Witch, cock, dwarf, luck, wind, fart

What do these words all have in common? Hold those bizarre interpretations – I’ll just tell you. They all have been used to describe a rare, tiny egg laid with little or no yolk. Instead, wind eggs contain albumin (the egg white), usually laid around a small piece of tissue.

wind egg, cock egg, dwarf egg

Ameraucana eggs – the ‘wind egg’ is the tiny one!

Why does this happen? Amazingly, no one knows. At least, I could find no definitive scientific explanation in the professional literature or lay media. The going hypothesis is that a bit of reproductive debris heading down the oviduct gets treated like a yolk – i.e. surrounded by albumin and encased in a shell.

In 6 years of hen-keeping, I have seen two wind eggs. Roughly calculating 4 hens x 6 months daily laying x 6 years, that is 4560 eggs. 2/4560 = 0.04%, so wind eggs are pretty rare. And its not just my chickens. Although rare, wind eggs have been well documented to occur at a rate of <0.1% in domesticated chickens. This statistic comes from an exhaustive analysis published in 1916 (Pearl & Curtis. Journal Agricultural Research 6:977).

The other interesting statistic is that “The production of a dwarf egg is usually an isolated phenomenon occurring only once or twice during the life of a bird. Only 3.5% of the birds which produced one or more dwarf eggs produced more than two.” There was no correlation with season, age, clutch position, health, etc.

Treatise on wind eggs

Treatise on wind eggs

The only more recent study I found was a letter published in Science in 1966 titled ‘Dwarf eggs and the timing of ovulation in the domestic fowl” by Rookledge & Heald (210:1371). They documented that the timing of wind eggs was not associated with a disruption in the timing of ovulation – i.e., wind eggs showed up as would a normal egg – roughly a day (25-27 h) after the last egg and roughly a day (25-28 h) before the next egg.

The letter concludes with the paragraph:

Rookledge and Heald. 1966. Nature 210:1371.

Rookledge and Heald. 1966. Nature 210:1371.

Alas, no one has taken up the baton as this article was in turn only cited once, on a different topic.  Wind eggs remain a rare curiosity of apparently no importance or concern.

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One Response to Witch, cock, dwarf, luck, wind, fart

  1. Nancy says:

    sort of like miscarriages! (OK, not technically)

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