Editing Parrotbill (section)

== Egg recognition ==
Parrotbill egg recognition is the ability of the parrotbill to distinguish its own eggs against the eggs of a [[brood parasite]].<ref name=":0">Yang, C., Møller, A. P., Røskaft, E., Moksnes, A., Liang, W., & Stokke, B. (2014). Reject the odd egg: Egg recognition mechanisms in parrotbills.'' Behavioral Ecology, 25''(6), 1320–1324. doi:10.1093/beheco/aru124</ref> Without their own eggs in the nest, parrotbills are not able to identify whether their nest has been intruded by the eggs of a brood parasite.<ref name=":0" /> Because the colour and number of eggs may vary, there are varying outcomes to whether parrotbills will reject or accept the eggs whether it be their own or if they are acting host for another species.<ref name=":0" /> Cognitive mechanisms including recognition by discordance and template-based recognition are hypothesized to be the manner in which a host's eggs are identified.<ref name=":1">Liang, W., Yang, C., Antonov, A., Fossøy, F., Stokke, B., Moksnes, A., et al. (2012). Sex roles in egg recognition and egg polymorphism in avian brood parasitism.'' Behavioral    Ecology, 23''(2), 397–402. doi:10.1093/beheco/arr203</ref> The common cuckoo lays its eggs in the nests of parrotbills and the two have [[Coevolution|co-evolved]] together over time to promote the reproductive success of both species.<ref name=":2">Yang, C., Li, D., Wang, L., Liang, G., Zhang, Z., & Liang, W. (2014). Geographic variation in parasitism rates of two sympatric cuckoo hosts in china.'' Zoological Research, 35''(1), 67–71.</ref> The common cuckoo is an example of an avian brood parasite that reduces the energy cost of caring for its eggs by placing them in the parrotbill's nest.<ref name=":0" />

Depending on the parrotbill species, the eggs will either be maculate with spots or marks or immaculate, meaning without spots or marks.<ref name=":0" /><ref>{{Cite web|url=http://www.dictionary.com/browse/immaculate|title=the definition of immaculate|website=Dictionary.com|access-date=18 November 2017|archive-date=14 November 2017|archive-url=https://web.archive.org/web/20171114025442/http://www.dictionary.com/browse/immaculate|url-status=live}}</ref> The cuckoo is also able to lay eggs that replicate the ones of its hosts in a means to have its eggs accepted by the host.<ref name=":0" />  Whether the parasitic eggs are accepted by the host is based on two hypothetical cognitive mechanisms.<ref name=":0" /> True or template-based recognition predicts that by learning or by instinct, the parrotbill would be able to reject the brood parasite eggs.<ref name=":0" /> If learned, the parrotbill would [[Imprinting (psychology)|imprint]] on its own eggs and would be able to use it as a template to compare to foreign eggs.<ref name=":0" /> Recognition by discordancy is the least favoured hypothesis among scientists of the two mechanisms, but describes the action of rejecting the eggs which appear to be the minority whether it is their own eggs or the parasite's eggs; it does not require learning or instinctive behaviour.<ref name=":0" /> Some studies have predicted discordancy is favoured as certain species demonstrate the behaviour at all life stages; if the behaviour is demonstrated at a young age, it may not be an example of learning as the time for learning could be too short.<ref name=":1" />

One parrotbill species that has been studied is the ashy-throated parrotbill (''Paradoxornis alphonsianus'') and demonstrated the use of both mechanisms relaying there may not be one "universal method".<ref name=":0" />  The eggs of the ashy-throated parrotbill are immaculate and [[Polymorphism (biology)|polymorphic]] in which multiple [[Phenotype|phenotypic]] colours in that species is produced; its eggs are placed in competition with the eggs of the common cuckoo (''Cuculus canorus'').<ref name=":0" /> Typically, the female cuckoo lays its eggs in the nest of the parrotbill after taking out one of the host's eggs.<ref name=":1" /> The immaculate colours in this species are blue, pale blue and white, but only one colour is present at a time and the female produces only one colour over its lifetime.<ref name=":0" /><ref name=":1" />

If parrotbills do not have their own eggs within the nest, it has been observed they accept the eggs of the avian brood parasite, as the "cue" of the presence of their own eggs has not been established.<ref name=":0" /> Time is also important for both male and female parrotbills as it can be the factor in whether the parrotbill will recognize parasitic eggs.<ref name=":1" /> For females, it is crucial they learn the egg phenotype as the eggs are being laid, but if this learning is not immediate, parasitic eggs can be accepted and imprinted.<ref name=":1" /> Males learn their respective egg phenotype once the clutch has reached completion.<ref name=":1" />

In some species, male parrotbills also incubate eggs, and they are predicted to follow discordancy recognition for this behaviour as the males may encounter multiple egg types with different mates over time.<ref name=":0" /> This could lead to rejection of their own eggs based on previous knowledge of egg colour.<ref name=":0" /> A possible exception to this idea is if the host parrotbill produces eggs that are monomorphic.<ref name=":1" /> If male parrotbills do not imprint on their own eggs, they increase the probability of production of varied phenotypes of egg colour and patterns within the population.<ref name=":1" />

If a host species is new to an area, it is suspected cuckoo parasitism will be favoured as recognition of parasitic eggs has not yet occurred.<ref name=":2" /> Over time, the two species co-evolve with the parrotbill first utilizing one of the hypothesized cognitive mechanisms in order to recognize parasitic eggs.<ref name=":1" /> In order to compensate for this new behaviour in parrotbills, the parasite produces eggs that are similar to those of the host and leads to the evolution of polymorphisms over time for both species.<ref name=":1" />