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The escape distance (ED) of animals is the distance within which an animal will, upon observing a disturbing stimulus such as a human, exhibit an escape response, such as flushing (in the sense of being "flushed out") in the case of birds. More specifically, it is the upper bound of the set of distances within which the animal is certain to exhibit such a response should it observe the stimulus. It may also be termed flight initiation distance (FID), flush distance, or escape flight distance. The alert distance (AD) is the distance, by definition greater, within which the animal changes its behaviour in a manner enabling it to better observe the stimulus, as by raising the head in an alert posture, but does not necessarily flee unless the stimulus is also within the escape distance. These measures are usually used to quantify the tolerance of wildlife to humans. The area surrounding the animal which will cause escape behavior when encroached upon is called the flight zone. ==Usage== Wildlife managers often use ED and FID to develop set-back distances to reduce human impacts on wildlife, both in wildlife refuges, and, e.g., in planning areas for outdoor recreation.〔(Alert distance as an alternative measure of bird tolerance to human disturbance: implications for park design )〕 These measures are also important in birding and nature photography. While escape distance has been generally used as a measure of tolerance, other changes in animal behavior in presence of humans, such as increased vigilance time at the cost of decreased feeding time, may have significant overall impact on wildlife. Therefore it is suggested that a more conservative measure, namely, the alert distance, should be used in determining minimum approaching distance.〔 The latter typically adds a certain buffer distance to the given tolerance measure. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「escape distance」の詳細全文を読む スポンサード リンク
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