10.5061/DRYAD.1R2B0
O'Connor, Ryan S.
University of Pretoria
Brigham, R. Mark
University of Regina
McKechnie, Andrew E.
University of Pretoria
Data from: Diurnal body temperature patterns in free-ranging populations
of two southern African arid-zone nightjars
Dryad
dataset
2017
Hyperthermia
adaptive thermoregulation
2017-05-24T14:19:43Z
2017-05-24T14:19:43Z
en
https://doi.org/10.1111/jav.01341
2439473 bytes
1
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Endotherms allocate large amounts of energy and water to the regulation of
a precise body temperature (Tb), but can potentially reduce
thermoregulatory costs by allowing Tb to deviate from normothermic levels.
Many data on heterothermy at low air temperatures (Ta) exist for
caprimulgids, whereas data on thermoregulation at high Ta are largely
absent, despite members of this taxon frequently roosting and nesting in
sites exposed to high operative temperatures. We investigated
thermoregulation in free-ranging Rufous-cheeked Nightjars (Caprimulgus
rufigena) and Freckled Nightjars (Caprimulgus tristigma) in the southern
African arid zone. Individuals of both species showed labile Tb
fluctuating around a single modal Tb (Tb-mod). Average Tb-mod was 39.7 °C
for Rufous-cheeked Nightjars and 39.0 °C for Freckled Nightjars. In both
species, diurnal Tb increased with increasing Ta. At Ta ≥ 38 °C,
Rufous-cheeked Nightjar mean Tb increased to 42 °C, equivalent to 2.3 °C
above Tb-mod. Under similar conditions, Freckled Nightjar Tb was on
average only 1.1 °C above Tb-mod, with a mean Tb of 40.0 °C. Freckled
Nightjars are one of the most heterothermic caprimulgids investigated to
date, but our data suggest that during hot conditions this species
maintains Tb within a narrow range above Tb-mod, possibly reflecting an
evolutionary tradeoff between decreased thermal sensitivity to lower Tb
but increased sensitivity to high Tb. These findings reveal how general
thermoregulatory patterns at similar Ta can vary even among closely
related species.
O'Connor_et_al_2017_DataTb data from free-ranging rufous-cheeked and
freckled nightjars