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It is often said that if one were to add surfactants to water ducks would not be able to float as their feathers would start soaking water instead of repelling it.

Has anyone actually tried this experiment? What were the results?

  • 4
    Well I know how I'm spending my vacation now. – GordonM Mar 13 '17 at 10:00
  • 2
    If it comes to rubber ducks I can refute this claim by personal experience in my bath tub! – Scrontch Mar 13 '17 at 13:05
  • A duck without feathers would still float because their body is shaped like a boat and displaces more water then they weigh. – Reactgular Mar 13 '17 at 16:48
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One paper (the only one I could find in support), does claim that surfactants will change the surface tension and result in drowning.

When a bird comes into contact with water containing surfactants, the surfactant will reduce the surface tension of the water; thus, allowing water to penetrate through the feathers and onto the skin. This compromises the insulation properties of the feathers and subjects the bird to hypothermia. The loss of water repellency by the feathers due to reductions in surface tension will cause the bird to become water logged and the loss of buoyancy will cause the bird to drown.

However all of my other readings indicate that soap alone will not drown a bird (although oil will).

The relation of the uropygial gland and flotation is not definitive and there are also other mechanisms which make ducks float, including hollow bones, feather structure, and lung air retention. It's very unlikely that a little soap on the water would make one sink. For instance, diving is accomplished by quick variations to plume density and exhalation from the lungs, not adjustment of the oil concentration on the feathers. Indeed, oil is more likely to drown a duck than soap, as oil does not create the same plumed air pockets, thus destroying bouyancy.

Also, while soap won't drown a bird, it is quite likely to cause hypothermia since more water will touch the skin.

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    To avoid confusion, it would be useful to mention whether oil is the thing used for lubrication/cooking or crude oil. – yo' Mar 18 '17 at 11:52

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