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The flight zone of an animal is the area surrounding an animal that if encroached upon by a potential predator or threat, including humans, will cause alarm and escape behavior; the flight zone is determined by the animal's flight distance, sometimes called flight initiation distance (FID) which extends horizontally from the animal and sometimes vertically. It may also be termed escape distance, alert distance, flush distance, and escape flight distance.
Contents
- Factors influencing size
- Wildlife management
- Animal handling
- Husbandry
- General Adaptation Syndrome
- Sample values
- Factors affecting escape distances for birds
- References
Swiss zoologist Heini Hediger distinguished between flight distance (run boundary), critical distance (attack boundary), personal distance (distance separating members of non-contact species, as a pair of swans), and social distance (intraspecies communication distance).
Flight distance can be used as a measure of the willingness of an animal to take risks. Escape theory predicts that the probability of fleeing and flight distance increase as predation risk increases and decrease as escape cost increases. Flight initiation distance is one measure of animals' fear responses to humans.
In a study comparing 56 bird species with long flight distances, it was found these had declining populations Europe. This indicates that standardized measures of flight distance can provide reliable information about the population consequences of risk-taking behaviour by individuals and the susceptibility of different species to increased levels of disturbance by humans. A further study analyzing 75 flight initiation distance studies of 212 species found that larger species are more tolerant of humans.
When the flight zone of a group of bulls was invaded by a mechanical trolley, the bulls moved away and maintained a constant distance between themselves and the trolley. This indicates animals sometimes maintain a flight zone around inanimate objects.
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.
Factors influencing size
Animals faced with approaching predators must decide at which distance to initiate their flight, and they are expected to do so in a way that maximizes their fitness. As flight has both costs (including lost opportunity) and benefits, there will be in general an optimal flight initiation distance, defined as the first point in a predator's approach at which the benefit of flight exceeds the cost. The benefit of flight is equivalent to the cost of remaining in place or, in other words, to the risk of capture. The size of the flight zone can therefore vary according to circumstances. However, it has been shown in burrowing owls that individuals showed high repeatability in their FID.
Wildlife management
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.
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.
Animal handling
The flight zone is an important principle for herding, working, and mustering livestock. An animal can be stimulated to move simply by skirting its flight zone, and the animal will move in the desired direction according to the point of balance. The point of balance is usually located at the animals shoulder according to their wide angled vision. An over-stimulated animal will have a larger flight zone, for example an excited or scared animal. A Cumulative Flight Zone is formed when animals move in a herd. In this situation the lead animal and the following animals Points of Balance, within the cumulative flight zone, must both be crossed to entice movement.
The flight distance during handling is usually 1.5 to 7.6 m for beef cattle raised in a feeding operation and up to 30 m on mountain ranges. Brahman cattle have a larger flight zone than most English breeds. The flight zone can be thought of as the animals personal space. The size of the flight zone is determined by the tameness of the animal; the more domesticated an animal, the smaller the zone. Fully tame animals have no flight zone.
Studies with sheep indicated that animals confined in a narrow alley had a smaller flight zone compared to animals confined in a wider alley.
Handlers sometimes make the mistake of deeply invading the flight zone when animals are being driven down an alley or into an enclosed area such as a crowd pen. If the handler deeply penetrates the flight zone, the animals may turn back and run over them in an attempt to escape. Confining a livestock animal in a crush (chute) or alley can make it feel more secure and thus reduce the size of the flight zone; however, it does not eliminate the flight zone. An animal in a livestock raceway or alley that feels threatened may panic and injure itself or other animals. If handlers lean over fences around animals they penetrate the "zone of safety" and may cause the animals to rear.
Husbandry
Animals have a tendency to move in the opposite direction when their handler walks deep into their flight zone. By crossing an animal's point of balance, within the flight zone, a handler can move the herd in a particular direction and control their speed of movement. For example, crossing the point of balance from front to back will move the animal forwards, while the opposite is also true. The handler's pace should always reflect the animal's speed when herding. Additionally, pressure should be alternated on the flight zone to reduce stress. Constant pressure should never be applied.
If animals turn to face the handler he or she is considered to be no longer penetrating the flight zone.
It is important that a handler does not pursue any struggling animals as this will cause undue stress. Instead the animal should be allowed to return to the group as animals naturally have herd instincts, and will follow the groups leader. A good herding practice applying this is the movement of animals through a race by maintaining a steady flow of animals, not herding in groups, this allows new animals to follow the leader calmly. When yarded, animals should always have room to turn away from the handler to reduce stress. Minimal stress prevents injury to the animal and maintains good production, such as increased quality of meat and improved muscle and fat scores.
Appropriate frequent penetration of the flight zone can train the animals to minimise their flight zone to the handler.
Poor husbandry skills including over penetration of the flight zone results in the following behaviours: stress, panic, aggression, bolting, prey behaviour, charging, fainting, sickness and self-inflicted damage. Rough handling, such as constant flight zone pressure, can raise the heart rate of an animal. These factors are all reflective of the General Adaptation Syndrome.
General Adaptation Syndrome
The general adaptation syndrome (GAS) is a three-phase response to stress in animals.
Sample values
Sample escape distances (mostly mean) from humans:
Birds of Europe
Factors affecting escape distances for birds
Escape distance may differ significantly depending on many circumstances. 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. Surprisingly, an analysis of hundreds of studies found that larger birds are more tolerant of humans, despite substantial research that shows larger animals are less tolerant of humans.
Among the affecting factors: