Mobbing behavior is most commonly seen as a cooperative form of an alarm call, in which an individual will call out to conspecifics to warn them of potential threats. Most commonly, this call will be stimulated by a potential predator and will be in the form of a vocalization (Magrath et al., 2015). Historically, Konrad Lorenz was one of the first ethologists to state that mobbing vocalizations are caused by innate releasing mechanisms, or ‘fixed action patterns’ carried out by neural systems (Lorenz 1966). As Lorenz stated, “Geese and ducks ‘know’ by very selective, innate releasing mechanism that anything furry, red-brown, long-shaped, and slinking is extremely dangerous” (Lorenz 1966). This hypothesis was then furthered in 1970 when Curio et al. showed that the mobbing response of breeding flycatchers (Ficedula hypoleuca) to shrikes and owls is stimuls specific (i.e, the two predators are recognized by two unique innate releasing mechanisms) (Curio and Bach, 1970). The ability for mobbing individuals to show different responses to different predators is intimately related to the adaptive value of mobbing, and will be described in the section Adaptive Value.
Figure 1. Diagram of the 'consummatory act,' or the instinctive acts produced by innate releasing mechanisms. Pioneered by Konrad Lorenz, diagram taken from http://images.slideplayer.com/28/9316958/slides/slide_19.jpg
As depicted in the figure above, the 'fighting' reproductive instinct (which can result in mobbing), is a subset of behaviors caused by an innate releasing mechanism and is associated with other behaviors such as offspring care, mating, and building.