Tetrapod Zoology

Here is a Secretary bird Sagittarius serpentarius skeleton I photographed some time ago: as usual, apologies for my terrible photography. The bird is lying on its back, and both its wings and legs are folded up. I would like you to concentrate in particular on its humeri: what the hell is going on?

Here’s a close-up. Both humeri were like this. It looks as if they were broken mid-shaft, and then healed, but with the two halves of the shaft being totally misaligned (though I’m not saying that this is necessarily what happened: I really don’t know). You might assume that a bird with injuries like this was incapable of flying. Unfortunately I know nothing of the individual’s history, nor whether it was a captive individual or a wild-caught one [I do have the specimen number and repository details on file if anyone wants them and is prepared to chase this up].

Incidentally, Secretary birds have lovely eyelashes. I have a good video on my mobile phone of a captive one bashing the hell out of a rubber snake.

Comments

#1 Dartian
May 22, 2009

Unfortunately I know nothing of the individual’s history, nor whether it was a captive individual or a wild-caught one

The fact that both wings are similarly injured suggests some sort of human involvement to me, though I can’t think of exactly what kind. An in-flight collision with something? A very crude – and cruel – attempt of pinioning a captive* bird? In any case, it seems unlikely that such a seriously injured bird would survive in the wild long enough for the broken bones to heal, so perhaps it’s most likely that that individual spent at least the last part of its life in captivity.

* Speaking of captivity: in many zoos, secretary birds are kept in ‘mixed species’ exhibits, sometimes including ungulates and other – supposedly compatible – large mammals. Under such circumstances, birds often come in harm’s way (they get trampled, bitten, or gored by their cage-mates, either by mistake or intentionally). Perhaps that particular secretary bird was a zoo animal that had a run-in with a grumpy antelope?
#2 Jorge Velez-Juarbe
May 22, 2009

Pathological specimens are always interesting! I wonder if such an individual would be able to survive in the wild. Are captive animals, in general, more prone to have more pathologies like this?
I remember reading somewhere that one evidence for the domestication of Isolobodon portoricensis by the Tainos, was the presence of pathologies, such as fractures and healed bones.
#3 Matt Mullenix
May 22, 2009

Bird bones heal fast (limb bones in about 12 days), and given the mostly-terrestrial habits of the Secretary bird and a suitable prey base (perhaps the timing of the injury coincided with a good hunting season), it could have survived in the wild long enough to heal. Injury could also have occured in the nest and healed while the parents were still feeding.

I have trapped adult wild Cooper’s hawks (Accipter cooperi) for radio marking, which had suffered very serious leg, foot and keel injuries that had obviously healed over. And this is not a social species; they would have probably have had to support themselves or go hungry while recuperating.

If you consider a social hawk, like the Harris’ (Parabuteo unicinctus), you see living adult individuals with very serious injuries, including crippling electrocution burns that impair flight. These individuals are cared for by their family members and share in meals. There is a paper detailing these injuries in HHs and some attempt to determine if they are seen at a higher rate in social raptors.

Finally, my trained hawks have caught several starlings with well-healed broken wings that were surviving near the refuge of thick cover, with access to lawns for foraging. It seemed to me they were survivors of wire or car collisions. Of course, they succumbed eventually to predation.
#4 Darren Naish
May 22, 2009

Wow, amazing. Thanks Matt. I was going to say that – on occasion – wild animals can get by with the most horrendous injuries, and live to heal those injuries up.

I resisted the urge to say RAPTORS ARE AWESOME in the brief text above. Mike Habib, who works on flight dynamics and so on, points out that – if extinct and known only from their bones – raptors would just astound us. Well, they already astound us, but you know what I mean.
#5 Graydon
May 22, 2009

What’s especially astounding about the skeletons of raptorial birds?
#6 Dartian
May 22, 2009

Matt:

Bird bones heal fast (limb bones in about 12 days), and given the mostly-terrestrial habits of the Secretary bird and a suitable prey base (perhaps the timing of the injury coincided with a good hunting season), it could have survived in the wild long enough to heal.

The secretary bird is terrestrial, yes, and hunts normally on foot so I don’t doubt that it could find food for itself even while flightless. But I was thinking more of how it could avoid becoming prey itself while it’s flightless. Twelve days sounds like an awfully long time on the predator-infested African savanna. At night, in particular, I’d imagine that a flightless secretary bird would be incredibly vulnerable (secretary birds normally roost in trees at night, AFAIK) to jackals, hyaenas, servals, caracals, leopards and other such predators.

Synapsids are the reason why terrestrial flightless archosaurs are so few in this post-Mesozoic world…
#7 Matt Mullenix
May 22, 2009

Dartian,

There’s some video floating around of a caracal killing a young Black Eagle–better armed than any Administrative Assistant Bird. I don’t doubt the dangers of life on the savannah (partly why I live in Louisiana, where we fear only alligators and stray bullets).

Yet, assuming it is a wild specimen, this bird somehow survived long enough to heal. I agree human intervention one way or another is likely; after all, the thing DID turn up in a museum.
#8 Matt Mullenix
May 22, 2009

Darren,

I share your amazement in the raptors! And the more you see of them in action, the more amazing they seem.

Matt
#9 Jerzy
May 22, 2009

Maybe it was captive bird? If it was kept in a small aviary, keepers might not notice that it broke and healed both wings (maybe not at the same time).

BTW – large birds kept in too small zoo aviaries are very sad sight.
#10 Craig York
May 22, 2009

Both bones being broken in the same place suggests some
kind of trap injury to me, but thats just a wild guess-
its well known I have no sense of humeri.

For what its worth, I think they’re gorgeous birds, too-
for some reson I’ve always liked terrestrial birds. ( I’m
just close enough to the Hill Country here in Texas to
see the occasional Roadrunner. )
#11 Craig York
May 22, 2009

Both bones being broken in the same place suggests some
kind of trap injury to me, but thats just a wild guess-
its well known I have no sense of humeri.

For what its worth, I think they’re gorgeous birds, too-
for some reson I’ve always liked terrestrial birds. ( I’m
just close enough to the Hill Country here in Texas to
see the occasional Roadrunner. )
#12 Zach Miller
May 22, 2009

Our zoo has two largish bald eagles in a mid-sized cage. Neither bird can fly–the male had its wing surgically removed, and the female has both wings but is permenantly injured and can’t fly. They do okay, and seem to like people-watching (whenever I get over there). The male hops around and flaps his one wing, which is kind of funny. The female prefers high elevations but the male likes being on or near the ground, which is funny to me.
#13 Susannah
May 22, 2009

Darren,
Do you use a point-and-shoot? I would suggest three simple fixes: make sure you wait until the little green focussing light goes on before you click, use the flash indoors (it may change your colour balance, but it reduces the duration of the image capture, so helps to neutralize hand shake. And if you can, lean on or hold onto something stable while you take the shot. That should do it.
#14 Nathan Myers
May 22, 2009

You can stabilize your shots without compromising color balance. Put a screw into the camera’s tripod mount and tie a heavy string to it. Before a shot, step on the string and draw it taut. That helps you to hold the camera steady.