Animals have many different tactics for defending themselves, depending on the severity of the threat they are encountering. Stages of threat vary along a spectrum referred to as the "predatory imminence continuum", spanning from low-risk (pre-encounter) to high-risk (interaction) threats. The main assumption of the predatory imminence continuum is that as threat levels increase, defensive response strategies change. During the pre-encounter period, an animal may engage in activities like exploration or foraging. But if the animal senses that a predator is nearby, the animal may begin to express species specific defense reactions such as freezing in an attempt to avoid detection by the predator. However, in situations where a threat is imminent, once the animal is detected by its predator, freezing may no longer be the optimal behaviour for survival. At this point, the animal enters the circa-strike phase, where its behaviour will transition from passive freezing to active flight, or even attack if escape is not possible.
Development The development of the predatory imminence continuum began with the description of species-specific defence reactions. Species-specific defence reactions are innate responses demonstrated by an animal when they experience a threat. Since survival behaviours are so vital for an animal to acquire and demonstrate rapidly, it has been theorized that these defence reactions would not have time to be learned and therefore, must be innate. While these behaviours are species-specific, there are three general categories of defence reactions - fleeing, freezing, and threatening. Species-specific defence reactions are now recognized as being organized in a hierarchical system where different behaviours are exhibited, depending on the level of threat experienced. However, when this concept was first proposed, the dominant species-specific defence reaction in a certain context was thought to be controlled by operant conditioning. That is, if a species-specific defence reaction was unsuccessful in evading or controlling conflict, the hierarchical system would be rearranged because of the punishment, in the form of failure, experienced by an animal. It would then be unlikely for that species-specific defence reaction to be used in a similar situation again; instead, an alternative behaviour would be dominant. However, if the dominant behaviour was successful it would remain the recurring behaviour for that situation. After experimentation, this theory was met with much opposition, even by the person who proposed it. One point of opposition was found through the use of shock on rats and the species-specific defence reaction of freezing. This experiment found that while punishment did seem to affect freezing, it was not through response weakening but through the evoking of different levels of the behaviour. Other criticisms for this theory focused on the inability for species-specific defence reactions to effectively rearrange in this manner in natural situations. It has been argued that there would not be enough time for punishment, in the form of an animal being unsuccessful in its defence, to reorder the hierarchy of species-specific defence reactions. The rejection of the operant conditioning mechanism for the reorganization of species-specific defence reactions, led to the development of the predatory imminence continuum. The organization of defensive behaviours can be attributed to the level of threat an animal perceives itself to be in. This theory is one of adaptiveness, as the dominant defence reaction is the behaviour which is most effective in allowing the survival of the animal and the one which is most effective in preventing an increasing level of threat, also known as increasing imminence. The probability of being killed by a predator, known as predatory imminence, is what is responsible for the expressed defensive behaviour. The predatory imminence is dependent on many factors such as the distance from a predator, the potential for escape, and the likelihood of meeting a predator. Three general categories of defensive behaviours, based on increasing predatory imminence, have been identified. These are labelled as pre-encounter, post-encounter, and circa-strike defensive behaviours.
Stages of threat
… excerpt ends here. Continue reading the full article.
