Climate and weather impact timing of emergence of bats

PLoS One. 2012;7(8):e42737. doi: 10.1371/journal.pone.0042737. Epub 2012 Aug 2.

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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Behavior, Animal
  • Chiroptera / physiology*
  • Climate*
  • Population Dynamics
  • Temperature
  • Weather*

Grants and funding

WFF was supported by NSF DBI-0905881. JFK was supported by NSF EPS 0919466. PBC was funded in part through the National Oceanic and Atmospheric Administration National Severe Storms Laboratory Grant NA08OAR4320904. PBC and PMS were partially supported through internal funding from the University of Oklahoma. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.