How is the mimicry system related to human cultural processes?
Regarding human cultural involvement and influences, egg mimicry turns out to be an especially rich and interesting case. The phenomenon itself has been known long before the rise of modern science. For instance Aristotle in his “Historia ani- malium” gives a long description and different explanations of cuckoo’s nesting behaviour:
The cuckoo, as has been said elsewhere, makes no nest, but deposits its eggs in an alien nest, generally in the nest of the ring-dove, or on the ground in the nest of the hypolais or lark, or on a tree in the nest of the green linnet. It lays only one egg and does not hatch it itself, but the mother-bird in whose nest it has deposited it hatches and rears it; and, as they say, this mother bird, when the young cuckoo has grown big, thrusts her own brood out of the nest and lets them perish; others say that this mother-bird kills her own brood and gives them to the alien to devour, despising her own young owing to the beauty of the cuckoo. (Aristotle 2002, Dd6r).
The cuckoo’s brood parasitism seems to have even become a cultural model for describing certain parasitic relations, as there are cuckoo bumblebees Psithyrus, cuckoo finches Anomalospiza and cuckoo ants Leptothorax in the zoological nomenclature. There is also a larger cultural mythological background for interpreting brood parasitism: the motif of changelings or human children swapped by an elf, a troll or some other supernatural creature is rather common in folklore. The theme of changelings in different variations is widely used also in contemporary fiction (e.g. John Wyndham’s “The Midwich cuckoos”, 1957). It appears that the topic of an alien offspring is a strong cultural narrative and brood parasitism is also the primary characteristic that people associate with cuckoos.
Scientific studies of the egg mimicry of cuckoos can also be shaped (although mostly unconsciously) by this strong cultural narrative (see e.g. Schulze-Hagen et al. 2009; Smith 1999). Although the egg mimicry of cuckoos is scientifically a rather well-established case, a possible methodological error can arise from replacing the position of the receiver with that of the human observer and proceeding from human perceptual and behavioural possibilities. This becomes obvious for instance in the experiments with artificial eggs that are produced according to the human perceptual system and understanding of similarity and difference: “The resemblance was so good that, by visual inspection alone, an observer could not distinguish between the artificial eggs and the genuine cuckoo eggs from the same area” (Moksnes and R0skaft 1989: 27). Artificial eggs could also be described as “similar in size and mass to real cuckoo eggs, made of hard plastic [...] the mimetic egg type was painted to resemble eggs laid by the blackcap” (Honza et al. 2004: 176). This issue becomes methodologically crucial, as there are differences between human and bird visual systems. The principles of colour distinction in birds are different from mammals (birds having tetrachromatic vision), with many bird groups also being sensitive to ultraviolet light. Some parasitic eggs that appear nonmimetic in visible light are highly similar to host eggs in UV-light (Grim 2005: 75; Polacikova et al. 2007; Honza et al. 2007). In some studies, even human test persons are used to assess the similarity or difference of eggs in a clutch and the results are used to argue for the resistance of some species to brood parasitism (Honza et al. 2004: 177). From a semiotic viewpoint, such studies can be interpreted critically and assumed to provide biased results since the position of the receiver (song bird) is at least partly replaced by that of the human receiver. David C. Lahti (2015: 530-531) smartly denotes such uncritical use of artificial objects in behaviour studies as Umwelt gamble: “when we perform experiments that assume continuity between our own perceptual and cognitive infrastructure and that of an animal—for instance, using artificial stimuli—we engage in what we might call an umwelt gamble. We bet that something we think would be perceived in a certain way will indeed be perceived in that way” (Lahti 2015: 530-531).
The five-stage semiotic analysis of the common cuckoo’s brood parasitism demonstrates the complexity of the mimics’ and receivers’ relations as well as the several layers of resemblance compared to the simple schematisation of the tripartite mimicry system. The method allows for bringing out different aspects of the mimicry system in an organised manner. It shows the specifics of egg mimicry as a detached and complete mimicry resemblance corresponding to Peircean secondness. The validity of the mimicry system could be supported by the strong behavioural reactions of the adult birds (receivers) toward the cuckoo eggs, although at the same time, the human cultural narrative and perceptual involvement can also influence the description. The dynamics and development of egg mimicry take place mostly at the level of genetic information and phylogenetic feedback, although there is also some individual learning involved. To fully articulate the specific features of egg mimicry, a comparative analysis should be made in other mimicry systems as well, which will be carried out in the next subchapter.