Evening Emergence Behavior and Seasonal Dynamics in Large Colonies of Brazilian Free-tailed Bats

Reichard, Jonathan D.; Gonzalez, Lauren E; Casey, Caitlin M.; Allen, Louise C.; Hristov, Nickolay I.; Kunz, Thomas

doi:10.1644/08-mamm-a-266r1.1

Cited by 34 publications

(45 citation statements)

References 48 publications

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“…In particular, lactating females are the most energetically stressed and therefore should emerge earlier if energetic demands outweigh costs of increased risk of predation. This pattern has been demonstrated in several species [14], [17]. The hypothesis that increased physiological stress results in earlier emergence times leads to predictions about how climate variation may influence emergence behavior of bats.…”

Section: Introductionmentioning

confidence: 78%

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Climate and Weather Impact Timing of Emergence of Bats

et al. 2012

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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.

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Section: Introductionmentioning

confidence: 78%

“…Reichard et al [17] reported emergence times for captured individuals in different reproductive classes during early summer. Median emergence time for lactating bats, which were the majority of captured bats (65%) in that season, was 47 minutes after sunset [17].…”

Section: Discussionmentioning

confidence: 99%

Climate and Weather Impact Timing of Emergence of Bats

et al. 2012

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“…The later emergence of mature females could be explained by optimal foraging theory. Roost departure by the female bats is widely discussed as a functional trade off between predation risk and food requirements according to their reproductive state (Reichard et al 2009;Lima and O'Keefe 2013). Predation risk from rap torial birds is well known in bats and is suggested to be more intense at dusk (Jones and Rydell 1994;Duvergé et al 2000).…”

Section: Discussionmentioning

confidence: 99%

Timing of Cave Emergence and Return in the Dawn Bat (Eonycteris spelaea, Chiroptera: Pteropodidae) in Southern Thailand

et al. 2015

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“…The high frequency of incidents from August to October (≥ 30 incidents/month) agrees with Peurach et al (2009) who documented bat incidents with USAF aircraft occurred most frequently during August-October. Bat parturition occurs in early summer and young begin to emerge from roosts in July (Reichard et al, 2009). Thus, the greater number of incidents reported in August may be explained by the greater number of juvenile bats.…”

Section: Discussionmentioning

confidence: 99%