Does plucking the feathers from live and conscious birds cause them pain?

Question

From: http://www.peta.org/issues/Animals-Used-for-Clothing/down-and-silk-birds-and-insects-exploited-for-fabric.aspx

Plucking birds causes them considerable pain and distress.

Is there any truth in the claim that birds (live and concious) do feel severe pain when feathers are being plucked?

Answer 1

The short answer is yes, plucking feathers causes a pain to birds.

First, can bird feel pain?

This compendium explains:

It is generally accepted that birds perceive pain similarly to mammals. Birds have neurologic components to respond to painful stimuli and endogenous antinociceptive (antipain) mechanisms to modulate pain, and some pharmacologic agents administered for pain in mammals also modulate pain pathways and behavioral responses to painful stimuli in birds. Pain perception allows animals to minimize their exposure to potentially harmful stimuli. Birds often do not indicate pain in an obvious manner because species that may be preyed on are less likely to display overt pain-associated behavior that may attract attention from predators.

This 1992 Animal Welfare article[1] has a similar conclusion:

• Gentle, M.J.:Pain in Birds, Animal Welfare, Volume 1, Number 4, November 1992 , pp. 235-247(13)

"Comparing pain in birds with mammals it is clear that, with regard to the anatomical, physiological and behavioural parameters measured, there are no major differences and therefore the ethical considerations normally afforded to mammals should be extended to birds."

So, birds can feel pain and also in this animal group, pain has probably evolved as a adaptive mechanism to avoid potentially harmful stimuli. This is proposed, for example, by Richard Dawkins in his book The Greatest Show on Earth: The Evidence for Evolution. For a summary of his argument, see Wikipedia.

Just theoretically, plucking the feathers may cause a harm - at least in the way it may cause a skin rupture, what may lead to infection. One can then expect plucking to be painful.

Indeed, in this 1991 study (with the same lead author as the Animal Welfare article), plucking the feathers was shown to be indeed painful for a chicken.

• Gentle, M.J. and Hunter, L.N. 1991. Physiological and behavioural responses associated with feather removal in Gallus gallus var domesticus. Research in Veterinary Science, 50: 95-101

It was concluded that feather removal is likely to be painful to the bird and feather removal by flockmates can be categorised as a welfare problem.

Answer 2

Most likely yes, plucking feathers from a live bird causes the bird pain.

There is a problem of existence of 'animal pain', and if we agree that animal pain exists, of whether the action of plucking feathers causes pain.

Does animal pain exist? It is obviously difficult to know first hand what an animal is thinking or feeling -- or even if it does think or feel -- in comparison to a human, because a human can communicate verbally. However, humans normally avoid painful stimuli and this is a response that can be observed in animals. That animals feel pain is part of the current scientific and legal consensus. It is well known that many governments have created laws that, in particular circumstances, can incarcerate or fine humans for causing unnecessary pain to some animals. See animal cruelty

Since existence of animal pain seems to be part of current consensus, what is animal pain?
How is it defined?

Wikipedia Pain in Animals cites Zimmerman for a definition of pain in animals as "an aversive sensory experience caused by actual or potential injury that elicits protective motor and vegetative reactions, results in learned avoidance and may modify species-specific behaviour, including social behaviour."

Zimmerman M., (1986). Physiological mechanisms of pain and its treatment. Klinische Anaesthesiol Intensivether, 32:1–19

Notice that this definition can be linked to elements observable by humans: actual or potential injury, protective reaction, learned avoidance... The definition is also symmetric with respect to humans in the sense that it characterizes the usual human response to a painful stimulus.

Now we can try to answer "Does removing feathers from a live bird cause pain?"

Noting the Zimmerman definition, removing feathers from a live bird is an actual injury, especially for birds that fly. Even for flightless birds one would expect bleeding from pulling feathers. If the bird tried to avoid being plucked further, this would indicate pain according to the Zimmerman definition.

In contrast, I have witnessed a live sheep being sheared on a farm in New Zealand. The sheep did not try to avoid the process to the degree one would expect if pain were involved.
Similarly, humans do not avoid normal hair or fingernail grooming.

Is the question 'Do animals feel pain as we do?' knowable? Clearly there is an existence hypothesis that is involved. The scientific method thrives on replication and experiment, and the Zimmerman definition provides a characterization of pain that is not wholly subjective but relies on elements that can be replicated or observed in an experiment.