Activity patterns of bats are known to vary substantially among nights, seasons, years, and geographic regions but the underlying reasons for those patterns are poorly understood. Our objectives were to assess the temporal variability of acoustically-determined bat activity during autumn in central Georgia and to evaluate the influence of barometric pressure and nighttime temperature on nightly activity using AICc and regression models. We recorded 134,392 bat calls and 13,753 sequences using an ANABAT SD2 detector during 87 sample nights (11 August - 11 November 2011) at a residence in Barnesville, Georgia. The number of sequences recorded nightly ranged from 3 to 763. On average, activity was consistent throughout the night with a slight peak just before sunrise, but within-night activity patterns varied among nights. Modelling results indicate that nightly bat activity was positively related to average nightly temperature and average nightly barometric pressure. In contrast to our expectations, measures of pressure change prior to or during sample nights were not plausibly related to bat activity. The positive relationship between autumn bat activity, temperature, and barometric pressure likely was related to the energetic costs and benefits associated with flight and prey availability during this season in central Georgia.
Dept of Biology, Gordon State College, Barnesville, GA
P18 • Kelsey B. Ortiz1, Joshua W. Campbell1, Matthew N. Waters2, Frederick Rich3
A Record of Ecological/Anthropological Change From Bat Guano Deposits in Fern Cave, Jackson County, Alabama
Bat guano can accumulate in caves resulting in a stratigraphic record that may record anthropological/ecological change. Southeastern bats forage for insects and their feces build up beneath their roosting areas, depositing insect remains, pollen, fungal spores, etc. On July 1, 2011 a 104 cm bat guano core was taken from Fern Cave located in Fern Cave National Wildlife Refuge near Paint Rock, Alabama. During the coring process, the guano core compacted to 43 cm. We gathered heavy metal (Mg, Fe, Pb, Zn, Mn, Cu, Cr, Cd, Co, Ni, Al) and nutrient data (C, N, P, Ca), relative pollen counts, and quantified chitin pieces. Based on carbon dates, the core dated AMS 14C 5920 +/- 40 yr BP. A three cm charcoal layer was discernable between the 26-29 cm layer, which was dated to AMS 14C 2690 +/- 30 BP. Numerous heavy metals and nutrients exhibited several variations throughout the core. The pollen record within the guano core showed numerous marked changes in potential plant cover of the immediate area. Corn also spiked within the core; probably resulting from Paleo-Indian or early Europeans cultivation of corn. Chitinous exoskeletal pieces were observed up until the charcoal layer. Chitinous material was well preserved within the first 10 cm but began to show signs of diagenesis towards the charcoal layer (26-29 cm). Overall, our bat guano core exhibited many anthropological and ecological changes throughout time that could be observed through pollen, nutrient/heavy metal data, and chitinous exoskeletal pieces.
Landscape Heterogeneity of Airborne Hg (Mixed Dissolved, Particulate and Vaporous) and a Sampling of Total Hg Concentration in Macro-Invertebrates Within Rockingham Co., VA
Distribution of Airborne Hg is known to occur at the landscape level. Passive air samplers consisting of inverted plastic Petri plates containing Tangle Trap (a sticky organic) have been used to examine its presence at a variety of locations in Rockingham Co VA. The assumption is that this deposition serves as a relative indexof the different locations in the landscape. The total Hg content when plates were exposed to the air over a fixed period was measured. Five contaminated locations, which had consistently above average Hg concentrations, and a low Hg control site, were selected for more extensive study in 2010-2012. In addition to dust, Hg vapor, and Hg dissolved in precipitation, the Tangle Trap captured various invertebrates and debris. All items greater than ~0.5 mm in diameter were removed for airborne determination. During 2010-2012, separate fly, beetle, wasp, and spider traps were deployed with the intent of obtaining greater invertebrate biomass for analysis. A comparison was made of the relative Hg content of the air dried invertebrate tissue (mostly insects) to the relative airborne Hg measured by the plate samplers. Some invertebrates from the contaminated locations had 2-5 times higher Hg concentrations than those at the low Hg control site. This supports the presence of a repeatable pattern of distribution of low level Hg in a rural, non-industrial landscape. Whether or not this is a result of existing background airborne contamination or due to local sources is to be determined.
Dept of Biology, James Madison University, Harrisonburg, VA
P20 • Walt Thompson1, Jennie Haskell1, Doug Aubrey2
Short Term Effects From a Late Season Freeze on White Oak (Quercusa alba L.) Acorn Production in the Southeastern Coastal Plain
Since 1995 acorn collections have been made for the hardwood reforestation program maintained by the US Forest Service on the Savannah River Site in South Carolina. On April 8th and 9th, 2007, a late season freeze damaged white oaks and killed the 2007 white oak acorn crop with recorded temperatures of 26°F and 30.5°. This also had an effect on the 2008 acorn crop for white oaks on the southwestern part of the forest. Hard mast production varies yearly and consecutive years of poor mast production affect potential natural and artificial regeneration opportunities and hard mast for wildlife. With changing climate conditions, white oak seed production and natural regeneration may be jeopardized.
1 USDA Forest Service-Savannah River, New Ellenton, SC; 2 Georgia Southern University, Statesboro, GA
