What is the communicative function in mimicry and how is mimicry regulated in ontogenetic and evolutionary processes?

Foregrounding the communicative function in mimicry enables us to bring out the specific aspect of communication that allows the mimic to be successful in its deceptive display. From the six communicative functions distinguished by Roman Jakobson, it seems to be predominantly the poetic function that is foregrounded in the case of egg mimicry. I make this claim based on the specific qualitative properties that make a female bird accept or reject an egg as part of its brood. There is no apparent usage of other communicative functions: no reference is made to an external object or contextual meaning, a cuckoo egg does not express any behavioural activity (which excludes expressive function), no attempt is made to alter the behaviour of the female compared to the normal fostering behaviour, and there is no manipulation with the communication code or phatic contact. In the context of animal communication, the notion of poetic dominant could be extended to cover all cases where it is predominantly the inner aesthetics of the message or the qualities and patterns of the biological form that make the communication effective. In studies of brood parasitism a lot of attention has been given to the formal characteristics of the eggs: their colour, patterns and size. The presence of a poetic dominant could perhaps be an argument to pay even more systematic attention to the specific aesthetic qualities that make birds become attached to their nest, eggs and brood.

Asking about the regulation of egg mimicry in ontogenetic and evolutionary processes enables us to describe the mimicry system in terms of change and fixed adaptations. In the case of brood parasitism, the communicative feedback, understood as feedback within a single act of communication, plays a minimal role as eggs are passive and do not participate in communication with adult birds. The relationship between the eggs and the adult birds follows rather the logic of unidirectional communication or signification (sensu Noth 2001: 72), so that the adult birds are the active subjects who recognise eggs, attribute meaning to them, and act selectively according to this attributed meaning. The quickest feedback cycle in brood parasitism takes place on the level of the clutch, and depending on the host species, there are between a few and tenfold communication-feedback cycles during the life of an individual. Ontogenetic learning and feedback has some role in recognition, as birds may improve their egg-recognition skills on the basis of previous experience. At the same time, there is not much individual variety known to exist in the behaviour of hosts or parasites in this ecological relation, nor is the individual experience known to pass from generation to generation by cultural learning. It seems that egg mimicry is to a large degree (in comparison to many other mimicry systems) genetically induced and controlled. This is also supported by the existence of various genetically induced gents of the cuckoo that differ by their egg appearances and preferred host species. Such stable mimicry systems allow fixed bodily adaptations and counter-adaptations to emerge, as for instance in some species like Eurasian blackcaps Sylvia atricapilla, egg variation in the clutch seems to have decreased because of brood parasitism (Honza et al. 2004).

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