Thanks to reader Skip Pothier for sending in these photos. They show a Purple Finch with yellow color instead of red. My first thought was to call it a male that didn’t develop the full red pigment (a similar variant due to poor diet and/or poor health is fairly common in male House Finches) but the answer here may not be so simple.
Birds get red and yellow pigments from carotenoid compounds in their food, so a diet that doesn’t include enough carotenoids will lead to a bird with weaker color. The same carotenoid chemicals are also important for immune system function, so a sick bird can also show weaker color. Even if it gets lots of carotenoids in its diet, it will use them to fight disease and won’t have enough left to color the feathers.
On this bird, however, the explanation may not be that simple. On closer study I notice that it shows some thin streaking on the sides of the breast. This is more than a male would usually have, but far less than a typical female. This kind of variation in streaking (which involves melanin pigments) is usually controlled hormonally – adult males with lots of testosterone would grow breast feathers with no streaks, all other birds (females and immature males) grow feathers with broad brown streaks.
If this bird is hormonally intermediate, that could also conceivably explain the yellow color. It could be a male that was not producing enough testosterone as the new feathers grew during its last molt, or it could be a female producing a lot of testosterone. The existence of “male-like females” is known in waterfowl, and those are generally assumed to be older birds that grow feathers with some male-like colors and patterns. I’m not sure how we could distinguish a male from a female in these photos, given that the bird is abnormal.
As mentioned above, yellow color is fairly common in male House Finches, with birds showing a full range of color variation from red, to orange, to yellow, but no obvious differences in plumage pattern, suggesting it involves only carotenoids and is all diet-related. In Purple Finch yellow color is very rare, and often comes along with abnormal streaking, which may mean that it is hormonal.
Why don’t male Purple Finches show a simple “carotenoid-limited” yellowish color more often? Are Purple Finches healthier than House Finches? Do they have an easier time getting the necessary carotenoids in their diets? Or is there a fundamental difference in the mechanism of red coloration in the two species?
Some other examples of yellow Purple Finches from around the web
Below is one photo apparently an Eastern bird in Jan 2010 – photo copyright Stanley York; here alongside a typical female showing the difference in extent of streaking on the breast. Click to see the full size photo on Flickr.
Below is an Eastern bird from NS in May 2010; photo copyright Maxine Quinton. Click to see the original photo and more examples on Flickr.
http://www.redhawksquest.com/?p=1472 – apparently a Western bird in Feb 2009 (click the link then scroll down for photos). This looks more like a male that has simply reduced the normal red color to orange.
Thanks to Skip Pothier for sending the photos and for help with web research.
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I have been trying to identify a bird that is very similar to the above, I have had at the feeders in VT. Thanks for the article and clarification. Very interesting.
I have several photos and can send links (i don’t want to leave a link in a comment)
Dan
FWIW, in some breeds of poultry, females will take on male characteristics if there are no males present in their general area. I always thought this an old wive’s tale, but one year I actually heard an older hen crowing. She was in a pen with no males, and they had been without one for over six months. So I would not be surprised to see a female finch showing some male characteristics.
Of note, I have an orange young male Purple Finch along with the “intermediate female” at my feeders, seemingly watched over by an adult male. (posted on my site tonite if interested.) Thanks for the good article
dan
I have always had an interest in the diversity of the colour of bird feathers.
The thing is I did not know that alot of it is due to melanin pigments to affect colour, the same as in mammals with fur, and our own hair colour as humans, is this correct?.
On the other hand I once read some literature from a chemical manufacturer of Mica that its colour ranges are due to a property of light reflection and light scatter know as irridescence. These same properties can be found in the tiny structure making up bird feathers as well. So, are both factors contributing to the ultimate colour that we see when observing a bird? I am not sure and need to spend some time to research it when I can, but I wondered if you knew anything about these properties.
David, I’m excited to discover one of my photos of the yellow Purple Finches has been published here…just found out today. Your thoughts on the colour variation are fascinating. In light of what you’ve said, I should add that for a number of years on our island in Mahone Bay Nova Scotia we’ve hosted many of these yellow Purples (always in a flock with conventional raspberry coloured Purple Finches). While occasionally I’ve seen some very ill male (raspberry coloured) and female Purple Finches (eye disease that looked much like the disease that afflicts the House Finch), I’ve yet to see a yellow that looked sick; they’ve all been robust looking. I can say that with some degree of certainty, because I’ve been closely monitoring them for four years and have taken thousands of photographs. Thank you! I look forward to more of your thoughts on the subject.
Hi Maxine, Thanks for commenting. That’s fascinating that you have a group of Purple Finches that are consistently yellow – definitely worth more study to figure out what’s causing it.
Hi David,
The Purple Finches just started arriving for the season…late this year. Again, the flock is mixed with some quite yellow Purples and some very raspberry-coloured Purples. If you’d like photos of this year’s birds, please let me know. I’ll for sure keep track of them as the season progresses.