Cardhuloxia: a query from Steven Mlodinow

Northern Cardinals (Cardinalis cardinalis) and Pyrrhuloxias (Cardinalis sinuatus) are two closely related species that inhabit many of the same locations in the U.S. desert southwest, from Arizona to Texas, as well as in much of northern Mexico, including Baja California Sur. Despite their geographic and taxonomic proximity, few hybrids between these two species have been reported. The only confirmed hybrid in the wild was collected at Komatke, Arizona in the 1800s, but the Tucson Desert Museum had two in captivity during 2004 (Handbook of Avian Hybrids of the World; McCarthy 2006)  

While birding near San Jose del Cabo, Baja California Sur this past March, I encountered an odd Cardinalis, that I later nicknamed “Cardhuloxia.” Three photos of the Cardhuloxia can be found below. Upon first blush, the rather gray plumage contrasting sharply with the brilliant red folded primaries gives a strong impression of Pyrrhuloxia. However, the red bill cries “Cardinal.”

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Image 1: This view of the "Cardhuloxia" shows its well-curved culmen, imparting a stubby appearance to the bill. Note that the wing coverts have but the faintest of a red wash, apparently not something found in "pure" Northern Cardinals.

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Image 2: This view shows the limited white patch on belly, the fairly extensive dark feathering on the crest, and again, the nearly pure gray wing-coverts.



Close examination of the photos seems to reveal a bird that is intermediate between a Northern Cardinal and a Pyrrhuloxia. The Cardhuloxia has the wispy crest typical of Pyrrhuloxia, but not terribly rare in N. Cardinals from the desert Southwest. However, the blackish on the crest seems to be a feature shown only by Pyrrhuloxias. A review of photos on various Flickr websites reveals a number of grayer-than-normal N. Cardinals from across the species’ range, but all of those that I looked at showed red on the wing coverts, which the Cardhuloxia essentially lacks. The white (or near white) between the Cardhuloxia’s legs is a feature not consistent with Pyrrhuloxia, but I am not sure how commonly N. Cardinals have white between the legs combined with a fairly buffy vent. I didn’t carefully assess this potential mark during my photo survey.

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Image 3: In this image, the oddly shaped (notched) mandible can be seen well as can most of the marks mentioned in the two photographs above.

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Image 4: A male Northern Cardinal (from Baja population) was used for comparison because I did not have any pictures of females holding their heads at a similar angle. In this photo-comparison, the Cardhuloxia's more steeply curved culmen is best appreciated, and the bill seems truly stouter, even when one considers the effect of the male's erect crest on the bill's initial appearance.


The Cardhuloxia’s red bill quickly brings Northern Cardinal to mind, though to those living in eastern North America, its bill might seem distinctly too large for a N. Cardinal. However, the desert populations of that species, including the N. Cardinals of Baja California Sur, often have larger bills than those from eastern North America. Therefore, I created a fourth “photo” that offers a close-up comparison of a male N. Cardinal from Baja California Sur and the Cardhuloxia, both holding their bills at roughly the same angle (to the camera). This comparison seems to demonstrate that the culmen of the Cardhuloxia is more curved than that of the N. Cardinal, imparting a stubbier appearance. Additionally, there seems to be an odd angle change that creates a slight notch (see Image 3) along the bottom of the Cardhuloxia’s mandible (that is, the lower mandible).

While the discussion above seems to make a good argument for the Cardhuloxia being a Northern Cardinal x Pyrrhuloxia hybrid, this cross seems to be extremely rare, thus great caution is warranted. For this reason, these photos are placed here for your review and thoughtful comments. It is worth asking the question, “If this bird is not a female Northern Cardinal x Pyrrhuloxia, how would such a bird differ from the photographed bird?”

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Image 5: A female Northern Cardinal photographed at Miraflores, Baja California Sur, January 2009. This bird is typical of of female Northern Cardinals in the region, with rather buffy underparts and a distinct red wash to the wing coverts.

The images above have been previously circulated among a small group of experts selected by the author. While some believed that this bird exhibited expected intermediate characteristics between these two species, others were less comfortable in labeling it as an apparent hybrid. None of the respondents believed that the bird was simply an aberrant Northern Cardinal. Hence, the author requested that we post this discussion and the associated images to the BirdFellow journal and open up the debate to a broader audience. Birders of all experience levels can learn from this sort exercise. Not only is there an opportunity to hear the opinions of veteran observers and experts from all over North America, but this is also a chance to test and hone your own observational skills. Hybridization is fairly common in the bird world, but many hybrids pass before us unnoticed because we don't stop to take closer look after forming our initial impression about a bird.

We have numbered the images above so that they can be easily referenced by those who wish to offer comments. We encourage lively debate and discussion of this interesting bird, but please keep in mind that the BirdFellow audience is highly diverse in terms of experience level. There must be room at the table for anyone who commits to offering a public opinion. Please refrain from engaging in contests of ego and/or making dismissive or disrespectful comments about others who post comments. 

All photographs used in this article were taken, cropped, and edited by Steven Mlodinow.

1

Excellent discussion – wish we had taken photos at a feeder in Portal, AZ where there appeared to be at least two intermediate birds. Now that Steve has brought this issue up for consideration, maybe people visting/living in Portal can document more occurances. The birds appeared to be more Pyrrhuloxia in appearance but with the bright orange bill of Northern Cardinal and much more red – locations unnoted unfortunately – but more than on Steve’s subject and on different areas than a typical male Pyrrhuloxia.

2

I guess my general feeling is that I am not 100 % convinced your bird is a hybrid. I did a google image search and looked at the variation in coloration and bill size and shape, and my conclusion is that your bird seems to fall within Cardinal variation. On my monitor (A Mac of course which is superior :-) ) I see some red on the coverts – it is reduced but still present as it is on images of very dull gray female Cardinals I have found. The pattern of red over the eye in combination with a dark gray area around the bill and onto the chin area looks to me like a Cardinal pattern, and if this was a hybrid, I would expect more red in this area (or at least “not” a typical Cardinal pattern. As you noted the white belly in combination with buffy undertail coverts seems to be a Cardinal character. The bill looks a bit heavy, but I often get this impression on young birds of many species, and the shape is much more aligned with Cardinal, as is the coloration of the bill. The dark on the crest may be caused by those feathers being very worn and the gray bases showing more???

In short, this bird may have mixed blood, but I would want to see more Pyrrhuloxia characters – particularly in the bill.

3

I’d like to hear more about the previous confirmed hybrids. What characteristics did they show? Did they resemble each other, or did they vary? Those details might shed some light. That being said, I probably would have called the bird a female cardinal, and not looked more closely.

4

The Birds of North America Online has “Immature female hybrid with Pyrrhuloxia taken 23 Feb 1967 at Komatke, AZ (Rea 1983)” Rea 1983 is the book “Once a River” by Amadeo Rea. That is not much help for Chad’s questions.

5

I think this is clearly a hybrid bird, based on a combination of characteristics. The plumage is too gray for Northern Cardinal, and the red concentrated in areas where found on Pyrrhuloxia. But while one could try to claim that these are within perceived variation for Northern Cardinal (in my experience, they are not), the bill shape alone is a clincher. Basically, there is no variation in bill shape that can account for what you see in Steve’s bird. It is simply intermediate in shape. There are indeed aberrant bill shapes, but such a bill has so many ways to vary in all dimensions, the chances seems ridiculously low that the aberration would lead toward a shape that is exactly in the direction of a sympatric congener. Which leads me to my last point, which is that there is nothing surprising that such a hybrid would exist. The species are very closely related, they have similar songs, they co-occur, and such hybrids have been documented before. I have seen two myself, one at Patagonia Lake State Park, and one at Rattlesnake Springs, NM (which exhibited bilateral asymmetry).

6
We live in the Tucson Mts on the western edge of Tucson, AZ. For the past two years we have what appears to be hybrids visiting us. We are not “birders”, but this is our experience:

They appeared last year (2008), five in all, already “tamed”. We took them to be a family of two parents and three young ones, as there was much feeding of the smaller ones by the larger ones.

Originally, we did nothing to modify their behavior. However, as they were so bold and friendly, we began to give them bread crusts and sunflower seeds.

Late in the summer (2008), they no longer came to solicit food and were seen no more. We were sad; it had been fun.

We were pleasantly surprised when two returned this year(2009). We believe they are nesting nearby as they come individually to solicit food, eat some and then carry some away.

They have us well trained. If we are outside they hover, follow and thus “send” us to get food for them. It (they) come when we call and will eat from our hand. We have several photographs of them.

They are gray with red like a pyrrhuloxia, but the red seems much redder than the usual pyrrhuloxia. Both have an orange beak and one has partially orange legs. One of them often flares his topknot into a “mohawk”. I believe that they are able to call as both pyrrhuloxias and cardinals, as I often hear both sounds…however, it could be that both cardinals and pyrrhuloxias are about.

We truly enjoy being able to observe them so close-up. We are hoping to see their offspring (if they are, indeed nesting) as we did last year.

Fun to watch, feed and photograph!

7

Hello Norma

I would love to see your photographs if you wouldn’t mind sending them to me. My email address is SGMlod@aol.com

Thanks Much
Steven Mlodinow

8

im doing this for a project so im reading this sooo ya

9

i love birds and if u mark brown is from arthur i love ur books i loved them when i was small.oh and any single guys here talk 2 me im single.

10

I was excited to see thus discussion. I am in Houston, Texas. I recently saw a bird at my feeder that looks like the one in the picture. Right away it looked off to me. I have a fee female cardinals that visit but this bird looks different. The beak is bright orange but larger. The color is dull except for red on wings. I was trying to identify it and finally found this site.

11

BEAUTIFUL!!!! You inspire me to get back to my art could you come and clean out the smaebent room with me so I can get started ha ja?

12

Greetings All
If you go to my Flickr site, you can see several photos of known hybrids in captivity

13

Greetings All
If you go to my Flickr site, you can see several photos of known hybrids in captivity

14

It is very strange… Earlier this morning i saw both of them outside my bathroom window in Bangor, Maine… They had made a nest in a row of small trees…. I had never seen a bird like it before…. It was very interesting, so i decided to look it up and see what type of bird it was….

15

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