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Color polymorphism in Tyto alba
Color polymorphism in birds arises from an adaptive consequence of selection. The ability of the general scope of birds to be polymorphic has been concluded to have evolved in many different bird species independently, or within separate lineages. Tyto alba is often used in studies that investigate color polymorphism and how different color patterns within a species might affect the success individuals have on capturing certain prey. The benefits associated with habitat, light and dark activeness, and feather structure seem to play a major role in color polymorphism.

Studies have found that the plumage color of the barn owl is correlated with other feather attributes that help to resist abrasions and help with foraging.Plumage color is correlated with the level of melanin pigments the birds have, their age, their gender, the length of their vane feathers, and barb density. Different birds are going to be more successful in environments where their color set and lifestyle factors make them better predators.

Environmental
Birds, in general, tend to live in areas where their color is better suited to blend in. Environment, for these owls, plays a key role in color polymorphism. Variation in environment is linked to variation of color seen in these owls. One variation in environment is light. There is evidence to support of the idea of disruptive selection in which a tendency is seen to favor species that are better able to blend into environments with greater variations of light.Certain environments have higher variations of light than others. Open habitats tend to be fields and prairies whereas closed habitats are more dense wooded areas. Lighter plumaged owls tend to live in open areas where they are able to be more camouflaged where more reddish-brown owls tend to live in closed habitats. Species that live in open as well as closed habitats, therefore are active during the day and night, tend to be more polymorphic. These birds also tend to have better success in foraging for food.

Another variation in the environment is prey. There is evidence that diet has a correlation with the color of the plumage for the birds. Being a different color would appear to help certain owls catch certain prey. For example, Barn owls in the more Northern regions of Sweden are likely to be darker colored while barn owls in the more Southern regions of Sweden tend to be lighter colored. Success at foraging in certain environments is linked to color polymorphism in these owls.

Melanin pigmentation
The levels of melanin found across these owls has been linked to other factors about these owls. Melanin pigmentation is associated with color but not spot size or feather mass. In terms of levels of melanin pigmentation, owls with darker reddish feathers have feathers that are better able to resist physical damage. Birds with darker reddish feathers might have an advantage in areas where physical damage is greater and more likely, that populations with darker reddish feathers are better suited to exploit harsher habitats. This characteristic of darker colored owls might allow them to renew their feathers less often than lighter colored owls, not only because they resist damage but also because they require more energy to make.

Feather structure
Feather structure is another variation correlated with color variation. There is a correlation between the length of their vanes as well as the density of their barbs and the length of their barbs. Owls with longer vanes tend to have greater barb densities. In terms of color variation, owls with lighter plumage colors, rather than those with reddish-brown plumage, tend to have greater barb densities and thus have longer vane lengths.Owls with higher barb density had heavier feathers.It has been documented that owls with larger spots are more resistant to physical and biological damage therefore they may be stronger as well as heavier. It was theorized that owls might produce heaver feathers because these feathers are in better condition to handle harsher environments and stress factors.

Barb density was not correlated with spot size, however both feather mass and spot size might be linked to the quality of the barb structure. These owls also tend to display more and larger black bars and contain higher levels of eumelanin pigmentation that contributes to brownish color in plumage.

Feather length is correlated to color variation as well. There is also support for the claim that longer feathers are covered in more black bars because the black bars help to reduce bending during flight. These black bars are seen on the wings of the owls in a transverse, parallel fashion. Plumage color is not associated with the size of the black spots also seen on the owls, nor the number of black spots they have. However, there is a correlation between the size of the spots they have and the number of black bars they have. Owls that displayed larger black spots or lighter plumage also displayed more black bars. This might be due to similar foraging strategies or diets, or perhaps because heavier birds tend to have larger spots or lighter plumage.

Since females tend to have more black bars than males and tend to weigh more than males, it was hypothesized that the greater number of black bars might help to support their weight during flight since having more black bars seems to help reduce bending during flight.