Mar 27, 2014

Moon Cycle?

So, you've heard about the moon affecting rabbits' breeding habits and results, right?  You haven't?  Well, neither had I until a couple months ago.  Like you, I was definitely skeptical.  What sane, scientifically-minded person wouldn't be?  (And, if you know me, you know that I'm quite scientifically-minded--although I won't say one way or the other on the sanity part.  Give me anything to do with the scientific method, and I'm there, especially if it has to do with rabbits.)

The general points to the moon-phase theory are:
  • You get more does than bucks when you breed during the full moon[1]
  • You get more bucks than does when you breed during the new moon[1]
  • You get larger litters when you breed during the full moon than when you breed during the new moon[2]
  • You get larger litters when you breed when the moon is waxing (getting bigger) than when the moon is waning (getting smaller)[3]
I will be honest, here, and say that I consider myself a Witch, and practice along the lines of Wicca (not completely, but mostly).  In that theology (as well as a number of other ancient culture theologies), the moon plays an important role.  The moon can be a powerful force (it controls the tides, after all!).  However, I've never applied it to my everyday life.  I don't even use it for gardening, which so many people do.  Despite my belief in the power of the moon, spiritually, and knowledge of its effects, geographically, I've never held to the thought that it had any power over biology.

Anyway, the topic has come up frequently in recent days, so I figured I'd take a look at my old records and see if there's any foundation to these [highly improbable] claims.

Scope of Data
23 does were used, all either purebred Californian, New Zealand, or Rex.  They were all bred to purebred bucks of the same breed.  Does were between the ages of 5 and 49 months. 74 breedings were recorded (where the buck definitely fell off while lined up properly), which resulted in 49 litters.  Kits were sexed at weaning between 6 and 8 weeks old.  Kits which died before weaning were not counted for gender, although they were counted for average litter size.

Comparison of Full Moon vs. New Moon breeding.
Unfortunately, only 5 of the 74 breedings were done on the actual day of the full or new moon (not considered a significant research pool).  Of those, only one resulted in a litter.  That breeding was on a full moon and resulted in 6 kits, all of which died before weaning.  Again, this is not significant data, but I'm providing it anyway.

However, in Wicca, the full- and new-moon phases are considered to be on three-day spans, so I can expand my data to look at the 3-day spans.  When you consider the data that way, there were 22 total breedings (11 each for full and new moon).

Full MoonNew Moon
Number of breedings1111
Number of successes95
Success %81.8%45.5%
Average litter size when successful6.17.4
Average Number of Kits Dead Before Weaning3.44.4
Mortality rate56.4%59.5%
Average Net Litter Size2.73
Average Number of Bucks Weaned per Litter1.71.6
Average Number of Does Weaned per Litter1.01.4
Weaned Buck:Doe ratio1.7:11.1:1


What this data suggests is that:

  • Full-moon breedings are more likely to be successful (almost twice as likely)
  • New-moon breedings tend to result in larger litters than full-moon breedings (21.3% larger)
  • Mortality rate is marginally increased for new-moon breedings, but not significantly
  • Even after mortality, new-moon breedings still result in more kits being weaned, but the difference may not be significant
  • Full-moon breedings tend to produce a higher percentage of bucks at weaning
What I want you to note is that my data shows that New Moon breedings resulted in larger litters, which is contrary to the proposed theory.  However, if you look at litter size after mortality, the new moon litter size is not much larger.

I also want you to note that while this data leans toward confirming that you get a higher percentage of bucks with full-moon breedings, but not much more.  Also, if you were to consider the number of kits of unknown gender, there are more than enough to completely reverse the ratio (potentially even quadruple it in favor of the other direction).  Then again, should the gender of the unweaned kits really be considered?

Keep in mind that the above assessment does not take into consideration p-values, which are what researchers use to determine if data is significant.  (I may come back to this, when I'm feeling up to some higher math, and calculate p-values).

Comparison of Waxing vs. Waning
Waxing days include the day immediately following the singular day of the new moon to the day immediately before the singular day of the full moon.  Waning days include the day immediately following the singular day of the full moon to the day immediately before the singular day of the new moon.

WaxingWaning
Number of breedings3435
Number of successes2523
Success %73.5%65.7%
Average litter size when successful6.46.5
Average Number of Kits Dead Before Weaning3.22.5
Mortality rate50.0%38.8%
Average Net Litter Size3.23.0
Average Number of Bucks Weaned per Litter1.82.4
Average Number of Does Weaned per Litter1.41.6
Weaned Buck:Doe ratio1.3:11.5:1


This data suggests that:

  • There is a slightly greater chance of success when breeding while the moon waxes
  • There is no significant litter size difference
  • There is a slightly greater mortality rate from breedings done while the moon waxes
  • There is a slightly higher percentage of bucks when breeding while the moon wanes
I do not consider this data to be significant enough to say that there is indeed a difference between breeding during the waxing or waning moons.  When I'm feeling math-y, I'll come back here and calculate the p-values, which will show more definitively.  (I will probably also add some more litters to the stats, and promise to start trying to document number of bucks/does alive AND dead).