AUTHORS: Becky Hansis-O'Neill, University of Missouri - St. Louis Aimee Dunlap, University of Missouri - St. Louis
ABSTRACT: Aphonopelma hentzi has not been a species of concern for arachnologists in North America. Researchers report high densities at their field sites in the states of Colorado (CO) and Texas (TX) with no major conservation concerns. Central Missouri (MO) represents the most northern and easterly range edge for A. hentzi where they are primarily found in native glade grasslands. We have conducted a population assessment on three such glades over the past two years and discovered very low population densities compared to other researcher sites around the USA. Glades in central MO may represent habitat islands within the edge of A. hentzi’s range. Additionally, MO glades have been degraded over time by changing fire regimes and disturbance by hobby herpetologists. Our research aims to assess these populations over time in terms of density, preferred habitat, genetic health, and effects of disturbance. These tarantulas may be at risk due to a confluence of factors such as range edge effects, illegal collecting, habitat fragmentation, or other unknowns like pesticide exposure or disease. These factors may be causing low population densities, creating an Allee effect where these subpopulations may not easily recover. Small predator biodiversity is likely important for bottom-up maintenance of native vegetation via control of grazing invertebrates like orthopterans. This paper presentation will cover our current work on this project and future directions.
AUTHORS: Cassidy Lathrom, Kansas State University; Dave Haukos, United States Geological Survey; Caroline Skidmore, Kansas State University; Brian Monser, Fort Riley Environmental Division; Derek Moon, Fort Riley Environmental Division
ABSTRACT: We assessed the influence of management actions on the occurrence and density of native bumblebee populations in the Great Plains region. Occurrence, density, and distribution of native bumblebees (Bombus spp.) were assessed relative to landscape characteristics and environmental conditions (e.g., fire, haying, mechanical and herbicide control of invading trees and herbaceous plants) on Fort Riley, Kansas. Multi-scale assessments were used to estimate distribution and density of species-specific Bombus at landscape and unit scales across accessible areas of the study area. Unit scales were categorized by dominant cover type (e.g., natural prairie, go-back land, woodland, cultivated/crop land, water, burned, and hayed). Distance sampling was used to estimate distribution and density of species-specific Bombus at landscape scales across accessible areas of the study area. Site locations within predetermined unit scales were selected using randomized surveys resulting in 151, 500-m transects. We conducted sampling during early summer (May and June) and late summer (July and August). Location of all bumblebees observed along the transect were recorded using a Trimble GPS unit. Package Distance in Program R was used to estimate density of Bombus spp. across Fort Riley, within certain cover types, and by management action. Data were comprised of six species including American (B. pensylvanicus), Southern Plains (B. fraternus), Black and Gold (B. auricomus), Common Eastern (B. impatiens), Brown-Belted (B. griseocollis), and Two Spotted (B. bimaculatus). We estimated 1.30 Bombus/ha (CV = 0.184) and 1.40 Bombus/ha (CV = 0.122) during 2022 and 2023, respectively. These data are the first known estimates of Bombus density in tallgrass prairie and serve as a baseline for future assessments.
AUTHORS: Joseph B. Deas, U.S. Geological Survey, Lake Michigan Ecological Research Station; Desi Robertson-Thompson, U.S. Geological Survey, Midwest Climate Adaptation Science Center; Ralph Grundel, U.S. Geological Survey, Lake Michigan Ecological Research Station
ABSTRACT: Oak savannas are among the most imperiled habitats worldwide, characterized by their unique structure and biodiversity. These ecosystems have experienced significant decline due to habitat conversion and altered disturbance regimes. To understand the impact of these changes on butterfly diversity, we conducted extensive surveys in 1998/1999 and 2023 across 17-25 sites in Midwestern oak savannas, representing a gradient of canopy cover. Our study aimed to assess butterfly abundance and species composition, alongside additional environmental variables that might influence the relationship between butterfly diversity and canopy cover. We collected data on various environmental factors, including flower abundance, composition, and fire frequency, to determine their predictive value for butterfly presence/absence and to identify key environmental predictors. By comparing data from different time periods, we evaluated how the relationship between butterfly diversity and canopy cover has changed and whether these patterns were influenced by temporal or spatial changes in environmental conditions. Preliminary analyses suggest that the relationship between canopy cover and species richness is influenced by the frequency of historic fires, plant diversity, and local climate. Our findings emphasize the importance of considering multiple environmental factors when assessing biodiversity in oak savannas and highlight the need for ongoing conservation efforts to preserve these critical habitats.
AUTHORS: Becky Hansis-O'Neill, University of Missouri - St. Louis; Aimee Sue Dunlap, University of Missouri - St. Louis
ABSTRACT: The tarantula, Aphonopelma hentzi has not been a species of concern for arachnologists in North America. In Missouri, A. hentzi tend to inhabit glade habitats. Glades have been affected by changing fire regimes resulting in the proliferation of red cedar in some areas. Red cedar contributes to habitat degradation, making glades less favorable for glade specialist species. Small predators like lizards, and possibly arachnids, can reduce damage to native plants by controlling herbivorous insect populations. The effects of tarantulas on ecosystems they inhabit has not been well studied but they may be important for controlling herbivorous insects. Therefore, tarantulas may be important for maintaining glade habitats in addition to their intrinsic and cultural value. In three central Missouri glades, we have found A. hentzi populations that appear to be much smaller than we expected given population densities in other parts of North America. Partnering with the Missouri Department of Conservation, we have monitored these populations for the past three summers and will be adding new sites in the coming field season to understand if small populations are a widespread phenomenon in Missouri glades. We believe these tarantula populations are likely at risk from habitat fragmentation and degradation, edge of range effects, and illegal collecting. In addition to population monitoring, we have been working on monitoring habitat disturbance, natural history, population genetics, and wild tarantula welfare.
