Carotenoids are the answer. The question is: What gives the yellow plumage of birds? (Think, Big Bird.)
Carotenoids are pigments produced by plants. The pigments are transferred to insects that eat those plants and are then available to birds that eat those insects. In birds, these pigments might be signals of fitness because they are derived from special diets which might be difficult to obtain. These pictures were taken this last week.
A juvenile Cedar Waxwing shows a pale yellowish belly, but a distinctly yellowish tail.
The yellow plumage of this immature male Common Yellowthroat will be even more spectacular when the bird becomes an adult.
A Yellow-rumped Warbler eyes the photographer with suspicion.
fascinating! and lovely too.
interesting that the moth under your headline is feeding off a brilliant yellow flower also.
The LBB suffers yet another ostracism. Calls into question if anyone does see the little sparrow fall.
I think that is an adult Cedar Waxwing. Young waxwings this time of year are streaky on the breast and have few if any red waxy tips.
Lindell, thank you, I struck the word
juvenile. I often learn from those who comment.Regional differences in appearances can also be due to very localized differences in diet and the timing of when they ingest it. My first ever sighting of a Cedar Waxwing showed a bird with bright orange tipped tail feathers instead of yellow. I wondered if I had found a different variety of the bird until I found this article:
http://www.allaboutbirds.org/guide/Cedar_Waxwing/lifehistory
“Cedar Waxwings with orange instead of yellow tail tips began appearing in the northeastern U.S. and southeastern Canada in the 1960s. The orange color is the result of a red pigment picked up from the berries of an introduced species of honeysuckle. If a waxwing eats enough of the berries while it is growing a tail feather, the tip of the feather will be orange.”
-John H, Connecticut