I imagine it would have been interesting to hear his theory as to why.
I do know they will regurgitate their food when threatened (which would have to be almost unimaginably disgusting, given what they eat).
Maybe the hubby was thinking they only regurgitated and never defecated?
Interesting factoid: New World vultures (including condors) aren’t directly related to the raptors, as Old World vultures are. They descend from the stork/heron/ibis group.
[B=CannyDan]We once had a visitor ask if vultures defecate, and we answered in the affirmative. She said that her husband, who ‘knows everything’, declared that they didn’t. She asked us to collect some, as proof. So I had my animal care staff fill a coffee can with vulture poop, which she carried away.**
When I was poking around for my first post, one source (which I can’t seem to find again) said that turkey vultures defecate on their own feet to cool them by evaporation.
I’m familiar with an alternate, even more bizarre explanation: they defecate on their legs for hygenic reasons. Supposedly the digestive tract of a vulture is exceptionally hostile to bacteria, which is why they are even capable of safely eating carrion contaminated by anthrax and other nasty pathogens. According to this theory, defecating on their own legs kills off any disease organisms that they pick up while feeding.
Superficially, it sounds slightly more plausible to me than the ‘cooling’ theory-- wouldn’t freshly generated vulture droppings initially be just as warm as the bird’s internal temperature, i.e., even higher than its surroundings? If anything, I’d think that such a practice would tend to cause the bird to become even hotter-- kind of like trying to combat heatstroke by bathing the victim in warm chicken soup.
I wonder whether anyone has considered the possibility that vultures just have really bad aim?
I’ve also heard that the larger vultures simultaneously regurgitate and defecate (on their legs, presumably) when threatened-- not only alarming predators, but also lightening themselves for a quick takeoff. I am uncertain if this is actually true, or merely a conflation of the regurgitation and leg-defecation trivia. Vulturologists, please advise.
Actually a number of birds besides vultures do this, including storks. And it is not just defecation, it is also urination. Bird urine is composed mainly of uric acid and is semisolid. It’s the white stuff you see in bird droppings. Since birds only have one orifice for voiding waste, the cloaca, the distinction between urination and defecation is a bit moot.
The practice of voiding waste on the legs is almost certainly for thermoregulation. Heat is lost when the moisture in the waste evaporates, just the same as when we sweat. (Of course sweat is initially at body temperature too.) The legs of course being bare of feathers and just below the cloaca are a convenient place to use for such evaporative cooling.
Do you happen to have a cite for the idea that vultures defecate on their legs for hygenic reasons? I’m not challenging you, I just have not heard this before and I am interested in seeing more on it.
No cite, it’s just some random morsel of vulture-related lore that I probably overheard at a dinner party somewhere. It sounded plausible at the time, but if the thermoregulation effect is well-documented in other birds, then I’m sure it’s the correct explanation for vultures as well.
May I ask a related vulture question? When driving (an MR2) in a fairly remote area in west Texas, My car was “attacked” by a large black bird that had been eating carrion on the side of the road. The wing span was wider than my car wind shield.
The bird flew straight at the car and sort of draped itself over the windshield.
I’m asuming it was some sort of vulture, but what sort?
Depending on exactly where you were in West Texas, and when, it could have been a black vulture or the aforementioned turkey vulture. The heads of immature turkey vultures are grey, like those of black vultures.
Both birds have difficulty taking off from the ground quickly, is it possible the bird was just trying to get out of the way of your car?
The BV is not quite as big as the TV, and has a much shorter tail (not that this would have been especially apparent with the bird spread across a windshield).
I agree that it’s likely the “attack” was an accident.
I’ve been gone for a week-- surprised this thread is still active!
Yes, our captive vultures (both black and turkey) void onto their legs in very hot weather. As Colibri notes, this appears to function as an evaporative cooling mechanism.
As for why “hubby” believed that vultures do not defecate, I am virtually clueless as wife unit did not explain. Perhaps he observed the area under a roost to be devoid of excrement. As Colibri also offers, vultures rarely have opportunity to feed on migration, thereby greatly reducing their need to eliminate waste. And even in non-migratory situations, vultures are usually by necessity ‘gorge or starve’ feeders. When food is available, like an animal carcass, they gorge themselves (or attempt to). But frequently, there is simply no food available. During such times, defecation would also be, perforce, reduced.
Related to vomiting as a defense, indeed they do. Anyone who has ever handled a vulture will testify to that, and to the especially noxious aroma of vulture vomit. But a related factoid I thought was apocryphal until I observed it myself.
Another carrion eater found near us is the Audubon’s (or Crested) Caracara (Polyborus plancus). (Caracaras are apparently highly modified falcon relatives-- they are not obligate carrion feeders, preying also on small ground living animals including insects and lizards, but opportunistically eating carrion as well.) The tale is that Caracaras will pester vultures to obtain food.
We have on more than one occasion observed a Caracara attempting to feed alongside vultures on a carcass. Rebuffed by the flock of larger birds, the Caracara approached a vulture that had already eaten its fill and was apparently too over-burdened by payload to take flight. The Caracara jumped on the vulture’s back, plucked at its feathers, fluttered around its head, and generally made a nuisance of himself for more than 10 minutes. At that point the vulture regurgitated a huge quantity of its meal and flew away. The Caracara proceeded to devour a hot lunch.
Actually, looking at the map, it was really central TX, west of Austin, maybe between Johnson City and Fredricksburg. The birds were off the roadway, but you’re probably right, in that they were just trying to get away. Scared me, though.
They were huge birds and if memory serves, all black. I remember noting that the ends of the wings were beyond my mirrors and the windshield was completely covered.
I had to stop to avoid running off the road. By the time I came to a full stop the bird was gone.
Sometimes Mother Nature is awe-inspiring. Sometimes she’s deadly. But most of the time, she’s just freakin’ gross…