Torpor in an African caprimulgid, the freckled nightjar Caprimulgus tristigma

McKechnie, Andrew E.; Ashdown, Robert A. M.; Christian, Murray; Brigham, R. Mark

doi:10.1111/j.0908-8857.2007.04116.x

Cited by 16 publications

(28 citation statements)

References 18 publications

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“…This produced torpor thresholds from 22 to 29°C, which resulted in measurements of torpor durations that were much shorter. Similar to other studies (Willis et al, ), our results suggest that females can use torpor for extended periods post‐hibernation, in which current methods used to define torpor based on T sk (Barclay et al, ; McKechnie et al, ) are not always suitable for measuring torpor patterns during reproduction. Establishing concurrent measures of metabolic rates or T b with T sk to extrapolate a threshold (Willis, ) may better quantify the effect of intrinsic and weather variables on torpor patterns.…”

Section: Discussionsupporting

confidence: 87%

“…Additionally, metabolically determined thresholds cannot be inferred from T sk without T b measurements (Willis, ). Some individuals in our study maintained low T sk (i.e., <32°C) for prolonged periods and a threshold based on the active temperature (Barclay, Lausen, & Hollis, ) or the modal method (McKechnie et al, ) may underestimate torpor use. We defined a threshold as 3°C less than the 80th percentile of all T sk for each individual as this yielded the most reasonable threshold for all individuals.…”

Section: Methodsmentioning

confidence: 77%

“…Interindividual variation in torpor use may have implications for fitness as differences in the timing of parturition and weaning may have different consequences for offspring survival (Frick, Reynolds, & Kunz, ; Kunz, Wrazen, & Burnett, ). Additionally, current methods of defining a torpor threshold may over‐or underestimate torpor use in some individuals (Barclay et al, ; McKechnie et al, ), which may influence the effect of reproductive condition and individual on some torpor patterns. Our study illustrates the importance of including individual effects within reproductive condition when explaining thermoregulatory strategies, which may be useful for understanding how individuals of populations will respond to environmental fluctuations or disease.…”

Section: Discussionmentioning

confidence: 99%

“…Current methods for defining a torpor threshold based on T sk are biased for at least some individuals as transmitter readings of T sk may result in differences from T b up to 6°C (McKechnie, Ashdown, Christian, & Brigham, ; Willis, ). Additionally, metabolically determined thresholds cannot be inferred from T sk without T b measurements (Willis, ).…”

Section: Methodsmentioning

confidence: 99%

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Combinations of reproductive, individual, and weather effects best explain torpor patterns among female little brown bats (Myotis lucifugus)

Besler

Broders

2019

Ecology and Evolution

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Heterothermic mammals can use torpor, a state of metabolic suppression, to conserve energy during times of limited food and poor environmental conditions. Females may use torpor throughout gestation and lactation; however, there are associated physiological and ecological costs with potential fitness consequences. Previous studies have controlled for, but not quantified the impact of interindividual variation on torpor patterns and understanding this may provide insight on why certain thermoregulatory responses are employed. The objective of this study was to identify and quantitatively characterize the intrinsic variables and weather conditions that best explain variation in torpor patterns among individual female little brown bats, Myotis lucifugus . We used temperature‐sensitive radio‐transmitters affixed to females to measure skin temperature patterns of 35 individuals roosting in bat boxes in the spring and summer. We used Bayesian multi‐model inference to rank a priori‐selected models and variables based on their explanatory power. Reproductive condition and interindividual effects best explained torpor duration and depth, and weather best explained torpor frequency. Of the reproductive conditions, lactating females used torpor for the shortest durations and at shallower depths (i.e., smallest drop in minimum T sk ), while females in early spring (i.e., not‐obviously‐pregnant) used torpor for the longest and deepest. Among individuals, the greatest difference in effects on duration occurred between pregnant individuals, suggesting interindividual variation within reproductive condition. Increases in precipitation and wind were associated with a higher probability of torpor use. Our results provide further support that multiple variables explain torpor patterns and highlight the importance of including individual effects when studying thermoregulatory patterns in heterothermic species. OPEN RESEARCH BADGES This article has earned an Open Data Badge for making publicly available the digitally‐shareable data necessary to reproduce the reported results. The data is available at https://doi.org/10.5061/dryad.c04tj85 .

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Section: Discussionsupporting

confidence: 87%

Section: Methodsmentioning

confidence: 77%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Combinations of reproductive, individual, and weather effects best explain torpor patterns among female little brown bats (Myotis lucifugus)

Besler

Broders

2019

Ecology and Evolution

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“…One additional male in winter 2010 and three males and four females in winter 2011 did not return to the roosts where they had been captured, likely due to the disturbance to the animals. We distinguished normothermy from torpor using the method proposed by McKechnie et al (2007) as modified by Wojciechowski and Pinshow (2009). This method assumes that normothermic T b during the resting phase is normally distributed and centered on the modal resting T b value.…”

Section: Measurementsmentioning

confidence: 99%

Winter and Summer Torpor in a Free-Ranging Subtropical Desert Bat: The Fishing Myotis (Myotis vivesi)

Salinas

Herrera

Flores‐Martínez

et al. 2014

Acta Chiropterologica

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Heterothermy in two mole‐rat species subjected to interacting thermoregulatory challenges

Boyles

Verburgt²,

McKechnie³

et al. 2011

J. Exp. Zool.

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Maintaining a high and constant body temperature (T(b) ) is often viewed as a fundamental benefit of endothermy, but variation in T(b) is likely the norm rather than an exception among endotherms. Thus, attempts to elucidate which factors cause T(b) of endotherms to deviate away from the T(b) that maximizes performance are becoming more common. One approach relies on an adaptive framework of thermoregulation, used for a long time to predict variation in T(b) of ectotherms, as a starting point to make predictions about the factors that should lead to thermoregulatory variation in endotherms. Here we test the predictions that when confronted with thermoregulatory challenges endotherms should (1) become more heterothermic, (2) lower their T(b) setpoint, and/or (3) increase behavioral thermoregulation (e.g., activity levels or social thermoregulation). We exposed two species of relatively homeothermic mole-rats to two such challenges: (a) ambient temperatures (T(a)) well below the thermoneutral zone and (b) increased heat loss caused by the removal of dorsal fur. In general, our results support the adaptive framework of endothermic thermoregulation with each species conforming to some of the predictions. For example, Mashona mole-rats (Fukomys darlingi) increased heterothermy as T(a) decreased, highveld mole-rats (Cryptomys hottentotus pretoriae) displayed lower T(b) 's after shaving, and both species increased behavioral thermoregulation as T(a) decreased. This suggests that there is some merit in extending the adaptive framework to endotherms. However, none of the three predictions we tested was supported under all experimental conditions, reiterating that attempts to determine universal factors causing variation in T(b) of endotherms may prove challenging.

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Torpor in an African caprimulgid, the freckled nightjar Caprimulgus tristigma

Cited by 16 publications

References 18 publications

Combinations of reproductive, individual, and weather effects best explain torpor patterns among female little brown bats (Myotis lucifugus)

Combinations of reproductive, individual, and weather effects best explain torpor patterns among female little brown bats (Myotis lucifugus)

Winter and Summer Torpor in a Free-Ranging Subtropical Desert Bat: The Fishing Myotis (Myotis vivesi)

Heterothermy in two mole‐rat species subjected to interacting thermoregulatory challenges

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