最后一个问题:斑头雁能飞多高?
看上图,上图是斑头雁的静脉血氧分压数据,黑点是正常情况,蓝点是中度缺氧状态,红点是高度缺氧状态。在高度缺氧的情况下,静脉血氧值也有25mmHg,说明了斑头雁一直保留血氧储备,在9000米高空飞行时也没有受到血氧的限制。或者说,斑头雁在珠峰上没有受到氧气稀薄的困扰,它还有潜能飞得更高。
天高任鸟飞,珠峰不是斑头雁的极限,天空才是它的尽头。
参考资料:
1: “Reduced metabolism supports hypoxic flight in the high-flying bar-headed goose (Anser indicus)”,by Jessica U Meir, etc. elife, Sep.3, 2019
2:“The paradox of extreme high-altitude migration in bar-headed geese Anser indicus”,Biological Sciences, the Royal Society, Jan.07, 2013
3:“How Bar-Headed Geese Fly Over the Himalayas”,Physiology, US National Library of Medicine, National Institutes of Health, Mar. 2015
4:“The roller coaster flight strategy of bar-headed geese conserves energy during Himalayan migrations”,Science 347: 250–254, 2015
5: “Control of breathing and the circulation in high-altitude mammals and birds”,Comp Biochem Physiol A Mol Integr Physiol.
6:“The trans-Himalayan flights of bar-headed geese (Anser indicus)”,PNAS 108:9516–9519.
附:今天更新自然界里的秘密系列文章,这是第8篇:高飞的鸟。