The northern bobwhite (Colinus virginianus; bobwhite) exists at the edge of its thermal tolerance in southern Texas, USA, a region characterized by extreme heat and periodic drought. Extreme heat and drought events are predicted to increase in frequency and intensity in semi‐arid regions, leading biologists to emphasize management of thermal cover. The degree to which temperatures within patches of woody vegetation vary and the specific vegetation structural characteristics that create cooler microclimates within these patches are unknown. We evaluated temperature variation between selected and available sites, vegetation characteristics facilitating cooler microsites, and whether these characteristics in addition to temperature were important predictors of microsite selection within woody patches. We radio‐tracked 83 bobwhites 2–3 times/week during April–August 2017–2018. We recorded operative and ground surface temperatures and measured woody and herbaceous vegetation height, canopy density, and overlapping woody and herbaceous cover at used and paired random locations. Within the same woody patch, 80% of used locations contained operative temperatures lower than or equal to random locations. There was a weak relationship between the vegetation variables we measured and temperature at paired locations, indicating that none of the vegetation variables alone can effectively reduce temperatures. Temperatures within woody patches are likely strongly tied to diurnal variation in solar angle and ability to create shade. Cooler temperatures, dense canopies, and overlapping woody vegetation had the greatest effects on relative probability of microsite use during the middle of the day, whereas warmer temperatures and taller woody vegetation had the greatest relative effects during the morning and evening. Our results suggest that temperature was influential across diurnal periods but foraging and predation avoidance may have also been important. Maintenance and preservation of dense woody vegetation and diverse shrub understories must be prioritized in habitat management for bobwhites in semi‐arid regions. © 2021 The Wildlife Society.

中文翻译：

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植被结构特征为北鲍勃怀特群岛提供热庇护

北方鲍勃怀特（Colinus virginianus; bobwhite）位于美国得克萨斯州南部的热容边缘，该地区以极热和周期性干旱为特征。预计半干旱地区的极端高温和干旱事件会增加频率和强度，从而促使生物学家强调对热量覆盖的管理。尚不清楚木质植被斑块内温度的变化程度以及在这些斑块内产生凉爽微气候的特定植被结构特征。我们评估了选定站点与可用站点之间的温度变化，有利于凉爽微站点的植被特征，以及温度以外的这些特征是否是木质斑块内微站点选择的重要预测指标。在2017年4月至8月期间，我们每周2至3次以无线电方式跟踪83个bobwhite。我们记录了操作和地面的温度，并测量了木质和草本植物的高度，冠层密度以及在使用过的和成对的随机位置处木质和草本覆盖物的重叠。在同一个木质林地中，80％的使用位置所包含的工作温度低于或等于随机位置。在配对位​​置处，我们测量的植被变量与温度之间的关系很弱，这表明没有任何一个植被变量可以有效地降低温度。木本斑块内的温度很可能与日照角度的日变化和形成阴影的能力密切相关。温度较低，树冠茂密和木质植被重叠对中午使用微型站点的相对概率影响最大，而较高的温度和较高的木本植被在早晨和傍晚具有最大的相对影响。我们的研究结果表明温度在整个昼夜期间都具有影响力，但觅食和避免捕食也可能很重要。在半干旱地区，对短白粉虱的栖息地管理必须优先考虑维持和保护茂密的木本植被和各种灌木林。©2021野生动物协会。