An account of an extreme heat event at a flying-fox roost in New South Wales, Australia: impacts and mitigation

Extreme heat events can have serious impacts on wildlife, and this is especially concerning as the frequency, intensity, and duration of these events are expected to increase with ongoing climate change. In Australian flying-foxes, Pteropus spp., heat stress-related mass mortality is highly correlated with exposure to air temperatures ≥ 42°C. Young Grey-headed Flying-foxes (Pteropus poliocephalus) are dependent on their mothers for milk during their first 3 months of life, and this coincides with the austral summer. Extreme heat events particularly affect young individuals and lactating females, and so these events can have disproportionate effects on recruitment and the effective breeding population – two key parameters for conservation. In this study we provide a detailed account of an extreme heat event that occurred at a permanently occupied Grey-headed Flying-fox roost in Campbelltown, NSW. This account includes documentation of animal movements during the extreme heat event and its aftermath, reports on the weather conditions throughout the day, and provides two independent methods for estimating the number of individuals that died from the extreme heat event. Additionally, a sprinkler trial was conducted at the focal roost to test the efficacy of sprinklers in heat stress mitigation, and we provide an assessment of how the sprinklers affected the microclimatic conditions of the roost during extreme heat conditions. This extreme heat event resulted in the death of flying-foxes at the focal roost and at other flying-fox roosts in the greater Sydney and Hunter regions.
This dataset contains 3 files that pertain to weather data recorded on the 09th December 2023: two .csv files that include the data from a) weather stations, and b) data logger arrays, and one .txt file that describes the variables in each of the csv files.

The “WEATHERSTATION_DATA.csv” file represents the data collected using Davis Pro 2 weather stations that were installed at the two sprinkler sites (Site A and Site B) and a control site that was not subject to the sprinklers (Control).

The “ARRAY_DATA.csv” file represents the data collected using data loggers deployed at ten locations within the vegetation occupied by flying-foxes. At each of the ten locations, data loggers were installed at four vertical heights (0, 1.5, 3 and 6 m), for a total of n = 40 data loggers. Kestrel Drops (D2) were used (Kestrel, AU), and housed in plastic Stevenson’s screens. Kestrel D2 Drops (Ta resolution: 0.1° C; RH: 0.1%; dewpoint = 0.1° C) were calibrated in an incubator at four temperature points (15, 25, 35 and 45° C) against a standardised high precision digital thermometer (Platinum Ultra-Accurate Digital Thermometer, Model 6413CC, Traceable, Texas, USA). A linear regression was fitted to explain measured temperature as a function of logger temperature, and the intercept and slope of this equation was used to adjust the data for each logger.

极端高温事件可对野生动物造成严重危害，且随着气候变化持续发展，此类事件的发生频率、强度与持续时长预计均会上升，这一趋势尤为令人担忧。针对澳大利亚狐蝠属（Pteropus spp.）物种而言，热应激相关的大规模死亡与暴露于≥42℃的气温高度相关。幼年灰头狐蝠（Pteropus poliocephalus）在出生后的前3个月完全依赖母蝠乳汁存活，而这一阶段恰好与澳大利亚夏季重合。极端高温事件对幼体和泌乳雌性个体的影响尤为突出，因此此类事件会对种群补充与有效繁殖种群——这两项保护工作的核心参数——产生不成比例的冲击。本研究详细记录了发生在新南威尔士州坎贝尔敦一处常年被灰头狐蝠占据的夜栖地的极端高温事件，内容涵盖极端高温事件发生期间及灾后的蝙蝠活动记录、当日全天的气象状况报告，并提供了两种独立方法以估算此次极端高温事件导致的个体死亡数量。此外，研究团队在该目标夜栖地开展了喷淋试验，以检验喷淋装置缓解热应激的效果，并评估了极端高温条件下喷淋装置对夜栖地微气候条件的影响。此次极端高温事件造成了目标夜栖地以及大悉尼和亨特地区其他狐蝠夜栖地内的狐蝠死亡。

本数据集包含3份与2023年12月9日记录的气象数据相关的文件：两份.csv格式文件，分别包含a）气象站采集数据，以及b）数据记录仪阵列采集数据；另有一份.txt格式文件，用于说明每份CSV文件中的变量含义。

"WEATHERSTATION_DATA.csv"文件对应两套安装在喷淋布设站点（A站点与B站点）以及一处未设置喷淋的对照站点（Control）的Davis Pro 2气象站所采集的数据。

"ARRAY_DATA.csv"文件对应部署在狐蝠栖息植被内10个位置的数据记录仪所采集的数据。在这10个位置中，每个位置均在4个垂直高度（0米、1.5米、3米和6米）处安装了数据记录仪，总计布设n=40台数据记录仪。本次使用的Kestrel Drops（D2型，澳大利亚Kestrel公司生产）被安置在塑料制斯蒂芬森防辐射罩（Stevenson’s screens）内。Kestrel D2型测温仪（温度分辨率：0.1℃；相对湿度（RH）分辨率：0.1%；露点温度分辨率：0.1℃）曾在恒温箱中以4个温度点（15℃、25℃、35℃和45℃）进行校准，校准对照物为经标准化处理的高精度数字温度计（Platinum Ultra-Accurate Digital Thermometer，型号6413CC，Traceable品牌，美国得克萨斯州生产）。研究人员通过拟合线性回归方程，以记录仪测得温度为自变量解释实测温度，并利用该方程的截距和斜率对每台记录仪的原始数据进行校正。