Many animals mimic the behavior or the appearance of venomous snakes. When humans or other potential predators place their hand near the nest of tits belonging to the family Paridae (and a few other species), the incubating female performs a hissing display that mimics the inhalation hiss of a viper or another snake. They hiss vigorously while lunging their head forward and shaking their wings and tail, repeating this behavior several times. The structure of the hiss in tits is similar to that of the inhalation hiss of a snake, providing evidence of significant convergence of the mimic toward the model. The behavior of individual females is repeatable among trials. Individuals that flew away from their nest box only performed the hissing display on 6% of later trials, when present at their box, whereas individuals that did not fly away hissed on 28% of occasions, consistent with great tits Parus major either cautiously flying away or staying put on their nest while actively defending it. Individuals that flew away produced fewer chicks than individuals that stayed and hissed. The hissing display was more common when snakes were more abundant: 1) When breeding late during the season; 2) when breeding at sites with more snakes; and 3) when breeding in subtropical and tropical China with a higher abundance of snakes than in Denmark with a lower abundance. The frequency of nest predation was higher in sites with no snakes, and the frequency of predation increased with decreasing frequency of hissing display. These findings are consistent with expectations for frequency-dependent selection acting on snake mimicry.

中文翻译：

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繁殖山雀中的行为蛇模仿

许多动物模仿毒蛇的行为或外观。当人类或其他潜在的掠食者将手放到Paridae家族（和其他一些物种）的山雀巢附近时，正在孵化的雌性会发出嘶嘶声，模仿毒蛇或另一条蛇的吸入嘶嘶声。他们猛烈嘶嘶，同时向前ing着头，摇动翅膀和尾巴，多次重复这种行为。雀的嘶嘶声的结构类似于蛇的吸入嘶嘶声的结构，为模仿物向模型的明显收敛提供了证据。在试验中，女性个体的行为是可重复的。从巢箱飞走的人只有在以后的试验中有6％的时候才发出嘶嘶声，帕鲁斯少校会小心翼翼地飞走，或者在积极防御时留在巢穴中。飞走的个体产生的雏鸡少于呆着和嘶嘶的个体。当蛇数量更多时，嘶嘶声的显示更为普遍：1）在季节后期繁殖时；2）在蛇多的地方繁殖。（3）在亚热带和热带地区，蛇的数量要比在丹麦的数量少的丹麦高。在没有蛇的地方，巢捕食的频率更高，并且随着嘶嘶声显示频率的降低，捕食的频率也增加。这些发现与对模仿蛇的频率依赖性选择的期望是一致的。