Bomber birds?

John Hewitt

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A friend of mine is the proud possessor of a red sports car with a long streamlined bonnet. It seems this bonnet has become a popular target among the local bird population despite there being no perch above where the car is parked. (It is certainly true that there is more guano on the car bonnet than elsewhere on the car.)

The owner believes the reason birds tend to target the car bonnet is that she also has a cat which likes to enjoy the warmth the car bonnet after it has been used for a drive. She believes that the birds target the cat rather than the car. I can certainly believe that birds might dislike cats and want to drive them off but has anyone else heard of birds using their droppings as a weapon like this?
 
Lifelong birdwatcher here. I have never heard of birds deliberately targeting predators with their feces. I have heard of birds deliberately dive-bombing predators with their beaks, but not with poo.

My guess would be that since it's a shiny new red sports car, you notice bird poo more than you would on a decrepit old dark-colored wreck, and that there are pigeons roosting somewhere nearby--pigeons are notorious for pooping in flight, and if their roost is somewhere on a rooftop nearby, that would account for bird poo appearing seemingly out of thin air.

The Scientific Method is to "change one thing". So you can test the "cat hypothesis" quite simply, by preventing the cat from lying there--I'd put laundry baskets, weighted down with stones, all over the hood of the car. Then see how much poo the laundry baskets receive.
 
You'd think that if the pigeons aim was any good, the cat wouldn't want to stay there.

'Tis due to pigeons that alight
on Nelson's hat, that makes it white.
(S. Milligan)
 
I saw some birds on a David Attenborough documentary projectile poop in self defense to scare off another bigger bird. No, seriously. But that's the most compelling evidence I have.
 
But...you'd have to prove that the birds were experiencing the thought process of, "I will poop on this bigger bird deliberately in order to scare it away", and not merely (a) passing feces coincidentally while flying, or (b) passing feces out of sheer fright--or exertion--which many birds do.

Just because David Attenborough might intone, "See how these birds attempt to frighten away their nemesis by excreting on him" doesn't mean that's what was happening there.
 
Goshawk said:
But...you'd have to prove that the birds were experiencing the thought process of, "I will poop on this bigger bird deliberately in order to scare it away", and not merely (a) passing feces coincidentally while flying, or (b) passing feces out of sheer fright--or exertion--which many birds do.

Just because David Attenborough might intone, "See how these birds attempt to frighten away their nemesis by excreting on him" doesn't mean that's what was happening there.
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Nevermind.
 
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Goshawk said:
Lifelong birdwatcher here.
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Same here.

Goshawk said:
I have never heard of birds deliberately targeting predators with their feces. I have heard of birds deliberately dive-bombing predators with their beaks, but not with poo.
Click to expand...

I wouldn't care to state that no birds would use faeces as a predator deterrent even in other situations; I simply don't know if it happens (though like Goshawk, I've never heard of it apart from as mentioned below). When handling many small warblers they usually seem to use every method available to them to try to scare you away. This includes biting (feebly, I admit), flapping their wings, making themselves appear larger, making horrible sounds, and pooing.

Granted, having the bird in your hand is a somewhat unusual situation for the bird...

Gannets, auks and cormorants deliberately target nest predators with vomit, don't they? Though, having handled several cormorants less than a month ago, they don't seem to be too keen on doing that in a non-nest situation, nor do they seem inclined to project faeces onto ringers apart from the way most birds seem to do it, i.e., due to fright.

So maybe, just maybe, the car is a nest predator on auk cliffs by night? You could test this by waiting up all night beside the car and see if it drives away on its own volition.
 
Might the greater area of said "long streamlined bonnet" be a factor? What about the colour? I'd go with Goshawk otherwise - you just notice it more readily. I know I do with my car, and it is a "dark-coloured wreck"! If I had a red Viper say (drool) you can bet I would be even more alert for avian payload deliveries...
 
Kotatsu said:
Gannets, auks and cormorants deliberately target nest predators with vomit, don't they?
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I think it's fulmars you're thinking of, which are notorious for projectile vomiting when disturbed.

But all you actually see is that the nesting fulmar is disturbed, and in response, it vomits. But you don't have any way of knowing that this is a deliberate attempt to drive away a nest intruder--it could just be a symptom of distress, or nervousness. "Oh, no! Intruders! Watch out, I feel sick! [barf]"...

This mentions that fulmar chicks will puke tiny yellow vomit on people who handle them, and that during competition for nest sites, adult fulmars will sometimes puke on each other. But, again, it could just be a nervous reflex, not deliberately choosing to empty the stomach with the specific intention of discouraging a predator or competitor.

In order to prove that they were using projectile vomiting specifically to target nest robbers, you'd have to use various stuffed birds, such as known predators like jaegers and gulls, and then other birds like geese, and other fulmars, and then maybe a stuffed dog or cat, and of course people in various postures as they approach the nest. And see which ones get puked on.

From what I've read of fulmars, it sounds like they puke just anytime they feel nervous about their nest, not when specific predators approach.

The above cite mentions that chicks that get moved from their nest even a few feet are abandoned by their parents--and will then vomit on their own parents if they approach too closely. This says to me that it's a defensive reflex, not deliberate targeting.

Just musing aloud here, BTW. :)

I still wanna see the OP try the laundry basket experiment.
 
Goshawk said:
I still wanna see the OP try the laundry basket experiment.
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Its not my car (which is also red but tiny and cheap) and I fear I'm not going to set up any controlled experiments. I just felt it seemed interesting and rather plausible.
Thank you for the commentaries though.
 
I have watched birds systematically harass one of my cats. There were two overhead cables on two sides of the yards. Birds (starlings or grackles, not sure which) were on each cable. The cat was in the middle. A bird would fly down from one cable, swoop near, but just out of reach, of the cat, and land on the other cable. Then, a bird from the alternate cable would swoop down and repeat the process. I watched this for several minutes, with probably 20 swooping attacks on the cat, until the cat became disgusted and walked away (trying to act with the typical feline "I meant to do that" style).

If this sort of dance was repeated on the cat, even if the birds weren't deliberately launching bird poop at the cat, they would be near the car bonnet often enough for droppings to accumulate.
 
I remember a story about breeding colonies of redstarts attacking crows by defacating on them; some Scandinavian naturalist tethered a corvid by such a colony and the thrushes divebombed it until it was taken away. The theory was that the chemical nature of the poo destroys the weather-proofing on the crow's feathers.
 
But, same thing as Meadmaker said: maybe it was just because the redstarts were close enough to the corvid that it accumulated feces, since many birds defecate in flight.
 
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