Shrews use several different call types for communication. In previous studies, two call types have been additionally associated with a possible function for echolocation: ultrasonic click-like emissions and sonic twittering calls. There is anecdotal evidence that the rate of shrew twittering calls is high in unfamiliar environments and lower in familiar ones. Here we quantitatively tested this assumption for the first time. In a simple laboratory experiment, we confronted three different shrew species with environments of different degrees of novelty. We could show that the twittering call rate indeed decreased with increasing familiarity with the environment. In a separate experiment, we tested if shrews would increase twittering call rate after a stressful event, which they did not. The finding of an increased call rate inside a novel environment that is not caused by stress is in line with the hypothesis of a very basic echolocation-like system in shrews, as also bats increase their echolocation call rate in novel environments. However, it is not in full agreement with the hypothesis that twittering in shrews mainly has a function for communication, as in territorial signalling, call rates are usually higher in familiar than in unfamiliar environments. Call rates did not change after a small structural alteration inside the familiar environment, suggesting that shrews use their twittering calls not for a fine-tuned echolocation like bats, but rather a coarse acoustic orientation in their surroundings (‘echo-orientation’). Certainly, echo-orientation and communication might be two parallel, non-mutually exclusive functions of shrew twittering.

中文翻译：

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在新颖的环境中，rew鸣叫的呼叫率很高-一项实验室研究

rew使用几种不同的呼叫类型进行通信。在先前的研究中，另外两种呼叫类型已与可能的回声定位功能相关联：类似超声点击的发射和声音鸣叫呼叫。有轶事证据表明，在不熟悉的环境中，rew叫的电话发生率很高，而在熟悉的环境中，则较低。在这里，我们首次对这一假设进行了定量测试。在一个简单的实验室实验中，我们面对了三种不同的sh物种，它们具有不同程度的新颖性环境。我们可以证明，随着对环境的熟悉程度的提高，twittering呼叫率确实下降了。在一个单独的实验中，我们测试了在压力事件发生后，sh是否会提高twitter的呼叫率，但不会。在新环境中发现不是由压力引起的呼率升高的发现与sh中非常基本的类似回声定位系统的假设相符，蝙蝠在新环境中也增加了它们的回声定位呼率。但是，与sh的推特主要具有通信功能这一假设并不一致，因为在区域信令中，熟悉的呼叫率通常比不熟悉的环境要高。在熟悉的环境中进行了微小的结构更改后，通话速率没有变化，这表明sh使用其twitter叫声不是为了像蝙蝠这样的微调回声定位，而是在周围环境中进行粗糙的声学定向（“回声定向”）。当然，回声定向和通信可能是两个平行的，