Climate and Weather Impact Timing of Emergence of Bats

Abstract

Interest in forecasting impacts of climate change have heightened attention in recent decades to how animals respond to variation in climate and weather patterns. One difficulty in determining animal response to climate variation is lack of long-term datasets that record animal behaviors over decadal scales. We used radar observations from the national NEXRAD network of Doppler weather radars to measure how group behavior in a colonially-roosting bat species responded to annual variation in climate and daily variation in weather over the past 11 years. Brazilian free-tailed bats (Tadarida brasiliensis) form dense aggregations in cave roosts in Texas. These bats emerge from caves daily to forage at high altitudes, which makes them detectable with Doppler weather radars. Timing of emergence in bats is often viewed as an adaptive trade-off between emerging early and risking predation or increased competition and emerging late which restricts foraging opportunities. We used timing of emergence from five maternity colonies of Brazilian free-tailed bats in south-central Texas during the peak lactation period (15 June–15 July) to determine whether emergence behavior was associated with summer drought conditions and daily temperatures. Bats emerged significantly earlier during years with extreme drought conditions than during moist years. Bats emerged later on days with high surface temperatures in both dry and moist years, but there was no relationship between surface temperatures and timing of emergence in summers with normal moisture levels. We conclude that emergence behavior is a flexible animal response to climate and weather conditions and may be a useful indicator for monitoring animal response to long-term shifts in climate.

Comprehensive Enzymatic Analysis of the Cellulolytic System in Digestive Fluid of the Sea Hare Aplysia kurodai. Efficient Glucose Release from Sea Lettuce by Synergistic Action of 45 kDa Endoglucanase and 210 kDa ß-Glucosidase

“…When these enzymes were incubated with filter paper, cellobiose, cellotriose, and cellotetraose were produced by 21 K cellulose; cellobiose, and glucose were produced by 45 K and 65 K cellulose; and glucose was produced by 95 K cellulase. Endo-ß-1,4-glucanases derived from crustaceans and insects are also active in hydrolyzing cellulose to glucose [14], [40]–[43]. These enzymes seem to possess characteristic properties of cellobiohydrolase and ß-glucosidase.…”

Timing Effects of Heat-Stress on Plant Ecophysiological Characteristics and Growth

“…In addition to rising mean annual temperatures, the frequency, duration, and severity of periods with exceptionally high temperatures are also increasing (Easterling et al, 2000; Tripathi et al, 2016). HS events with a trend of high frequency and extremity have already been reported in different parts of the world (Henderson and Muller, 1997; Gaffen and Ross, 1998; Yan, 2002). Thus, plants in the future will be exposed to both higher mean temperatures, and likely more extreme HS.…”

Polarimetric Radar Observations of Biological Scatterers in Hurricanes Irene (2011) and Sandy (2012)

“…Bats often emerge from caves in large numbers around sunset, particularly Mexican free-tailed bats (Tadarida brasiliensis) in Texas and Oklahoma. Evening dispersion patterns have been studied for these bats (Horn and Kunz 2008;Frick et al 2012), and it may be possible to derive number density of bats or other bioscatterers using radar data (Chilson et al 2012a). Insect scattering properties using nonpolarimetric radar have also been occasionally examined.…”