Investigation on how the combination of heat and humidity affect forest hornbill thermoregulation

Twenty eight trumpeter hornbills (Bycanistes bucinator) using mist nets (Avinet Nylon 100-mm mesh, Denier/ply 210/4, 5 shelves, 3 m height) in the lowland coastal forests of KwaZulu-Natal province, South Africa, in the towns of St Lucia, Richard’s Bay and Mtunzini (28.3726° S, 32.4142° E – 28.9597° S, 31.7501° E) within the Indian Ocean coastal belt biome (Rutherford et al., 2006). Once caught, birds were transported in clean large cotton pillowcases (for ≤ 1 h) to temporary outdoor aviaries (2 x 2 x 2 m) where they were housed in family groups when >1 individual was kept at a time. The researcher obtained data for 16 males and 12 females.Average surface temperature measurements of the beak and skin regions were extracted from thermal images using the ThermaCam software (ThermaCAM Researcher Pro 2.9, FLIR Systems Inc, Wilsonville). The polygon and line functions were used to specify the region where surface temperature was to be measured. Mean temperatures across the beak were extracted. I tested whether surface temperatures of the distal, proximal, upper, lower and casque sections of the beak differed significantly at increasing Tair, and found no significant difference. As such, all surface temperature measurements of the beak and casque were pooled and averaged for every 1°C of Tair for each bird. Values of Tbeak consist of a mean ± SD of these Ts readings from across the beak and were used in further analyses.

在南非夸祖鲁-纳塔尔省的低地沿海森林中，即圣卢西亚、理查德湾和姆图津齐尼（南纬28.3726°，东经32.4142°至南纬28.9597°，东经31.7501°）的区域内，采用迷彩网（Avinet 尼龙100毫米网眼，线密度/层210/4，5层，3米高）捕捉了28只犀鸟（Bycanistes bucinator）。一旦捕获，这些鸟类被置于清洁的大号棉质枕套中（不超过1小时）并运送至临时的户外鸟类栖息地（2 x 2 x 2米），若同时饲养多于一只个体，则按家族群体进行饲养。研究人员对16只雄性和12只雌性进行了数据采集。通过ThermaCam软件（ThermaCAM Researcher Pro 2.9，FLIR Systems Inc，威尔逊维尔）从热像图中提取了喙部和皮肤区域的平均表面温度测量值。使用多边形和线条功能指定表面温度测量的区域，并从喙部提取了平均温度。我测试了在逐渐升高的空气温度（Tair）下，喙部远端、近端、上端、下端和盔状部分的表面温度是否存在显著差异，发现并无显著差异。因此，将喙部和盔状部分的表面温度测量值合并并平均，以每只鸟的每1°C的Tair为基准。Tbeak的值包括从喙部各点读取的Ts的平均值和标准差，这些值被用于后续分析。