Some songbirds have such fine control over the multiple muscles in both sides of their syrinx that they can produce different sounds at the same time, in essence, singing a duet with themselves.

好厉害！！

目前觉得这本书还挺好的，但是作为一本介绍鸟类的书过于 human-centric 了，举几个例子：
“These penguins can dive deeper and longer than any other bird and can tolerate extremely low levels of oxygen in their blood—far below those that would render a human unconscious.”
“Bar-headed geese sustain the high oxygen demands of flight in air that is so thin that even the most elite human athletes can barely walk in it.”
“collaborate on tasks in a way we previously thought was possible only in humans.”
“It was once thought that the hearing of birds was limited to a smaller frequency range than human hearing.”
“spontaneity and diversity of movement to music are not uniquely human.”
“These more precisely coordinated, complex duets are the closest analogue we have in the animal world to the structure of human conversation.”
？？到底为什么大大小小的事都要拿来跟人类比啊？人类是全能吗？是标杆吗？你物种多样性比得上动物吗，就在这里乱猜测乱惊讶。人类，不行。

In human speech, words referring to a specific object usually evoke a visual mental image. Think moon or dog or snake. Suzuki found evidence that Japanese tit alarm calls create just this kind of search image in the heads of listening birds. The tit’s jar call causes the birds to search for snakes and to become more visually responsive to any object resembling a snake. It was the first evidence that a non-human animal could visualize something referred to in a vocalization.

人类啊，啧啧啧，能不能不要这么自以为是

读到鸟儿能在危险来临的时候发出警告，而警告声里包含丰富的信号，包括捕食者是在陆地上还是在空中、体型是大还是小。而人类在危险来临的时候貌似只会尖叫，尖叫声里不包含任何有效信息。但在山区和丛林里就不一样了，那里的人们会用口哨和歌唱声来传达信息。
我读到这儿想的就是人类也没那么烂嘛，只不过有些技能只在特定环境下才需要而已。
结果作者紧接着：

If humans can encode all those specific messages in whistles, why not birds?

我惊呆了，这说的什么屁话啊，感情刚才举的人类例子仅仅是为了帮助理解鸟儿的能力啊？不是，鸟儿有点厉害技能这么让人不能理解吗？真就一定要跟人类比啊？反过来说，if birds can fly, why not humans? 这话有任何逻辑吗？
虽然书里的知识很好，但我也太不喜欢这个作者的视角了。

For centuries, it was thought that male songbirds alone used song as they used fancy plumage and elaborate tails, to attract females and compete with rival males. The female role was to listen and choose and, in so doing, exert influence through sexual selection, driving the evolution of elaborate singing by preferring males with ever more melodious and complex songs. This was considered a classic example of the power of sexual selection to generate extreme sex differences in brain and behavior. Instances of female song were largely dismissed as atypical—rare exceptions or the outcome of hormonal abnormalities.
All that changed when the international team of researchers led by Karan Odom surveyed the occurrence of female song in 1,141 species from all over the world. The team suspected that male-only song was not the whole story by any stretch. Most songbird species live in tropical regions, which have been less studied. And female song is more common in Australia and surrounding areas, where songbirds originated. There, it’s a much more egalitarian setup. Sure enough, the results of the study, published in 2014, showed that female song occurs in more than two-thirds of surveyed songbird species and families—and that it’s structurally similar to male songs (long and complex) and used for similar purposes. In the songs of male and female superb starlings of eastern Africa, for instance, there’s no difference in the structure or the number of motifs that each sex sings. Both sexes in this highly social species sing all year long and may do so to signal identity and establish rank within their groups. The study made it clear: Birdsong is not just a male thing. And elaborate song did not evolve just through sexual selection—females choosing males for their vocal prowess—but through the broader process of social selection: both sexes competing for food, nest sites, territories, and mates.

No wonder birds have evolved numerous strategies for raising alarm. [...] Sometimes the warning isn’t a sound at all but the silence between sounds. When noisy, social birds like red-winged blackbirds suddenly get quiet, it’s a strong signal there’s danger nearby.

最怕空气突然安静​​

Crows are among the most frequent mobbers, [...]. Gulls often resort to the practice, too, with anunusual twist: vomiting on the predator with keen aim. Colonies offieldfares fire from another orifice, ejecting feces on a predator insuch volume and with such accuracy that the threatening creature isliterally grounded or stopped in its tracks. If enough of thesedroppings-bombs hit their target, they can soak a bird’s wings so itcan’t fly.

​丢粪攻击太可怕了吧