author={Mary Caswell Stoddard and Martin Stevens},
Coevolutionary arms races are a potent force in evolution, and brood parasite–host dynamics provide classical examples. Different host‐races of the common cuckoo, Cuculus canorus, lay eggs in the nests of other species, leaving all parental care to hosts. Cuckoo eggs often (but not always) appear to match remarkably the color and pattern of host eggs, thus reducing detection by hosts. However, most studies of egg mimicry focus on human assessments or reflectance spectra, which fail to account… 
No evidence of host-specific egg mimicry in Asian koels
This study found no evidence for Asian koel host-specific egg mimicry in three sympatrically occurring host species in Bangladesh.
A shared chemical basis of avian host–parasite egg colour mimicry
Analysis of pigment composition reveals a novel proximate dimension of coevolutionary interactions between avian brood parasites and hosts, and implies that alternative phenotypes may arise by the modifications of already existing biochemical and physiological mechanisms and pathways.
Host-Parasite Arms Races and Rapid Changes in Bird Egg Appearance
Coevolutionary arms races are a powerful force driving evolution, adaptation, and diversification. They can generate phenotypic polymorphisms that render it harder for a coevolving parasite or
Cryptic cuckoo eggs hide from competing cuckoos
The results suggest that competition between cuckoos has been the key selective agent for egg crypsis, which may be favoured over mimicry in intraspecific arms races because it can reduce the risk of egg removal to levels below chance.
Host and brood parasite coevolutionary interactions covary with comparative patterns of the avian visual system
It is implied that both host-use by parasites and anti-parasitic responses by hosts covary with a metric of the visual system across relevant bird species, providing comparative evidence for coevolutionary patterns of host and brood parasite sensory systems.
Colour, vision and coevolution in avian brood parasitism
  • M. Stoddard, M. Hauber
  • Biology
    Philosophical Transactions of the Royal Society B: Biological Sciences
  • 2017
Vision-based adaptations that arise in parasite–host interactions are reviewed, emphasizing that these adaptations can be visual/sensory, cognitive or phenotypic in nature and highlighting recent breakthroughs in chemistry, genomics, neuroscience and computer vision.
Brood parasites lay eggs matching the appearance of host clutches
The results indicate that cuckoos select certain host nests to increase matching of their own eggs with host clutches, but only in chromatic characteristics, and suggest that the ability of cuckoo to actively choose host nests based on the eggshell appearance imposes a strong selection pressure on host egg recognition.
Does contrast between eggshell ground and spot coloration affect egg rejection?
It is found that robins were more likely to reject eggs whose spots had greater chromatic (hue) but not achromatic (brightness) contrast, therefore, egg rejection decision rules in the American robin may depend on the colour contrast between parasite eggshell spot and host ground coloration.
Dynamic egg color mimicry
Eggshell coloration in the great reed warbler and its brood parasite, the common cuckoo, changes rapidly, and the extent of eggshell color mimicry shifts dynamically over the host response period, the first evidence that such changes impact brood parasite–host eggshellcolor mimicry during the incubation stage.


Pattern mimicry of host eggs by the common cuckoo, as seen through a bird's eye
It is shown that various features of host egg pattern are mimicked by the eggs of their respective cuckoo host-races, and that cuckoos have evolved better pattern mimicry for host species that exhibit stronger egg rejection.
Egg colour mimicry in the common cuckoo Cuculus canorus as revealed by modelling host retinal function
  • J. Avilés
  • Biology
    Proceedings of the Royal Society B: Biological Sciences
  • 2008
Cuckoo races as assessed by humans do not entirely match with host perception of matching and that achromatic mechanisms could play a main role in the discrimination of cuckoo eggs at low-light levels.
Are dark cuckoo eggs cryptic in host nests?
Visual modeling shows that avian host parents use multiple visual cues in rejecting parasitic eggs
These cues correspond exactly to the principal differences between host and parasitic eggs, showing that hosts use the most reliable available cues in making rejection decisions, and select for parasitic eggs that are increasingly mimetic in a range of visual attributes.
Egg rejection in a passerine bird: size does matter
Examination of egg discrimination behaviour in the yellow-browed leaf warbler, Phylloscopus humei, a presumed former host of parasitic cuckoos, shows how discrimination ability has become very strong, making it a difficult strategy for a cuckoo to defeat.
The evolution of host‐specific variation in cuckoo eggshell strength
This is the first report of host‐specific differences in cuckoo egg properties other than colour and pattern and lends correlational support to the hypothesis that the strong eggshells of brood parasites are an adaptation to reduce host rejection.
Constraints on egg discrimination and cuckoo-host co-evolution
It is suggested that host egg variability is a major constraint on the learning mechanism of egg recognition, and justifies a prolonged learning mechanism in which a host can learn to recognize the variation range of its own eggs.
Genetic evidence for female host-specific races of the common cuckoo
Genetic evidence that gentes are restricted to female lineages is provided, with cross mating by males maintaining the common cuckoo genetically as one species, and there is differentiation between gentes in maternally inherited mitochondrial DNA, but not in microsatellite loci of nuclear DNA is shown.
The evolution of egg colour and patterning in birds
  • R. Kilner
  • Biology
    Biological reviews of the Cambridge Philosophical Society
  • 2006
A critical review of the literature is presented which, when combined with the results of some comparative analyses, suggests that just a few selective agents can explain much of the variation in egg appearance.
Egg‐morphs and host preference in the common cuckoo (Cuculus canorus): an analysis of cuckoo and host eggs from European museum collections
Support is provided for the ‘nest site hypothesis’ which states that each cuckoo female parasitizes a group of host species with similar eggs or nest sites, which indicates that cuckoos also parasitize several species whose nest sites are similar to those of their main host.