The colors in the feathers of a bird are formed in two different ways, from either pigments or from light refraction caused by the structure of the feather. Red and yellow feathers get their color from actual pigments (carotenoids) that come from the bird’s diet. Blue, however, is a structural color, created by the way light waves interact with the feathers and their arrangement of protein molecules, called keratin.
Thus, no birds have blue feathers made from pigments – they are blue strictly from the structure of the feathers. Different keratin structures reflect light in subtly different ways to produce different shades of what our eyes perceive as the color blue.
If you observe the blue feather of an Eastern Bluebird, Blue Jay or Indigo Bunting in normal lighting conditions you will see the expected blue color. However, if the feather is back-lit, and the light is transmitted through the feather, it will look brown. The blues are lost because the light is no longer being reflected back and the brown shows up because of the melanin in the feathers.
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Things are looking up for those of us who look forward to winters when boreal finches come south in relatively large numbers in search of food. This is an irruption year for winter finches in the East due to the poor cone and birch seed production in northern Ontario and Quebec. Seed-eating birds such as finches, grosbeaks, redpolls and siskins will be frequenting our feeders.
Even at this early date, Evening Grosbeak sightings are up noticeably. Pine Grosbeaks will be taking advantage of good Mountain-ash berry and cone production in New England. Purple Finch numbers should also be healthy this winter. While Red Crossbills sightings may be scarce, White-winged Crossbills sightings may well be up due to the poor cone crops in the eastern boreal forest. Both Common and Hoary Redpolls should be numerous this winter due to poor crops of birch, alder and conifer seeds further north.
In addition to these finches, large numbers of Blue Jays, Red-breasted Nuthatches and Bohemian Waxwings are predicted due to poor nut, conifer seed and berry crops, respectively, further north. (Ron Pittaway’s Winter Finch Forecast, 2018-2019, http://jeaniron.ca/2018/wff18.htm ) (Photo: Common Redpoll)
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Even though signs as well as sightings of active bears are plentiful, and black-oiled sunflower seeds are an open invitation for them to visit and potentially become “nuisance” bears, many devoted bird-lovers have already hung out feeders in hopes of luring feathered friends closer to their home. Throughout northern New England so few birds have been attracted to these feeders that they have remained full, some not having been refilled since September. Our usual fall and winter visitors appear to have all but vanished, and concern has been growing amongst those who feed birds.
Those familiar with bird feeding habits know that in the fall, when seeds are abundant, feeder visits by resident birds typically slow down. However, this year, at least anecdotally, appears to be extreme in this regard. Warm weather extending into November certainly has lessened birds’ food requirements. But having sunflower seeds sprout in your feeder before the need to replenish them arrives is unusual, if not alarming.
Dr. Pam Hunt, Senior Biologist in Avian Conservation at New Hampshire Audubon, recently shared some of her personal research with the birding world (UV- Birders). Hunt has conducted a weekly, 10 km-long, bird survey near Concord, NH for the past 13 years. In addressing the current concern over a lack of feeder birds, she extracted the data she had accumulated on 12 common birds (Mourning Dove, Downy Woodpecker, Hairy Woodpecker, Blue Jay, Black-capped Chickadee, Tufted Titmouse, White-breasted Nuthatch, White-throated Sparrow, Dark-eyed Junco, Northern Cardinal, House Finch, American Goldfinch) over the last 13 falls, focusing on the period between Oct 1 and Nov 15. After extensive analysis, Hunt concluded that there has not been a dramatic decline in the number of birds this year, relative to the averages of the past 13 years. One cannot argue with scientific evidence (except for, perhaps, #45), but it does seem mighty quiet on the western (northeastern?) front this year.