National Wildlife Research Center, Animal Plant Health Inspection Service, US Department of Agriculture, 4101 LaPorte Avenue, Fort Collins, CO 80521, USA.
National Wildlife Research Center, Animal Plant Health Inspection Service, US Department of Agriculture, 4101 LaPorte Avenue, Fort Collins, CO 80521, USA.
Sci Total Environ. 2020 May 20;718:137380. doi: 10.1016/j.scitotenv.2020.137380. Epub 2020 Feb 18.
Impacts of large-scale oil spills on avian species are far-reaching. While media attention often focuses on lethal impacts, sub-lethal effects and the impacts of rehabilitation receive less attention. The objective of our study was to characterize effects of moderate external oiling and subsequent rehabilitation on feather structure and thermoregulation in gulls. We captured 30 wild ring-billed gulls (Larus delawarensis) and randomly assigned each individual to an experimental group: 1) controls, 2) rehabilitated birds (externally oiled, rehabilitated by washing), or 3) oiled birds (externally oiled, not rehabilitated). We externally oiled birds with weathered MC252 Deepwater Horizon oil (water for controls) and collected feathers and thermography imagery (FLIR) approximately weekly for four weeks to investigate feather structure (quantified using a barbule clumping index) and thermoregulatory ability (characterized by internal body temperature and external surface temperature). Post-oiling feather clumping was significantly higher in oiled and rehabilitated birds compared to controls, but steadily declined over time in both groups. However, feather microstructure in rehabilitated birds was indistinguishable from controls within three weeks of washing whereas the feathers of oiled birds were still significantly clumped a month post oiling. Internal body temperatures didn't differ in any of the groups, suggesting birds maintain thermoregulatory homeostasis in spite of moderate external oiling. External temperatures for rehabilitated birds didn't differ from controls within a week of rehabilitation. Overall, rehabilitation procedures were effective and washed birds were in better condition compared to non-rehabilitated, oiled birds. This study provides evidence that the benefits of rehabilitation for moderately oiled birds likely outweigh the costs with regard to feather structure and thermoregulation. While feather preening and time were insufficient to reestablish baseline fine scale feather structure in moderately oiled birds, the significant clumping reduction over time may indicate that rehabilitation of lightly oiled birds may not be necessary and deserves further study.
大规模石油泄漏对鸟类物种的影响是深远的。尽管媒体的注意力通常集中在致命影响上，但亚致死效应和康复的影响却较少受到关注。我们研究的目的是描述中度外部油污和随后的康复对海鸥羽毛结构和体温调节的影响。我们捕获了 30 只野生环嘴鸥（Larus delawarensis），并将每个个体随机分配到一个实验组：1）对照组，2）康复组（外部油污，通过清洗康复），或 3）油污组（外部油污，未康复）。我们用风化的 MC252 深海地平线石油（对照组用水）对鸟类进行外部油污处理，并在四周内每周收集一次羽毛和热成像图像（FLIR），以研究羽毛结构（用羽枝簇指数量化）和体温调节能力（由内部体温和外部表面温度特征化）。与对照组相比，油污和康复组的羽毛簇在油污后明显更高，但在两组中随时间的推移逐渐下降。然而，在清洗后三周内，康复组的羽毛微观结构与对照组无法区分，而油污组的羽毛仍然明显簇集一个月后。在任何一组中，内部体温都没有差异，这表明鸟类尽管受到中度外部油污的影响，但仍能维持体温调节的内稳态。在康复后的一周内，康复组的外部温度与对照组没有差异。总体而言，康复程序是有效的，与未康复的、油污的鸟类相比，清洗后的鸟类状况更好。这项研究提供了证据，表明康复对中度油污鸟类的好处可能超过了羽毛结构和体温调节方面的成本。虽然羽毛梳理和时间不足以使中度油污鸟类重新建立基线的精细羽毛结构，但随着时间的推移，羽毛簇的显著减少可能表明轻度油污鸟类的康复可能不是必要的，值得进一步研究。
