Tuesday, January 22, 2013

Are your House Finches getting redder?

I believe that my house finches have been getting redder and redder over the years. Do you think some day they'll be as red as a cardinal?

Good nutrition is important for birds, too!
House Finch eating seed cylinder on Wild Birds Unlimited Dinner Bell feeder
Today House Finches (Carpodacus mexicanus) are a familiar sight at mid-Michigan bird feeders if you offer sunflower, safflower or Nyjer® (thistle) seed. These talkative little 6 inch birds get their name from their habit of hanging around human houses. Their cheery warble and variety of chirps are a constant around the feeders and you may find their nests in your hanging baskets, wreaths, or nearby pine trees.

They are very good at adapting. The House Finch was not always a local bird. In 1940, they were captured illegally in California and imported to New York by pet dealers. Fearing prosecution, the dealers released their “Hollywood Finches” on Long Island and since then the finches have spread to all corners of the east and have even rejoined their relatives in the west. But have they also been getting redder?

Male and female House Finch on WBU Hopper Feeder
Adult males are rosy red around the face and upper breast, with streaky brown back, belly and tail. Adult females aren’t red; they are plain grayish-brown with thick, blurry streaks and an indistinctly marked face. 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.

Your redder finches may just be well fed older, more experienced birds or in fact may be evolving into redder, more vibrant house finches of the future. The research is still out on the bird's 'carotenoid circle of life', but you made a very good observation. Thank you for sharing.
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