House Finches eat almost exclusively plant materials, including seeds, buds and fruits. Wild foods include wild mustard seeds, knotweed, thistle, poison oak, grass and many other flower seeds. In orchards, House Finches eat cherries, apricots, peaches, pears, plums, strawberries, blackberries, mulberries and grapes. At feeders they eat safflower, sunflower, nyjer, dried fruit, oranges and jelly.
The amount of red the male finch has can vary depending on the amount of carotenoid pigments he eats during his fall molt. Many brilliant red, orange, and yellow color displays of birds are the result of carotenoid pigments deposited in the feathers.
Carotenoids are the class of hydrocarbons, widespread in nature and important pigments in living organisms. They are found in foods that are deep green, yellow, orange, and red like fruits, vegetables and seeds.
Normal male House Finches exhibit individual variation in coloration, with their plumage ranging from pale orange to bright red, but the brighter males have an advantage with the females. Carotenoid-based feather coloration has been found to be an important criterion in female mate choice because brighter finches usually have better foraging ability, better health, more testosterone and less parasite loads.
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