Movement ecology: the role of environmental cues and sensory mechanisms in bat navigation

蝙蝠是最神秘的动物之一。作为唯一的飞行哺乳动物，它们是夜行性的，这意味着我们很少看到它们。尽管如此，在整个欧洲，春天、夏天和秋天的每个晚上，蝙蝠都会从洞穴、树木和建筑物中的栖息地出发，寻找昆虫猎物。它们通过发出频率高于人类听力范围的声纳呼叫（“回声定位”）来探测这些声音。它们可能一夜之间活动数百公里，但必须在日出前返回栖息地以躲避捕食者。它们是如何实现这些非凡的导航壮举的仍然是一个谜。如果不尽快采取行动，它可能仍然是一个谜，因为蝙蝠物种在整个欧洲正在减少，尽管立法保护它们。蝙蝠提供了一种不常被认识到的重要服务：控制害虫。据估计，蝙蝠减少昆虫的经济价值可能超过数百万英镑，仅就杀虫剂而言。像许多其他物种一样，蝙蝠很容易受到栖息地破坏和其他人类引起的环境变化的影响。具有讽刺意味的是，为减轻人类对环境条件的改变而采取的一项措施正在导致其数量的减少。蝙蝠在“绿色电力”风力涡轮机上很容易受到碰撞。我们仍然不完全理解它们为什么这样做，令人惊讶的是，它们可以精确地探测到一只小飞虫，却无法避开如此巨大的结构。更多地了解它们的运动行为、感觉系统和蝙蝠用于导航的环境线索，以及诱导它们觅食或返回栖息地的环境条件，将有助于减轻这些威胁。不过，这是一个挑战，因为蝙蝠已经被证明很难在野外进行研究，所以我们对它们在觅食或迁徙途中的导航行为知之甚少。由于是夜行动物，它们比鸟类更难观察，因此研究它们导航能力的标准技术用处不大。然而，技术的进步使我们能够在了解蝙蝠如何在环境中移动方面迈出第一步，并有可能发现哪些环境线索对它们最重要。该项目将通过操纵蝙蝠对太阳和磁场等环境线索的感知来研究蝙蝠的导航行为，以了解它们如何相互作用，告诉动物在需要返回栖息地时向哪个方向飞行。通过了解蝙蝠用来导航的感觉系统，我们可以了解哪些环境线索对它们的运动很重要。这些知识可以用来帮助减轻人类对蝙蝠数量的影响。了解它们的行为将使我们能够预测它们何时何地移动，这将使风力涡轮机能够更好地放置和活动，以最大限度地减少对蝙蝠的干扰。它还将使我们能够了解蝙蝠在环境线索的可用性方面的运动模式，这将有助于预测其活动和栖息地要求的时间模式。虽然蝙蝠很少出现，也从未听说过，但如果我们失去了这个在环境平衡中至关重要的齿轮，我们肯定会想念它们。因此，我们必须了解它们的运动行为，以便我们采取行动，避免在我们的夜空中巡逻的蝙蝠数量进一步下降。

Bats are one of the most enigmatic groups of animals. The only flying mammal, they are nocturnal which means we rarely see them. Nevertheless, across Europe, every night through the spring, summer and autumn, bats range out from their roosts in caves, trees and buildings to forage for insect prey. They detect these by producing sonar calls ("echolocation") that are at a frequency high above the human range of hearing. They may range hundreds of kilometers in a night, but must return to their roost before sunrise to avoid predators. How they achieve these remarkable feats of navigation is still a mystery. If action is not taken soon it may remain a mystery as bat species are declining across Europe, despite legislation to protect them. Bats provide a vital service that is not often recognized: that of insect pest control. It has been estimated that the economic value of the reduction of insects by bats may be in excess of millions of pounds in terms of savings in pesticides alone. Like many other species, bats are vulnerable to habitat destruction and other human induced environmental changes. Ironically, one measure introduced to mitigate human change to environmental conditions is causing a reduction in their numbers. Bats are vulnerable to collisions at "green power" wind turbines. Still we do not understand fully why they do this, and it is surprising given the precision with which they can detect a small flying insect that they are unable to avoid such large structures. Understanding more about their movement behaviour and the sensory systems and environmental cues that bats use for navigation, as well as the environmental conditions that induce them to forage or return to their roost will help to mitigate these threats. This is challenging though, as bats have proven hard to study in the wild and so we understand little about their navigation behaviour on foraging or migration trips. Being nocturnal they are far more difficult to observe than birds and so standard techniques for studying their navigational ability are less useful. However advances in technology have allowed us to make the first steps in understanding how bats move about their environment and have the potential to discover which environmental cues are most important to them. This project will study the navigation behaviour of bats by manipulating their perception of environmental cues such as the sun and the magnetic field to understand how they interact to tell the animal which direction to fly when it needs to return to its roost. By understanding the sensory systems that bats use to navigate, we can understand which environmental cues are important for their movement. This knowledge can be used to help mitigate some of the human impacts on bat abundance. Understanding their behaviour will allow us to predict when and where they move, which will enable better placement and activity of wind turbines to minimize disruption to bats. It will also allow us to understand the patterns of movement of bats in terms of the availability of environmental cues, which will aid in predicting their temporal patterns of activity and habitat requirements. While bats are rarely seen and never heard, if we lose this vital cog in the balance of the environment, we would surely miss them. It is thus vital that we understand their movement behaviour in order to allow us to take action to avoid further decline in the number of bats that patrol our night skies.