And an avian mystery. How about a little help from my friends?
1/4000, f/7.1, ISO 500, Canon 7D Mark II, Canon EF 500mm f/4L IS II USM + EF 1.4 III Extender, not baited, set up or called in
Eleven days ago I posted several photos of a young female Red-tailed Hawk with an engorged crop as she was about to take off. Last night I ran across photos of her in flight that I thought made the fullness of her crop even more evident. And impressive.
I don’t remember ever seeing a raptor’s crop bulge with food more than this but falconer Laura Culley say’s it’s only about 2/3 full.
1/4000, f/7.1, ISO 500, Canon 7D Mark II, Canon EF 500mm f/4L IS II USM + EF 1.4 III Extender, not baited, set up or called in
I don’t question Laura’s statement but it’s still hard for me to imagine. This bird’s crop looks to me like it’s about ready to pop.
The crop is a thin-walled expanded portion of the alimentary tract used for storing food prior to digestion. We tend to think of only birds having crops but they’re also found in many invertebrate animals including gastropods (snails and slugs), earthworms, leeches and insects.
But not all birds have crops. Most raptors do but owls don’t. Chickens and turkeys have crops but geese don’t. All of which makes this biologist marvel once again at the processes and complexities of evolution.
OK, now for the unrelated avian mystery.
The following photo is one of the lowest quality images I’ve ever posted to Feathered Photography. You’ll probably wonder why I even bothered to take it. I could explain my motivation for taking the photo but it would take more space and more time than it’s worth. I’ll simply say that it was taken through my dirty patio door window and my active focus point was never able to lock on to the backlit bird so it’s soft. Really soft.
But it’s sharp enough to show why I’m puzzled about it.
This is a young House Sparrow perched on my wrought iron bird feeder stand. I took the photo a couple of days ago but never looked at it until last night.
What in the world is going on with that bright white upper mandible? The lower mandible is the normal color for the species at this age but I’ve never seen anything like that upper mandible.
My first thought was that the bird may have a stained bill from some foreign substance but the color seems too uniform and too precisely confined to the upper mandible for that to be the likely explanation. Then I wondered if it was some kind of weird optical effect from light reflection but I don’t think that explains it either.
This is the only photo I took of the bird. Cropping tightly on the bill doesn’t reveal any more detail because the bird is so soft.
I’m stumped. Any thoughts?
I wouldn’t lie about the size of that crop and I’m not much into exaggeration, either. 😉 It wasn’t necessary. LOL! I SO wish I had a photo of that, but alas, that was back in our first year when I was SO concentrated on Mariah I couldn’t even think of anything else. And that’s persisted over the years. I have to keep a shovel with me so I can routinely scrape my jaw off the ground with these birds. Now if I could just transfer mental images…
I don’t know if 2/3rds is correct, but it’s darn close. That said, she held her crop a little higher than the individual in your photo so that it extended over the tops of her folded wings. She stopped frequently to maneuver her head/neck to rearrange the crop to pack more in there. There was also the same feather spread at the front of her crop. I have no idea if she could have flown with that load. I suspect that sustained flight would have been a struggle. She might have had to waddle over to a bush to digest for a while. But since she had her trusty slave in attendance, it wasn’t necessary.
I didn’t know it at the time, but that kind of gorge can be dangerous and even deadly, especially if the bird hasn’t been eating much for an extended period of time. It can result in what falconers call sour crop, which is a failure of the digestive process to keep up with processing the excessive amount of food before it begins to rot in the crop. I believe the term is it turns septic (not sure septic is the right term. I’m not a vet and I don’t play one on TV). That might be why you don’t see it happen often among the wild population, but that’s a wild guess.
Anyway, I didn’t learn that until Mariah’s second gorge that resulted in sour crop and started a string of bad events that nearly killed her! She was anesthetized to empty her crop, a little piece aspirated and caused a respiratory infection and the situation carried on from there as a gift that just kept on giving. Thankfully, I was back home with my raptor vet/falconer who brought her through. Suffice to say that I’ve never let Mariah gorge again. She’s had hefty meals, but NOT even close to a gorge. It was a stupid apprentice mistake, but I learned it without lethal results and I’m so very grateful for that.
A very interesting explanation of sour crop, Laura. I’m so glad that Mariah survived your first experience with it.
Huge thanks to you and to Dan. I was (as usual) clueless and am had that state lifted a little.
On the crop front? A member of our extended family says he cannot do anything after a meal because he is digesting. If he stuffs his crop as thoroughly as that bird he might have some justification. And if Laura is right and the crop can get bigger I expect that those birds are compelled to digest close to the ‘table’.
You’re probably right EC. When I eat that much (relatively) I can barely more. And often don’t for several hours…
Occam’s razor leads me to go with Dan and Laura. Plus, I don’t have a clue.
Thought-provoking post along with the unusual photos. Now go clean your windows.😉
They definitely need cleaning, Lyle. Now I’ll feel guilty until I get it done.
So delighted to see a well-fed Red Tailed Hawk! Whatever % full her crop is, she seems to be handling it with ease.
As for the sparrow, I got nothin’ other than to agree with the posters that have said that even the mandible looks a little “off.” And, of course, to thank Dan for another wonderful lesson in bird anatomy! 🙂 Hope this little thing’s OK and that you get some more opportunities with it.
” Hope this little thing’s OK and that you get some more opportunities with it”
Marty, I’ve been keeping my camera and lens on the tripod by the patio door just in case that sparrow comes back. I’d love to get a sharper shot of that bill.
My guess is that the rhamphotheca has been damaged and stripped away from the bill. The rhamphotheca is a keratinized covering over the bill. In many birds, like this bird, it is somewhat thin and tightly covers the bill, but in some birds it is quite enlarged. Puffins have a very enlarged rhamphotheca during the breeding season, hence that very large appearing bill. During non-breeding it is greatly reduced giving the bill a much more slender look. The ramphotheca is shed periodically in some species and will regrow. In other birds this is shed much more gradually, slowly growing and wearing away, similar but somewhat different from our fingernails. Occasionally, some trauma occurs where it is cracked and stripped away all at once. It can regrow, but until then, the bird’s bill is more vulnerable to damage and opening hard seeds will be more difficult. When I was still teaching at the university I had a skull of an Evening Grosbeak. The tenuous connection between the skull and the ramphotheca was broken and you could slide off the ramphotheca like a glove to show the smaller beak within. It was the perfect demonstration of this feature which most people are unaware of.
Dan, thanks for the fascinating lesson on bill anatomy. And for the likely explanation for my little mystery.
I agree with Judy–there’s something strange about the shape of the
lower beak, as well……..I’m so glad that the natural world STILL offers lots
of anomalies–even mysteries !
I enjoy the mysteries too, Kris. A lot.
could it be a lighting artifact – the feeder stand is, I assume, uniform black but the image shows it as ‘light’ on the top, black on the bottom
Robert, I think it’s possible but it wouldn’t be my first guess.
Stumped on both. Have never seen a raptor with a crop like that. Not even close. Have no idea as to why. With the sparrow I would be afraid to even hazard a guess. Hopefully some of your most knowledgeable birders will come up with answers. Thanks for posting.
Everett, once again Dan Gleason may have the answer. See his comment above.
That crop does look about to pop! I know some raptors are unable to take off after gorging (or engorging their crops) on a large meal. So I suppose the fact this bird is flying makes it likely Laura’s statement is correct. Amazing!
I think your initial thought of the impact of the strange lighting/poor focus/dirty window on the beak may be right… and agree it’s so extreme that it does look like the beak has somehow been painted. I concluded this by looking at the gradation of the colors on the wrought iron shepherd’s hook. Some of that black looks as white the beak. But, of course, it doesn’t prove my theory is right.
An interesting idea, Nancy. Within the realm of possibility I think.
Whole beak looks a bit strange to me and upper beak looks “rough” in texture. This link in the US shows something similar but not “it”. https://www.gardenbird.co.uk/house-sparrow.html
That IS a HUGE crop – would almost worry it was impacted……
I also wondered about an impacted crop Judy but apparently a crop this large isn’t that far out of the ordinary.