Nightly selection of resting sites and group behavior reveal antipredator strategies in giraffe
Nightly selection of resting sites and group behavior reveal antipredator strategies in giraffe
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DOI：
10.1002/ece3.6106
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发表时间：
2020-03-01
影响因子：
2.6
通讯作者：
Dierkes, Paul W.
中科院分区：
文献类型：
--
作者：
Burger, Anna Lena;Fennessy, Julian;Dierkes, Paul W.
这项研究首次发现了野生安哥拉长颈鹿的夜间行为模式。我们描述了它们的夜间行为，并分析了群体大小、季节和栖息地利用等生态因素的影响。在纳米比亚奥卡普卡牧场，人们使用夜视系统和热成像相机观察长颈鹿。在2016年7月至8月（旱季）和2017年2月至3月（雨季）的两个不同时期的24个夜晚，共观察到77只长颈鹿。光周期对它们的活动和运动行为有显著影响。黄昏时，长颈鹿减少了移动的时间，并在黑暗来临时躺下睡觉。长颈鹿坐下后15.8 +/- 18.3分钟观察到可能对应于快速眼动（REM）睡眠姿势（RSP）的身体姿势。季节对旱季的RSP阶段有显着影响（旱季：155.2 +/- 191.1 s，n = 79;雨季：85.8 +/- 94.9 s，n = 73）。进一步分析的社会行为模式的影响，并没有显示组的大小对RSP长度的影响。当一群长颈鹿在一个特定的休息地点休息时，几个人保持警惕，而其他成员则坐下或拿起RSP。很少观察到一组内同时发生RSP事件。栖息地的特点是在开阔的地方有单一的树木或稀疏的灌木丛，在相对隐蔽的地方有良好的能见度。
This study presents the first findings on nocturnal behavior patterns of wild Angolan giraffe. We characterized their nocturnal behavior and analyzed the influence of ecological factors such as group size, season, and habitat use. Giraffe were observed using night vision systems and thermal imaging cameras on Okapuka Ranch, Namibia. A total of 77 giraffe were observed during 24 nights over two distinct periods-July-August 2016 (dry season) and February-March 2017 (wet season). Photoperiod had a marked influence on their activity and moving behavior. At dusk, giraffe reduced the time spent moving and increasingly lay down and slept at the onset of darkness. Body postures that likely correspond to rapid eye movement (REM) sleep posture (RSP) were observed 15.8 +/- 18.3 min after giraffe sat down. Season had a significant effect with longer RSP phases during the dry season (dry: 155.2 +/- 191.1 s, n = 79; wet: 85.8 +/- 94.9 s, n = 73). Further analyses of the influence of social behavior patterns did not show an effect of group size on RSP lengths. When a group of giraffe spent time at a specific resting site, several individuals were alert (vigilant) while other group members sat down or took up RSP. Simultaneous RSP events within a group were rarely observed. Resting sites were characterized by single trees or sparse bushes on open areas allowing for good visibility in a relatively sheltered location.