other causes of mortality, generally occurred during early morning hours (0300-0800 hr), and decreased when calves reached about 100 days of age. Assuming wolf predation on neonates is completely additive, annual calf survival could increase from 35% to 67% if wolf-kills were eliminated. Wolves and moose have been sympatric in this system historically, yet wolves have recently been implicated in the moose decline, whether resulting from apparent competition between deer (Odocoileus virginianus) and moose, or poor overall moose health. Although wolf predation accounted for 30% of adult moose mortality, ≥40% of cases exhibited health issues possibly predisposing them to predation. The overall poor health of the northeastern Minnesota moose population could potentially explain the high rate of predation on calves. Current legal status of wolves under the Endangered Species Act precludes management of wolves to benefit moose numbers, so alternative forms of management must be implemented if moose are to persist in Minnesota.
8:50AM Determining the Appropriate Scale for Measuring Habitat Heterogeneity and Productivity When Modeling Species Richness of Different Vertebrate Taxa
William Justin Cooper; Willam J. McShea; David Luther; Tavis Forrester
As natural habitats continue to decrease and become fragmented, pressure increases to better manage and conserve remaining ecologically valuable areas. To do so, it is imperative to understand the complex systems of species-habitat interactions and the spatial scale at which we measure these habitat characteristics. In this study, we explore the performance of multiple scales of high-resolution habitat heterogeneity and productivity metrics as predictors of 19 vertebrate guilds across 3 taxonomic classes. Using a Bayesian approach, we modeled species richness for each taxonomic class and guild. To select the most appropriate scale for each guild, we systematically calculated the receiver operating characteristic area under the curve (ROC AUC) for each model iteration, quantifying the uncertainty in model predictions with each measurement scale. Our results show the performance of these models depend on the scale at which measurements are made, and different guilds depend on different scales. Frogs were most strongly related to a spatial scale with a radius of 20-meters, showing areas with high water content and homogeneous structure predict higher frog diversity. Bat diversity was best predicted with a 20-meter radius spatial and strongly related to vertical structure. When dividing bird species into habitat guilds we found edge species responded strongest to a spatial scale with a radius of 160-meters, forest species with a 20-meter spatial scale, and grassland species with a 60-meter spatial scale. Each guild responded differently to habitat structure and productivity characteristics. Terrestrial mammal diversity was modeled best with a 180-meter radius spatial scale. Approaches that identify diversity and distribution patterns relative to vegetation conditions and structure using high-resolution data can only increase our ability to model small spatial units and increase the effectiveness of management practices when measured at appropriate scales.
9:10AM Spatiotemporal Patterns of Wildlife-Vehicle Collisions along Physiographically Distinct Routes in Southwest Virginia.
James Vance; Walter Smith; Gabrielle Smith
Wildlife-vehicle collisions (WVCs) are a major area of focus in wildlife conservation, particularly in areas characterized by a high degree of anthropogenic development. Knowledge of the spatiotemporal patterns of WVCs is essential to developing measures that aim to mitigate negative impacts. To that end, we conducted a yearlong WVC study in the Appalachian Mountains of Virginia to (1) compare patterns of road mortality for mammals, birds, and herpetofauna across two adjacent routes with different vehicle densities, (2) compare temporal variation in WVC frequency to the seasonal activity of focal taxa, (3) determine spatial patterns of WVC hotspots and (4) determine spatial clustering or over dispersion. The mean weekly roadkill rate across all species (n = 65) was 13.8 ± 1.73 per 100 km. We found that WVCs were not evenly distributed across routes with overall differences driven primarily by the relative abundance of small mammals. We detected significant temporal variation in WVC rates for woodchucks, eastern box turtles, and eastern ratsknakes with contrasting peaks in frequency for passerine birds and birds of prey. For the 11 most abundant species, we identified road mortality hotspots but did not find spatial clustering for white-tailed deer, eastern cottontail rabbit, and eastern box turtle. Our findings suggest that managers may be able to overcome variability between differing routes by considering the activity patterns of focal taxa, especially when mitigation efforts are targeted at one or a few species of high conservation concern.
9:30AM Animal Diversity Declines with Broad-Scale Homogenization of Canopy Cover in African Animal Diversity Declines with Broad-Scale Homogenization of Canopy Cover in African Savannas
Robert A. McCleery; Ara Monadjem; Robert Fletcher; Benjamin Baiser; Laurence Kruger
Tropical savannas are increasingly threatened by anthropogenic forces that are causing broad-scale directional shifts in woody vegetation that homogenizes their structure. Still, researchers only have an incomplete understanding of how animal communities respond to changing savannas and if responses are consistent across taxonomic groups and scales. Studying birds, bats and terrestrial small mammals twice a year, for two years, on multiple scales, across a gradient of woody cover in the savannas of southeastern Africa, we found that homogenization of vegetation structure corresponded with decreases in animal richness, diversity and functional diversity. Additionally, metrics of animal diversity declined at opposing ends of a canopy cover gradient (< 10% and > 65%), where we found distinctly different animal assemblages. These patterns were consistently more pronounced on a broader grid scale (30 .25 ha) when compared with the plot scale (0.25 ha). The broad-scale reductions in the diversity and functions of animals observed may be indicative of reductions in the resilience, stability and ecosystem function of tropical savannas. Nonetheless, this study illustrates the clear benefits of fostering savanna landscapes with heterogeneous vegetative structure, which is likely critical for maintaining diversity and functionality.

 

Contributed Paper
Location: Huntington Convention Center of Cleveland Date: October 9, 2018 Time: 8:10 am - 9:50 am