Escape distance

Flight initiation distance (FID) buffer from critical wildlife area. ^{[ 1][ 1]}

The escape distance (ED) of animals is the distance at which they flush or otherwise move away from certain disturbing stimuli, namely humans, triggering an escape response. It may also be termed flight initiation distance (FID), flush distance, or escape flight distance. The alert distance (AD) is the distance where the animal changes its behaviour, for example, raising the head in an alert posture, in response to a disturbance. ^{[ 1][ 1][ 1]} 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, ^{[ 1][ 1][ 1][ 1]} both in wildlife refuges, and, e.g., in planning areas for outdoor recreation.^[1]

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.^[1] The latter typically adds a certain buffer distance to the given tolerance measure.^{[ 1]}

Sample values

Sample escape distances (mostly mean) from humans:

Birds of Europe

Because most of birds flee from humans, ornithologists and birdwatchers sometimes use digiscoping equipment, allowing them to take pictures from long distances.

Factors affecting escape distances for birds

Fleeing blackbird

Escape distance may differ significantly depending on many circumstances.

• Species ^{[ 1][ 1][ 1][ 1][ 1][ 1]} - for example Mallard Anas platyrhynchos has shorter ED than Pintail Anas acuta^{[ 1]}.
  • Body size is the best known general factor influencing interspecies differences. Very frequently large species are more timid than small species, because size affects how rapidly a bird can take off. ^{[ 1][ 1]}

moreover:

• Age - young birds are less shy, for example Dunlin Calidris alpina ^{[citation needed]})
• Location or rather habituation to walking people. ^{[ 1]} Mallards Anas platyrhynchos or Canada Geese Branta canadensis are less shy in a park than somewhere in the wild. Or Tits and Nuthatches near the feeder or in the park are less shy than in the wild.
• Season. For example wintering bullfinches Pyrrhula pyrrhula have shorter EDs than breeding ones. ^{[ 1]}
• Origin of birds - sometimes wintering birds from the north, perhaps not knowing people, are less shy than native, for example Nutcracker Nucifraga caryocatactes ^{[ 1]}
• Given bird individual ^{[citation needed]}
• Color of clothes of an observer and observer's behaviour ^{[ 1]}
• Hunting status - quarry species have longer EDs than non-quarry, increasing during hunting season or after days with hunting. ^{[ 1][ 1]}
• Flock size ^{[ 1]}
• Flock composition - for example birds in mixed flocks of mallard Anas platyrhynchos and teal Anas crecca react at longer distances than those in single species flocks for either species. ^{[ 1]} Or dunlin Calidris alpina in flocks with other waders. ^{[ 1]}
• Visibility of the stimulus to the birds^{[ 1]}
• Wind force ^{[ 1]}
• Vegetation height ^{[ 1]}

See also

• Birdwatching
• Digiscoping
• Fight-or-flight response
• Flight zone
• Nature photography
• Personal space
• Wildlife photography

References